Timing?
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Pro
Joined: Jan 2002
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From: W.V.C. Utah
Timing?
I'm going to take my 88 Iroc L98 to the track this friday what should I set the timing at for the best performance. The mods i have are Exhaust, hypertech, and 3.42 gears. I'm just looking to squeeze every ounce out of this thing hoping for a decent gain from last year. Also what are some things you thing I should do? Last year it pulled 15.5 at 90 mph with a 2.3 60'. I'm hoping the gears will help this year went from a 2.77. also my exhaust leaks a little bit at the cat will this effect my power output?
Last edited by 88421VETTE; May 3, 2005 at 12:34 AM.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
The stock L98 setting is 6 degrees BTDC. Most performance chips advance timing so you may want to advance it about 2 degrees (one mark on dampner) then make a pass and see what happens. If you see improvement advance again until you get a better time or if you get worse time stop and retard back until you find your sweet spot.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
You need to make at least three passes, the first one with the timing set as it is now, then with 2 degrees more advance dialed in and on the 3rd pass 2 additional degrees more.
So if you start at 6, your second pass will be made with 8 and the third with 10.
Use your Mile Per Hour (MPH) as the barometer of what the engine wants. When the MPH falls off, you'll know that you've gone too far, so back off the timing to the previous setting.
ET is not a good basis because the ET can vary quite a bit due to how the car hooks off the line.
Leave the trans in Drive and let it shift itself; that eliminates one more varible that manual shifting introduces.
Remember, if the ECM detects knock - as will happen when the timing is advanced too far - timing will be pulled out at a rather high rate and this will really show up in the lower MPH.
It's always best to have your timing set lower than is optimal than to have it set higher than optimal.
Jake
So if you start at 6, your second pass will be made with 8 and the third with 10.
Use your Mile Per Hour (MPH) as the barometer of what the engine wants. When the MPH falls off, you'll know that you've gone too far, so back off the timing to the previous setting.
ET is not a good basis because the ET can vary quite a bit due to how the car hooks off the line.
Leave the trans in Drive and let it shift itself; that eliminates one more varible that manual shifting introduces.
Remember, if the ECM detects knock - as will happen when the timing is advanced too far - timing will be pulled out at a rather high rate and this will really show up in the lower MPH.
It's always best to have your timing set lower than is optimal than to have it set higher than optimal.
Jake
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Originally Posted by JAKE
Remember, if the ECM detects knock - as will happen when the timing is advanced too far - timing will be pulled out at a rather high rate and this will really show up in the lower MPH.
It's always best to have your timing set lower than is optimal than to have it set higher than optimal.
Jake
It's always best to have your timing set lower than is optimal than to have it set higher than optimal.
Jake
Safety Car
Joined: Apr 2004
Posts: 4,532
Likes: 7
From: Lahaina Hi
I would find some 106 unleaded race fuel 1/2 tank would work.
I run pump gas and 4 deg is as far as I can advance the motor.
I run 12 degrees with 106 race fuel.
I did not see any drag radials for the runs you will need them.
With a 15.50 last time I would say spinning was your forte.
The header leak should not matter the O2 sensor is before the header flange.
If you can't afford the race gas.Run a can of NITROUS addative it will not hurt the cats or motor and will make a big diff.
Have fun and don't burn your fingers getting to the est to set timing.
I run pump gas and 4 deg is as far as I can advance the motor.
I run 12 degrees with 106 race fuel.
I did not see any drag radials for the runs you will need them.
With a 15.50 last time I would say spinning was your forte.
The header leak should not matter the O2 sensor is before the header flange.
If you can't afford the race gas.Run a can of NITROUS addative it will not hurt the cats or motor and will make a big diff.
Have fun and don't burn your fingers getting to the est to set timing.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
He is only going to get two time trials, max, before eliminations. He can't play around if he has any thoughts of doing well. *I* would set the base at 8* and leave it. It will probably will take more, but there is no time to experiment on a Friday night. Go back on a Wednesday night, T&T and play with it.
RACE ON!!!
RACE ON!!!
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by 88421VETTE
I'm going to take my 88 Iroc L98 to the track this friday what should I set the timing at for the best performance. The mods i have are Exhaust, hypertech, and 3.42 gears. I'm just looking to squeeze every ounce out of this thing hoping for a decent gain from last year. Also what are some things you thing I should do? Last year it pulled 15.5 at 90 mph with a 2.3 60'. I'm hoping the gears will help this year went from a 2.77. also my exhaust leaks a little bit at the cat will this effect my power output?
In that vein, and the stated goal, my answer is the correct one.
Remember, too, only change one thing at a time. Don't for example, change base timing and fuel pressure at the same time. Changing more than one thing at a time muddies the waters. You may see an increase or decrease in performance but there'd be no way to pin-point which change did what. Sometimes when more than one change is made at a time they tend to cancel each other out.
At least three runs using different timing settings on each run is the ideal way to zero in on the setting the engine likes best. As someone who has normally run over 170 MPH in the quarter I believe - as they say - I know of what I speak.
Jake
