Top Fuel bike engine 3

[outlaw695]

Designing a V4 2500cc, OHC 4 valve engine based on the yamaha VMAX engine. Target is 1000HP @ 9500rpm!supercharged, nos, running ELF race fuel. Help me out with the right bore/stroke ratio, rod/stroke ratio, valve sizing, etc. Very interested to hear your results

 

[patprimmer]

There is no correct bore:stroke or rod:stroke or valve size for this application.

The best bore is the largest that retains sufficient strength to minimise blow by and retain structural integrity under maximum cylinder pressure.

The correct stroke is the longest that retains enough structural integrity and piston speed to endure the rpm you will use.

The correct rod to stroke ratio is very likely the longest you can fit in without compromising the ring lands.

The correct valve size is that which gives the highest airflow when the effects of shrouding from cylinder wall and valve to valve spacing are considered.

The flow ratio of inlet to exhaust should be less biased against the exhaust than for NA petrol engines due to the extra volume of exhaust to air. As far as I know, exhaust flowing about 80% of inlet is considered normal for top fuel.

Regards
Pat
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[outlaw695]

keep in mind that the block/crankcase, crankshaft, etc will be manufactured. Is anyone willing to commit to some dimensions?

 

[patprimmer]

4" bore, 3" stroke and 6" rod or there about, same as a 5 litre SBC. You would get away with revving it to 10,000 occasionally.

Valve size should be in the order of 39 to 40mm inlets and 35 to 36mm exhausts


Regards
Pat
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[outlaw695]

Thanks for your input Pat. Very much appreciated

 

[LionelHutz]

So you're going to build, from scratch, an engine based on the advice from a message board?

You did notice this is an engineering tips website?

 

[TrackRat]

Probably better advice here than most places... *LOL*

 

[ornerynorsk]

What's this??? Where are all of the naysayers to pick apart the impossibility of 2.5 liters producing 1000 hp?

 

[evelrod]

Perhaps because it's not all that impressive? Perhaps because in the early 90's the Toyota Eagle GTP car, 1.4 litre @ 750 hp on gasoline?

http://www.conceptcarz.com/vehicle/z13732/Toyota-IMSA-GTP-Eagle-MKIII.aspx

Ya gotta give us racers enough credit to distinguish most of the really impossible goals.

Rod

 

[evelrod]

Here is a better link to the MkIII with the 2.1 restrictor engine.

http://www.allamericanracers.com/eagl_mkIII_gtp.html

Rod

 

[TrackRat]

Olds made over 1000 HP on alky with a 2300cc Quad 4 engine back in the early 90's with the Aerotech that set a closed course speed record of 263 mph. 1000 HP from 2500 cc and nitro won't be any problem with a properly designed engine.

 

[ornerynorsk]

Just found a little humor in it because on some other post I had mentioned my brother and I getting 600 hp out of Mopar 360's, and I was almost afraid to read the responses after the 2nd or 3rd day. Had all kinds of rabid naysayers coming out of the woodwork.

I know this kind of power is very achievable.

So if it's a clean piece of paper on the drawing board, why are you staying with a vee configuration? Why not go rotary (3 cylinder w/master rod ala aero engine) or 4 opposed?

 

[YvesLLewelyn]

The BMW 1500cc turbo F1 engines of the mid-1980s were claimed to be able to produce 1300HP for short periods to set fast qualifying times. They ran on some form of petrol - certainly not nitro.

 

[TrackRat]

The 1.5L turbo F1 engines used about 80% Toluene and 60+ PSI boost for qualifying. They had to heat the rocket fuel before putting it in the engines or it would not ignite. The rocket fuel they used back then was extremely toxic and dangerous as is nitro.

 

[outlaw695]

lol, well that started the ball rolling, enigne has to be based on a production motorcyle engine, yes a blank peice on paper to do as needed to produce the results. some are producing over 1100HP with a 1500cc inline four set up on nitro.

 

[evelrod]

I was at an SCTA event a few years ago, El Mirage, and some crazy guy went a bit over 200 on a Harley, sans fairings. The sign on his rig said it was a 1500 hp V twin...I don't remember the displacement or fuel class... but it WAS a Harley!

Rod

 

[izzmus]

Given that current Top Fuel (car) engines are generating on the order of 1000hp/liter with fewer valves per cylinder, I don't see how a 1000hp/2.5l multivalve engine wouldn't be feasible.

Finding somebody loony enough to aim it would probably be more difficult! I hesitate to use the verb "ride" for a machine like that.

 

[BrianPetersen]

Re the comparison to the other thread (600 hp from Mopar 360, etc.), the whole situation changes with (A) forced induction and/or (B) chemical cocktails used as fuel as opposed to gasoline! And it changes with the engine only having to make that power output for 6 seconds or thereabouts, too ...

Take away the forced induction, and make the engine run on pump gasoline, and make it have to produce that power output for an extended period of time, and the maximum BMEP goes down a lot.

 

[patprimmer]

And it was a fairly clean sheet modern design with race only in mind and it is multi valve.

I must admit I am still not quite clear with regards to just how clean the sheet is and what restrictions "based on" imposes.

Regards
Pat
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[patprimmer]

Also, he says what he is trying for, not claiming what he gets.

Regards
Pat
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