35 replies to this topic

[knighty]

which way does the coolant flow through an F1 engine?.........from the heads to the block.........or the block to the head?..........the conventional way for production engines is block to head........but I have heard that some bike engine tuners reverse the flow in order to keep the combustion chamber cooler, and therefore reduce the det limit.........I'm interested to hear what you guys know

[JwS]

I am not sure about F1, but it seems that 'reverse' flow is now found on some production engines. If I am not mistaken the normal flow direction is a relic of the time when coolant flowed by thermal siphon. This was used in the early days, the hot coolant is less dense so it rises up through the block to the head and then to the radiator. The system was designed so that the radiator inlet was the high point. As you noted, it makes more sense to concentrate the cooling on the head now with forced cooling. I think Smokey did this quite a bit, I don't know if he can be credited with it, but I think he did use it.
JwS

[desmo]

It appears to me after looking at a small sample of F1 engine pics that the plumbing out of the water pumps is routed first into the block. It should be noted that detonation is a non-concern in F1 due to the rpms and the relatively low compression ratios.

[ciaoduc1]

Detonation a non-concern?? Really?

Maybe I'm way off here but don't you get the most power/effeciency from an engine at the point just before detonation? If I'm right then I'd have thought that's exactly where these engines need to run. If I'm wrong then what's all the huff about raising your compression ratio for power?

At high RPM's detonation isn't a problem? Perhaps I'm comparing apples to oranges here but don't the little two stroke engines in model airplanes run off of detonation? And at speeds far exceeding F1 engines??

I'm only asking...I don't actually know...

[bobqzzi]

Detonation a non-concern?? Really?

F1 compression ratios are low because of the geometry of the combustion chamber. Given that the bore is very large in comparicos to the stroke, it is hard to get much compression without a large dome- which you can't use if you hope to have camshafts that give proper valve timing for 19,000rpm. In actuallity the cumbustion space ends up being the valve reliefs. I'm guessing compression is somewhere around 11:1.

At elevated rpms, there is little time for detonation to occur even if it was inclined to. Two stoke engines in model airplane engines run on nitro methane and are compression ignition.

[Tooheavy]

Originally posted by bobqzzi


F1 compression ratios are low because of the geometry of the combustion chamber. Given that the bore is very large in comparicos to the stroke, it is hard to get much compression without a large dome- which you can't use if you hope to have camshafts that give proper valve timing for 19,000rpm. In actuallity the cumbustion space ends up being the valve reliefs. I'm guessing compression is somewhere around 11:1

From what I've read the compression ratios are more like 13:1 and would be higher if they could acheive it within the constraints of the head shape and valve cut-outs. F1 engine makers are always trying to improve the efficiency of their engines to give the drivers that extra lap before the pitstop.

[m9a3r5i7o2n]

The reverse flow cooling is old stuff, the 1955 Pontiac had it in 1955. That was the first year of the Pontiac 287.5 cubic inch V-8. The only requirement seems to be a tube, similar to the one in old straight sixes and eight “L heads” that directed the flow more evenly to the exhaust valve seats. Just who was the first I don’t have any idea but my guess is that it was much older than that. M.L. Anderson

[phantom II]

All small block Chevys since the second 92 LT1 (first 1970) have been reversr flow. From the L98 to the LT1. Most of the 50hp gain beteen 91 and 92 when the change occured was because of this. They also have a high volume gear driven water pump with two inlets and two otlets. The new LS1 all aluminum versions cylinder heads water temp runs around 80'f and the block water temp will go as high as 260. Incidently, my 06,C6, Z06 gets 24mpg in town and 31 on the highway with US gallons. Long live push rods.

Originally posted by m9a3r5i7o2n
The reverse flow cooling is old stuff, the 1955 Pontiac had it in 1955. That was the first year of the Pontiac 287.5 cubic inch V-8. The only requirement seems to be a tube, similar to the one in old straight sixes and eight “L heads” that directed the flow more evenly to the exhaust valve seats. Just who was the first I don’t have any idea but my guess is that it was much older than that. M.L. Anderson

[desmo]

Originally posted by phantom II
Incidently, my 06,C6, Z06 gets 24mpg in town and 31 on the highway with US gallons. Long live push rods.

It seems a bit like a dirty little secret that pushrod engines still make perfect sense in many respects for roadcars where peak specific outputs are essentially irrelevant. Not that you can't get eyebrow raising specific outputs from them either. They have distinct advantages in terms of mass, complication and packaging, particularly for V engines.

[phantom II]

427 CI, 505hp and 370lbs ain't too shabby either.

Originally posted by desmo


It seems a bit like a dirty little secret that pushrod engines still make perfect sense in many respects for roadcars where peak specific outputs are essentially irrelevant. Not that you can't get eyebrow raising specific outputs from them either. They have distinct advantages in terms of mass, complication and packaging, particularly for V engines.

[hydra]

Originally posted by phantom II
All small block Chevys since the second 92 LT1 (first 1970) have been reversr flow. From the L98 to the LT1. Most of the 50hp gain beteen 91 and 92 when the change occured was because of this. They also have a high volume gear driven water pump with two inlets and two otlets. The new LS1 all aluminum versions cylinder heads water temp runs around 80'f and the block water temp will go as high as 260. Incidently, my 06,C6, Z06 gets 24mpg in town and 31 on the highway with US gallons. Long live push rods.

While the LT1 had reverse-cooling, GM engineers reverted to conventional cooling for the LS1... Not sure about the LS2 but I'd bet it hasn't changed in that respect...

[McGuire]

Originally posted by desmo
It seems a bit like a dirty little secret that pushrod engines still make perfect sense in many respects for roadcars where peak specific outputs are essentially irrelevant. Not that you can't get eyebrow raising specific outputs from them either. They have distinct advantages in terms of mass, complication and packaging, particularly for V engines.

In racing too. For example in the Rolex Series Daytona Prototypes...here all the engines are regulated to 500 bhp, so the advantage goes to the engine with the broadest torque curve. Since the Gen III GM has the largest displacement, it has a leg up on everyone else in this regard.

...and once again demonstrating that there is more to engine development than hp, should we wish to open that can of worms again.

The other advantage of the pushrod V8 is its signifcantly smaller package dimensions and lower CG over the DOHC V8's from Lexus, BMW and Ford. If you look at the back end of a Riley chassis powered by Pontiac vs. one powered by a Lexus etc, it's pretty obvious. So in this series, based on production engines, the GM pushrod V8 is currently the engine to beat.

[McGuire]

Originally posted by m9a3r5i7o2n
The reverse flow cooling is old stuff, the 1955 Pontiac had it in 1955. That was the first year of the Pontiac 287.5 cubic inch V-8. The only requirement seems to be a tube, similar to the one in old straight sixes and eight “L heads” that directed the flow more evenly to the exhaust valve seats. Just who was the first I don’t have any idea but my guess is that it was much older than that. M.L. Anderson

The original 1955 Pontiac V8 employed "reverse cooling" by virtue of the fact that the water pump fed directly into the cylinder heads. A few years later (1958?) it was reversed back to Chevy-like.

Though they shared some features like the stamped rocker arms, the Pontiac was in some ways an attempt to move the ball forward wrt to the Chevrolet. For example, the right bank was offset forward rather than the left bank, so that the distributor's thrust was in the proper direction.

[phantom II]

Is that right? You just can't believe this car. I have nearly 5000 miles on it and my 03 had 12000 miles when I traded it. The most astonishing thing is how the suspension sucks up any type of bump. The shocks are not phased by any frequency and I steer for the bumps just to marvel at the advancements in American suspension know how. Dare I say it but it feels more German or French. I blast along and swerve over rail road crossings and the damned thing doesn't dart off in an unexpected direction like every American car before.The HUD is amusing as it doesn't only have the usual tach and speed indications but it has a G meter, gear shift and turn signal indications.
Even my wife likes they car because of its compliant ride and space. It is very quite and you cant hear it idle both outside and in. The gearbox makes delicious sounds like an old M22 and some assholes have complained about it. They are going to quieten it like they did to the 93 1/2 ZF in the ZR1 and lowered the torque rating in the process. Some people just don't understand true beauty. What is the name for those sounds at low lugging rpm? Greg??
To change the subject a little, Gordon Murray has joined the staff at Road&Track and his first article in the latest issue is a technical and aerodynamic analysis of the Bugatti Veyron 16.4. He berates it if you read between the lines and plugs his own F1. Great story and drawings

Originally posted by hydra


While the LT1 had reverse-cooling, GM engineers reverted to conventional cooling for the LS1... Not sure about the LS2 but I'd bet it hasn't changed in that respect...

[phantom II]

In keeping with the title of this thread, Murray also discusses cooling considerations and only then can the styling begin with any car. I look forward to his monthly column.

Originally posted by phantom II
[ To change the subject a little, Gordon Murray has joined the staff at Road&Track and his first article in the latest issue is a technical and aerodynamic analysis of the Bugatti Veyron 16.4. He berates it if you read between the lines and plugs his own F1. Great story and drawings

[/B]

[Freebird]

Hydra:

While the LT1 had reverse-cooling, GM engineers reverted to conventional cooling for the LS1... Not sure about the LS2 but I'd bet it hasn't changed in that respect...

That's my understanding also, based on what my friend said about his LS1 Camaro.

Phantom II:

LT4, 396 CID Camaro here. Not as light as your your bullet, but I'm able to squeeze 525 out of it.

One other thing that I have noticed with regards to reverse cooling. As the ambient temp drops, my car seems to "pick up" power significantly better than other cars I've driven.

msw

[zac510]

Originally posted by phantom II

To change the subject a little, Gordon Murray has joined the staff at Road&Track and his first article in the latest issue is a technical and aerodynamic analysis of the Bugatti Veyron 16.4. He berates it if you read between the lines and plugs his own F1. Great story and drawings

I read that, but in the UK Top Gear magazine. R&T must use articles from it? It will be great to read his regular articles.

We have this pushrod vs capacity vs valves argument on another forum I frequent almost every year GM release a Corvette update. It's always very heated!

[McGuire]

Originally posted by zac510


I read that, but in the UK Top Gear magazine. R&T must use articles from it?

Reminds me of a London Times headline, possibly aprocryphal: "Massive storm hits Europe, Continent Isloated."

[WPT]

Posted by phantom II
To change the subject a little, Gordon Murray has joined the staff at Road&Track and his first article in the latest issue is a technical and aerodynamic analysis of the Bugatti Veyron 16.4. He berates it if you read between the lines and plugs his own F1. Great story and drawings

Posted by phantom II
In keeping with the title of this thread, Murray also discusses cooling considerations....

I read the R&T article by GM about the Bugatti and had the same feeling, that GM expressed sour grapes. I also re-read R&T's road test of the McLaren F-1. It over heated on them three or four times. Also the air conditioner could not keep the interior cool. The test was done in Arizona in the summer. GM does not mention the acceleration ability of the Bugatti compared to his F-1, either. WPT

[m9a3r5i7o2n]

What about all the German aircraft engines of WW-2 Mercedes and Junkers Jumo.
M.L. Anderson

[McGuire]

To me the concept of "reverse-cooling" mainly works in reference to the idea of "non-reverse cooling" if you will. Sort of an arbitrary distinction. I thought JWS was very clever and astute in noting that the "standard" setup is an artifact of thermo-siphon cooling and convenience in plumbing.

[m9a3r5i7o2n]

Mc Guire states: In racing too. For example in the Rolex Series Daytona Prototypes...here all the engines are regulated to 500 bhp, so the advantage goes to the engine with the broadest torque curve. Since the Gen III GM has the largest displacement, it has a leg up on everyone else in this regard.

Yes, and Chrysler used the same principle in their engine for midget OW, didn't they? 155 inches versus whatever the Fords and others have. This may be one of the reasons that Ford went to their Focus series. M.L. Anderson

[phantom II]

Far out. What Camaro? The LT4 powered '96 Vette GS is overlooked a being one of the most desirable cars to own in the world with outstanding bullet proof performance. Just put a roll cage in it to stiffen the chassis and put your 505 hp engine in it with a set of Brembos and I'll stack it against even my 06 Z06. I am not happy with massive polar moment of enertias that the transaxle offers and long wheel basis. Bolt the engine to the gearbox like God intended. That is why the Viper beats the Vette on slalom courses. Still love it though, but it is not easy to drive.

Originally posted by Freebird




Phantom II:

LT4, 396 CID Camaro here. Not as light as your your bullet, but I'm able to squeeze 525 out of it.

One other thing that I have noticed with regards to reverse cooling. As the ambient temp drops, my car seems to "pick up" power significantly better than other cars I've driven.

msw

[NTSOS]

Bolt the engine to the gearbox like God intended.

phantom,

That's interesting, so not having a transaxle combo for my '56 is not all that bad after all.....at least for a slalom course I guess.

Does your Z06 launch like this one? I see more 06 Z06 videos with horrendous launches and then the car recovers quite easily and manages a fairly spectacular et/mph. The LS7 seems to have a wide power band and relatively good gas mileage......$14k for a crate motor.

Z06 Lauch

John

Althea's Garage

[dosco]

Originally posted by McGuire
...and once again demonstrating that there is more to engine development than hp, should we wish to open that can of worms again.

I'm so tempted to make a snide remark.....

[m9a3r5i7o2n]

Toyota Midget Engine Details
166-cubic-inch, two valve pushrod head, 4.19” x 3.05” bore x stroke, aluminum head and block, three-gear camdrive, high camshaft position, adjustable oil pump belt pulley, 2.165” cam journals, extensive use of O-ring seals, provision for eight piston oilers and integral oil-filter assembly.
Question; just how they get 166” out of that B & S I don’t know as I get it as being 168.22”. I wonder if this is correct as Chrysler claims theirs is 155”. Is this enough to get it disqualified?
Anyway due to the pushrod engine it is allowed more displacement than the Overhead cam engines.
M.L. Anderson

[Fat Boy]

Originally posted by McGuire


In racing too. For example in the Rolex Series Daytona Prototypes...here all the engines are regulated to 500 bhp, so the advantage goes to the engine with the broadest torque curve. Since the Gen III GM has the largest displacement, it has a leg up on everyone else in this regard.

...and once again demonstrating that there is more to engine development than hp, should we wish to open that can of worms again.

The other advantage of the pushrod V8 is its signifcantly smaller package dimensions and lower CG over the DOHC V8's from Lexus, BMW and Ford. If you look at the back end of a Riley chassis powered by Pontiac vs. one powered by a Lexus etc, it's pretty obvious. So in this series, based on production engines, the GM pushrod V8 is currently the engine to beat.

Check me if I'm wrong here, but don't the BMW and Ford also run as 5 liter engines? No arguement that the pushrod engine is a smaller package than the OHC engines, but in terms of output (power or torque, if we're talking the same rev ranges, then the point is a semantic), why would a pushrod engine have an advantage on a OHC engine of the same displacement?

I believe the Ford has been called the most powerful and most fuel efficient engine of the lot. Getting that engine with the right chassis/driver/team combination has, so far, not happened. I think they will have good combinations with a couple cars in 2006, though. It will be interesting to see what combination comes out on top.

[phantom II]

Nice toys John, I like the blonde one. Love that Chevy. Is all the work yours? Everyone wants to go for a blast in the Vette so I oblige,'cause that's the kind of guy I am. I try to avoid launches because the tires are in bad shape after 5000miles. I find a rapid release of the clutch(not dumped at 2500rpm) followed by jamming the gas pedal is the best way to launch. Popping the clutch just boils the hides and you have to back pedal immediately. The ratios are wide apart compared to the Z51 version of the stock Vette, so you stay in the gears longer. The tires hook up well with no spin if you do it right. I don't hear the popping during gear shifts as in the video from the inside but it sounds smooth and sweet and much quieter than the '03 Z06. Before you know it, you are doing a hundred and plenty. Since I've had it, it has been raining and I have tamed it pretty much in the wet and although it is fast you always wish for more. My roadster has spoilt me in this regard. As usual for Vettes, the tires are compromised toward inclement weather. I think the whole character of the car will change when I replace those hard runflats and it might be good for the low 11s. The tires actually squeal in the wet as though you were on a dry road.

Originally posted by NTSOS


phantom,

That's interesting, so not having a transaxle combo for my '56 is not all that bad after all.....at least for a slalom course I guess.

Does your Z06 launch like this one? I see more 06 Z06 videos with horrendous launches and then the car recovers quite easily and manages a fairly spectacular et/mph. The LS7 seems to have a wide power band and relatively good gas mileage......$14k for a crate motor.

Z06 Lauch

John

Althea's Garage

[McGuire]

Originally posted by Fat Boy


Check me if I'm wrong here, but don't the BMW and Ford also run as 5 liter engines? No arguement that the pushrod engine is a smaller package than the OHC engines, but in terms of output (power or torque, if we're talking the same rev ranges, then the point is a semantic), why would a pushrod engine have an advantage on a OHC engine of the same displacement?

I believe the Ford has been called the most powerful and most fuel efficient engine of the lot. Getting that engine with the right chassis/driver/team combination has, so far, not happened. I think they will have good combinations with a couple cars in 2006, though. It will be interesting to see what combination comes out on top.

Yep, that's how it stands right now... but originally the "Pontiac" was at 5.35 liters, now cut back to 5.0 liters, while the Toyota-Lexus and Infiniti are still at 4.3 liters. The Pontiac also had its rev limit cut back to 7100 rpm early last season, while the Lexus is allowed 8100 if I recall correctly.

The Porsche flat six is especialty hopeless as there is no way to get enough displacement with that package, and for whatever reason Porsche does not want to bring in its V8.

The Grand Am is one series that still has its complete rulebook up on its web site, worth checking out if you are interested.

[NTSOS]

Deuce,

Thanks so much for the various launch scenario's.........Martha Stewart says that low 11's will be a good thing!

The chassis is a bare Newman conversion and the headers are not mine and I agree about the blonde, I certainly never had a teacher that looked like that.

The chassis is in for powder coat as we speak and then I can start to assemble it.

I just love the new Z06! Whilst we have you here, please tell me all about the PBR brakes. I was going to go with a set of Movit's but they want around $7000 for a complete bolt on setup for my C4 pieces and parts.

I noticed we can get the PBR calipers for around $175 each and I can machine the adaptors myself and Precision Brake is coming out with a set of 2 piece rotors. I think eventually the difference in price between the Movit's and the Z06 setup will equal a lot of extra Budweiser.

John

[J. Edlund]

Originally posted by knighty
which way does the coolant flow through an F1 engine?.........from the heads to the block.........or the block to the head?..........the conventional way for production engines is block to head........but I have heard that some bike engine tuners reverse the flow in order to keep the combustion chamber cooler, and therefore reduce the det limit.........I'm interested to hear what you guys know

F1 engines are cooled from block to head. The exact cooling layout may differ among engines but if we take one of the later ferrari engines as an example the coolant flow something like this:

1. From the single coolant pump into a manifold (aka water gallery) which is cast into the block inside the V.
2.1. The manifold supply the 10 cylinders with coolant. There are one separate chamber for each cylinder and one in and one out port for each cylinder. The manifold supply the coolant inside the V, the coolant does a 180 around the cylinders/liners and then goes up to the head on the exhaust side.
2.2 From the manifold there is also a port per cylinder from the coolant manifold to the head on the intake side.
3. The coolant goes up in the head. There are one coolant exhaust port per cylinder. There is an coolant exhaust manifold in the valve cover with collects the coolant to one exhaust port.
4. From the coolant exhaust port the coolant goes to the radiator. One radiator per bank. From the two radiators the coolant goes back to the pump through two ducts.

The use of coolant manifolds allow a very even temperature among cylinders (coolant manifolds can also be found on some production high performance engines, such as BMW M engines and Yamaha MC engines). The coolant is taken out of the top of the head which is the highest place.

Some of the turbocharged F1 engines of the eighties were rumoured to use separate cooling of the head and block. Dont know what engine that should be but at least the Honda and BMW did use block to head cooling with the use of coolant manifolds. In the case of the Honda the cooling system was similar to that of the Ferrari that I described, the main difference being that two manifolds placed on the outside of the V together with two pumps was used instead.

The coolant exhaust ports are in general designed to give some restriction of the flow, that increase the water pressure inside the engine and with that the boiling point.

The system pressure is about 3.5 bar i a F1 engine against around 1 bar for a normal car (above atmospheric pressure).

[rhm]

That makes a lot of sense. If you cooled the exhaust valve aread of the head first the coolant would likely be too hot to have a net cooling effect on the cyclinder. The intake valve is adequately cooled by the airflow past it, but it makes sense to push some of the coolant at it's coldest past the intake side of the head to form a thermal barrier.

The other thing that gets very hot in the heads of a F1 engine is the pnuematic value system. Is that cooled by the water that's passed the intake value (on it's way to the value cover), or is it cooled by the oil used to lubricate the valvegear?

[McGuire]

Originally posted by m9a3r5i7o2n
Yes, and Chrysler used the same principle in their engine for midget OW, didn't they? 155 inches versus whatever the Fords and others have. This may be one of the reasons that Ford went to their Focus series. M.L. Anderson

Far as I know, in USAC all two-valve, inline fours with aftermarket blocks and heads are allowed 166 CID. Two-valve opposed fours (VW-based) are allowed 174 CID. Four-valve fours are allowed 122 CID.

The Chevy, Ford, Dodge and Toyota midget engines are all based on the respective pushrod V8 parts and architecture, and are very popular on that basis. Good power and service life, easy cost and availability.

The Ford Focus series is a different deal...sealed, production-based spec engines, reduced cost, entry level series. Got to drive one; they're a blast.

[phantom II]

I use the C5 rotors and calipers on my roadster. The Australian C5 PBRs are considerably better than the C4 brakes which I had before. The C5 stuff is real cheap and could take a lot of abuse on the 03 Z06 but a Brembo update is required if you go racing. My roadster is so light and the C5 brakes have shown no sign of deterioration. I can get all four rotors glowing red. Switching to the C5 brakes, I had to boost the system which I tried to avoid. My roadster is a exercise in simplicity and purity. It took me forever to balance the C4 brakes and to get pedal travel right. I had to keep changing the front calipers often because of warpage. If you are not going racing, the C5 brakes are perfect and cheap. $105 each for front and $76 each for rear calipers. Pads front $ 52 set and $33 set rear. The rotors are $63 each frnt and $56 ea. for rears.$45 for hardware per wheel. A little extra for the red Z06 calipers which are the same as the stock Vette otherwise. I use a Tilten pressure adjuster valve to the rear and as the fronts get hot, I increase the pressure to the back from the dash. For the handbrake, I press a pad onto the drive shaft like a steam train brake.
The C6 stuff is over kill for my roadster and I don't want to go to 18" wheels. I have my own Ideas about suspenson design. The front calipers have 6 pistons and 6 pads up front and 4X4 at the rear. They don't work as you would expect but there again, I'm spoilt by 1750lbs compared to the 3300lbs of the Vette.



I use BMW hubs both back and front, which have the same bolt pattern as the Chevy. I used the Vette wheel bearings before but they cost $300 compared to the M3s $70. I use the M3 differential which as an infinate amount of ratios and clutch and spider gear packs.





Most of it is made of wood first before I mill it out Aluminum. Low roll centres and low CGs because I hate ARBs. Remember purity? I load a cut section of the tire filled with foam and test the patch at max lateral and longitudinal transfer and use my own definition of scrub including turn in scrub to detrmine castor.

I think your '56 will look cool with red C5 Z06 calipers all round.

Originally posted by NTSOS
Deuce,

Thanks so much for the various launch scenario's.........Martha Stewart says that low 11's will be a good thing!

The chassis is a bare Newman conversion and the headers are not mine and I agree about the blonde, I certainly never had a teacher that looked like that.

The chassis is in for powder coat as we speak and then I can start to assemble it.

I just love the new Z06! Whilst we have you here, please tell me all about the PBR brakes. I was going to go with a set of Movit's but they want around $7000 for a complete bolt on setup for my C4 pieces and parts.

I noticed we can get the PBR calipers for around $175 each and I can machine the adaptors myself and Precision Brake is coming out with a set of 2 piece rotors. I think eventually the difference in price between the Movit's and the Z06 setup will equal a lot of extra Budweiser.

John

[NTSOS]

My roadster is a exercise in simplicity and purity.

phantom,

Forget about my brakes for a moment.........would you mind pulling the camera out a bit on your 1750 lbs hot rod?

John

[phantom II]

I'm rushing out the door to catch a plane. Later. Sides, I don't want bums like Fatboy and McGuire stealing my Ideas and passing them along to Frank Williams.

Have a good Chrismas all.

Originally posted by NTSOS


phantom,

Forget about my brakes for a moment.........would you mind pulling the camera out a bit on your 1750 lbs hot rod?

John