Larry Herman

Well all you have to do is get a GT3 down to 2100 lbs. You don't even have to touch the motor! It's amazing what 2 extra valves will do.

N51

Not given Bob Linton's resources, is that possible - a 2100# GT3? Geoffrey's approach would, I think, be far less costly. I would also expect the two valve engine to produce more torque, but give up some power to the stability of a watercooled engine.

Noah

Geoffrey

I've done some work with the 4 valve engines and they are far better than the air cooled engines in every respect including cost, except for weight and produce more power and torque across the range. A GT3RSR is listed at 2400lbs and I know Rick Deman's freshly built GT3RS weighed in the 2500lbs range, so getting much below 2400lbs is going to be very difficult if not impossible using normal manufactured parts.

I had considered installing a modified GT3 Cup engine into my chassis, but I didn't want to deal with the extra weight penalty.

VE% = Volumetric Efficiency - The theoretical maximum amount of air that each cylinder can ingest during the intake cycle at a given RPM. VE will change based on engine load and engine RPM and will mirror the torque curve of an engine. 100% VE is equal to the volume or displacement of a cylinder or an engine depending on what you are measuring. Ignoring the fact that a 3.8l engine is quite 3.8l, 100% VE for a 3.8l (231.89ci) engine operating at 6000rpm is 231.89 x (6000/2) / 1728 which gives you 402.59CFM of air. On an engine dyno, if you had an air turbine measuring the incomming air through the intake system if you saw 402.59CFM at 6000RPM, then your engine would be operating at 100% VE. Volumetric Efficiency is really a poor choice of wording although it is the industry standard termonology. My reasoning is that the cylinder always has the same volume of air, it is the density that changes, so really it should be called massemetric efficiency.

NVR = Non VarioRam intake (I'm guessing here)

Larry Herman

That's the "tongue in cheek". It will be much easier to build Geoffery's car than to get a GT3 down to 2100 lbs. I don't think that would be remotely possible, unless you built a tube frame off of the cabin and used carbon fiber bodywork everywhere.

audipwr1

After spending the last hour reading all of the Racecar Project posts I am
Very very impressed

I think i will start to embark on a mini-Geoffrey project for the street

The level of thought here takes me back to my FSAE days. Prove everything you do.

I did some similiar research on port flow in school and it is a safe assumption to go with imcompressible flow when doing calculations based on flow bench numbers

Indycam

"NVR = Non VarioRam intake (I'm guessing here)"
Non variable resonance ?

agentpennypacker

996 platform? Hmm...

Cupcar

Are the 9M heads available for early engines as well?

How much $$$?