Turbo guys?

[retfr8flyr]

I am currently running 3.27 rear gears because I was told they would load the turbos better and the car would be quicker. The problem is my setup weighs 4000lbs with me in it and it just wont 60ft with the 3.27 gears. I am thinking of going back to 3.73 gears as the car sixty footed much better when I ran 3.73. I never ran it under full boost with the 3.73's but I think the turbos will still load well enough and the car should be faster. I also run a MT 295/45/17 DR.

What do you guys with turbo experience say? Should I stay with the 3.27's or go with 3.73 or even 3.55 gears?


Earl

 

[RocketcarX]

3.55

 

[thunderstang]

I've had good luck with 3.55s and a 28" tall tire. 1.5-1.6 sec 60ft through a stock 3650. I would like to try a 26" tire to see what the difference would be.

 

[rcm90]

How much boost are you leaving on and what is the boost level going down the track?


FWIW.. a buddy of mine has a fox that weighs roughly 3600 with a powerglide (1.76 first gear ratio), a 3.27 gear and a 28" tire that goes high 1.3x's with the wheels up.. and the car probably makes less power than yours

 

[NotQuik]

I'm planning on 3.55's with a 28" tire myself....I'm just not sure how much of a difference you'll notice going to the from the 3.27's. What kind of 60''s is the car cutting in it's current configuration?

 

[retfr8flyr]

How much boost are you leaving on and what is the boost level going down the track?


FWIW.. a buddy of mine has a fox that weighs roughly 3600 with a powerglide (1.76 first gear ratio), a 3.27 gear and a 28" tire that goes high 1.3x's with the wheels up.. and the car probably makes less power than yours

I foot brake to only about 2# and run 15# max.

I'm planning on 3.55's with a 28" tire myself....I'm just not sure how much of a difference you'll notice going to the from the 3.27's. What kind of 60''s is the car cutting in it's current configuration?

The car only does 1.87 or higher on the 60ft times. I agree I don't think 3.55's would make much of a difference, I liked the way the car felt with the 3.73's that's why I am thinking of going back to them.


Earl

 

[rcm90]

Before you start playing with the rear gear, see what you can do to get the launch psi over 2lbs. Have you tried a 2step? It might be worth a try.

That fox I brought up would absolutly lay over at the track with no two step off the trans brake since it would only make 5lbs off the line. Once the 2 step was installed it would make 14lbs off the line.

 

[CPRsm]

Depends on how much power you make. A 3.27 is not always faster. You need a good amount of power for 28's and 3.2x. What does your mph look like compared to the new gearing? My car was a good bit faster w 3.75's than 3.25's and I was probably 800lbs lighter.

 

[RocketcarX]

How much boost are you leaving on and what is the boost level going down the track?


FWIW.. a buddy of mine has a fox that weighs roughly 3600 with a powerglide (1.76 first gear ratio), a 3.27 gear and a 28" tire that goes high 1.3x's with the wheels up.. and the car probably makes less power than yours

That's a fat fox, those are serious times none the less. What's the stall speed on the converter?

OP what transmission are you running? Auto? If so bump the stall speed, if manual, 2 step and higher RPM launches on stickier tires might help a lot. I think more info is needed at this point.

 

[RocketcarX]

That's a fat fox, those are serious times none the less. What's the stall speed on the converter?

OP what transmission are you running? Auto? If so bump the stall speed, if manual, 2 step and higher RPM launches on stickier tires might help a lot. I think more info is needed at this point.

Nevermind, I see it's an auto. I think if you're serious about 60' times a converter is in your future, gears will just be a bandaid that will hurt you on the big end.

 

[stretch]

I cut a 1.35 sixty foot with 3.27s in my 06 I had.

 

[retfr8flyr]

Depends on how much power you make. A 3.27 is not always faster. You need a good amount of power for 28's and 3.2x. What does your mph look like compared to the new gearing? My car was a good bit faster w 3.75's than 3.25's and I was probably 800lbs lighter.

Like i said I never ran it with the 3.73's at full boost, just 10#. Last year, on about 15lbs, I ran 10.99 @ 129, 1.87 60ft with the 3.27 gears. I have a Circle D 4C converter but it will only foot brake to about 2800rpm and that's about 2# of boost. The car leaves very soft and doesn't really start pulling until about 100ft. I think the 3.73's will get it moving and in the power range better that the current 3.27's. 2 Steps aren't legal for an automatic, in all the footbrake bracket classes, so I can't see spending money on one.


Earl

 

[rcm90]

That's a fat fox, those are serious times none the less. What's the stall speed on the converter?

The driver is about 430 lbs.. I want to say its around 35-3800 rpm. They keep cranking the boost up and up to see how long the stock bottom end holds.. on 18 lbs it goes mid to high 9's at 140 with a 1.33 60'


Op sorry about hijacking the thread for a second there. I definatly agree with CPRsm.. I would just try to leave on as much power as possible before I start tearing into things.

Edit..

Just seen you can't run a two step

 

[Weou09]

Like i said I never ran it with the 3.73's at full boost, just 10#. Last year, on about 15lbs, I ran 10.99 @ 129, 1.87 60ft with the 3.27 gears. I have a Circle D 4C converter but it will only foot brake to about 2800rpm and that's about 2# of boost. The car leaves very soft and doesn't really start pulling until about 100ft. I think the 3.73's will get it moving and in the power range better that the current 3.27's. 2 Steps aren't legal for an automatic, in all the footbrake bracket classes, so I can't see spending money on one.


Earl

Maybe play with the tune some to load the launch. Buddy of mine has a centri 2 valve auto and i think they fattened it and took some timing (definitely not sure so don't quote me) and it went from making 6# to 10#.

 

[Hatchman]

Earl, from watching your car at the track the last couple of track days, your car leaves much softer than most, if not all, the other cars at the track those days. Your car just sort of eases off the line... and then hauls ass.

What are your RPMs at the quarter? If you've got some room,
I'd say go back to 3.73. Should get RPMs and the boost up quicker. There are some calculators on line that will tell you what a gear change will do to your RPMs.

 

[retfr8flyr]

Brady, I have the RPM available to run the 3.73's and I agree the car just will not move. I am going to talk to Mike about it and will probably go back to some 3.73's this winter.


Earl