DanaT

I think the "shot" affects it a lot where you bring the N2O in. Many of the "high end" systems are using multistage systems or pulsed selenoids to bring nitrous in early and then ramp it up.

I don't think for spool up wet vs dry matters. I have never worked with dry systems, but you have to map your EFI to supply the required fuel. With a wet system you put in a nitrous jet and fuel jet and you have the right ratios. I think wet is "safer" unless you get fuel puddling in the intake manifold.

The comment about nitrous puddling is not true. It goes from a liquid to a gas and stays as a gas. The only reason it is liquid in the bottle is the pressure it is at.

Also, air in an intake does "flow" from one end to the other. When I was playing around with a GSXR on nitrous, I was using open velocity stacks and flat slide carbs. You could see the carbs when it ran on the dyno. What was seen is that outside of the carbs (velocity stacks), there was a "fog" of air/fuel.

You must remember, that air going into the engine is accelerated, the intake closes, and that air hits a "wall". It then compresses, and bounces backwards out the carb (intake) track. When the cylinder opens, it then changes direction again. The air flow in waves related to the speed of sound where it resonates. Just a rough guess (there are better equations) at 6000rpm, you have a 100HZ wave. This means a wavelength of 3.43 meters. When you seal up a manifold you start getting harmonics of the wave that reflect. If you are at a peak when the harmonics hit the valve, you are tuned.

So, when we are talking about "pooling" keep in mind that waves are moving back and forth the whole time keeping gases mixed up in the intake track.

-Dana

DivineE

Out of a thread that could have got really silly I think some really interesting stuff has come out. Sure the figures might be wrong but the idea of increasing the bore and shortening the stroke is definitely an interesting one (obviously in combination with greatly reducing the weight of the crank which looks like it came out of the Titanic compared to high revving cranks).

My car has options 1 and 2 from your original post. High lift cams, bigger valves (+porting and all the usual titanium bits), flow matched ports and manifold etc to maximise flow that way. Then a gigantic turbo and a steady 22+psi boost right through to the change point. It also has full stand alone management running real time independent knock control per cylinder allowing it to run very close to pre-det and 40kv of spark from its individual coil pack ignition. Intake temps are surprisingly cool especially due to the climate here..

It was built by Rick in the UK who is well known here. It runs very smoothly, reliably and sweetly and yet on the dyno it would be lucky to produce the 400rwhp figure your talking about.

Maybe this is the thread to ask what gives on the difference in the figures seen on this board compared with cars I've owned? My 3.2 at 18psi only produced 420 flywheel hp and 495lb/ft torque. That's about what 370rwhp?

JDS968

I believe you have that backwards...short stroke for high revs, long stroke for high torque.

David Floyd

^^^ I agree. Kinda like a rabbit and a rhino

gt37vgt

some VGT's turbo's will kind of fit in the standard location ..a mega $aerocharger will.
I managed to fit a gt35vgt in but with a fabricatied engine mount and rhd drive car ..and i little grind of the balance shaft cover ..I think the quick spool vavle with twinscoll gt35bb is a better option..

944obscene

I've learned to keep my mouth (or in this case, my fingers) shut unless I know exactly what I'm talking about. Reading your post about the intake dynamics makes sense for me. Similar to how 2-stroke engines use a special exhaust scavenging system to help pull extra exhaust fumes out of the cylinder with tuned pressure waves.

Looking more into the engine comparisons between smaller 4 cylinders and ours, I've noticed a similar length in stroke. My only conclusion is that our big bore makes for a heavy piston, and the rods probably don't help. But IIRC, the cranks are pretty beefy too.

toddk911

I would put a lot of that on difference in dynos from US and abroad as well as Mustang vs Dyno jet and general dyno operator variances.

944J

dare i post this but Bob Norwood emailed me this info:

Rogue_Ant

944J, what is the date on the email?

JDS968

How many hours running time at [900, 1600, 2500, 3000] before rebuild?

944J

nov 4, 2009

944J

i dont know

George D

It was the most powerful engine Grand Prix racing has ever seen - including the glorious pre-war era with the mighty V12- and V16 units of Mercedes-Benz and Auto Union.The 1.5-litre engine Bavarian Motor Works from Munich entered Formula One atthe South African Grand Prix in 1983 in a Brabham BT50 chassis reached a top level of nearly 1.500 bhp in its qualifying version. In spite of a politically difficult first season with a non-qualification in Detroit as its climax the Paul Rosche designed 4-cylinder-engine became so very fast a competitive one, that Nelson Piquet was able to win the Canadian Grand Prix one week later.

http://www.research-racing.de/bmwturbo.htm

May be a read of interest. Know money, engineering, and money will make your HP dreams come true.

333pg333

Btw, he is still racing a 951 too. Had a motor rebuilt not so long ago after it went bang having purchased it from a very well respected builder. Sent it to Performance Developments to fix.
To clarify, the builder does not appear in this forum.

Chris White

The old Doom engine had a reported life span of .5 hours in race trim.