Shownomercy

iTrader: (1)

In the land of theory here, so bear with me.

Car is mechanically limited via gearing and cam to roughly 143mph. 6400 shift, 3.73s, and 28s. pt76gts turbo, 10-12psi area

Question arises on whats easier; add boost in quicker and try to ET quicker, or re-gear for a better ET?

Again in theory, a shallower gear set, 3.54 area should build boost much faster. But, if I do toss 3.54s in, and the turbo runs out of steam, its all for nothing and I waste a lot of money.

Thoughts?

Busa_rob

iTrader: (1)

Pull some gear out of it. Turbos need to be able to lean on somthin. With my experience in turbo hayabusas the less the gear the better. I've never had to say it needs more gear.

yenkomike

iTrader: (2)

this is true I changed from a 3.42 to a 4.00 gear in my buick when I went to a 9" axle and the car slowed down half a second. I had a 3.00 gear so I put it in for street driving and it felt so good I ran it at the track and it was .3 faster than my best with a 3.42. never changed it. the strange thing is the 3.00 gear was the fastest 60' as well.

RonSSNova

iTrader: (3)

I was just looking at logs from my track runs.
I'm 3.73 gears and a 30" tire TH400.

I don't get full boost in low gear. But I do in 3rd. About 2 psi difference.

I ran 143 mph at 6800. Converter slip.

I'd like to go to a 3.31 gear.

Ron

Ryans99ls1

iTrader: (16)

what size motor? itd have to be pretty big for that thing to run out of steam at such low boost. I actually have 76GTS-H and i know its got more than the 16psi ive had it up to on my 346

at the very least put 3.50s in

Shownomercy

iTrader: (1)

383ci, and can only go to 3.54s (S60)

Old Geezer

iTrader: (3)

and see how much help you'll get w/ the 3.54 and say a 29 or 30" tire.

Shownomercy

iTrader: (1)

Tire height will remain at 28s, not gonna minitub the car.

But, 3.54s are putting me around 150, who knows if it has the steam for that.

stevieturbo

I doubt there would be any downsides to using the taller gear even if you may still not hit 150.

toytech93

iTrader: (2)

3.73 TO 3.54, is it really worth the cost of changing ?

just doesn't seem cost effective. just my .02

Shownomercy

iTrader: (1)

So even if I don't utilize the gearing to get max speed, they won't hurt the current power level's ability to ET?

Busa_rob

iTrader: (1)

Yep. And it's funny cuz you tell a nitrous or blower guy that your gonna put that tall of a gear in and they look at you like your retarded. But it works so damn well. And hell when you got a th400 like me you gotta love being able to do 70 on the highway and not revving the **** out of it.

Shownomercy

iTrader: (1)

So, is it worth selling the S60 rear to fund a ford 9 with say 3.08/3.23s or should 3.54s work sufficiently?

Old Geezer

iTrader: (3)

Is this a converter car? If so, what kind of slip are you seeing? [I see no mention of it, is why I ask.]

F110Mech

iTrader: (2)

pretty sure that he has a 4L80e

Shownomercy

iTrader: (1)

80e, triple disk converter, and its locked.

coolmanvette75

iTrader: (2)

Matt if you wanna keep the S60 throw the 3.54s in it. I can only see it going faster. I don't think the gear swap alone will hurt the efficiency of the turbo more than it already is. If you wanna go through the trouble of pulling that rear back out and selling it, get a 9in with 3.23s

dezlfrek

iTrader: (1)

I have a little 302cid 4.8 and 3.25 gears in my 9" going 142mph in the 1/4 on low 14psi boost.. and it cruises down the highway at 2800 going 76 mph with 28" tires..
people have always told me you can never have to much gear just not enough power to pull it..

Ryans99ls1

iTrader: (16)

FWIW I had 3.25s in my 6 speed car last year, which most consider way too low. Car had absolutely no issues getting through the power band and my butt dyno tells me its faster because . The only issue was that 6th gear was useless untill about 90mph haha.

I put 3.50s back in this year but i threw on 28" tires so its still the same final drive as having 3.25s, i love it.