Thread: upgrading performance

Originally Posted by JGT010

Hi all, I've heard of this U-Bend Delete mod. before. I have a little better idea of the concept of this modification from these posts. I have a 07 3.8 Grand Prix GT (supercharged). What do ya all think, would my car benefit from this type of modification? The only mod I have right now is a Cold Air Intake. I would like to get this car up to about 300 horses. Right now I would give it 270, maybe a few more. I don't know if I want to go with a complete reconstruction of the total exhaust system. I don't think its that restrictive.

270? Intercooler/Headers/3.1" Pulley

Maybe 300.

Originally Posted by bluegtp91

270? Intercooler/Headers/3.1" Pulley

Maybe 300.

I think he is thinking crank horsepower not wheel horsepower.

JGT, realize that 260 rating is at the crankshaft. When we begin modding our cars we test for horsepower at the wheels. Because of the parasitic loss caused by the engine needing to turn the gears in the transmission, the axles, hubs, and finally tires/wheels, 100% of that power does not make it to the ground. Most experts in our community place our drivetrain loss at around 15-20%. Thus if you see someone on here saying they have 300 HP they mean they have 300 wheel horsepower. That would be apx 350-375 crank horsepower. Your 260 crank hp winds up being apx. 208-221 wheel hp.

Originally Posted by Robotech

I think he is thinking crank horsepower not wheel horsepower

That's what I meant too

I just wasn't in the mood for explaining it like you did

Funny, but most L32 cars I have seen don't make as much power as L67 cars stock for stock...I've just wondered why that was...maybe it was the dyno's being used idk. You would think they would make more because of the GenV Or maybe I just haven't seen enough dyno sheets...

Originally Posted by bluegtp91

That's what I meant too

I just wasn't in the mood for explaining it like you did

Funny, but most L32 cars I have seen don't make as much power as L67 cars stock for stock...I've just wondered why that was...maybe it was the dyno's being used idk. You would think they would make more because of the GenV Or maybe I just haven't seen enough dyno sheets...

I haven't seen any dyno sheets on this, but I did drive a couple of the 04+'s and was not impressed by their performance both handling and acceleration.....imho....maybe I just wasn't test driving the right ones????? I was looking at getting one for the wife........but it doesnt look like that will happen. I will look for something else.

the 04+ cars make a little bit more power, but they are heavier. its really a trade off. i still think the 97-03 look better.

Originally Posted by Robotech

I think he is thinking crank horsepower not wheel horsepower.

JGT, realize that 260 rating is at the crankshaft. When we begin modding our cars we test for horsepower at the wheels. Because of the parasitic loss caused by the engine needing to turn the gears in the transmission, the axles, hubs, and finally tires/wheels, 100% of that power does not make it to the ground. Most experts in our community place our drivetrain loss at around 15-20%. Thus if you see someone on here saying they have 300 HP they mean they have 300 wheel horsepower. That would be apx 350-375 crank horsepower. Your 260 crank hp winds up being apx. 208-221 wheel hp.

I got such a hard on reading that...I love it when you use those big, sexy words.


-Swash

Originally Posted by bluegtp91

That's what I meant too

I just wasn't in the mood for explaining it like you did

I'd hope with an I/C, 3.1, and the rest that he'd see more than a 40 crank HP gain! LOL

Originally Posted by swash

I got such a hard on reading that...I love it when you use those big, sexy words.

Down boy!

Originally Posted by Standby

i know you guys keep saying delete the u-bend, well i still have to do this but ive been reading and if i just delete the ubend its only a 2.5 inch isnt it better to go to a 3 inch dp? just wondering

Sure it is...sort of. If you "just" delete the U-bend - you will stay at the stock exhaust size from the manifold to the muffler = 2.25". If you put in a 3" downpipe - you will help the motor breathe - but you are still going from manifold -> 3" -> 2.25". The "ideal" situation is to go 3" DP to full 3" exhuast - but that can create a cash hemorrhage.


-Swash

Originally Posted by Standby

so your saying either way at the end it is going to 2.25 right? unless you finish the 3 right to the end

You got it.

-Swash

3" is a waste of money past the downpipe. all you need is 2.5". hell, i run a stock catback because its nice and quiet.

Originally Posted by Bio248

3" is a waste of money past the downpipe. all you need is 2.5". hell, i run a stock catback because its nice and quiet.

Actually - that is true - you can run 2.5" and it will be more than adequate. I'm not sure what the diff is between 2.5 and 3" (cost).

-Swash

Originally Posted by Swash

Actually - that is true - you can run 2.5" and it will be more than adequate. I'm not sure what the diff is between 2.5 and 3" (cost).

-Swash

Calvin made mine Shannon...3" all the way from the downpipe back for $250

Originally Posted by bluegtp91

Calvin made mine Shannon...3" all the way from the downpipe back for $250

G&C's is the hook up. He did both of my Spintechs and modified my GTO DP a bit - for $50.

-Swash

For sure...did I mention the $250 got me my original single outlet tips, 2 Flowmaster 40's AND labor? LOL I love that place!!

Dang. I'm in need of a new exhaust but I have a feeling the drive to MO would offset the cost savings from getting it done here.

IF you have someone redo your exhaust, I HIGHLY suggest having them center the Y in the back so that the length of the exhaust to each muffler is the same. Ever see a stock GP idling in the morning and notice that the passenger side muffler is putting out more water vapor than the drivers?