I've searched and read a ton of different things. I have a s484, 4l80e, she lq4, and a Ford 9" I got the rear for a steal but still has 4.56s in it. I know people always say longer gears for boost, but exactly Why? As of right now I can't change the gear ratio but I plan on down the road, but still curious to what will happen? The 4l80e is pretty much bullet proof with a brake and a 5k steal. Guess it just pretty much comes down to driving the car and seeing how it'll perform.

 

Your motor will NOT like those 4.56s. If you tried to run it at the track, I wouldn't be surprised if it ran out of gear even with three overdrive tranny. Turbo cars don't need much gear, and it probably won't build boost very well..... then again it might. But if I were you I would ditch those gears asap. Just taking a stab in the dark, I would do something around a 3.00 gear.

 

I wouldn't go any lower than a 3.23. 3.23-3.55 seems to be the sweet spot for most turbo cars I've seen

 

ive been asking the same questions these recent days. But im guessing since that you are running a 80e that you can get away with higher gears like 3.25-3.55. Im running a PG and have been taught to lean toward 4.56 gears for 1/8th mile drag

 

Tire size matters to
im running almost exact combo as you, but on a 26"-27" tall tire n went with 3:25
I was told once that turbo lights off, you ll wanna be in it for long as possible. The yee haw effect.

 

I have a friend with the same rear and we are going to switch gears. He has 3.50s on his n/a car just comes down to when we want to switch. But top priority is finishing the car and having it able to move.

 

OP, it comes down to what you're going to use the car for. 1/8, 1/4, mile, etc. To summarize the approach - weight and HP determine speed. Speed is reached based on tire dia, gear, rpm (excluding converter slip where if applicable. You'll note numerically gear goes up when HP (i.e. MPH) goes down. Define the variables and calculate gear ratio. Google wallaceracing for calculators.

 

I'll say this my car has 2.73 gears in it now and I absolutely hate them. I'm going to 3.55 so I can actually use 3rd gear

 

Ha! I'm the exact opposite, I absolutely love em. You just need to keep it matted longer

 

I don't know why lol. It's decent for cruising but for racing or anything they are way to low. Literally goes 130mph in second lol. I'd much rather have 3.55 so I can hit 3rd by 100mph

 

I had 3.08s in my Nova with a 275/60 tire. It hung on the converter cruising a little more than I liked. Changed to a 3.31 over the winter, TOTALLY new car. Converters' tightened up better cruising and builds boost just as good if not better. Definitely a change in the right direction IMO.

 

I just ran into this situation. I'd had 3.55's in a hybrid Ford 8.8. I also had a vigilante 2800 stall in my TH350. I'd tried footbraking to see if it'd get any boost. Nope. And... very lethargic off the line. So I took the TH350 out, put my T56 back in and sent the Vigilante off to be restalled. I *thought* they restalled it to 3800, maybe 4000. Also, since I too had read the longer gears would load the turbo better, I opted for a new set of 3.08 gears. Well, put it all together and after breaking in the gearset, went to Lebanon Valley Drags 2 weekends ago. Blew right thru the converter on both passes. 11.9 at 118mph (14psi?) and a 11.3 at 120mp(16.x psi and 1.7sixty foot). I'd logged both passes and found that on the 2nd to 3rd shift, my RPM only dropped 200rpm. I contacted Precision about it. They said they found my records for the restall. They'd actually restalled it to 4,300 (!) I talked to Frank Cahall about it and he said my gear ration and stall were all wrong for my combo. He said 3.55's would be better and that the torque converter needed to be much tighter. I think he mentioned something like a 2600 stall. I have a transbrake and a 2 step so that should work. I ordered new 3.55's, installed them. I also ordered a new PTC torque converter specific to my combo. Should be able to test again after I break in the gears.

 

Thanks for all the replies so far guys! I think what I will do is get everything buttoned up drive the car and see how it does with the 4.56s. It's just gunna be a street car for the next few months. Gotta get everything dialed in and working properly, besides that the closest track is over 2 hours away and lots of tolls to be passed along the way. I know it may not be ideal for this setup but it will drive, most likely slay tires to but it will do.

 

Im in for results....My guess is you will get through first and second gear before you build any appreciable boost. Once your in 1 to 1 of 3rd gear you will hold the gear long enough to let the turbo load up. Just a guess.

 

It really comes down to what you want to spin it to in the 1/8th or the 1/4.

Depends on the application and what you're going to do with it.

Gear it for the application then spec a converter accordingly.

 

That's what I'm going to do. Everything I bought is used for all types of different applications. I got a few good deals on everything for my car. Kinda Frankensteined it and we'll see what happens.

 

Just a follow up to my earlier post about buying a PTC Torque converter from Dusty.
Prior setup:
Car:96 Z28
Engine: Built 2002 5.3 (PRC stage 2.5 heads, ISKY triple 12 cam(212/212 .56x/.56x LSA 112), Wiseco forged pistons, Compstar H-Beam rods, balanced/blueprinted)
Turbo: PT7675 .96 A/R billet wheel
Hotside: CXRacing tubular header design (no crossover)
Transmission: Built th350 w/transbrake and Precision Industries Vigilante (4300 stall)
Differential: Ford 8.8 Hybrid (uses stock GM 7.5 10 bolt legs on an Explorer center section) and 3.08 gears
Tires: 315x35x17 M/T Drag radials

Issue: Blowing through the converter. Shifting from 1st to 2nd, RPM only dropped 200rpm and from 2nd to 3rd, 300 rpm.

New setup:
Regeared the differential with 3.55 gears.
Installed a new PTC spragless TC configured by Dusty for my setup/goals (Light daily driver with weekends at the drags). Fluid, per Dusty’s suggestion for the transbrake application, is tractor fluid.

Took several days to break in the gears properly, then took the car out today to test a few things.
1. Transbrake and Stall – I’d always read you could tell the stall of a given torque converter by activating the Transbrake and flooring the gas. That seemed to make sense to me, though I’d never tried it till today. I found a secluded spot (ie: no traffic), activated the transbrake and then floored the gas. I watched the tachometer as the RPM’s began to climb. To my surprise, It got up to 5K pretty quick and had built 9psi of boost. Woot! I think I’ve been mis-informed about the stall determination from transbrakes. Obviously, it’s not stalled to 5K. I’m pretty excited at the prospect of trying to launch the car when the strip is open again.
2. I found an unoccupied stretch of straight highway, stopped and then pressed the gas as aggressively as I could while maintaining traction in first, then wound it out to 5,788 rpm(52mph), then shifted. On the shift, The RPM dropped to 4,939. A LOT better than the 200rpm drop with the Vigi. Then wound it out to 6,111 in second(94mph) before shifting to 3rd. The rpm dropped to 4,939 rpm on that shift. So the PTC TC is working great.

Thanks for all your guidance and help Dusty and the rest of you good do-it-yourself guys on this board.
Dave