audipwr1

Motorsports folks

I am looking to buy a racecar with a 997.2 GTS motor in it (so crank rated ~410hp) its the 3.8 liter 9a1 final variant more or less - is there a reasonably feasible way to get that detuned to 285whp?
What would be the best way to do so?

Matt Romanowski

That's a pretty loaded question. You could do it with just an inlet restrictor, but I think that would be a bit crude. If you had a good tuner/calibration specialist, it would take some work to find the best way to restrict airflow and then have a good ECU profile to get a great torque curve. That assumes you can change the ECU.

Nowanker

Define 'reasonably feasible'...
A.) Inlet restrictor.
B.) Reprogram the ECU to only allow X throttle. Essentially the same, but might allow better tailoring of the HP curve.
C.) Change camshafts to favor low end torque at the expense of high RPM torque. HP curve has more 'meat' in it, but peak HP is limited.
D.) Some combination of A/B and C.
Depending on the sanctioning body's rules, C might not be as productive as it could be.
NASA (for example) is wise to the detuning game.
Some (all?) of their power to weight ratio classes can also put torque values into the equation.
E.) Lower compression and/or retard timing (don't do that...), in combination with any/all above. E sounds like 'not reasonably feasible'...

dan212

So much surgery.

But before you do ANYTHING, check with whatever sanctioning body is appropriate to see if they will accept these changes at all.

Veloce Raptor

Or......run it on Pemex 85 octane swill

jerome951

Limit RPMs so you maintain good torque??

Nowanker

Might work....
Holes in the pistons are pretty effective at limiting power!

analogmike

Don't forget to mount a switch so you can go to original power during the race, as expected with dyno-based classes.

RossP

I imagine this is pretty straight forward with a custom tune. (This was very common when I was racing BMWs)

Cory M

You might try Vision Motorsports. They have done this for customers in power to weight GT classes. Maybe they could do a remote tune.

mehoff

Has anyone tried putting a 68mm boxster throttle body on a later motor? Restrictor packages don’t seem to exist for street motors

bgiere

Here ya go. We use them, they work perfectly.

https://demonspeed.com/product/restr...1-and-997-cup/

powdrhound

We did this with my engine running on a Motec M150 ECU. We have 10 torque based maps that are cockpit selectable on the C1812 display. Any competent tuner should be able to write a reduced output map although it will be much easier with a standalone.

Nowanker

Gotta ask....
What engine is that making 800+ HP?

powdrhound

Its a 4.0 Turbo Mezger....