Alright guys here's the question. When you talk about your car and someone asks how much horsepower the GXP has what do you say, 275 or 300. I know we have the VIN Y motor that GM rates at 275 but with our factory tuned exhaust system I'm thinking in reality we're somewhere in the middle. People like a round number and even though 300 HP isn't quite what it used to be it still gets respect. So what do you say about your horsepower level to a layman and how do you feel about our cars possibly being under rated just a bit?

my answer always been 300 lol

i think John will be the only one with 400 :P

depends on if you want to run em, then you probably say its a stock six like i do

i assume the HP rating is SAE verified, in which gase GM would have had to print/state an accurate number

The HP~Ft/Lbs was certified http://archives.media.gm.com/us/powe...0LD8%20DTS.pdf 275HP@295 Ft/Lbs.

And people often misquote the certified specs for the L37, it was not the rounded 300. http://archives.media.gm.com/us/powe...0L37%20DTS.pdf It was 292HP@288Ft/Lbs

The LD8 motor's tuning profile wasn't actually "de-tuned" It was altered to provide slightly more torque then the L37. One of many cases of "it isn't the HP.... but what is done to deliver the most torque out of HP. A physics item hard to explain or rationalize to numbers oriented people. But the simple fact is more torque, faster car. A LD8 has an advantage over the L37 torque-wise and I've read that was the reason Pontiac's concept team went with it. Same price point really to them.

To bad they couldn't have swallowed some warranty worry and used the LD8's brother the LH2. Same engine with 10.5 to 1 compression (LD8 10 to 1) That half point takes the 4.6L to 320 hp @ 315 Ft/Lbs. A bit more than the GM Engineering's 305 max for the pricey (in Pontiac terms) 4T80e tranny.

I just state both numbers when people ask and sometimes add "up to 350ish HP" with spraying. I really don't use the nitrous much anymore and even though my kit has 75-100-150 HP add nozzles; the engine has stumbled on the 100 HP nozzles and caused me to back down.

The whole thing really doesn't bother me. I bought the car new and if I wanted sheer numbers/performance there was a nice black on black GTO sitting next to it with solid numbers. For less money. I bought the car because of it's room, style, and comfort along with a nice smooth Northstar. Unique to Pontiac as well as the GXP badging. Coming into this forum 5+ years ago gave me a Mod bite but it has faded. Still happy with my purchase and never looked back at the GTO. If I wanted a nice looking track car, it can be found for half the tradein value of what I now own. But it would not have the things that attracted me to the GXP in the first place. If I wanted raw muscle, with 30k cash in my hand, I wouldn't have been shopping at Pontiac in the 2000's. ;)

so the LD8 is rated at 295 torque? i always thought it was 300

There's a catch to auto figures like most things. It is rated and advertised @ 275HP/300FtLbs but they only pushed it to 292 for that cetification. And it was in a DTS. I find it interesting the torque fell off so quickly. If we had gotten the LH2 tune profile the car would be a different animal and most likely put the fat girl into the 13's stock.

the only difference between the LD8 and LH2 is the compression ratio?
so i guess even if they hack into the GXP's PCM it wouldnt change much tune wise, would it?

the LH2 has VVT.