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Thread: HP or Torque ? for lower lap time ?

  1. #41
    Senior Member robburgoon's Avatar
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    Quote Originally Posted by bellwilliam View Post
    am I the only one confused by what Tyler and Burgoon said ?
    Yes.

    Ask us again when you have hp curves to show us. Until then, I refuse to answer since you aren't asking an answerable question with the data you have provided.

  2. #42
    Senior Member robburgoon's Avatar
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    Here's half of it, now you just need to find Gordon's dyno curve.

    reid-z28-dyno-10-07-06.jpg
    Last edited by robburgoon; 08-25-2011 at 01:57 PM.

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    Senior Member robburgoon's Avatar
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    Oh, and you also need to tell us what RPM you end up at after a shift. Maybe like 4,000?

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    Gearhead gixxer_drew's Avatar
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    Take the peaky power curve and the non peak power curve, do your gear optimization for both (or if you have just one gearbox calculate from that) and what you need to compare is motive thrust average over the course of a lap, the end. You can do that in excel, you dont necessarily need a sim package for it.
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  5. #45
    Gearhead gixxer_drew's Avatar
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    Quote Originally Posted by emilio700 View Post
    Spoken like an engineer.

    IOW, huh?
    I think I take that as a compliment

    Not sure what IOW means though?
    Andrew M Brilliant
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  6. #46
    Smack-Talkin' Member J. Tyler's Avatar
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    Quote Originally Posted by robburgoon View Post
    Yes.

    Ask us again when you have hp curves to show us. Until then, I refuse to answer since you aren't asking an answerable question with the data you have provided.
    +1

    William, that question is now getting into real-world applications which adds a lot more variables than my simple theoretical speculations about Power, Work, & Force.

    Quote Originally Posted by gixxer_drew View Post
    Take the peaky power curve and the non peak power curve, do your gear optimization for both (or if you have just one gearbox calculate from that) and what you need to compare is motive thrust average over the course of a lap, the end. You can do that in excel, you dont necessarily need a sim package for it.
    +2, the end. My dad does this for every track he goes to.

  7. #47
    Senior Member bellwilliam's Avatar
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    bmw-335i-335is-dyno-test-n54-group-torque.jpg
    that's the kind of torque I am talking about... for a gas engine.
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    Senior Member robburgoon's Avatar
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    Back to William's original question, the other reason why Richard Petty is winning with his big torque (wide horsepower curve) is when racing wheel to wheel in traffic, often times something strange will happen like you'll run down a slow ass E36 bmw, have to brake, and you'll find yourself in the wrong gear. In my miata, I curse and slam it down into 3rd. In a corvette, you say "wrong gear? what's that?" and give the slow prickster the finger as you rumble past quickly back into the powerband.

  9. #49
    Senior Member robburgoon's Avatar
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    A Horsepower curve would help William, I don't want to plot anything.

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    Senior Member vetteguy2005's Avatar
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    Default Hp/tq

    final CSOC tune Jan 2011.pdfGraph.pdfAttachment 3660Attachment 3661Attachment 3658Attachment 3659Attachment 3657Attachment 3657Sorry for butting in William, but maybe we can learn something from a problem I am having. I bought an engine that was advertised as 510 HP.

    The builder asked me where I wanted the torque curve? I told him low end torque because I thought it would give me more exit speed out of the corners. I ended up with a forged engine with a cam and head package that is actually slower than my old OEM stock engine.

    The original engine dynoed at 359 Whp, the new motor even on the same dyno and with the same tuner can only produce 350 whp.
    I also changed the differential from a 270 gear to a 315 gear.

    Did I get ripped off or is it just the gearing and set up of the cam causing it to be slower?

    Thanks for any help you guys can give me. I feel ripped off as I explained to the builder I needed to run with the ZO6's and they run off and leave me on the straights even more now than before.
    Attachment 3658Attachment 3659
    Last edited by vetteguy2005; 08-25-2011 at 08:19 PM.
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    Senior Member robburgoon's Avatar
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    Diff change shouldn't have much effect on horsepower. Perhaps it was a 510hp engine before you asked for low end torque? Maybe you only get 510hp if you say "up high"

    Sounds like either a ripoff or some serious miscommunication. He should have told you that the peak horsepower output would suffer if you sacrificed top end torque in favor of low end.
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    Senior Member vetteguy2005's Avatar
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    He dynoed it on a bench dyno and it sent me a sheet showing 508 fwHP. He claims it is my fuel injection or exhaust or something else. Everything else on the car is the same as before except the gears and the motor. I don;t fully understand the torgue curve, I am trying to add the dyno sheets and I am a little stupid.
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    Senior Member bellwilliam's Avatar
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    It could be something else. Rebuilding a powerful engine isnt rocket science (getting last few HP and reliable is). It shouldn't differ by 30%. I would have to agree it has to be something else.

    When he ran it on dyno. Was there a a/f chart ?

    Finding a good engine builder is next to impossible. May be that's why the top shops command top dollar.
    Last edited by bellwilliam; 08-25-2011 at 08:33 PM.
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    Senior Member vetteguy2005's Avatar
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    End page of new engine tune in Sacramento.pdfThe builder says it runs it at about 12.5/1 I think and the original engine tuner says 13.5/1 is in the safe zone.

    A stock ZO6 with 505 hp has about 450 whp, I only have 350 so I am down almost 100 whp from what a stock Zo6 has and what I thought I was buying.
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    I left a large book on internal combustion theory at Emilio's shop. In that book there are equations relating, Hp, Tq, Gear Ratios, Final Drive Ratio, Weight, Aero Drag, and any other SAE correction you want to throw in there. From that, I can write a Matlab code that will take your Hp/Tq curves and convert them into a pretty acceleration graph. I had to do this once, and know that I can do it again.

    But I am a poor excuse for an engineer and can't remember them 10 years after graduating from school. When I have the time, I will do it. It may not answer your question, but it will be fun to do.

  16. #56
    http://www.trackhq.com/Banners/yellowsitesponsor.gif emilio700's Avatar
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    Quote Originally Posted by Satisaii View Post
    I left a large book on internal combustion theory at Emilio's shop. In that book there are equations relating, Hp, Tq, Gear Ratios, Final Drive Ratio, Weight, Aero Drag, and any other SAE correction you want to throw in there. From that, I can write a Matlab code that will take your Hp/Tq curves and convert them into a pretty acceleration graph. I had to do this once, and know that I can do it again.

    But I am a poor excuse for an engineer and can't remember them 10 years after graduating from school. When I have the time, I will do it. It may not answer your question, but it will be fun to do.
    I'll probably ask you to do just that at some point.
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    Senior Member bellwilliam's Avatar
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    Quote Originally Posted by emilio700 View Post
    I'll probably ask you to do just that at some point.
    paypal $10 every time one need the number crunched on 949racing.com !!
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  18. #58
    NA Power, Every hour! andrewdruiz's Avatar
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    Tom,

    Something is wrong with that engine. I'm assuming it's an LS2? An LS2 with a basic heads/cam package, and we're talking a baby cam, should net an easy 450+rwhp. What heads and cam?

    You should do a leakdown and compression test on that engine to see what's wrong.
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  19. #59
    Member Zazz's Avatar
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    Quote Originally Posted by vetteguy2005 View Post
    Attachment 3665Attachment 3664Attachment 3660Attachment 3661Attachment 3658Attachment 3659Attachment 3657Attachment 3657Sorry for butting in William, but maybe we can learn something from a problem I am having. I bought an engine that was advertised as 510 HP.

    The builder asked me where I wanted the torque curve? I told him low end torque because I thought it would give me more exit speed out of the corners. I ended up with a forged engine with a cam and head package that is actually slower than my old OEM stock engine.

    The original engine dynoed at 359 Whp, the new motor even on the same dyno and with the same tuner can only produce 350 whp.
    I also changed the differential from a 270 gear to a 315 gear.

    Did I get ripped off or is it just the gearing and set up of the cam causing it to be slower?

    Thanks for any help you guys can give me. I feel ripped off as I explained to the builder I needed to run with the ZO6's and they run off and leave me on the straights even more now than before.
    Attachment 3658Attachment 3659
    Sorry to hear, thats about 70+ horses off... I'd imagine it feels a little sick and probably gets horrible mileage. Maybe an installation issue like missed timing or something like semi bad coils, air leaks or all of the above... lots to go over.

  20. #60
    Senior Member Todd R's Avatar
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    Factory OEM engines are where it is at. They are usually cheaper than the performance rebuilds, last longer, and just make more power all things being equal. I agree that finding a good engine builder is almost impossible. Some of the best results I have seen from American V-8s have been taking a used OEM shortblock and using a nice head/cam package. Even back in the days of Trans Am of 60's using a "seasoned" short block with redone heads was worth 20+hp. I would check the normal new rebuild issues like the rings not sealing and the leak down numbers.

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