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Does my car suck or what? Someone talk me down!
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08-25-2009, 11:42 PM | #1 |
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Does my car suck or what? Someone talk me down!
I dyno'd my car last week and was happy with my numbers until I SEARCHED this forum and saw the numbers other people are getting! If our cars are rated at 300 HP/300 TQ stock at the engine and I'm told there is a "generally accepted" 25% loss through the drive train - specifically an automatic transmission - wouldn't a stock baseline of 240 HP/240 TQ be expected on a dyno? My 335 has automatic trans with only mod being SSTT and I'm running 91 octane. I pulled 293.89 HP / 300.23 TQ. I quickly broke out my calculator, multiplied the results by 1.25 and came up with 367 HP/375 TQ and thought - "NICE!" But, having seen stock 335's dyno on this forum at 275 HP...was my SSTT only good for about 18 HP? What is more incredible are the JB3 guys with cold air intakes and a few other goodies making 375+ HP / 420+ TQ because wouldn't that convert to 468 HP / 525 TQ at the engine? Is the 1.25 a good rule of thumb when converting dyno runs to actual HP & TQ? This was done on a Dynojet dyno at 83 degrees F. Thoughts on this?
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08-25-2009, 11:50 PM | #2 |
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It's nowhere near 25%. 15% is the conservative guess.
Your best bet is to go back and dyno without the SSTT and see what you get. I dynoed 279whp, 288wtq stock and 338whp,350wtq with v3 and a dci (similar temp, sea level, 93 octane, same dyno). My results seem to be the norm, but all dynos are different. You'll only really know what the SSTT is doing with a delta. Sidenote, IIRC, most SSTT cars were dynoing in the 305-315 range a year or so ago when they were at their peak popularity.
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08-26-2009, 12:02 AM | #3 |
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Most people dyno on dynojet dynos, they're a bit cheaper. Your numbers look like they were done on a mustang dyno, which have about an -18% drivetrain loss average. One of my good friends own's a AWD mustang dyno, and he's always stating the -18% loss on average.
So at the end of the day, the type of dyno is always a factor when comparing numbers.
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08-26-2009, 02:41 AM | #4 |
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Yeah, I think 15% is more accurate on drivetrain loss...
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08-26-2009, 03:09 AM | #5 |
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my AT car dynoed Stock 250 whp on a mustang like dyno with -15% drive train loss and 310 with JB3 map 3.
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08-26-2009, 03:13 AM | #6 |
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Did you break in the SSTT?
Like, did you punch it a couple times so the car would get used to it?
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08-26-2009, 10:04 AM | #7 |
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Definately a Dynojet dyno and SSTT was fully adapted at the time of the run. I wish I would have done numerous pulls with and without the SSTT, but as you can imagine removing it after the run would have required quite a wait for the engine to cool down enough! I'm starting to realize the dyno thing is an apples and oranges kind of thing where it may not be totally realistic to compare different cars, different conditions, different dynos! I'll have to do it again with a baseline stock pull. Here's the actual data. Thanks!
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08-26-2009, 10:48 AM | #8 |
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You need to do your own baseline to see what YOU gained. Using a standard baseline from random stock cars off of this site is not going to be very accurate.
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08-26-2009, 10:52 AM | #9 |
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Dynos should be used for tuning, not for bragging rights. They are absolutely useless as a comparative tool unless used against other tests on the same car and same dyno.
I'm absolutely amazed at how much money must be wasted on these forums on dyno runs with absolutely no tuning being performed. If you want to know how much faster your car is, take it to the track. The numbers from a dyno don't mean anything. At all. |
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08-26-2009, 11:12 AM | #10 |
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yup don't jump
without dyno'ing your car there 100% stock you have no idea what power you have gained
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08-26-2009, 11:20 AM | #11 |
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Also, check your math. Multiplying your whp by (1+percentage loss you think you have) is not equal to multiplying your engine hp by the percentage loss you think you have.
case in point: 294 *1.25 = 367.5 but does not equal 367.5 * (0.75) = 275.6 You need to divide the whp by (1-percentage loss you think you have) 294 / (0.75) = 392 hp And the drivetrain loss is much closer to 15%. I think Dinan or Alpina (or someone) had came to that conclusion a long time ago.
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08-26-2009, 11:22 AM | #12 |
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It could be a million things, Dyno isn't calibrated correctly, temperature is too high, poor quality gas, doing the dyno run in the wrong gear etc etc.
Like every says, so a run without the SSTT and then do a run with it and see how much gain you get, same day, same dyno, same temp!
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08-26-2009, 06:04 PM | #13 |
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GeorgiaTech335coupe,
Oh my God. You're totally right! I hate math. New plan: Remove SSTT & dyno the car stock...then reinstall, beat it a bit and re-dyno same day. Plus I'll have them do more than 1 run with each set up. Thanks guys, I was just looking to backup my butt dyno and happened to be in OKC OK where they had a dyno ready to go. I appreciate the input.
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08-26-2009, 07:13 PM | #14 | |
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I was always under the assumption mustang gave higher numbers than dynojet. Someone please correct me if I'm wrong. |
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08-26-2009, 07:20 PM | #15 |
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mustang's often read a lot lower than dynojets.
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08-26-2009, 07:35 PM | #16 | |
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08-27-2009, 12:50 PM | #17 | |
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