superGTO

iTrader: (2)

I've always trapped 111-112 mph at the track in 1/4 mile. Previously had 3.46 gears and JBA shorties. This week I installed 3.91 gears and long tube headers without cats. Last night the best I could trap was 104.

Two weeks ago I was running 12.65@110-111 with 1.85 60s. Density altitude was 4100. Last night DA was 5200 and my best was 12.65@104 with a 1.75 60. I expected it to be a little slower but that seems off to me. I was able to add two more degrees of timing after the headers and still didn't have KR, but it still ran the same numbers three more times.

Any thoughts?
Coupleweeksago:

Last nights:

350znal

iTrader: (2)

what is your full mod list? Can you post both slips to compare

superGTO

iTrader: (2)

Updated first post with slips. Mods are LS1, stock heads with double springs, stock valve train, cam 218/228 114, and a Maggie 112. Previously had JBA shorties, with catted mids. Like I said the only change was to pacesetter long tubes and 3.91 gears for 3.42s. M6 too. Shift points the same between runs and I dont lift off the gas to shift.

350znal

iTrader: (2)

I would get your tune looked at first.. You're doing good in the 1/8.. The back end is killing you. I hope nothing is wrong with your motor, but i would look into the tune.

I figured you would be trapping more than 110 though with a cam and a maggie.

lazerlemonta

Looks like the trap speeds are off at the big end. 94 mph 1/8 should be well over 113 in the 1/4.

clonedws6

iTrader: (6)

Where the f did he trap 94 in the 1/8? My car cam only traps 86 in 1/8 and 115 1/4

Doug G

Were you spinning before and not spinning now ?

everything looks in line except the MPH....timers moved ?

nmass399

You don't lift of the gas to shift, what kind of tires are you running? Did you have the car tuned for either setup? What clutch is in the car? Do you have stock pushrods in there? You also have a maggie to and the mph is that low. Something is way off here, i know the da is 5200 but dang that way off. I am assuming this is an 04 gto.

superGTO

iTrader: (2)

Yeah, 04 GTO. I'm still tuning it. It's a little rich still IMO but running well. I was trapping 111 before the gear change. I was thinking less back pressure from long tubes and no cats plus 3" instead of 2.5 from the JBAshorties. So could still be tune. I didn't change the tune from the times I trapped 111 to now except for the gear change.

Motor is fine. Runs strong and has no issues. I run M/T ET streets at the track. Launch is the same. No spinning issues in the runs I put up with all the 60s pretty consistent IMO. 1/8 mile traps are 86-88. Don't know where you where looking for 96. I'll go in to the tune some more and see if I can put in some more there.

350znal

iTrader: (2)

Yeah, your mph on the back side has suffered. Work alittle more on the tune and you should be golden.

nmass399

Do you data log the runs with afr? If your not it helps to see what its doing down the track. Mine always pulled timing in 4th gear going down the track but not in any other gear. How much timing do you have in it and what afr are you shooting for? I assume your running an aftermarket clutch cause stock clutch can slip very easily when powershifting. Everything seems to be pointing at the tune to me.

superGTO

iTrader: (2)

Yeah I am WB tuning. Commanding 11.5 right now with 18* timing currently. Like I said I think it can lean out some more and add a little more timing. Doesn't drop anywhere during the run. Spec 3 clutch and it chirps the tires even into 4th.