Poor Trap Speed
Thread Starter
Teching In
Joined: Sep 2005
Posts: 22
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Poor Trap Speed Hey All,
I need some help from those with more experience than me in Drag Racing. I feel like my vette is running much slower trap #s than the sum of my parts would suggest it should run. The car is an 97 coupe M6 w/ 4.10 gears and a 402. On the strip scales the car weighed in at 3300 pounds. The car dynoed at 530 rwhp/490tq. My only trip to the drag strip in the car netted me a 12.2 @ 118 with a 2.0 60ft. I understand the slow ET as I am not launching the car very hard(Blows the street tires off with anything more than ~2k rpm). Does that trap number sound right? The car runs like a raped ape on the street.
TIA
I need some help from those with more experience than me in Drag Racing. I feel like my vette is running much slower trap #s than the sum of my parts would suggest it should run. The car is an 97 coupe M6 w/ 4.10 gears and a 402. On the strip scales the car weighed in at 3300 pounds. The car dynoed at 530 rwhp/490tq. My only trip to the drag strip in the car netted me a 12.2 @ 118 with a 2.0 60ft. I understand the slow ET as I am not launching the car very hard(Blows the street tires off with anything more than ~2k rpm). Does that trap number sound right? The car runs like a raped ape on the street.
TIA
Mine has a 402, when I had the Auto in it with a SS3600 Stall, 3.73 Gears, it pulled a 11.19@120, 1.56 60ft running rich as hell. I put 3.50 Gears in mine for the T56 Swap, but I have 3.89's, and I would predict it to trap a little higher if I ran it with them..
Something is up with yours..that is a low 11's trap speed with a good hook.
I don't know what RWHP mine has, haven't had the chance to Dyno it.
Something is up with yours..that is a low 11's trap speed with a good hook.
I don't know what RWHP mine has, haven't had the chance to Dyno it.
Thread Starter
Teching In
Joined: Sep 2005
Posts: 22
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Yeah, thats why I asked. I figured maybe the engine was hurt based on the trap. So I stuck the thing on the dyno and made 530 to the wheels. What could affect my trap like that? It really didnt feel like I was spinning the tires all the way down the track. Could the air have been really bad that day? How much of an effect can the air have?
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TECH Regular
Joined: Sep 2008
Posts: 425
Likes: 1
From: Scottsdale, Arizona
What gear are you in going thru the traps? Also, are you holding the revs up all the way thru the gears? Are you short shifting? My guess would be
1. shift just before the traps
2. letting the car nose over before the next shift.
3. track conditions aren't great
4. it could be the clutch?
These are just some of the questions I have for ya.
1. shift just before the traps
2. letting the car nose over before the next shift.
3. track conditions aren't great
4. it could be the clutch?
These are just some of the questions I have for ya.
with 530hp your car should be 130mph+ in good air and in the 128 129 range in the middle of the summer.
my guess would be the driver, but I cant imagine you being so terrible that you would kill off 10+ mph. your gearing is correct, though 3.90's would suit your power level better with a 26" tires IF you were trapping what you should. I have seen bad shifting kill 4, maybe 5 mph, but not 10, so I don't think its completly you.
I would have to say that you may be getting severe false knock. When your car is stationary on the dyno it may not show up, but going down the track, shifting, spinning, maybe something is setting of the knock sensors?
Also, depending on the tune your car may be great on the dyno, and crap at the track. I have seen that as well. Don't forget that on the dyno you are only under load in 1 gear and for a short period of time, at the track you are in 4 gears, and for a longer period of time. A tune for a great dyno number, will not do well at the track. But that is a long shot, most of today's tuners know that.
my guess would be the driver, but I cant imagine you being so terrible that you would kill off 10+ mph. your gearing is correct, though 3.90's would suit your power level better with a 26" tires IF you were trapping what you should. I have seen bad shifting kill 4, maybe 5 mph, but not 10, so I don't think its completly you.
I would have to say that you may be getting severe false knock. When your car is stationary on the dyno it may not show up, but going down the track, shifting, spinning, maybe something is setting of the knock sensors?
Also, depending on the tune your car may be great on the dyno, and crap at the track. I have seen that as well. Don't forget that on the dyno you are only under load in 1 gear and for a short period of time, at the track you are in 4 gears, and for a longer period of time. A tune for a great dyno number, will not do well at the track. But that is a long shot, most of today's tuners know that.
Thread Starter
Teching In
Joined: Sep 2005
Posts: 22
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Hmm.
1) I wasnt shifting like I hated my car, just like I disliked it.
2) Clutch doesnt appear to be slipping. It's an OZ700. Grabs plenty hard.
3) I'm running a 27" tall tire on the street, but that day at the track I had a 25.35" tall tire on the car. I was shifting into 5th as I ran through the traps.
4)I was logging the runs in HP Tuners and I didnt see any knock. The car was tuned on the street by me. I'm running stock timing. The dyno numbers I spoke of before are based on this tune.
I'm clueless at this point. I guess I will just have to take it back to the track and compare again. It's only been once with the current motor.
1) I wasnt shifting like I hated my car, just like I disliked it.
2) Clutch doesnt appear to be slipping. It's an OZ700. Grabs plenty hard.
3) I'm running a 27" tall tire on the street, but that day at the track I had a 25.35" tall tire on the car. I was shifting into 5th as I ran through the traps.
4)I was logging the runs in HP Tuners and I didnt see any knock. The car was tuned on the street by me. I'm running stock timing. The dyno numbers I spoke of before are based on this tune.
I'm clueless at this point. I guess I will just have to take it back to the track and compare again. It's only been once with the current motor.
Last edited by Mechryn; Dec 10, 2008 at 02:35 PM.
What's the TECH Regular
Joined: Sep 2008
Posts: 425
Likes: 1
From: Scottsdale, Arizona
how much RPM are you losing going into 5th gear? Also, you are running a shorter tire and that doesn't help much either. If you could find a tire a little taller it would help you on the top end. That way you won't have to shift into 5th gear.
I'm sure there might be some other things going on but I'd start with that. Shifting always kills time and MPH, unless you can shift without a clutch (not recommended).
Keep us informed on your progress.
I'm sure there might be some other things going on but I'd start with that. Shifting always kills time and MPH, unless you can shift without a clutch (not recommended).
Keep us informed on your progress.
Thread Starter
Teching In
Joined: Sep 2005
Posts: 22
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Yeah. I just figured out the tire height thing. That might have been a large part of the problem. They were the stickiest thing I had on hand so I ran them...thinking they were a 26-27" tall tire. Oh well. I'll give it another go with some different tires down the road.
