Self Supercharging engine 3

[CSLufkin]

Last night during a bench racing session, some friends and I discussed a concept that was new to us. I assume that it has been tried somewhere by someone (as almost everything has thanks to Smokey). Anyone please speak up, as this is probably tragically flawed.

There is a class that limits engines to four cylinders and forbids turbochargers and superchargers, but does not specify Natural Aspiration strictly. What if you took a V8 engine and used the exhaust charge from four cylinders to compress the intake charge for the other four cylinders? Let me explain a little more. It would have to be direct injected, the 'compressor' side would have no ignition, just air in, compression, and release compressed air thru a one way flow control of some sort into a chamber to be used in the intake charge of the other four cylinders. Understanding that there would be energy wasted in running the piston thru the power stroke without actually making power, do you think the power increase from the charged intake would overcome the power losses of swinging that heavier mass(8 cyl VS 4 cyl) and the wasted power stroke of the compressor side.

 

[WGJ]

Static pressure -- no flow (?)

Bill

 

[patprimmer]

22 psi from a flywheel at 6000 rpm. Just give it a bit more of a rev and it could pump up tyres.

Regards

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[FoMoCoMoFo]

22 inches of water maybe ?

 

[patprimmer]

The weight of 22 gnats whiskers per sq metre maybe, unless it has a very special shape to the clutch pressure plate and / or flywheel.

Regards

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[FoMoCoMoFo]

And don't forget to remove the transmission, it's blocking the inlet.

 

[TStaples]

My copy of Smokey's book states:

"Now I have everything clean inside and stick a bottle of urethane at a hole and press the button, everything inside gets full of foam. Let it harden. Now crank engine up and cut a path for the rotating parts. Then...opened the entrance and exit areas up with a knife, then cut room for throwout bearing and fork. Then run engine up to 7000 rpm AND FIND OUT YOU GET 10 PSI OF PRESSURE, AND ARE PUMPING 800 CFM WITH NO PARASITIC LOSSES."

800CFM at 10 psi????? Jeez, that's a lot of air. I don't buy it. Unless he left out the part about building the engine with a special turbine shaped . . .. Aw, never mind.

-Tony Staples

http://www.tscombustion.com

 

[Lou Scannon]

I like the part about "no parasitic losses"... the turbocharger and supercharger manufacturers will definitely want to keep this one suppressed.
With all that foam insulation, I guess you'll need an adiabatic clutch & t/o bearing that can really "take the heat"!

 

[MikeHalloran]

Heat is not a problem. When the clutch gets warm, the urethane will melt and/or burn away.





Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

And as it burns, it will produce cyanide gas, thereby eliminating competition that is following closely, that is so long as the firewall and floorboards are gas leak proof.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[WGJ]

I think I can understand (maybe) the use of the flywheel ring gear teeth as a pumping mechanism. After all, a lot of current electric fuel pumps do just about the same thing - peripheral toothed wheels rotated at high speed.

To get these things to work with any sort of efficiency, you have to use very fine tolerances and have the 'turbine' shaft running at quite high speed to generate the sort of peripheral speeds where the pump works best.

I can imagine the foam providing these sort of close-fit conditions, but as to how wide a speed range that would provide a useful boost....?????

What happens when the crank end float gets so that the foam is worn away from the flywheel.....efficiency drops/dissappears.

Bill

 

[gazza285]

Haven't been on here for a bit.

I have been involved with a project that uses crankcase pressure as a source of forced induction. The mixture is pulled into the crankcase as the piston rises and expelled as the piston drops, airflow is controlled by a rotary valve running at crank speed, so you get two displacements per power stroke. This feeds a plenumn which feeds the inlet to the cylinder. In terms of psi boost the figures were low compared to more traditional forced inductions, but required very little in the way of extra moving parts, and the figures were obviously higher than a NA engine. The fuel was mixed 50:1 with stroker oil for lubrication of the bearings and rotary valve. The majority of the engines built were only small capacity for use in an Ecomarathon car, but a larger engine was still born when the UK motorcycle speedway authority got wind of it and banned the concept before the prototype was finished, let alone running. Without a market the research ended. Only works if the engine is a single or has seperate crankcases.

 

[WGJ]

Hmmm.....isn't that just a traditional 2-stroke ?

Bill

 

[gazza285]

No, because its a four stroke that uses crankcase pressure to force the inlet, hence the comment of two displacements per power stroke. Above the piston everything is as a four stroke, with the overhead cam drive also turning the rotary valve for the crankcase, no transfer ports, and non of the two stroke inefficiency.

 

[Lou Scannon]

So you are gaining positive displacement supercharging via internal design mods instead of an external device. What are the pluses & minuses relative to conventional positive displacment supercharging? (in terms of cost, efficiency, flexibility (i.e. control of pressure ratio), & oil fouling/smoke/particulates)?

 

[chief]

Many large bore 2-stroke, x-head,slow speed Marine diesel engines use under piston compression to supercharge the air manifold. This concept has been around for many years. The drawbacks are large accumulation of sludge in the air manifolds over time and danger of fires in this area.

 

[GregLocock]

He who does not study history is condemned to repeat it

1891

http://www.lindsaybks.com/arch/backus/index.html

1930s

http://en.wikipedia.org/wiki/Bourke_engine

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[PEW]

Mike Halloran,

The Triumph project you mentioned was a two stroke 500cc twin called the Norton Wulf. (Norton Viliiers Triumph by then, no matter).

The concept was to develop a two stroke engine with low emissions. Because the crankcase was sealed with regard to the combustion chambers, it could be lubricated by pump and return tank as a 4 stroke, rather than by the usual total loss / burn it and blow it out system.

It looked fairly conventional from the outside with carbs on the rear of the two cylinders. I recall it looked like a cross between an Ariel Square four and a Suzuki twin. However, the intakes were crossed over, so that a mixture adjustment on the left cylinder was made at the right hand carb.

There may be some merit in the concept even now. Like all the other good ideas from that factory, such as the Bandit and Fury modular bike engines, they were sadly strangled at birth due to the foolish refusal of the mangement to reinvest in the business in the face of new and rapidly emerging technology from the far east.

The prominent engine designer for Norton at the time was Bernard Hooper, who, I understand, is still experimenting with this type of engine.

I read all this almost as it happened, at school in the early 1970s from my smuggled in copies of Motorcycle Mechanics, whilst supposedly reading Shakespeare in English literature lessons. Consequently, I know a little about British bikes but I still don't know my Puck from my Bottom.

 

[WGJ]

PEW - not knowing yer Puck from yer botteom.....could be nasty if you ever have to explain any pains to your doctor.

Bill

 

[Fabrico]

How about a Puck from a Puch? The zenith of self supercharging...

http://physiology.usouthal.edu/restore/allstate.htm