'05 STi vs '04 LS1 GTO - Page 2
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This is a discussion on '05 STi vs '04 LS1 GTO within the Comparison: WRX vs World forums, part of the Community - Meet other Enthusiasts category; i see that you said "Current Ride - Black 6 Speed, 05 GTO (358 rwhp, 354 lb ft)" so you ...

  1. #16
    Registered User NewCar20's Avatar
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    i see that you said "Current Ride - Black 6 Speed, 05 GTO (358 rwhp, 354 lb ft)" so you have 400 tourque hp and 358 wheel hp? is that correct?

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  3. #17
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by NewCar20
    i see that you said "Current Ride - Black 6 Speed, 05 GTO (358 rwhp, 354 lb ft)" so you have 400 tourque hp and 358 wheel hp? is that correct?

    I made 358 rear wheel hp and 354 lb ft of torque at the rear wheels. This was also in a
    97 degree shop with 60% humidity. So the numbers are a little low.

    Most bone stock 05 GTO's are running in the 330 - 340 rwhp range. A few 05s have pulled
    340-350 rwhp bone stock. There's even been reports of one or two making 350+ rwhp. But these pulls, In my opinion are a little suspect (dyno operators working their magic to get high numbers).


    Wheel hp and wheel torque is usually 15-25% of engine hp and engine torque . It depends on many factors including the type of dyno, transmission, etc.. But 17% is a good place to start for a manual transmission.
    Example
    400hp x .17 = 68
    400 - 68 = 332
    So 332 wheel hp should equal 400 crank hp (or engine hp).

    Using this formula to determine my engine hp.
    430hp x .17 = 73
    430 - 73 = 357hp
    So my 358 wheel hp should equal about 430 crank hp
    My 354 lb ft of torque should be about 425 lb ft of torque at the motor.

    Lets us this formula for an STi.
    300hp x .17 = 51
    300 - 51 = 249 wheel hp
    So 249 wheel hp should equal 300 crank hp. And most STi's dyno in the 240-250 wheel hp range.

    Lets do a WRX
    227hp x .17 = 38
    227 - 38 = 189
    So a WRX should dyno around 189hp at the wheels? I'm not sure what a WRX really dyno's at but I would bet its close to this number.

    Another thing is awd dyno's typically produce lower numbers than other fwd/rwd dynos.

    But you get the idea.

  4. #18
    Registered User 04wrx4keeps's Avatar
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    Quote Originally Posted by SGOSWRX
    I made 358 rear wheel hp and 354 lb ft of torque at the rear wheels.
    Wheel hp and wheel torque is usually 15-25% of engine hp and engine torque . It depends on many factors including the type of dyno, transmission, etc.. But 17% is a good place to start for a manual transmission.
    Example
    400hp x .17 = 68
    400 - 68 = 332
    So 332 wheel hp should equal 400 crank hp (or engine hp).

    Using this formula to determine my engine hp.
    430hp x .17 = 73
    430 - 73 = 357hp
    So my 358 wheel hp should equal about 430 crank hp
    My 354 lb ft of torque should be about 425 lb ft of torque at the motor.

    Lets us this formula for an STi.
    300hp x .17 = 51
    300 - 51 = 249 wheel hp
    So 249 wheel hp should equal 300 crank hp. And most STi's dyno in the 240-250 wheel hp range.

    Lets do a WRX
    227hp x .17 = 38
    227 - 38 = 189
    So a WRX should dyno around 189hp at the wheels? I'm not sure what a WRX really dyno's at but I would bet its close to this number.

    Another thing is awd dyno's typically produce lower numbers than other fwd/rwd dynos.

    But you get the idea.
    just keep in mind that usually AWD drivetrains are a little less efficient than those in 2wd cars. I would use a 20% calculation rather than 17% as a rule of thumb, although depending on the dyno used there will be a difference, but thats why awd dynos tipically produce a little less power, because the cars simply put less down due to parasitic loss...besides its always nice to figure on the lower end and then be pleasently surprised on a nice dyno than to go expecting more and getting less.

    BTW nice numbers on the GTO, what mods do you have for the extra 30hp? I'm assuming simple bolt ons would do that on the GTO, maybe even just a catback (I know the LS1 TA and Camaros come with really restrictive exhausts and love exhaust mods, am I correct in thinking the beefier GTO motor has this problem too?)?
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  5. #19
    uke
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    How did the Regal do? (I'm assuming it was a Regal GS?)
    06 GTO - yeah, it's pretty quick
    Grand Prix GTP-gone

  6. #20
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by 04wrx4keeps
    just keep in mind that usually AWD drivetrains are a little less efficient than those in 2wd cars. I would use a 20% calculation rather than 17% as a rule of thumb, although depending on the dyno used there will be a difference, but thats why awd dynos tipically produce a little less power, because the cars simply put less down due to parasitic loss...besides its always nice to figure on the lower end and then be pleasently surprised on a nice dyno than to go expecting more and getting less.

    BTW nice numbers on the GTO, what mods do you have for the extra 30hp? I'm assuming simple bolt ons would do that on the GTO, maybe even just a catback (I know the LS1 TA and Camaros come with really restrictive exhausts and love exhaust mods, am I correct in thinking the beefier GTO motor has this problem too?)?

    I have Kooks long tube headers and a New Era intake. Those are my only power mods. I went from
    320 rwhp to 358 rwhp with headers, intake. and tuning.

    Yes, my 05 GTO only made 320 rwhp bone stock (on this particular dyno - 04 (ls1) GTO's only make 280 rwhp). My GTO was also running extremely rich and out of tune from the factory. So I picked up 38hp with headers, intake, and tuning - not too bad

  7. #21
    Registered User wrxaddicted's Avatar
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    Quote Originally Posted by SGOSWRX
    I have Kooks long tube headers and a New Era intake. Those are my only power mods. I went from
    320 rwhp to 358 rwhp with headers, intake. and tuning.

  8. #22
    Registered User Slick:6:STi's Avatar
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    Do not take offense to this!

    I find it very weird that your "400 HP" car would dyno at 320 rwhp, while my "390 HP" car dynoed at 356 rwhp. I guess Chevy either overrates their cars or Ford underrates them. Something ain't right with GM though I think. Don't C6s only dyno at 333 rwhp or so? Hell I know one C6 that dynoed at 319 rwhp
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  9. #23
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by Slick:6:STi
    Do not take offense to this!

    I find it very weird that your "400 HP" car would dyno at 320 rwhp, while my "390 HP" car dynoed at 356 rwhp. I guess Chevy either overrates their cars or Ford underrates them. Something ain't right with GM though I think. Don't C6s only dyno at 333 rwhp or so? Hell I know one C6 that dynoed at 319 rwhp
    First off
    Comparing a 03+ Cobra to anything is difficult. Cobras are making a good 430hp stock and respond to mods better than anything around. But it hasn't always been this way.

    Ford/SVT learned from their mistake a few years ago when a bunch of Cobra owners found out their cars weren't making the advertised HP. You remember that. There were a bunch of very mad Cobra owners that had to bring their cars into the shop for the "fix". To bring them up to the advertised HP.


    The LS1 z28. They were suppose to only be making 305hp back in 1999. Yet many LS1 z28s were dynoing close to 300 rwhp stock -some even higher. That is a case where GM severely underrated one of their cars. The LS1 z28/Trans Am has always made close to 350hp . The 04 GTO (which was rated 350hp) runs the same engine setup.

    As far as the C6 and 05 GTO, its not over rated or under rated.
    Most C6s are dynoing in the 340 rwhp range (which is right where they should be for 400hp). 05 GTOs seem to be losing a little more power getting to the wheels. 330 rwhp-340 rwhp is about average for a 6 speed GTO.

    My 320 rwhp is a good 10-20hp lower than most 05 GTO's dyno. But on the dyno I used I watched an LS1 6 Speed only make 288 rwhp. Thats low for a 6 speed LS1. So its a conservative dyno. Not all dyno's are the same.

    But what matters is getting a good baseline from a dyno so you can see if your mods are working. It really is hard to compare dyno numbers from different dynos.

  10. #24
    Registered User Slick:6:STi's Avatar
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    I know dynos read differently, that is why I asked which dyno you used. I was on a Mustang Dyno, which generally reads lower than the dyno jet (I think that is the name). GM Said the LS1's (in camaros & T/As) were underrated but eveyone new it was the same engine as the Vette's LS1, so it was really 350 hp. That point is moot, along with the 99 cobras, that is history.

    I want to know why GM announces the numbers and then doesn't follow through.

    I agree that the Cobra is underrated, although one yellow vette owner told me I was full of isht about that.
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    466 rwhp
    473 rwtq
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    Southpaw = Ricer with a vette & 2 Gay 2 Curios (well not yet anyway!)

  11. #25
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by Slick:6:STi
    I know dynos read differently, that is why I asked which dyno you used. I was on a Mustang Dyno, which generally reads lower than the dyno jet (I think that is the name). GM Said the LS1's (in camaros & T/As) were underrated but eveyone new it was the same engine as the Vette's LS1, so it was really 350 hp. That point is moot, along with the 99 cobras, that is history.

    I want to know why GM announces the numbers and then doesn't follow through.

    I agree that the Cobra is underrated, although one yellow vette owner told me I was full of isht about that.

    I do tend to agree with you. I don't think any of the C6s or GTOs should dyno any lower than 340 rwhp. 340 rwhp is a very respectable number for a 400hp car.
    400 x .15 = 60 hp. So given a 15% loss that would give 340rwhp. Most cars will give up at least 15% or more getting the power to the ground.
    But when your making 330 rwhp or less, your numbers are getting too low for a 400hp car.

    It's becoming pretty well known that many (not all) of the LS2's are very out of tune from the factory. I think GM screwed up or went way too conservative with the tuning. My stock 05 GTO's AFR was way out of wack. This seems to be the case with most the stock GTO's.
    I know of a guy that went from 330 rwhp to 354 rwhp by just leaning out his AFR (still a stock GTO). So GM left a lot of power sitting on the table.

    There are also a few LS2 GTO's making decent power. I know of one that is making
    375 rwhp with headers. I also know of a couple making 355 rwhp stock.
    But as you know you can't always trust dyno numbers.
    Last edited by SGOSWRX; 07-20-2005 at 10:58 AM.

  12. #26
    Registered User Slick:6:STi's Avatar
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    That sucks that they kind of backed off on the tune. I have someone that is willing to buy my Cobra for a few grand more than I paid for it and I was contemplating a GTO. I am not a Ford only man, anything that is fast is good for me. I am actually disapointed in GM for doing that, but then again they have been screwing over GTO owners from the start. The guys I feel real bad for are the guys that bought the first 04s and paid a markup for them. They must be miserable right now.
    New Numbers
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    Southpaw = Ricer with a vette & 2 Gay 2 Curios (well not yet anyway!)

  13. #27
    Registered User 04wrx4keeps's Avatar
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    One thing to consider too is that if you look at alot newer cars its not hard to immagine some of the newer car manufacturers releasing under-tuned cars so that aftermarket tunners and hot-rodders acctually have something to play with, not to mention less warranty issues. since on most dynos the LS2 cars put down 340ish whp they didnt underrate it, but obviously if they really wanted to they could have tuned them a little better. Not to mention that a richer AFR is going to have less chance of knocking and therefor be safer in the multitude where the cars are sold across the entire country.

    One thought too, since you say some people are seeing this and some arent, is it possible that some of it might be due to ecu learning? I know back when the WRX first came out SCC mag had dyno'd over 10whp drop between the learned ecu (after driving it for a while) and then fresh after they reset it.
    Cobb Stage 2.5 VF-34 + uppipe
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  14. #28
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by 04wrx4keeps
    One thing to consider too is that if you look at alot newer cars its not hard to immagine some of the newer car manufacturers releasing under-tuned cars so that aftermarket tunners and hot-rodders acctually have something to play with, not to mention less warranty issues. since on most dynos the LS2 cars put down 340ish whp they didnt underrate it, but obviously if they really wanted to they could have tuned them a little better. Not to mention that a richer AFR is going to have less chance of knocking and therefor be safer in the multitude where the cars are sold across the entire country.

    One thought too, since you say some people are seeing this and some arent, is it possible that some of it might be due to ecu learning? I know back when the WRX first came out SCC mag had dyno'd over 10whp drop between the learned ecu (after driving it for a while) and then fresh after they reset it.

    It's funny you mentioned this.
    GTO owners are reporting running several tenths faster at the track by resetting their ECU.
    This is also the trick several GTO owners have used to produce higher than average dyno numbers.

  15. #29
    Registered User 04wrx4keeps's Avatar
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    Quote Originally Posted by SGOSWRX
    It's funny you mentioned this.
    GTO owners are reporting running several tenths faster at the track by resetting their ECU.
    This is also the trick several GTO owners have used to produce higher than average dyno numbers.
    interesting...so its like the opposite of the WRX's usual learning...the GTO gets slower as you drive it then, it must be pulling timing or something like that I would think. Or maybe since most people will probably use very little of the cars power just driving it around (with all that low end tq I would immagine you dont need to) it must get used to that driving style. hell, if resetting it puts it back to normal though, I'd be pulling the battery every night when I turned the car off lol...
    Last edited by 04wrx4keeps; 07-21-2005 at 02:08 PM.
    Cobb Stage 2.5 VF-34 + uppipe
    Best ET so far - 13.1@103 with a 1.81 60'

  16. #30
    Registered User SGOSWRX's Avatar
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    Quote Originally Posted by 04wrx4keeps
    interesting...so its like the opposite of the WRX's usual learning...the GTO gets slower as you drive it then, it must be pulling timing or something like that I would think. Or maybe since most people will probably use very little of the cars power just driving it around (with all that low end tq I would immagine you dont need to) it must get used to that driving style. hell, if resetting it puts it back to normal though, I'd be pulling the battery every night when I turned the car off lol...
    Yea, most cars increase performance with time after a reset. But I think a quick reset with the GTO is leaning it out by temporarily removing the conservative tune.
    One guy over in LS1GTO.COM said he took out the mas screen, and reset the ECU and made a quick 24rwhp on the dyno.

    The GTO also has something called Torque Managment. GM designed this torque managment as a way to control the power delivery (to make it smoother especially between shifts). For whatever reason they didn't want neck snapping power, especially in the automatics? What its done is taken away a lot of performance from the car. Luckily this can be removed with tuning.

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