37 replies to this topic

[Paul Vanderheijden]

I have spent the last couple of hours reading the patent applications and granted patents (United States Patent 5255636) of Mr. Evans with regard to a cooling modification incorporating reverse flow. It would appear that the latest Corvette motor employs this principle.

Mr. John W. Evans contends that the evolution of the modern cooling system may have been stuck in a time warp. He contends that the current method (in through the block and out through the head) may not best use the temperature delta available in the radiator system. His contention is that since around 65% of the heat generated by combustion events is absorbed by the head, that the cooling fluid should be directed there first and then to the block.

While this type of cooling system was used on some early Pontiac production cars, the uniqueness of Mr. Evans invention is the method by which he deals with steam pockets that may be generated within the head.

I have been trying to find out if this idea of using reverse flow cooling has ever been incorporated into any racing engine design?

[Kevin Johnson]

Originally posted by Paul Vanderheijden
I have spent the last couple of hours reading the patent applications and granted patents (United States Patent 5255636) of Mr. Evans with regard to a cooling modification incorporating reverse flow. It would appear that the latest Corvette motor employs this principle.

Mr. John W. Evans contends that the evolution of the modern cooling system may have been stuck in a time warp. He contends that the current method (in through the block and out through the head) may not best use the temperature delta available in the radiator system. His contention is that since around 65% of the heat generated by combustion events is absorbed by the head, that the cooling fluid should be directed there first and then to the block.

While this type of cooling system was used on some early Pontiac production cars, the uniqueness of Mr. Evans invention is the method by which he deals with steam pockets that may be generated within the head.

I have been trying to find out if this idea of using reverse flow cooling has ever been incorporated into any racing engine design?

My guess would be the DB 601. What do I win?

[Paul Vanderheijden]

Kevin

I did some research on the DB 601 and its derivates and came up with the following description:

For the rest of the designed performance increase, Walter turned to the risky method of cooling the engine via surface evaporation. Inside the engine the fluid is kept under pressure which stops it from boiling even though it's allowed to heat above its normal boiling point, the fluid is then run to cavity with lower pressure where it quickly starts to boil and releases steam. Since steam contains considerably more energy than the same temperature water, if you can remove the steam you can remove a lot of heat. The stream can be cooled by allowing it to condense in a series of pipes inside the plane. With no external openings at all, it's basically a zero-drag cooling system.

While Walter appears to have utilized the methodology, as Evans, with regard to converting steam to water, and returning it to the coolant system, I did not find any reference to the use of an "reverse flow" cooling system. From what I read the coolant flow was still done in a "conventional" sense. Yes the engine design is such that the engine is installed upside down, however this was adopted so that the intake for the motor would be on the lower side of the fusilage.

Pontiac used reverse flow, or "gusher" cooling, on its engines from 1955-59. It then abandoned the concept and adopted the more conventional cooling design. Why did Pontiac abandon reverse flow cooling? Over the years a number of possible reason have been proposed, from corrosion problems to lower production costs. Unfortunately none of the literature that I have examined contains anything definitive. I believe Pontiac may have had problems with how to deal with possible steam pockets in the head, but nothing was found to corroborate this.

In terms of competition vehicles, I not been able to confirm any that utilized the reverse flow cooling concept prior to the Corvette.

I decided that it is worth a try, in light of the success of the Corvette program. I plan on using an electric pump, which will draw coolant from the expansion tank and route the water to both ends of the cylinder head for consistent coolant distribution. Here the coolant, having just come from the radiator (hence at the lower point of the coolant temperature delta) will not only be under normal coolant system pressure (up to 22 PSI), but also subject to additional pumping pressures from the pump (perhaps an additional 3-4 PSI). This will enhance the coolants ability to resist the formation of steam bubbles due to pressure build-up in the head/block assembly.

The coolant, now carrying some heat from the head, will flow around all cylinder cooling jackets providing even and uniform cooling (or if you like heating) to the cylinders. This is quite the opposite from conventional cooling, where the cylinders closer to the block coolant entry will run cooler than the remainder of the cylinder further away from the entrance. The net effect may be that the cylinders run marginally warmer, but this may have positive effects in that the cylinders will be less subject to distortion, and the higher temperatures will decrease cylinder wall friction.

Once the coolant has passed through the cylinder cooling jackets it would exit the block through the original pump location opening. This opening would now be restricted, either with a thermostat or a simple flow restrictor. This mechanism would provide a certain amount of back pressure, needed both for the build-up of additional head/block pressure, as noted earlier, but also to assist the functioning of the pump (centrifugal type). From here the coolant, now carrying heat from the engine would flow to the radiator system.

On analysis of this design there are two destinctive pressure levels within the system. Pressure level "A" exists between the output of the centrifugal pump and the restrictor on the exit of the block (absorption phase). Pressure level "B", being lower than "A", exists from the exit of the block, through the radiator system, to the expansion tank (dissapation phase).

This diffential in pressure between phases, while beneficial in preventing steam pocket formation in the head, may also cause problems at the exit of the heated coolant as it exits the block. The attendant pressure drop at this orifice, if too extreme, could cause the formation of steam bubbles there as well.

As ANY steam pocket acts as an insulator of heat, not a conductor, causing ever greater steam pocket enlargement, specific action must be taken to conduct any steam from problem locations to a portion of the system where there is a large surface area to condense the steam into liguid, and then return it to the coolant stream. The three areas of concern, in terms of severity, I see as follows:

A. Steam formation in the cylinder head - ANY steam here must have a path for venting. The simplest method would be to have the steam pass through a small orifice into a larger chamber with a large surface area (read expansion tank) and in this process condense to liquid state.
B. Possible steam formation at the exit of the block - This may or may not eventuate, but contingency plans on now to deal with this will have be considered. If the steam is carried with the water flow to the radiator system, then the steam will condense to liquid at this point.
C. Venting the radiator - While this may not be a "steam" problem, as the radiator is remotely located, a small venting line from the input side tank of the radiator back to the expansion take will make this a self-purging system. As such any steam not condensed in the radiator would thereby condense in the expansion tank.

The principle advantage of this reverse flow system would be to take best advantage of the temperature delta, available in the cooling system, to lower overall head temperatures and equilaterally heat the cylinder bores. This would allow closer piston to cylinder clearances, increased dynamic compression and greater ignition advance, thereby increasing performance.

I would be interested in hearing critique of this proposal.

Paul Vanderheijden
Scuderia Topolino
c.
After absorption of heat from the head, the coolant would flow though the openings in the head/block interface to the water jacket areas around the cylinders.

[Kevin Johnson]

Originally posted by Paul Vanderheijden
Kevin

I did some research on the DB 601 and its derivates and came up with the following description:

For the rest of the designed performance increase, Walter turned to the risky method of cooling the engine via surface evaporation. Inside the engine the fluid is kept under pressure which stops it from boiling even though it's allowed to heat above its normal boiling point, the fluid is then run to cavity with lower pressure where it quickly starts to boil and releases steam. Since steam contains considerably more energy than the same temperature water, if you can remove the steam you can remove a lot of heat. The stream can be cooled by allowing it to condense in a series of pipes inside the plane. With no external openings at all, it's basically a zero-drag cooling system.

While Walter appears to have utilized the methodology, as Evans, with regard to converting steam to water, and returning it to the coolant system, I did not find any reference to the use of an "reverse flow" cooling system. From what I read the coolant flow was still done in a "conventional" sense. Yes the engine design is such that the engine is installed upside down, however this was adopted so that the intake for the motor would be on the lower side of the fusilage.

Since the liners are dry the cylinder head is liquid cooled first by default regardless of orientation. Do I win a Scuderia Topolino sticker?

Originally posted by Paul Vanderheijden

Pontiac used reverse flow, or "gusher" cooling, on its engines from 1955-59. It then abandoned the concept and adopted the more conventional cooling design. Why did Pontiac abandon reverse flow cooling? Over the years a number of possible reason have been proposed, from corrosion problems to lower production costs. Unfortunately none of the literature that I have examined contains anything definitive. I believe Pontiac may have had problems with how to deal with possible steam pockets in the head, but nothing was found to corroborate this.

I see warranty repairs listed as a reason -- I can believe that killed it.

Originally posted by Paul Vanderheijden

In terms of competition vehicles, I not been able to confirm any that utilized the reverse flow cooling concept prior to the Corvette.

The people that would likely know first hand are rapidly passing away.

You may want to investigate the demise (?) of the heralded hermetically sealed cooling system in the Renault R4 and R8 Major. The R1130 manuals that I have show an expansion tank with a threaded hermetic closure. The R1135 parts manual I have shows the same tank with a relief valve in that location (R8 Gordini). Matra used the same series of engines in the Djet and I see in that parts manual that an expansion chamber with relief valve is used (similar to the one seen in the Lotus Europa of the same time period). I am sure there is a tale there.

Other than that the coolant system is conventional. I played around with an R8 with a reverse flow pump about 18-20 years ago but I could not tell you of any big difference. I was simply pleased I could get the car to keep up with California freeway traffic (average at that time about 75-80mph). Anyways...

You may also want to contact Mr. Evans and make sure your thoughts don't tread on any of his patents. I suspect he is quite sensitive in that respect at present.

[Paul Vanderheijden]

Kevin,

Send me an email at pheyden@ieee.org with your address and the sticker is yours.

[J. Edlund]

Originally posted by Paul Vanderheijden
Mr. John W. Evans contends that the evolution of the modern cooling system may have been stuck in a time warp. He contends that the current method (in through the block and out through the head) may not best use the temperature delta available in the radiator system. His contention is that since around 65% of the heat generated by combustion events is absorbed by the head, that the cooling fluid should be directed there first and then to the block.

Cooling systems have hardly been stuck in a time warp. But, you generally want to avoid working against physical effects, such as that of hot water and steam rising. What is used in modern racing engines, and also some high performance engines, is water galleries which distribute the flow correctly.

If you for instance take a look at the drawings of the Ferrari Tipo 049 you will notice that the single cooling pump supply a water gallery in the V of the block. From the gallery coolant is fed to each of the ten cylinders through separate ports, the coolant then circulate around the cylinder and up to the head on the exhaust side. From the gallery there is also additional ports feeding the heads at each cylinder on the intake side. The coolant then goes through drillings in the heads, one for each cylinder, up to the valve covers where there is an coolant gallery collecting the coolant from all the cylinders, which is then fed to the two radiators and back to the cooling pump.
The system pressure in the cooling system is about 3.5 bar (circa 51 psi), limited by FIA regulations.

However, to make such a complex cooling system is hardly cost effective for most production engines where the cooling flow can analysed and controlled by much simpler means. As long the temperature measured in various places in the engine are controlled under maximum load there isn't really any reason for trying anything different.

[Paul Vanderheijden]

Mr. Edlund

Thank you for your insight. Obviously the cooling system you describe, pertaining to the Ferrrari Tipo 049, must be classified as a purpose designed system. Yes, you are correct in stating that production engines of a more pedestrian nature could not afford to be made this way and certainly would not be designed to run at cooling system pressures anywhere near 3.5 bar.

Perhaps it is I whom is stuck in a time warp, being as my business is almost exclusively building historic competition engines for small Abarth engines (circa 1960-1972). I am forever pushing the envelope within what is allowed under the rules. At this point in development I can quite reliably produce 105-110 HP from an OHV 1000cc (1.75HP per C.I.) naturally aspirated engine using two DCOE Weber carburetors. In a never ending quest for greater performance I am always looking for ways to improve on this, and given the real-world results obtained by the Corvette LT-1 engine, it seemed worth investigating.

Paul Vanderheijden

[McGuire]

Originally posted by J. Edlund


Cooling systems have hardly been stuck in a time warp. But, you generally want to avoid working against physical effects, such as that of hot water and steam rising. What is used in modern racing engines, and also some high performance engines, is water galleries which distribute the flow correctly.

Great post, excellent point. Having spent a lot of time with both flavors of production small-block Chevy (the original Gen I V8 which employed "standard" cooling (block first, heads second) and the LT1/LT4 etc which employed "reverse" cooling" (heads first) I find that reverse cooling tends to create as many problems as it solves.

Just as you say, with reverse cooling, at the end of the day you are pumping coolant backward from its natural direction due to convection or "thermo-siphon," and this introduces all kinds of problems with filling, topping, bleeding, air pockets, etc. It's a genuine pain in the ass to make work right, when the first priority of any cooling system is that it should just work.

Reverse cooling has been used on and off in NASCAR and similar applications for the SBC since time began, but as I see it there was really only one reason for it in the LT1 production engine: to squeeze out another half-point of compression ratio at the end of the engine's development cycle. Due to the SBC's antiquated "book-fold" cylinder head layout (mirror-symmetrical from the center out) the exhaust valves on the two center cylinders are adjacent, which creates a big hot spot. By cooling the heads first they got a bit better cooling of the hot spot to control knock.

But in the general case, standard vs. reverse cooling is six of one, half-dozen of the other. If you cool the heads first you do so at the risk of reduced ring life, ring and land coking, increased cylinder bore wear etc, along with all the plumbing problems. No magical solution there. The LS1 V8 that replaced the LT1 employed standard cooling.

[phantom II]

R8 Gordini could go a little faster than that. These cars have the same engine and they all could do 130mph.

Originally posted by Kevin Johnson


The R1135 parts manual I have shows the same tank with a relief valve in that location (R8 Gordini). Matra used the same series of engines in the Djet and I see in that parts manual that an expansion chamber with relief valve is used (similar to the one seen in the Lotus Europa of the same time period). I am sure there is a tale there.

Other than that the coolant system is conventional. I played around with an R8 with a reverse flow pump about 18-20 years ago but I could not tell you of any big difference. I was simply pleased I could get the car to keep up with California freeway traffic (average at that time about 75-80mph). Anyways...

[phantom II]

http://www.superchev...1/photo_01.html

The Chevy LT1 and LT 4 used a reverse-flow cooling system which cooled the cylinder heads first, maintaining lower cylinder temperatures and allowing the engine to run at a higher compression than its immediate predecessors. It had external steam tubes between the heads and the block for reasons you describbe.The recovery tank was an essential part of the system to get rid of the air bubbles. You could monitor cylinder head temps and crankcase temps separately as you scrolled thru the items on the enunciator panel. 250'f block 100'f heads. They must run on Mobil 1.
Corvettes and Camaros and Firebirds got aluminum heads and the full size cars got cast iron heads. The aluminum heads gained 25HP with this system. Corvettes which included the LT4 engine got 4 bolt mains. The LS X engines abandoned this system for reasons I don't know but they require larger radiators and even oil coolers to keep them cool. I replaced my LT4 with a LS2 in my roadster and fried the engine using the same radiator. Ran bearings.

Originally posted by Paul Vanderheijden
Kevin

Pontiac used reverse flow, or "gusher" cooling, on its engines from 1955-59. It then abandoned the concept and adopted the more conventional cooling design. Why did Pontiac abandon reverse flow cooling? Over the years a number of possible reason have been proposed, from corrosion problems to lower production costs. Unfortunately none of the literature that I have examined contains anything definitive. I believe Pontiac may have had problems with how to deal with possible steam pockets in the head, but nothing was found to corroborate this.

In terms of competition vehicles, I not been able to confirm any that utilized the reverse flow cooling concept prior to the Corvette.

I decided that it is worth a try, in light of the success of the Corvette program. I plan on using an electric pump, which will draw coolant from the expansion tank and route the water to both ends of the cylinder head for consistent coolant distribution. Here the coolant, having just come from the radiator (hence at the lower point of the coolant temperature delta) will not only be under normal coolant system pressure (up to 22 PSI), but also subject to additional pumping pressures from the pump (perhaps an additional 3-4 PSI). This will enhance the coolants ability to resist the formation of steam bubbles due to pressure build-up in the head/block assembly.

The coolant, now carrying some heat from the head, will flow around all cylinder cooling jackets providing even and uniform cooling (or if you like heating) to the cylinders. This is quite the opposite from conventional cooling, where the cylinders closer to the block coolant entry will run cooler than the remainder of the cylinder further away from the entrance. The net effect may be that the cylinders run marginally warmer, but this may have positive effects in that the cylinders will be less subject to distortion, and the higher temperatures will decrease cylinder wall friction.

Once the coolant has passed through the cylinder cooling jackets it would exit the block through the original pump location opening. This opening would now be restricted, either with a thermostat or a simple flow restrictor. This mechanism would provide a certain amount of back pressure, needed both for the build-up of additional head/block pressure, as noted earlier, but also to assist the functioning of the pump (centrifugal type). From here the coolant, now carrying heat from the engine would flow to the radiator system.

On analysis of this design there are two destinctive pressure levels within the system. Pressure level "A" exists between the output of the centrifugal pump and the restrictor on the exit of the block (absorption phase). Pressure level "B", being lower than "A", exists from the exit of the block, through the radiator system, to the expansion tank (dissapation phase).

This diffential in pressure between phases, while beneficial in preventing steam pocket formation in the head, may also cause problems at the exit of the heated coolant as it exits the block. The attendant pressure drop at this orifice, if too extreme, could cause the formation of steam bubbles there as well.

As ANY steam pocket acts as an insulator of heat, not a conductor, causing ever greater steam pocket enlargement, specific action must be taken to conduct any steam from problem locations to a portion of the system where there is a large surface area to condense the steam into liguid, and then return it to the coolant stream. The three areas of concern, in terms of severity, I see as follows:

A. Steam formation in the cylinder head - ANY steam here must have a path for venting. The simplest method would be to have the steam pass through a small orifice into a larger chamber with a large surface area (read expansion tank) and in this process condense to liquid state.
B. Possible steam formation at the exit of the block - This may or may not eventuate, but contingency plans on now to deal with this will have be considered. If the steam is carried with the water flow to the radiator system, then the steam will condense to liquid at this point.
C. Venting the radiator - While this may not be a "steam" problem, as the radiator is remotely located, a small venting line from the input side tank of the radiator back to the expansion take will make this a self-purging system. As such any steam not condensed in the radiator would thereby condense in the expansion tank.

The principle advantage of this reverse flow system would be to take best advantage of the temperature delta, available in the cooling system, to lower overall head temperatures and equilaterally heat the cylinder bores. This would allow closer piston to cylinder clearances, increased dynamic compression and greater ignition advance, thereby increasing performance.

I would be interested in hearing critique of this proposal.

Paul Vanderheijden
Scuderia Topolino
c.
After absorption of heat from the head, the coolant would flow though the openings in the head/block interface to the water jacket areas around the cylinders.

[Kevin Johnson]

The principal problem with the reverse flow system is the battle between the trapped air bubbles which want to rise and be caught in various places and the downward coolant flow. In some ways this is similar to the problem of battling blowby gases and oil draining from the heads.

If you use wire reinforced conventional hose or more expensive aircraft types you should be able to draw down a certain amount of atmosphere from the cooling system (nothing like evacuating an air conditioning unit but the same idea). You would need to learn the collapse point of the weakest part and stay above that. This would allow you to progressively feed in coolant and fill the system as ideally as possible. Combined with a reasonable 22psi relief valve in a raised purge tank you should have a minimal problem with trapped air. You might also consider [correction: preheating] the coolant substantially and letting it sit and flatten before feeding it into the system. That would put you further down the slope of the amount of dissolved air in the coolant.

Your idea of using an electric pump is a good one -- you could possibly run the/a pump in normal mode to help purge any remaining air and then reverse the flow for normal engine use (presumably race).

Smokey Yunick talked about exterior water distribution manifolds for the SBC -- I have not seen them but that would be closer to the vintage of these engines.

[phantom II]

You beat me to it. I was expecting your response but I couldnt wait any longer. Is there evidence that Gen II engines don't last as long as Gen Is? I have owned 3 LT1s and one LT4 and they seemed indestructible. I didn't keep them too long mind you, but those cast Iron LT99 powered Caprice police cruisers are still being used nation wide and LT 4s are still a popular Hot Rod engine. The LT 4 had 25 more HP than the manufacturer claimed.

Originally posted by McGuire


Great post, excellent point. Having spent a lot of time with both flavors of production small-block Chevy (the original Gen I V8 which employed "standard" cooling (block first, heads second) and the LT1/LT4 etc which employed "reverse" cooling" (heads first) I find that reverse cooling tends to create as many problems as it solves.

Just as you say, with reverse cooling, at the end of the day you are pumping coolant backward from its natural direction due to convection or "thermo-siphon," and this introduces all kinds of problems with filling, topping, bleeding, air pockets, etc. It's a genuine pain in the ass to make work right, when the first priority of any cooling system is that it should just work.

Reverse cooling has been used on and off in NASCAR and similar applications for the SBC since time began, but as I see it there was really only one reason for it in the LT1 production engine: to squeeze out another half-point of compression ratio at the end of the engine's development cycle. Due to the SBC's antiquated "book-fold" cylinder head layout (mirror-symmetrical from the center out) the exhaust valves on the two center cylinders are adjacent, which creates a big hot spot. By cooling the heads first they got a bit better cooling of the hot spot to control knock.

But in the general case, standard vs. reverse cooling is six of one, half-dozen of the other. If you cool the heads first you do so at the risk of reduced ring life, ring and land coking, increased cylinder bore wear etc, along with all the plumbing problems. No magical solution there. The LS1 V8 that replaced the LT1 employed standard cooling.

[Kevin Johnson]

Originally posted by phantom II
R8 Gordini could go a little faster than that. These cars have the same engine and they all could do 130mph.

Sadly, the pedestrian R8 I used had a wedge head and not the tuned cross-flows found in the Gordini, Alpine A110 (the fast ones) and the Djet. That engine eventually peaked with the R5 Turbo 1.

Cheap but hot ticket for the R8/R10 was to swap in the later Alliance/R9/R11 1397cc block. R5 block had the earlier mounts milled off but made a nice donor for a suitable head.

[Kevin Johnson]

Originally posted by phantom II
You beat me to it. I was expecting your response but I couldnt wait any longer. Is there evidence that Gen II engines don't last as long as Gen Is? I have owned 3 LT1s and one LT4 and they seemed indestructible. I didn't keep them too long mind you, but those cast Iron LT99 powered Caprice police cruisers are still being used nation wide and LT 4s are still a popular Hot Rod engine. The LT 4 had 25 more HP than the manufacturer claimed.

Worth pondering if Evans is GM's (re)incarnation of Kearns. Limiting their exposure?

[phantom II]

Not too many Americans know about these fantastic little cars. That Matra has a Aluminum body, monocoque chassis with forged aluminum uprights, 4 disc brakes and double A arms all round. The Alpine is a legend at Lemans and the R8 Gordini is a match for today's super kiddy cars in stock form. R5s are faster now than they were then.

Originally posted by Kevin Johnson


Sadly, the pedestrian R8 I used had a wedge head and not the tuned cross-flows found in the Gordini, Alpine A110 (the fast ones) and the Djet. That engine eventually peaked with the R5 Turbo 1.

Cheap but hot ticket for the R8/R10 was to swap in the later Alliance/R9/R11 1397cc block. R5 block had the earlier mounts milled off but made a nice donor for a suitable head.

[Canuck]

Originally posted by phantom II

What a stunning little car. A few too many lights on the front end perhaps but otherwise rather beautiful (at least from that angle).

[McGuire]

I know many here may not like this perspective, but Kearns and Evans are good examples of inventors who stumble across things on their own and then, since they are off in their corner working alone and have little knowledge of the industry or its history, assume they originated them. Evans invented "reverse cooling" or propylene glycol? Bwahahaha. I suppose he may claim he perfected them... except he hasn't really perfected them yet. Of course, staking out areas with patent claims is another matter.

[McGuire]

Originally posted by phantom II
You beat me to it. I was expecting your response but I couldnt wait any longer. Is there evidence that Gen II engines don't last as long as Gen Is? I have owned 3 LT1s and one LT4 and they seemed indestructible. I didn't keep them too long mind you, but those cast Iron LT99 powered Caprice police cruisers are still being used nation wide and LT 4s are still a popular Hot Rod engine. The LT 4 had 25 more HP than the manufacturer claimed.

The Gen II's sore spot is the Opti-spark. Other than that it's pretty good, except for some cooling problems that are not caused by the reverse-cooling system but exacerbate them. I do like the gear-drive water pump. The Gen II is probably as good as the Gen I overall, but it is a strange ranger parts-wise. With aluminum heads and a contemporary combustion chamber (fast burn etc) you can run the same CR with the Gen I, and that is by far the easier way to go. Otherwise you can just shuck it all and go Gen III/IV, which is superior to both.

Still, there are a lot of guys with street rods, restomods, etc who want to stick with the original SBC. Right now I am working up an all-iron (aftermarket block and heads) Gen I V8, 400 CID, very mild hydraulic roller cam, single carb, 500+ hp on pump gas. 10:1 CR, idles at 600 rpm. Bulletproof, last engine you will ever need. If you are a baby boomer this motor will outlast you; will the car to your kids.

[Powersteer]

Originally posted by Canuck
What a stunning little car. A few too many lights on the front end perhaps but otherwise rather beautiful (at least from that angle.

Well, the car has some rallying background but I am not sure whether it was designed as a rally car.

[Kevin Johnson]

Originally posted by McGuire
I know many here may not like this perspective, but Kearns and Evans are good examples of inventors who stumble across things on their own and then, since they are off in their corner working alone and have little knowledge of the industry or its history, assume they originated them. Evans invented "reverse cooling" or propylene glycol? Bwahahaha. I suppose he may claim he perfected them... except he hasn't really perfected them yet. Of course, staking out areas with patent claims is another matter.

At the time Evans came into the news I was selling drums (and the occasional tanker load) of USP PG to meat packing companies and such for use in their chilling/cooling systems. We didn't really get into EG -- that was usually handled direct because of the slim margins. I think what struck me as different was that his idea was anhydrous and zero pressure, if I remember correctly.

As we know from fairly recent events in F1, theft of trade secrets certainly does occur. GM was caught confabulating a bit too much "history" prior to Evans.

I should add that when I was in chemical sales many times we would be in contact with people that would ask us to sign secrecy agreements. When asked a bit further it would often emerge, for example, that they had a new idea for using the oil in an orange peel for cleaning. This while we were selling drums of d-limonene and providing free formularies. It is a difficult situation to be in and requires some diplomacy.

[Kevin Johnson]

Originally posted by Powersteer
Well, the car has some rallying background but I am not sure whether it was designed as a rally car.

A friend that worked with Bonnet, Gordini et al. told me it had a habit of the doors popping open when hitting bumps because of the flex in the fiberglass body. That will wake you right up. I would still love one along with a Djet. Walt Koopman let me look at his Alpines. I was all set to transfer the business end of an R5 Turbo into an R8 (actually a Fasa R8TS) when my friend told me that would create a death trap. I know many people have since done it and more radical things but it was good advice.

But we digress from cooling matters, alas.

[johnny yuma]

Even with normal flow you must still get steam pockets at the top of the head once the engine is overheating,so the problem may have the potential to be worse with reverse flow but only if the engine is for whatever reason already overheating.I like the idea of cooler water going to the head first,but I also like the heated water "falling" down through the radiator.It seems feasible to have the bottom radiator hose running up to the top of the head pumped by an electric pump mounted low,thermostat at the entrance to the head possibly centre area on one side (as soon as the head heats it opens). Directly above THE HIGHEST POINT OR POINTS OF THE HEAD WATER GALLERY a riser tube to GATHER RISING STEAM PIPED to a condenser venting through a very small pipe back into the top of the radiator.

The top radiator hose would accept heated waters from the bottom of the motor cooling jacket at pump pressure minus the small losses from venting the steam (and some water)back to the top of the radiator.In effect a "figure -eight" flow pattern.

Do the "water rails" often seen on older modified engines act partly as steam elimination systems,or just hot spot flow improvers ?

[Kevin Johnson]

Originally posted by johnny yuma
Even with normal flow you must still get steam pockets at the top of the head once the engine is overheating,so the problem may have the potential to be worse with reverse flow but only if the engine is for whatever reason already overheating.I like the idea of cooler water going to the head first,but I also like the heated water "falling" down through the radiator.It seems feasible to have the bottom radiator hose running up to the top of the head pumped by an electric pump mounted low,thermostat at the entrance to the head possibly centre area on one side (as soon as the head heats it opens). Directly above THE HIGHEST POINT OR POINTS OF THE HEAD WATER GALLERY a riser tube to GATHER RISING STEAM PIPED to a condenser venting through a very small pipe back into the top of the radiator.

The top radiator hose would accept heated waters from the bottom of the motor cooling jacket at pump pressure minus the small losses from venting the steam (and some water)back to the top of the radiator.In effect a "figure -eight" flow pattern.

Do the "water rails" often seen on older modified engines act partly as steam elimination systems,or just hot spot flow improvers ?

Time for some work; these are the references Evans cites in "Hermetically-sealed engine cooling system and related method of cooling" Document Type and Number:United States Patent 6230669.

Link to this page:http://www.freepaten...om/6230669.html

You should read through them and see if this has already been described. Often problems with previous technology are discussed which is illuminating.

2988068 June, 1961 Waydok 123/41.54 Engine cooling system
3238932 March, 1966 Simpson 123/41.5 Sealed cooling system for an internal combustion engine
3499481 March, 1970 Avrea 165/11 PRESSURIZED LIQUID COOLING SYSTEM
4006775 February, 1977 Avrea 165/51 Automatic positive anti-aeration system for engine cooling system
4079855 March, 1978 Avrea 220/203 Monolithic radiator cap for sealed pressurized cooling system
4196822 April, 1980 Avrea 220/203 Monolithic radiator cap for sealed pressurized cooling system
4461342 July, 1984 Avrea 165/104 Method and apparatus for automatically refilling a leaking liquid cooling system as an engine operates by utilizing a radiator and a remote coolant reservoir
4498599 February, 1985 Avrea 220/203 Closure and valving apparatus
4550694 November, 1985 Evans 123/41.02 Process and apparatus for cooling internal combustion engines
4630572 December, 1986 Evans 123/41.21 Boiling liquid cooling system for internal combustion engines
5031579 July, 1991 Evans 123/41.2 Cooling system for internal combustion engines
5044430 September, 1991 Avrea 123/41.51 Method and apparatus for continuously maintaining a volume of coolant within a pressurized cooling system
5172657 December, 1992 Sausner et al. 123/41.5 Evaporation cooled internal combustion engine
5255636 October, 1993 Evans 123/41.54 Aqueous reverse-flow engine cooling system
5317994 June, 1994 Evans 123/41.1 Engine cooling system and thermostat therefor
5353751 October, 1994 Evans 123/41.01 Engine cooling system and radiator therefor
5381762 January, 1995 Evans 123/41.54 Engine cooling system and radiator therefor
5385123 January, 1995 Evans 123/41.21 Segregated cooling chambers for aqueous reverse-flow engine cooling systems
5419287 May, 1995 Evans 123/41.29 Engine cooling system and heater circuit therefor

[McGuire]

Originally posted by Kevin Johnson


As we know from fairly recent events in F1, theft of trade secrets certainly does occur. GM was caught confabulating a bit too much "history" prior to Evans.

Guy at GM who allegedly backdated the evidence was this close to making VP. Now he has a nice job in R&D at Kia. Let that be a lesson to you kids out there.

It was all so stupid anyway. GM pioneered reverse cooling, in the '55 Pontiac V8 and elsewhere. And you can bet that a roomful of solid research data was compiled when they did it.

[Kevin Johnson]

I looked at a few of the patents from the 1940s and 1950s - a big issue at that time was keeping the cylinder head warmer than the block for better efficiency (130 degrees in the block; 185 in the head). You'll need to go to the PTO website and view the images.

"Tetra aryl ortho silicate" -- interesting. Fluorinerts could probably be used too but a bit pricey.

[Kevin Johnson]

Originally posted by McGuire


Guy at GM who allegedly backdated the evidence was this close to making VP. Now he has a nice job in R&D at Kia. Let that be a lesson to you kids out there.

It was all so stupid anyway. GM pioneered reverse cooling, in the '55 Pontiac V8 and elsewhere. And you can bet that a roomful of solid research data was compiled when they did it.

Remember that TV series "Profit" where the guy slept naked in a cardboard box? Take home message to kids now is probably that he just wasn't crafty enough. :

[britishtrident]

One major problem is the water pump, centrafugal pumps suffer from cavitation if you try and pump water at close to boiling point. Cavitation for those not with a background in marine engineering is the formation of microscopic pockets of highly superheated steam on the surface of the pump impeller -- cavitation badly erodes the impeller and knocks the pump throughput and pumping efficiency to hell.

Water pumps work more efficiently mounted low enough to have some natural pressure head and in the low temperature region of the system ie as per normal practice.

Rolls Royce built evaporative cooled aero engines in the 1930 (the steam cooled Goshawk) but they were complete failures and the company then developed he glycol coled Merlin.

[Kevin Johnson]

Originally posted by britishtrident
One major problem is the water pump, centrafugal pumps suffer from cavitation if you try and pump water at close to boiling point. Cavitation for those not with a background in marine engineering is the formation of microscopic pockets of highly superheated steam on the surface of the pump impeller -- cavitation badly erodes the impeller and knocks the pump throughput and pumping efficiency to hell.

Water pumps work more efficiently mounted low enough to have some natural pressure head and in the low temperature region of the system ie as per normal practice.

Rolls Royce built evaporative cooled aero engines in the 1930 (the steam cooled Goshawk) but they were complete failures and the company then developed he glycol coled Merlin.

Here's an early investigation of separate pressurized liquid cooling to the heads and cylinder jackets (separate flow paths). Paul -- this might be of interest for the Fiat engine, albeit a bit complicated to set up but you're already proposing (an) electric pump(s). See pic on page 288.

http://naca.central....-report-853.pdf

Loved reading about the Goshawk.

A sufficiently pressurized system should handle cavitation up to the point where you are overdriving the pump whilst still accounting for the increased pressure. This is a problem in the Nissan SR20 at competition rpms, for example. Mike Kojima related the use of a reduction pulley size as the pump was in full cavitation and no flow was taking place. Paul, has anyone investigated at what rpm partial or full cavitation takes place with the stock 850 pump?

[johnny yuma]

I have heard a couple of accounts of modifiers neatly breaking off every second vane of impellers where racing rpm were said to not allow sufficient TIME for pulses of water to be fed into the impeller,but no mention made of superheated steam .

[Joe Bosworth]

One of the first things I learned by hard experience was, "If it ain't broke don't fix it".

I think reverse cooling fits into this.

Reverse cooling has the advantage of a better delta T for cooling the hottest bits but is this a really good???

One has to ask, "What problem are we really trying to solve"?

If we can't annunciate a problem then going away from the tried and true becomes mostly a mind bending exercise for personnel fulfillment. Nothing wrong with that but isn't ones mental energies better spent on solving real problems.

On one hand, usually breaking new ground for intellects sake costs far more time, money and energy than any un-defined benefit.

On the other hand if there is a real problem being solved state the problem, there may be a more staight forward solution.

Regards

[Paul Vanderheijden]

In the development of the small Fiat motor, I have managed to document fairly defined, limiting factors that govern how much horsepower can be developed from 1 litre.

The general problem areas are head gaskets, valve train overstressing, detonation (under certain circumstances), reduced oil pressure running.

The current state-of-the-art for these 1 litre OHV, push rod engines (I know it sounds really prehistoric) is around 105 HP if using the standard Fiat 850 head and a maximum of around 120 HP using either the factory TCR (Radiale - Hemi chamber) or PBS aftermarket head. These HP levels are produced at RPMs approaching 9000 RPM. Given that this equates to 2 HP per cubic inch, this is not a bad result. It is however pushing the envelope of reliability.

Engines representative of this type of output will generally be running static compression ratios of 13.5:1 and, depending on the type of camshaft used, dynamic compression ratios can be in excess of 10:1, necessitating fuel with a octane rating of 105 or more in order to stave off detonation. Camshafts are flat tappet with a rocker ratio of 1.45:1 and lift at the valve of 12.4mm. I have tried various camshafts ranging in duration from 290 to 336 degrees in duration, and to date the best "average horsepower" was measured with a relatively short duration cam (246 degrees @ 0.050) with the intake closing at 69 degrees ABDC. This means that the effective swept volume of the engine is just over 800cc. While this combination may fall off above 8000 RPM slightly, dyno tests have shown that it does provide the best average torque and horsepower.

While cooling has not been a problem to date when all systems are in good working order, the idea of implementing reverse flow cooling and having some level of increased margin of safety, had some appeal.

[Bill Sherwood]

Originally posted by Paul Vanderheijden
In the development of the small Fiat motor, I have managed to document fairly defined, limiting factors that govern how much horsepower can be developed from 1 litre.

The general problem areas are head gaskets, valve train overstressing, detonation (under certain circumstances), reduced oil pressure running.

The current state-of-the-art for these 1 litre OHV, push rod engines (I know it sounds really prehistoric) is around 105 HP if using the standard Fiat 850 head and a maximum of around 120 HP using either the factory TCR (Radiale - Hemi chamber) or PBS aftermarket head. These HP levels are produced at RPMs approaching 9000 RPM. Given that this equates to 2 HP per cubic inch, this is not a bad result. It is however pushing the envelope of reliability.

Not really.
A very mediocore one litre bike engine would make that much power. A good one will be up around 180hp and very reliable, tractible, etc.

[Engineguy]

Originally posted by Bill Sherwood
Not really.
A very mediocore one litre bike engine would make that much power. A good one will be up around 180hp and very reliable, tractible, etc.

Not really what?


Originally posted by Paul Vanderheijden
In the development of the small Fiat motor, I have managed to document fairly defined, limiting factors that govern how much horsepower can be developed from 1 litre.

The general problem areas are head gaskets, valve train overstressing, detonation (under certain circumstances), reduced oil pressure running.

The current state-of-the-art for these 1 litre OHV, push rod engines (I know it sounds really prehistoric) is around 105 HP if using the standard Fiat 850 head and a maximum of around 120 HP using either the factory TCR (Radiale - Hemi chamber) or PBS aftermarket head. These HP levels are produced at RPMs approaching 9000 RPM. Given that this equates to 2 HP per cubic inch, this is not a bad result. It is however pushing the envelope of reliability.

[britishtrident]

Originally posted by Paul Vanderheijden
In the development of the small Fiat motor, I have managed to document fairly defined, limiting factors that govern how much horsepower can be developed from 1 litre.

The general problem areas are head gaskets, valve train overstressing, detonation (under certain circumstances), reduced oil pressure running.

The current state-of-the-art for these 1 litre OHV, push rod engines (I know it sounds really prehistoric) is around 105 HP if using the standard Fiat 850 head and a maximum of around 120 HP using either the factory TCR (Radiale - Hemi chamber) or PBS aftermarket head. These HP levels are produced at RPMs approaching 9000 RPM. Given that this equates to 2 HP per cubic inch, this is not a bad result. It is however pushing the envelope of reliability.

Engines representative of this type of output will generally be running static compression ratios of 13.5:1 and, depending on the type of camshaft used, dynamic compression ratios can be in excess of 10:1, necessitating fuel with a octane rating of 105 or more in order to stave off detonation. Camshafts are flat tappet with a rocker ratio of 1.45:1 and lift at the valve of 12.4mm. I have tried various camshafts ranging in duration from 290 to 336 degrees in duration, and to date the best "average horsepower" was measured with a relatively short duration cam (246 degrees @ 0.050) with the intake closing at 69 degrees ABDC. This means that the effective swept volume of the engine is just over 800cc. While this combination may fall off above 8000 RPM slightly, dyno tests have shown that it does provide the best average torque and horsepower.

While cooling has not been a problem to date when all systems are in good working order, the idea of implementing reverse flow cooling and having some level of increased margin of safety, had some appeal.

To compare like with like --- ie 1950s era engine technology
Based on the the Coventry Climax 750cc FWM SOHC engine cylinder head design with the 1960s 998cc Hillman Imp engine we found 100 BHP at around 8,500 rpm (full sized old fashioned British BHP) was easy to get with decent reliability, up to 125 could be achieved in full race trim and would still be reliable provided the driver kept strictly to the rev limit.
I don't recall that we used very high compression ratios -- standard engine was 10:1, ISTR the race engines were 11:1 or perhaps 11.5:1 on ordinary lightly leaded road fuel (UK 4 star) with 43 degrees ignition advance.

These days of course modern multivalve bike engines can do nearly double that without too much trouble --- however modern Japanese ponies aren't as big as old British Clydesdales.

[Bill Sherwood]

Originally posted by Engineguy


Not really what?

What I wrote.

[Kevin Johnson]

Originally posted by Bill Sherwood


What I wrote.

Hi Bill,

I am thinking that higher output levels would be possible if the engine is allowed to run with a course of development like the Kent engines through Cosworth.

Kevin

[Bill Sherwood]

Originally posted by Kevin Johnson


Hi Bill,

I am thinking that higher output levels would be possible if the engine is allowed to run with a course of development like the Kent engines through Cosworth.

Kevin

No doubt.
If they mean 120 hp/litre from a push-rod 2V engine then year that's pretty good.
But for a modern 4V twin-cam engine, such as a Suzuzki GSX-R1000 it's very sedate.

[Paul Vanderheijden]

Hello Bill and others,

Perhaps I should have been more "SPECIFIC" in my description of the motor.

1969 Vintage, 982cc, push rod, OHV 2 valve - side-by-side, wedge combustion chamber, 3 main bearing, 65mm bore, 74mm stroke, flat tappet camshaft.

Of course this is a far cry from a DOHC, large bore, short stroke, "current" production motorcycle engine. Even compared to the Coventry Climax and Sunbeam Imp motors, both SOHC cam designs, the Abarth Fiat derived motors did remarkably well.

Regards,
Paul