chas010

iTrader: (3)

Hey guys I posted this in the drag racing tech section but the LT1s dont get alot of attention there.
Guys I need some help with my 95 lt1 street/strip car. Last year the car was running 11.5 at 116-117. This year after removing roughly 100lbs of weight the car runs 11.5 at 115-116 .
One problem I know I have is that the car is shifting into overdrive 200ft before the end of the quarter (redlines).
The car is a stock bottom end lt1 with ported stock heads, 503 cam, 3200 vig, 3.73s with drag radials. The redline is currently set at 6400 and shift points are set at 6200, I need to raise the shift points inorder to run the whole 1/4 im wondering if I might see an ET gain from this?
Is there anything else I can do other than nos to gain something or anything?

I also posted some pics of the car (not that it will help)

Im thinkg of raising the redline to 6600 and the shift points to 6400, what do you guys think?

JB_97ws6TA

iTrader: (6)

Flirting with disaster spinning the stock shortblock that high but I shift mine at 6500 and have yet to see any problems. If you just replace the rod bolts with ARP I have been told that you can safely spin 6500. If you increase your shift points to where you are topping out in 3rd gear at the 1/4 mile mark you should be able to pick up some MPH and shave a couple tenths. Just my .02

ABA383

iTrader: (1)

What are your incrementals at the track? Might be easier to analyze your time slip to see where we can improve your set up. What tires are you running and what size? Have you been to the dyno to see where your torque peak is? Your converter should stall 500-700rpm below the torque peak. I think the converter may be a bit small on stall...Whats your suspension consist of? Just need a bit more info to adequately help you out...

--Alan

chas010

iTrader: (3)

Hey thanks for the responses guys!
I posted a pic of one of my time slips.
Im running mt drag radials 275 50 15.
Car has not been on a dyno, the converter feels to tight but the car will usually pull the left front tire a cpl of inches and carry it for a few feet. All stock suspension with the exception of bmr lower control arms and a set of relocator control arm mounts.

chas010

iTrader: (3)

the car lays right over 200ft from the finish line when it goes into overdrive.

LT1nitrouZ

You should immediately put subframe connectors on the car. That combined with a torque arm would net you a pretty good gain. Also I assume it hasnt been dyno tuned as you said that it hasnt been on a dyno, so a dyno tune would also help you out alot.

JB_97ws6TA

iTrader: (6)

Subframe connectors and a torque arm are a good idea but they are more for cutting down 60ft times and at 1.6 I don't see that much room for improvement. I would install them just to get the torque arm off of the transmission and to reduce body flex. I still don't think you should be shifting into overdrive but you need to find out where your peak HP and torque is then adjust your stall and shift points appropriately...bottom end willing

LT1nitrouZ

I cut a 1.4 60 ft with stock heads and a cc306 cam... I am seeing room for improvement. Plus a tenth in 60 ft is gonna be even more on the big end.


What gears are you running to be hitting overdrive at 116? Might get some arguement on this but really low gears dont seem to help LT1s too much... They tend to like to surf the torque wave

chas010

iTrader: (3)

It has 3.73 rear gears, also I should add the car already has bmr subframe connectors.

LT1nitrouZ

I would venture to say there is some slip in your converter or transmission. I was trapping 132 MPH with a TH350 and crossing the line at 6200 RPMs. 3.73s wouldnt make that much difference.

If you have the subframes I would suggest as suggested before getting the dynotune then adjusting shiftpoints and converter.

BSmiff

Seems like you should be moving quite a bit quicker to the 1/8th with those mods.

86 IROC

iTrader: (14)

I'm going to have to agree with some slippage. When I first put my car together I had 255/50-16 MT's on it with the 3.73's and didn't need OD. My limiter was at 6500 and shift points at 6300 back then. I trapped 120-121 in that configuartion. Better weather and some other tweaks, plus a swap to 275/60-15's have me trapping alost 125 with plenty of room to spare at the stripe. If you don't want to do anything with the converter, swap to the 275/60's the next time you buy tires. That alone should get you through the lights w/o shifting into OD.

chas010

iTrader: (3)

Maybe the tranny is going away? ill check the fluid and see if it smells burnt.

86 IROC

iTrader: (14)

It most likely isn't shot, it kinda sounds like your converter is too loose and you're blowing through it.

LT1nitrouZ

I second that motion. Is it hitting the rev limiter before it shifts?


I have been out of the game for a couple years... having to recall how to word things the way I want

Z-RATED94

iTrader: (6)

Your car seems to run pretty good, and I think the last sentence in your first post is right on the money. Raise the shift point a couple of hundred rpm.

chas010

iTrader: (3)

Im going to send the pcm to pcmforless, Z-RATED94 what are your shift points set at?

94Z28rag

iTrader: (10)

I wouldn't just raise the shift points on a whim...get it on a dyno and see where it stops making power. The way to lower ETs is to do it methodically, not guess

Bryan (PCMforless) will without a doubt help you (call him), but you need to address your converter and dyno sheets before you do anything else, IMO.

dlk1950

I dont know where you are located,but when you call Bryan ask him where he is going to be doing dyno tunes,he travels around a bit to do them.

LT1nitrouZ

one more to emphasize dyno tuning.