topley

Not your usual question here (I hope), but pardon my ignorance. I will be starting to tune my new engine soon and I'll be running in a weight/hp class. They just changed the rules so now you have to use either hp OR torque, whichever one is larger to find your ratio. With that being the case I would assume I want to have my motor as near equal values for both (assuming it runs well etc.) Most 944 dynos I've seen have a higher tq reading, sometimes a lot more. Is there anything one can do (and is it worth while?) to even out the numbers? Which is more advantageous in this case? Having higher HP and going with that number or higher TQ and going with that one? If they are now looking at TQ shouldn't it be better to use a max HP + max TQ/2 formula to make it fair?

Also since I'm not trying to hit some peak number (I'll adjust my weight to be where I want in class) Is it just larger area under the curve I'm looking for? I'm new to turbos and well.. anything besides spec racing.

Now for the last bit of fuel to the fire... Do different dyno types screw around with this hp/tq ratio for a given car?

Thanks
Jay

V2Rocket

you could take a page from the rally world where they are limited to power output
basically, they size the turbo to get maximum torque ASAP and put a restrictor on the inlet to the turbo to limit peak power by limiting max airflow...so they have these weird HP graphs that pretty much flat line after a certain rpm.

luckily the 951 makes over 240lbft in the middle of the rev range, and has a fairly small turbo standard which can spool well. do you have a target power/torque to weight number? what does the car weigh now?

if you are allowed some mods you could try a larger, catless exhaust post turbo and intake mods as you are allowed (MAF? or must use stock AFM/airbox?) to make the turbo's spooling life easier/faster to get your torque number earlier. adjustable cam gear/offset cam key will help a lot too.

topley

Yeah mods probably should have been posted. Freshly rebuilt turbo motor with stock internals (new stock thermal coated pistons). Aftermarket turbo (ball bearing-A/R .063, and #10 hot side with P trim) Vitesse MAF and a 3" exhaust (no cat.) I'm not planning on running crazy boost, I want reliability first and foremost, but I want to make sure that I don't do something that screws me under the new rule. Of course before this rule was enacted (when I started this crazy project a year and a half ago) I was stoked that 951's made more tq than hp. Under the old rules that would have felt like cheating.

Iridium

Get an rpm adjustable boost controller and set it so you are right at the line basically everywhere. You will have more area under the curve than anything else.

Paulyy

hp > torque on long fast tracks.
Torque > hp on short tight tracks