27 replies to this topic

[mariner]

know this is topic not FI ( althought it might be in 2 -3 yrs if Max has his way) but as this site has an ecletic range of topics and a number of US members I thought I would mention it.

I am old so I can remember reading Hot Rod magazine back in the late 60's or early 70's and there was an article about an experiment run by GM engineering. Basicaly they rigged up a small air pump onto the belt drive of an engine and pumped the compressed air into a storage tank.Then a pipe ran through a valve to a venturi in the intake system. The concept was that the compressed air was directed into the venturi restriction and it accelearted a much larger volume of air ( at lower pressure obviously) into the intake manifold.

Instant supercharging without any moving parts besides the small pump. The idea is actually even older because if any of you studied steam trains as a kid you may remember that the water from the tender can be injected into a boiler at 250psi simply by means of a steam injector with no moving parts which uses a somewhat similar process.

I dont know what GM ever did with this idea or how efficent it was but in today's hybrid obsessed world this air reservoir system serves the same purpose as a hybrid battery - it stores energy from a low input source to provide acceleration power. If you could use something like a "jake brake " from a truck fraternity to do the compressing then energy recovery is theorectically possible.

Iam no way a professional engineer so the maths of all of this are beyond me but I can imagine that if the basic efficiency was there then you could envisage sealing up the interior of a passenger car chassis ( like the wet tanks on a plane) and store energy without all the weight and cost penalties of the Toyota battery hybrid approach. Also no duplicate electric motors.

I suspect the maths may not support long term storage but as an approach to Max's "energy recycling F1" where the storage time is short and battery weight penalty severe it may be worth a desk analysis.

[McGuire]

Damn, I have some papers on that crazy thing somewhere...just can't remember where I filed them. It's called an Accumulator Supercharger and was developed in around 1960. The GM trade name made up for the system was Aircharger or Aerocharger or Aero-ramcharger or something hokey like that, but the science behind it is a lot more interesting and subtle than you might think. When I get some time I will try to dig up the documents.

[McGuire]

Nope, can't find the paperwork anywhere. I can tell you what little I was able to remember today... it's called Accumulator Supercharging but the proposed GM marketing name was "Ramaire Supercharger." It was developed in the late '50s and GM messed with it for probably a dozen years after that, trying to find a use for it.

An engine-driven air compressor charged an accumulator up to around 1600 PSI. Then when you mashed the pedal far enough to trigger a microswitch on the throttle, it would open a solenoid valve and send air through a regulator at down around 175 PSI, then into a venturi about two inches in diameter and two feet long. At the front of the venturi was an annular breather where outside air was pulled in, while the back end of the venturi went straight into the carburetor in blow-through fashion. The max hp increase was in the range of 30%. I don't have any further info but I know it was patented and there were SAE papers on it too, so it shouldn't be too difficult to research.

The device was developed by an honest-to-goodness genius named Worth Percival who was also responsible for the GM Stirling engine program and some other alternative engine/alternative energy projects back then, ammonia fuel, alumina storage, wild stuff like that. There were probably dozens, maybe a hundred people like that walking around GM at the time, guys about two to five times as smart as an ordinary human being.

[dosco]

Originally posted by McGuire
... the science behind it is a lot more interesting and subtle than you might think.

I know you can't find the paper(s), but I'd like to know why you said what you said (quoted).

[McGuire]

I would rather have drawings and photos of this thing to illustrate but briefly put, using a little air to move some more air is sort of an interesting job.

[Moon Tricky]

I have wondered before about the possibility of using a pure oxygen tank instead of breathing atmospheric air. Seeing as oxygen is only 20% or so of air, you could get something like 5 times the power - and with no NOx emmissions at all. It's only a shame it isn't possible to carry enough oxygen to do it, and getting pure oxygen in the first place isn't that easy.

Came across this today though...
http://jjap.ipap.jp/...?JJAP/45/L1039/

Imagine if you could separate the oxygen out of the intake air...

[blkirk]

Originally posted by McGuire
I would rather have drawings and photos of this thing to illustrate but briefly put, using a little air to move some more air is sort of an interesting job.

Is this what you're looking for?

http://www.process-c...r_amplifier.htm

[phantom II]

Good for you, you remembered. Since pressurization and air-conditioning in aircraft began, they have used this method since the mid 20s. Weight was of primary importance so normal refrigeration methods were out of the question. Compressed Air was taken from turbo super charger or turbine compressor bleed offs. Maybe Percival got the idea from there.

Originally posted by McGuire
Nope, can't find the paperwork anywhere. I can tell you what little I was able to remember today... it's called Accumulator Supercharging but the proposed GM marketing name was "Ramaire Supercharger." It was developed in the late '50s and GM messed with it for probably a dozen years after that, trying to find a use for it.

An engine-driven air compressor charged an accumulator up to around 1600 PSI. Then when you mashed the pedal far enough to trigger a microswitch on the throttle, it would open a solenoid valve and send air through a regulator at down around 175 PSI, then into a venturi about two inches in diameter and two feet long. At the front of the venturi was an annular breather where outside air was pulled in, while the back end of the venturi went straight into the carburetor in blow-through fashion. The max hp increase was in the range of 30%. I don't have any further info but I know it was patented and there were SAE papers on it too, so it shouldn't be too difficult to research.

The device was developed by an honest-to-goodness genius named Worth Percival who was also responsible for the GM Stirling engine program and some other alternative engine/alternative energy projects back then, ammonia fuel, alumina storage, wild stuff like that. There were probably dozens, maybe a hundred people like that walking around GM at the time, guys about two to five times as smart as an ordinary human being.

[mariner]

As I recall the idea from memory ( 35 years!) it was not quite like the air amplifer link above in that the hi pressure air was fed into the centre of the long venturi and it dragged ( accelerated) the ambient pressure air through the venturi. I think underbonnet space might have been an issue as I recall the system being quite bulky.

In those days it was all carburetors so with a "blow in" set up you would need to pressurize the float chambers and seal the carb. That is a problem which plagued boost set ups until EFI arrived.

As I say I am not a professional engineer so the maths is beyond me but I think the limiting factor is the storage capacity of compressed air. However for Mx's new " energy FI" the storage requirement would be small as the gap between corners on most F1 circuits is short.

[McGuire]

Originally posted by blkirk


Is this what you're looking for?

http://www.process-c...r_amplifier.htm

no.

[McGuire]

Originally posted by phantom II
Good for you, you remembered. Since pressurization and air-conditioning in aircraft began, they have used this method since the mid 20s. Weight was of primary importance so normal refrigeration methods were out of the question. Compressed Air was taken from turbo super charger or turbine compressor bleed offs. Maybe Percival got the idea from there.

Probably not.

[Greg Locock]

"I would rather have drawings and photos of this thing to illustrate but briefly put, using a little air to move some more air is sort of an interesting job. "

The spot coolers we used in the engine lab at BL were venturis 'driven' by shop air. Someone mentioned steam injectors - very similar idea.

[Engineguy]

The spot cooler, cleaning wand, and cabinet cooler type devices are all discharging free flow into the open atmosphere of course. I can't imagine the GM device, with what had to be a relatively small volume of air (compared to the total intake) could actually act quantitatively like a turbo or supercharger (i.e. 1.5x, 2x) to actually compress the intake charge in the confined combustion chamber to any degree. What I could imagine, is that it help bring a horrid old intake manifold and head port closer to atmospheric (i.e. 100% VE) than otherwise possible. Depending on the time period it was tried, that alone might have been pretty impressive though.

[McGuire]

This was not really compressed-air supercharging... although GM did mess around with that deal as well. Giant tanks in the trunk at 3000 to 4000 PSI, engine-driven compressor mainly for make-up.

The wrinkle in that particular system was that the pressurized air was injected directly into the cylinders, rather than jammed down through the intake ports. The air in the tanks was at ambient temperature, so instead of heating the air intake charge as with conventional superchargers, this setup cooled it -- extreme equivalent boost pressures with no knock, 250% power levels on stock, unmodified engines. Of course the disadvantages included a trunkful of big heavy pressure tanks and related hardware. And finite air supply on demand, needless to say.

[cheapracer]

Originally posted by McGuire
Nope, can't find the paperwork anywhere. I can tell you what little I was able to remember today... it's called Accumulator Supercharging but the proposed GM marketing name was "Ramaire Supercharger."

I can picture the female model with the lemon coloured knee length dress (big buttons), curly hair and the elbow length white gloves next to the Chev with "Ramaire Supoercharger"!

Disappointed you only spent 11.5 hours looking for the info and gave up on us.

[Henk]

See Percival’s patent applications (pdf files) :
http://v3.espacenet....BQPN__US2965083
and
http://v3.espacenet....BQPN__US2983267

[mariner]

Thanks for tracing the patent application.

What is interesting about the second patent is that no means of pressurizing the carb float chamber is shown on the drawing or mentioned in the claims. As shown the mixture strength would go very lean under supercharging conditions I would think.

I wonder if this was deliberate on his part so as to prevent easy copying. I can't imagine that he didnt know about the problem if he understood how to do the injector in the first place.

[scooperman]

the SAE papers search engine found one paper on "Ramaire" by Percival and Ahrens,

http://www.sae.org/t...l/papers/670109

I think the 67 in the document number indicates the paper is from 1967, not sure about that. Here is the title and abstract:

"Title: Ramaire System for Intermittent Supercharging of Internal-Combustion Engines
Document Number: 670109

Author(s):
Worth H. Percival - General Motors Res. Labs.
William H. Ahrens - General Motors Res. Labs.

Abstract:
A novel method for the intermittent supercharging of an internal combustion engine in a vehicle is described. During full throttle operation, high pressure motivating air entrains ambient air and compresses it to an intermediate pressure in the diffuser of an air ejector. Flowing through the carburetor and into the engine, the supplemental air augments engine power, reducing vehicle acceleration time by as much as one-third. By allowing engine size to be reduced, better economy without loss of performance is possible. "

I don't have a copy of this one. A lot of the SAE papers are downloadable after purchase, this one is available by mail or fax only.

[McGuire]

Originally posted by mariner
Thanks for tracing the patent application.

What is interesting about the second patent is that no means of pressurizing the carb float chamber is shown on the drawing or mentioned in the claims. As shown the mixture strength would go very lean under supercharging conditions I would think.

I wonder if this was deliberate on his part so as to prevent easy copying. I can't imagine that he didnt know about the problem if he understood how to do the injector in the first place.

You would simply select a "blow-through carb" designed and sold for such applications. In these carburetors the float chamber is vented to the air horn, among other features. (Some also employ air seals on the throttle shafts, etc.)

If you look at the blow-through supercharger installations on carbureted engines of yore, you will note that some placed the entire carburetor in a sealed box or chamber and then pressurized the box. In some others, the supercharger simply blew into a bell atop the carb. The latter type is likely employing a "blow-through carb." These carbs were obtained commercially, or it was not terribly difficult to perform a conversion -- mainly you are just moving a few passages around... plug this off, drill that out.

[phantom II]

There are so many applications of this principle in other industries particularly in aircraft that I am surprised it was not further developed in autos. When you get a type rating in an aircraft, the ground school covers systems opporation. I have notes on Lear Jet pressurization systems somewhere that looks a lot like some of these things. If I find it, I'll post.

http://www.rexresear...nda/1coanda.htm

Originally posted by McGuire



You would simply select a "blow-through carb" designed and sold for such applications. In these carburetors the float chamber is vented to the air horn, among other features. (Some also employ air seals on the throttle shafts, etc.)

If you look at the blow-through supercharger installations on carbureted engines of yore, you will note that some placed the entire carburetor in a sealed box or chamber and then pressurized the box. In some others, the supercharger simply blew into a bell atop the carb. The latter type is likely employing a "blow-through carb." These carbs were obtained commercially, or it was not terribly difficult to perform a conversion -- mainly you are just moving a few passages around... plug this off, drill that out.

[mariner]

Thanks for all the Coanda data, all the adaptations are amazing. I remember that way back before electronics became so rugged and cheap work was done on using the Coanda effect as a series of binary switches in a simple process control computer for very harsh environments. The idea I think was to micro etch all the switches into plastic and use air or oil.

Sailing ships have been built using the Coanda effect of a vertical rotating cylinder mounted on deck which generates thrust by being rotated via a small motor. It woked but I am not sure how efficiently vs sails.

This led me to an idea of how to get round the "no moving aerodynamics aids " rules by going to a solid rear axle made of a very large diameter tube , say 35-40 cm ( 14-16 ") with worm drive to one end. So basically the tube ( axle) rotates with the wheels and generates a downthrust aided by the small gap between the bottom of the axle and the track ( about 3-5"). As the axle is part of the suspension and all drive shafts have a similar rotational effect ( albeit small due to small diameter) then how could you ban it just because it rotates!!

Not sure if it would work in practice but given the tiny size of modern F1 engines you could probably acheive the necessary very waisted rear end to get the large tube axle into reasonably clean air.

[Joe Bosworth]

This thread started with the thought that the induced inlet air pressure principle might be worth a desk analysis.

Setting up the whole energy balance of the the induced air system vs other alternatives is possible but time consuming.

My thinking is that taking the time isn't worth it.

Whether one might develop this as a means of either increasing fuel efficiency or making more horsepower it doesn't appear to be effective.

The problem with the pressurised/induced air system is that you are using engine output HP to compress the air after loosing all of the energy losses to air/exhaust, water and friction used to make that HP. Then you are forcing air into the engine to make more air/exhaust, water and friction losses. The output HP used to pressurise the air is reducing the HP available for use as tractive effort which is the purpose of the whole exercise in the first place.

Compare this to the turbo-charger that uses energy already lost to the engine in the way of air/exhaust temperature to compress the air which the induced air system does with primary energy. Th energy used for pressurising the turbo-charger can not be used for tractive effort.

The energy balances of the two systems don't even come close. Too far different to burn more time to fully quantify.

Regards

[McGuire]

Originally posted by Joe Bosworth
This thread started with the thought that the induced inlet air pressure principle might be worth a desk analysis.

Setting up the whole energy balance of the the induced air system vs other alternatives is possible but time consuming.

My thinking is that taking the time isn't worth it.

Whether one might develop this as a means of either increasing fuel efficiency or making more horsepower it doesn't appear to be effective.

The problem with the pressurised/induced air system is that you are using engine output HP to compress the air after loosing all of the energy losses to air/exhaust, water and friction used to make that HP. Then you are forcing air into the engine to make more air/exhaust, water and friction losses. The output HP used to pressurise the air is reducing the HP available for use as tractive effort which is the purpose of the whole exercise in the first place.

Compare this to the turbo-charger that uses energy already lost to the engine in the way of air/exhaust temperature to compress the air which the induced air system does with primary energy. Th energy used for pressurising the turbo-charger can not be used for tractive effort.

The energy balances of the two systems don't even come close. Too far different to burn more time to fully quantify.

Regards

First, I will dispute the contention that you can operate an automotive turbocharger to any useful significant effect on the free portion of exhaust energy. It takes work to pump exhaust gas out of the engine, and more work to operate a turbine. If at any point the exhaust turbine presents back pressure to the exhaust sytem, the energy is no longer free. It may be more efficient than a crank-driven blower, but it is not free.

But more to the point, we seem to be assuming that increased efficiency was the purpose of the "accumulator supercharging" scheme. Actually, that was the furthest thing from their minds. This was the late 50s after all, when efficiency was barely on the radar in Detroit. Unless we know the historical context for the device we will have a very hard time understanding what it was about.

An engine-driven compressor and high-pressure accumulator circuit? Why on earth would they take that route? It so happens that at exactly that moment GM was also adopting air suspension systems -- introduced on the 1957 Cadillac, offered across the GM product line in 1958, and discontinued on Cadillacs after 1960. Key parts of the air suspension system included an engine-driven air compressor and a pressure accumulator.

[scooperman]

I received my copy of SAE 670109 "Performance with Economy - the Ramaire System" by Percival and Ahrens. A photo shows what may be the final evolution of the air ejector assembly, another shows a huge assortment of different ejectors that were developed and tested in the lab. There are photos of engine installations, graphs and tables of performance data, 17 figures and 4 tables in all.

After lab development, they tested the installation in a 58 Chevy 4-door sedan with a 283 V-8 and Powerglide; acceleration time 0 to 60mph was improved by 30% to 8.9 seconds. They measured some engine knock under supercharged condition, concluding that high octane fuel was needed. After 2000 test miles the car was returned to stock configuration and the engine torn down, they found one broken piston ring but could not attribute that to the supercharging. After these tests they started work on the inline six, to see if they could keep the economy of the six with the performance of a V8. The next installation was a 59 Chevy 4-dr sedan with the 235 6-cyl and Powerglide. Zero to 60 performance was about 22 sec for a stock Chevy, with the supercharger they achieved 15.5 sec, comparable to the non-supercharged V8 at 15.5 sec. They mention that "with a somewhat lower vehicle weight" they achieved 0 to 60 in 12.4 seconds with the supercharged 6-cyl. Fuel economy with the supercharger installed was negligibly different from stock. After the testing, the vehicle was put into normal transportation service for another 9000 miles, with no problems. The next installation tested was a 59 Chevy with the 283 V8, but this time they used an electric motor to drive a 3-stage air compressor, this installation said to be neater and smaller than the earlier engine-driven compressor installation. This car was used by one person in daily commuting as well as long trips, they put over 10000 miles on it, no problems. The fourth installation was 1960 Pontiac Ventura, with a 389, 8.6:1 CR, 2-barrel, Hydramatic, and an economy 2.69 rear axle. Evolution of the ejector mechanism now included a bypass valve and filter to reduce airflow restriction during normal operation. Excessive "wheel slip during the initial phases of acceleration from standstill" was eliminated by a time delay mechanism added to the solenoid valve; a transmission governor oil pressure switch in parallel defeated the delay switch, so that no delay was added if the vehicle was already in motion when full acceleration was demanded. Zero to 60 was as low as 8.5 sec with no wheel slip, compared with 12 sec for the stock Pontiac. They put 5500 miles on it in testing, with no failures or difficulties.

The tone of the paper suggests that at the time the paper was presented, work on the system was finishing up at GM. At the end of the paper they discuss safety and cost considerations, concluding that the multistage air compressor cost would have to be significantly reduced for the Ramaire to be economically feasible. They also state that the "general acceptance of air conditioning has eliminated much of the unused space in the engine compartment".


Clearly this gizmo worked very well. I think it may have been a solution in search of a problem. U.S. car manufacturers in 1960 could easily sell big cars with big engines, and didn't need this to get extra performance. Fuel economy was not a big concern then, so no need to make a 6 perform like an 8.

Today all engines are better than 1960. This thing could still improve performance, but I think it would still be cost prohibitive for a car manufacturer. I would not know where to apply this device, maybe diesel trucks. Maybe it could be applied to production-based race cars, for example the small-bore GT classes of SCCA, where the rules require a sealed air box and single-inlet restrictor (SIR). These cars are sufficiently large enough to accommodate the extra equipment, the air ejector could be enclosed within the airbox.

[dosco]

Originally posted by scooperman
This thing could still improve performance, but I think it would still be cost prohibitive for a car manufacturer.

Cost prohibitive in terms of what? In light of increased attention on gas mileage and increased gasoline costs, perhaps this idea is warranted. Coupled with modern engine control systems, it seems pretty straightforward.

[McGuire]

Originally posted by scooperman
I think it may have been a solution in search of a problem.

I'm sure you nailed it.

It's kind of a cool gadget, especially if there is already a supply on compressed air on board to keep the unit cost low. But it didn't fill any real need, except perhaps "reserve power for emergency overtaking situations."

[imaginesix]

Great overview of the paper scooperman, thanks.

[scooperman]

Cost prohibitive in terms of what?

The paper discusses the same components as cost and safety concerns. The air reservoirs were two 870 cubic inch fiberglass storage spheres, originally mounted in the trunk, later located between the frame members under the body. The early compressor configuration was capable of charging the reservoirs at the rate of 25 to 40 psi per mile driven. The use rate of the stored air was 200 to 250 psi per 10 seconds of ejector operation. They had enough storage pressure for 6 or 7 ten-second accelerations. So one of the safety concerns was whether a tank might be ruptured in an accident, which they concluded with proper packaging would be less hazardous than the fuel tank. Another safety concern was the possibility that all the stored air might be depleted during a passing maneuver, they concluded this danger could be minimized with a warning device. Besides the compressor cost mentioned earlier, weight and size were issues relating to cost, they said the Ramaire unit with all auxiliary equipment added about 100 lbs, and it took up much of the unused space available in a 59 Chevy four-door. Do I think it's a neat idea, yes. Do I think a car manufacturer would put it into production, no I don't, I think the window of opportunity closed in 1960. I think its cheaper for a car manufacturer today that wants faster 0 to 60 times to put in a supercharger and reprogram the ECU.