3.8 Whipple vs Stock Engine Dyno

[HKusp]

No reason to stay at only 650-700 unless you're limited by pump gas

Remember that turbos are more efficient than superchargers so they are going to making more power either way.

There certainly is a lot of parasitic draw on a supercharged engine versus a turbo. That drag takes a lot of HP (and stress) to overcome.

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[Mach1Racer]

The inherent thermodynamic advantage of turocharging…

IMO 850 is a nice place to live because the engine is reliable, fuel system is simple, and traction is manageable.

850rwhp does sound nice but I’m already pass that as it looks like you are too. I feel like I want to hit this 900rwhp club. You know, just dip my toes in the water a bit.

 

[HKusp]

850rwhp does sound nice but I’m already pass that as it looks like you are too. I feel like I want to hit this 900rwhp club. You know, just dip my toes in the water a bit.

I built mine to hold 1200whp (in theory) and my plan was always to go to a dyno day and see if I could get a 4 digit number just so I could say I was there, and then back it down to live a happy life in the 850-ish whp range. It has not, to date, played out that way...

 

[Autopart101]

Strange finding. 3.8 Whipple made 950whp on a 3.5 pulley 20* timming. Fast forward same tunner same 20* Timming 3.25 pulley same dyno same correction factor, made 1045whp. Was it weather conditions or 3.8 becoming more efficient with increased RPMs?

 

[Autopart101]

I’d like to know what it will actually hold as long as the tuning, rev limit, and fuel system have everything well controlled. I know drp tends to keep the timing a little conservative which helps manage cylinder pressure.

I would like to know also. How much WHP do you think it takes to turn a 3.8 Whipple? 75-100? If so stock Gen3 could be holding 1150whp.

 

[engineermike]

I would like to know also. How much WHP do you think it takes to turn a 3.8 Whipple? 75-100? If so stock Gen3 could be holding 1150whp.

Quick and dirty math says about 100-150.

 

[Mach1Racer]

Quick and dirty math says about 100-150.

Can you show us how you determined this? I’m very interested in how you determined the parasitic loss of the supercharger.

 

[engineermike]

Can you show us how you determined this? I’m very interested in how you determined the parasitic loss of the supercharger.

it’s a basic air compressor calculation and the calculators are available on various websites. I estimated airflow at 3.8 x 6.5 / 3.25 x 7500 to get LPM. Actual will be a little less due to <100% ve. Efficiency is a guesstimate as well.

Technically the power isn’t “lost” though. You get some of it back because the intake strokes with positive pressure become mini-power strokes. It’s just that with turbocharging you’re getting the energy from exhaust heat rather than taking it off the crank.

 

[xr4x4ti]

it’s a basic air compressor calculation and the calculators are available on various websites. I estimated airflow at 3.8 x 6.5 / 3.25 x 7500 to get LPM. Actual will be a little less due to <100% ve. Efficiency is a guesstimate as well.

Technically the power isn’t “lost” though. You get some of it back because the intake strokes with positive pressure become mini-power strokes. It’s just that with turbocharging you’re getting the energy from exhaust heat rather than taking it off the crank.

If you you want to get nerdy, it works both ways. While the supercharger does "push" the piston down on the intake stroke, a street turbo with a 2:1 back pressure to boost pressure pushes on the exhaust stroke. It still works out in the turbo's favor, but it is a reasonable amount of power loss.

Now, if you can tune the turbo so that the exhaust back pressure is less than the boost pressure, then you are literally extracting energy from the exhaust and adding it to the crank by pushing the piston down on the intake stroke. This is generally tough to do on street oriented turbo setup with reasonable response and boost threshold.

 

[xr4x4ti]

Quick and dirty math says about 100-150.

I calculated 142hp supercharger power for comparison using 65% compressor efficiency, 80% intercooler efficiency, 20psi boost at 8100 rpm.

 

[xr4x4ti]

Can you show us how you determined this? I’m very interested in how you determined the parasitic loss of the supercharger.

Here is a calculation sheet I have been using for years. I put in some values for OP.

 

[J17GT]

Impressive! That math gives me nightmares.

 

[wingnutt]

Impressive! That math gives me nightmares.

lol, same…that ain’t math, too many letters in it

 

[Autopart101]

The inherent thermodynamic advantage of turocharging…

IMO 850 is a nice place to live because the engine is reliable, fuel system is simple, and traction is manageable.

Above 850 the 10R80s start to slip if you dead hook. 850 and under is a good place to live and is a very fast car.

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