Real horsepower numbers

[Stella]

I've been into building engines and cars for 15 years. I know that a car manufacturer sometimes under rates the horsepower readings of a car for their own reasoning. The xlr is said to have 320 h.p. so if you deduct for the trans and so on your probably in the 275-300 h.p. range. I've read about people doing mods to their car and picking up big numbers like 40 h.p. from a simple filter mod. Having a little experience I just don't see those big number's. People are saying they've dynoed the car? Would like to know what the base line of the stock car ran. Would love for the car to have those number's just seems a little odd that you can change a air filter and some exhaust ( not full headers,gutted cats,and so on) and get a 40-60 h.p. increase. Now if you base line and the car is putting 320 to the tires yeah maybe you'll see 340 or even 350 h.p. But 360 or 385 just seems doubtful. If there is something I'm missing please let me know just been looking at mods and kind- of shocked at number's. Full throttle!

 

[1BADXLR]

I had mine dyno'd at car craft last july. besides k&n air filters, there was nothing else done performance wise... dyno was 236hp and something like 239 tq. people were hoping it would make more, but its only a northstar... exhaust and headers would help, but as far as the base xlr, you wont find big numbers out of it... just nothing for them.

 

[2004XLR]

I did not have a base line done but after doing a volant CAI and magnaflow exhaust it dyno`d 310hp 308tq I was thinking of getting cams and head work but never did http://www.chrfab.com/ but I am building long tube headers for it so I will re dyno after they are installed.

 

[Stella]

Exactly the numbers I would agree with. No way is a cai and basically mufflers gonna give you 40 or 50h.p. One guy was rattling that he has 385 h.p. first thought he was confusing with a V but not the case. With my experience nothing comes that cheap and easy. Haven't nailed down what's out there but when I do I'll pass it along!

 

[cubby558]

The manufacturer's ratings on the engines are at the flywheel, so you would have to get a baseline at the rear wheels before determining how much more HP you're going to get out of any mods. I haven't dyno'd any of the XLR's I've owned so I can't tell you exactly what I've gained.

If you go to MAM this fall, they have a dyno at the event and you can get it done.

I've been into building engines and cars for 15 years. I know that a car manufacturer sometimes under rates the horsepower readings of a car for their own reasoning. The xlr is said to have 320 h.p. so if you deduct for the trans and so on your probably in the 275-300 h.p. range. I've read about people doing mods to their car and picking up big numbers like 40 h.p. from a simple filter mod. Having a little experience I just don't see those big number's. People are saying they've dynoed the car? Would like to know what the base line of the stock car ran. Would love for the car to have those number's just seems a little odd that you can change a air filter and some exhaust ( not full headers,gutted cats,and so on) and get a 40-60 h.p. increase. Now if you base line and the car is putting 320 to the tires yeah maybe you'll see 340 or even 350 h.p. But 360 or 385 just seems doubtful. If there is something I'm missing please let me know just been looking at mods and kind- of shocked at number's. Full throttle!

 

[Stella]

Yes, those numbers are flywheel number's as we should know what matter's is what makes it to the pavement. Thanks I won't dyno anything until I find the right combination and tuner to make the dyno worth it. The car has a nice 300 h.p. from the factory. Now after a head job and some high lift cams definitely. I think the biggest hurdle is gonna be being the Ginny pig gotta get it right.

 

[rbweddle]

I've done K & N filters. How much HP increase should be expected (above baseline, what ever it is) with a cat-back exhaust (Corsa, etc.)? What about a moderate chip replacement? How difficult to replace chip?

 

[Stella]

The cats are connected to the headers so you'd be replacing both. There are no chips just reprograming if you can find someone knowledgeable . Filters might, might ,maybe 5-10 h.p. and you better take the rain blocker behind the grill off. I don't know for this particular car but ah engine is ah engine unless GM has the engine so restricted that's it's really given good numbers doughtful.

 

[steve246810]

Dyno results corsa exhaust and volant cold air intake

These were just done 3/13/12.
All rating are rear wheel HP
Base (nothing added) HP=254.39 torque 257.41
Volant only (no exhaust) HP=271.26 torque 276.69
exhaust and Volant HP = 280.92 torque 279.17
Real numbers from a Dynojet Winpep 7
I think these are good solid numbers
I can feel some more "go" in the seat of my pants and it sure sounds good.
I'll post some MPG rating as I'm really curious to see if I get an increase in fuel economy.
Hope you find this useful. I've got the sheets so if you want me to e-mail them to you, give me your e-mail and I'll fire them off.

 

[steve246810]

costs

FYI, I got the Corsa on Amazon (true believe it or not) for $1,469.00 delivered (no tax) and the Volant was like $300.00 on e-bay.
Hard to find a great price on the Corsa stuff, but I've got to say, it is high quality stuff and I'm picky. NO DRONE guarantee from Corsa, which I think is a super big deal.