03powers

I have a supercharged saleen 5spd with 9lbs of boost and about 460 rwhp with 4.10gears. I was thinking about swapping my gears to 3.55 or 3.73s so I have a first gear on the street. But I didn't know if it would slow me down alot in the 1/4 mile. I only race like twice a yr though. I didn't want to regret changing gears. I have a 275/40/20 drag radial on the back

proeagles

I would vote for 3.73 for all around. If you are doing it for the gas mileage save your money. Your car will be long gone and dead by the time you recover the cost.

03powers

I doing it the have a first gear and even with drag radials it still spins pretty good.

danzcool

It's tough. when I was at 11psi with 3.55s, I would still spin 1st and 2nd when I got on it and wound it up to redline. granted I was running summer max tires at the time. Probably the best thing to do is to see if there is a gearing that lets you reduce 1 shift by the end of the quarter mile. I'm assuming a few things here, like you are at the 6250 redline, and about 28.6" tire... your current 4.1 gear would wind out 4th at 130MPH... which is probably higher than you can get to with 9psi. 3.73 would put the top of 3rd @ 108 and 4th @ 143 (right about at the factory speed limiter), switching down to 3.55 would put 3rd @ 114 and 4th @ 150 (above the speed limiter, moving beyond that a 3.23 would put 3rd @ 125 and 4th @ 165 (above the speed limiter)... a very non-standard 3.08 would put 3rd @ 131 & 4th @ 173 (above the speed limiter).

So the 3.73 would not be able to reduce a shift as I expect you should be between 110 & 120 at the end of 1/4 mile at 9psi
the 3.55 would have you in the middle of that range at the top of 3rd, and if you tuned the redline up to 6500RPMs it would be toward the top at 118, however the 3.23 would really be the sweet spot for trap speed... not sure how well it would launch though.

03powers

I think with 3.55 and my tire it would be like a 3.38 gears. I have my rev limiter at 6500rpm. Really traction is still bad with the 1st gears.

03powers

Some of the time with drag radials I can get traction on the street with 4.10s. it's just not fun unless I'm launching it. Normal driving I'm in 4th gear by 35 or 40 mph. Does 3.55s make it alot slower off the line. It almost have a 29 in tire . That's why idn if I should good with 3.73 because that would make it around 3.55s with my tire. Or go 3.55 and be around 3.37.

Laga77

I have 3.73 with E-Force and 8# of boost. 295/45r18 all season tires on back. Great around town. No traction on track the one time I went there.

03powers

How's first gear.

Laga77

My tires are 28.45 inches and it’s an auto. First gear is just about perfect for street use. If I had traction, it would really launch. My Lito tune makes crazy power. That’s why I run all season tires. I’d rather have some tire spin than break things. I also drive in the cold. No snow though.

03powers

Ya because with 4.10s and 3650 1st is so quick. Its pointless and I have pretty good traction. It feels like it takes it out of boost to quick to