Help with 1/8 mile

[zipperhead]

I am running 373 gears on a 28 inch tire shifting at 6400 , twin screw supercharged on my S197 automatic GT in the 1/8 mile . My problem is my car shifts just before the finish line and I believe I am not taking advantage of my power with this set up on the top end. I have searched around the site for technical information to aid me in my decision but could not find any.

If there are any 1/8 mile racers out there I would appreciate your input

I do drive this car on the street

 

[psfracer]

Can you raise the shift point? Have you had it dyno'd to show you where its making power?

Hell with my car its into 4th well before the 1/8th mile mark, and the converter goes into lockup just before the finish. The vid below is kind of old, taken over a year ago, but you can clearly hear the shifts in this vid

[SFIRE]In-car-camera-Irwindale_156322[/SFIRE]

 

[zipperhead]

Can you raise the shift point? Have you had it dyno'd to show you where its making power?

Hell with my car its into 4th well before the 1/8th mile mark, and the converter goes into lockup just before the finish. The vid below is kind of old, taken over a year ago, but you can clearly hear the shifts in this vid

Thanks for the video . That's exactly how mine car sounds. So its the lockup I am hearing. Yes I have been dynoed . JDM set up my lockup and shift points. I really don't want to go any higher on my shift points as I am not forged.

Any comments on the 28 inch tire? I am considering going to a 27

 

[psfracer]

Yeah, I would only run the 28 tall with 4.10s or higher. The 28 tall tire is making your 3.73s basically 3.55s

 

[kleistang]

yeah, i'd go with 4.10 insteadd

 

[zipperhead]

I understand all the effects of tire size on gear ratios etc. If I need more effective gear why wouldn't I just go to a 26 or 27 inch tire or possibly up my stall to get her going up through the gears a little quicker. Kinda concerned about going to a smaller tire and loosing grip as my 28's hook perfect

BTW I am running a stock converter

Honestly I enjoy the technical side of drag racing as much a driving

 

[08gt4u]

i use 26 inch tires with 4.10s and mines shift into 4th 10 to 15 feet before the finish line.i thought going 28 inch tall just to carry me through the finish line at the end of 3rd but mickey thompson dosent make a drag radial 28 tall for a 17 inch rim.

 

[psfracer]

I understand all the effects of tire size on gear ratios etc. If I need more effective gear why wouldn't I just go to a 26 or 27 inch tire or possibly up my stall to get her going up through the gears a little quicker. Kinda concerned about going to a smaller tire and loosing grip as my 28's hook perfect

BTW I am running a stock converter

Honestly I enjoy the technical side of drag racing as much a driving

I like the 28 tall as well. They hook much better then a 26 tall once your in the 500+rwhp range. Personally, if cost isn't an option, I would put 4.10s in it. Either that or you could go with a 295/45/17 M/T DR, I believe that is 27 tall. Part#3745R.

 

[zipperhead]

I like the 28 tall as well. They hook much better then a 26 tall once your in the 500+rwhp range. Personally, if cost isn't an option, I would put 4.10s in it. Either that or you could go with a 295/45/17 M/T DR, I believe that is 27 tall. Part#3745R.

Well I am in the 440 rwhp range. I was going to buy those MT's last year but I couldn't find any and ended up with the M&H 275/50/17.

Thanks to all for the feedback. I will consider buying the MT's . They should work good on my 9 inch spare rims I have

I swear chasing tenths is never ending