Last night I ran my car in the quarter for the first time In about 5 years. The previous week I ran the 1/8th in 7.93 @ 85 mph running 20 lbs of boost. It has run 7.46 @ 92mph running 24 lbs of boost. Anyway, last nite it ran 12.60@ 105mph running 24 lbs of boost! WTH? It wouldn't get in the 7's at the 1/8th! 8.04! The 60 foot from last week was amost identical, 1.80! What's going on???
Need help!
- Thread starter rb68rr
- Start date
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Bescurred
BOOSTED SHAMU v2.0
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- Jun 10, 2001
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Did you change anything? Fuel, tires? Fuel pressure?
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There is no one answer. Allot of different things can effect this.
Do you have any data logs?
Do you have any data logs?
I have no data logs. There was only one change between the two runs, the boost! Same tires, same timing, no knock, same temperature, etc. Everything being the same, I'm just saying the car should have run faster! Just can't understand why it didn't! A/f ratio was the same on both runs! Still confused! 
what type of fuel were you running?
no alky?
also what kind of tires you running? how much air pressure in them between this week and last week?
I have that same cam.:biggrin:
I remember one night I was at the track with slicks and I had the tire psi @ 22. ran a 7:40
dropped it to 20 psi got a 7:24
A guy with an s-10 said I had way too much air in those tires, put 16 psi in them. I dropped it to 16. did a burn out left off at real good boost it brought the tires up about a foot in the air and ran a 7:16 in the 1/8th. I quit then and went home smiling. It was only until i went to another track about a month later (Reynolds) with street tires did I get into the 6's.
You may have had a bad night of track prep if everything were the same probably should have tried a different lane. But looking at things like mentioned above is when you will only progress. I'd look into fuel octane then upping some timing if you're going to keep it at that boost or drop the boost down a pound or two and try low boost high timing with that turbo. Better have race gas.
no alky?
also what kind of tires you running? how much air pressure in them between this week and last week?
I have that same cam.:biggrin:
I remember one night I was at the track with slicks and I had the tire psi @ 22. ran a 7:40
dropped it to 20 psi got a 7:24
A guy with an s-10 said I had way too much air in those tires, put 16 psi in them. I dropped it to 16. did a burn out left off at real good boost it brought the tires up about a foot in the air and ran a 7:16 in the 1/8th. I quit then and went home smiling. It was only until i went to another track about a month later (Reynolds) with street tires did I get into the 6's.
You may have had a bad night of track prep if everything were the same probably should have tried a different lane. But looking at things like mentioned above is when you will only progress. I'd look into fuel octane then upping some timing if you're going to keep it at that boost or drop the boost down a pound or two and try low boost high timing with that turbo. Better have race gas.
Hard to say without some recordings to look at, but if you had no knock I might suggest leaning it out a bit and see what happens. Wideband sensor could be contaminated depending on how much lead it has seen, you might have been richer than you thought.
Very good point Tonka,
Now youre giving a little more info. 114 ehh?
Good tires also those are exactly the size I had the night I had my runs.
Just in case, what I would do since race gas has been ran through it, I would buy another sensor , put it in.
Leave the boost were it is OR better yet put it back to 20 again at first, watch for knock
and put my timing 26 deg in first and 24 in third with that octane.
If no knock and fueling looks good definatley need a wideband (AFR). then bump it back up to 24psi boost.
how are you leaving off boost, how much? foot brake, transbrake?
I would try the emergency brake technique, build it up to at least 8-10psi, and then hold on. And watch your time slip drop!!
If all else fail could be track prep.
Now youre giving a little more info. 114 ehh?
Good tires also those are exactly the size I had the night I had my runs.
Just in case, what I would do since race gas has been ran through it, I would buy another sensor , put it in.
Leave the boost were it is OR better yet put it back to 20 again at first, watch for knock
and put my timing 26 deg in first and 24 in third with that octane.
If no knock and fueling looks good definatley need a wideband (AFR). then bump it back up to 24psi boost.
how are you leaving off boost, how much? foot brake, transbrake?
I would try the emergency brake technique, build it up to at least 8-10psi, and then hold on. And watch your time slip drop!!
If all else fail could be track prep.
Thanks for the responses guys. Leaving off the foot brake, maybe 3 lbs of boost. Any more and it pushes through the lights! Need brake upgrade! I did an e-brake launch a couple of times last year and got a 1.68! Just worried about tearing something up! I believe the sensor is good but who knows, could be bad. Haven't ran that much race gas through it. I'll also try raising the timing. Thanks again. R.B.
