Gears for the heaviest Whippled s550 with tall tires?

[SVT-DADDY]

I’ve been putting off my decision on gears until my wheels/tires and Whipple were on. The car feels great with the blower, carving tightish corners at 60 in second is a blast. However off the line and in out of boost situations the car feels a little doggy. I did a little math and figured out why:

Weight
2015 GT premium vert MT82 -3948lbs
Whipple 150 lbs
Me 275 lbs
Total 4,373
Call it 4400 with the tool kit and extra bracing I added.

Gears
Car came stock with 3.31’s
I upsized my tires to 305/35/20 28.4"
My effective ratio is now 3.17

So basically I have the heaviest S550 made with the tallest gears. I’ve been conditioned that 3.73’s are too much for a PD car. However with my actual weight of 4400 and the 3.73’s only yielding 3.59 I think they might be a good fit. My goal for the car is around 750whp, I figure thats 50-75 more than I am making now.

Am I crazy for considering the 3.73's?

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[Austinj427]

If it was me, I would be going with 3.55s.

What are you making for power now?

 

[SVT-DADDY]

If it was me, I would be going with 3.55s.

What are you making for power now?

No dyno yet but I am guessing in the 675-700 range. Seems pretty standard for a whipple with cats.

Thing is I found a 3.55 pumpkin for $400, just worried that it won't be enough

 

[Boduke0220]

what kind of driving are you doing with the car?

 

[F1scamp]

I am assuming a stick? I broke my 3.31's and accidently installed 3.73's. Took it to the track last night with drag radials in it's street form, and the 3.73's are pretty hard to get over. That 5th gear shift pulls the motor down too much for me, I want to get another set of 3.31's. On the street the 3.73's are great, rpms at cruising are more optimum than the 3.31's.

 

[SVT-DADDY]

what kind of driving are you doing with the car?

street, some canyon caving, maybe a little roll racing in Mexico.

I am assuming a stick? I broke my 3.31's and accidently installed 3.73's. Took it to the track last night with drag radials in it's street form, and the 3.73's are pretty hard to get over. That 5th gear shift pulls the motor down too much for me, I want to get another set of 3.31's. On the street the 3.73's are great, rpms at cruising are more optimum than the 3.31's.

Yes stick, I edited the thread. I doubt the car will see the strip much because I won't put a roll bar in it. How tall are your drag radials?

 

[BoostedBen]

I am assuming a stick? I broke my 3.31's and accidently installed 3.73's. Took it to the track last night with drag radials in it's street form, and the 3.73's are pretty hard to get over. That 5th gear shift pulls the motor down too much for me, I want to get another set of 3.31's. On the street the 3.73's are great, rpms at cruising are more optimum than the 3.31's.

How bad do you think the 3.73's hurt these FI S550's in the 1/4 mile?

 

[F1scamp]

How bad do you think the 3.73's hurt these FI S550's in the 1/4 mile?

Hard to tell for me as it was my first night with drag radials, different gear, different rear shocks... I kinda just wanted to see what it would run basically how I drive it everyday. Best I could muster last night was a 11.00 @ 135.67, I think the 60's were in the mid 1.8's. The tire I am using was a toyo re71r 265/45/18 on the stock wheels. I had the power down on first and second, but I still couldn't power shift it or it would head for the wall. Managed to pull the subframe bolts out of the frame on a launch though... drag radials are rough..:headbonk:

 

[Reds197]

3.31 is best possible. Especially with a PD BLOWER. No need to change.

 

[BoostedBen]

Hard to tell for me as it was my first night with drag radials, different gear, different rear shocks... I kinda just wanted to see what it would run basically how I drive it everyday. Best I could muster last night was a 11.00 @ 135.67, I think the 60's were in the mid 1.8's. The tire I am using was a toyo re71r 265/45/18 on the stock wheels. I had the power down on first and second, but I still couldn't power shift it or it would head for the wall. Managed to pull the subframe bolts out of the frame on a launch though... drag radials are rough..:headbonk:

What about trap speed? Better or worse with the 3.73s?

 

[SVT-DADDY]

3.31 is best possible. Especially with a PD BLOWER. No need to change.

I am sporting 3.17's effectively tho!

 

[F1scamp]

Again, hard to say. Technically they stayed the same, but I changed enough over the winter and spring that I expected mph to pick up and I think it was negated by the gear change.

 

[moffetts]

How bad do you think the 3.73's hurt these FI S550's in the 1/4 mile?

When you have to shift into 5th at ~100 mph, it's going to make your times suffer.

 

[Ponderthis]

hOLY shit that thing is heavy! Run a smaller pulley! lol

 

[SVT-DADDY]

hOLY shit that thing is heavy! Run a smaller pulley! lol

Yeah pulley and cat delete is coming. Also driver weight reduction mod.

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