Jean

It must be that I have language barrier problems I do not aspire to 100-150 additional hp.

I am just saying that a 3.2 ltr turbo cannot give you 735 hp at 1 Bar as Steve mentioned (With all due respect of course) since it would be in 996 GT3 RSR territory as far as efficiency is concerned. Can you see a bsac reading of 11-12 in a 3.2 ltr turbo engine at 7k RPM? I don't think so.

I always thought that US tuners were into the hp game whereas European were more into torque. Sportec in Switzerland only talked about low-mid-range torque and hp when I was dealing with them, and this is why they only wanted to give me modified K16s.

I feel I am a contrarian here so I will stop this debate if I am pushing too far.

Kevin

Jean are race track are shorter, our freeways don't have the unlimited speeds.. Yes, we want high HP, but we have to tune for the masses, and that is for torque. No lag, with power building as soon as possible, vs the approach of strapping large turbo's on an engine and creating drag cars.. You have two camps of thoughts with a turbocharged engine, power now or power later, you can't have it both ways in the RPM band.. It's funny the crowd seeking to build drag cars should be buying the early 935 engines and doing 6K burn outs..

Steve Weiner-Rennsport Systems

Jean:

LOL,.......Indeed, our N/A early 3.0 & 3.2 RSR race engines did exceed 400 HP on the dyno but these were 12 hour motors (at best)

Kevin mentioned some key things; the 935 engines were (are) somewhat cantankerous running things that make little power until 5000 RPM and the power delivery is sudden. These need to be rebuilt every 24 hours (or less, depending on boost pressures selected during a race).

Its all about increasing volumetric efficiencies over the selected RPM range one needs and that determines how you go about doing that.

For the record; we did very well for several years in IMSA & TransAM with the 935's using those 3.0 & 3.2 (factored for weight) motors and now we handle one for a local customer who needs decent engine longevity,...hence the 1.0 bar limit on his motor. That one made 735 HP (with MoTeC) on our Superflow engine dyno and 545 HP at the rear wheels on a Dynojet 248c. Chassis dyno figures are lower since the wheels were slipping on the rollers as we tested to 190 MPH.

Jean

Amazing numbers bearing in mind that the current racing 3.6/3.8 RSRs have similar output! You are a lucky man to have worked on those cars

Slippage is difficult to measure obviously, but 545 hp at the wheels is around 620-640 hp at the flywheel ( 2WD cars), which is in line with my earlier comments, .." The best 3.8 Ltr GT2 EVO had 640 hp at 0.8 Bar" .. and a greatly prepared 3.2 with Motec can be somewhere around that same 620+ at 1 Bar.

As you said, the late 935, with 4 valve heads were undrivable below 5000 RPMs (read , NO area under the curve ) due to radical cams and turbos, and they were seeing close to 750 hp, but at 1.4 Bar.

Back to the thread and sorry for the OT, Marty, you don't want to drive beyond 1 Bar if your engine needs to last, stress levels are exponential ( I think I have said that before?). I even got Steve W. and Kevin to agree with me to that

Steve Weiner-Rennsport Systems

Those motors were HIGHLY modified and represented thousands of hours of R&D time.

Slippage is a big problem with very high powered cars on slicks that never warm up enough to establish good grip on the rollers. We never saw accurate numbers on the Dynojet that reflected engine dyno performance. That's why engine dyno's are far better tools for engine development & tuning.

Indeed!

CP

2WD turbos are rarer than a hen's tooth, unless it's a GT2. Praise the lord for my RUF BTR and a RUF LWF. It's magical.

CP