As my car is coming along. The th350 is being sentenced to death and will be replaced with a th400. But the more I read around I see more and more powerglides. I really like the idea of 1 simple shift, and not having a bunch of little rules you have with a full manual valve body th400( no pedaling in 2nd, downshifting 3-2 for a highway roll, etc)

but am I going to weigh too much? Not make enough power to push through 1st? I dont want it to be a dog.

the car is a pretty well gutted out 1986 monte carlo
5.3 lm7
s475 t6 1.32/96
Ljms stg2 turbo cam,
will have a front mount A2A intercooler.
ford 9" 3.25. 28x10.5x15 tire
I'd guess the car weighs 3350lbs?

plan is a street/strip car. But mostly street mischief with 600whp

would a powerglide make it a pooch?

 

like any tranny it's all about the right converter

 

I plan on going to do a custom 9.5 converter through PTC

 

In general heavier setups do better with a TH400, esp with relatively low power. Also setups with tall gear favor the TH400. You seem to fit the bill on all of those, so I’d say TH400.

Neither would make it a pooch IMO, But you’ll have a better starting line ratio for a 600hp 3300+lb chassis.

I run the same gear in a lighter car with a 30" tire and a glide. You have to be kinda mean to it to leave hard.

 

Put a glide in it. My truck is 4300lbs with a 1.80 PTC glide. Leaving on 9psi and max of 28psi down the track was a 1.41 60ft and 5.7@123mph. Gear is a 3.42 with a 315 pro that is 30" tall.

 

 

Aren’t you making like 1200hp? I'm thinking with 600, the mechanical advantage of the TH400 will ET better.

 

pretty close to that at 28psi, he will be able to leave on all of it with the glide.

 

• does anyone know somebody with a 3300ish lb car with 600-650whp? With a powerglide is there little rules like a th400?
• Like if you're going in 2nd cruising at 45 you can just pull down to 1st and get ready to rip?...even with a transbrake? I dont know if what I want is even achievable.
• I dont like those things with the th400. If it didn't matter I'd be all for it and wouldn't care. The car is only going to see the strip probably a few times a year! Pretty much a summer time street burnout machine.

 

So im assuming that the ideal starting line ratio of 9,10,or 11 goes out the window with the turbo setups. My n/a car with a powerglide had a slr of around 8.59. Now its looking like it might be around a 6 something. Im also looking around 600 rwhp with powerglide and on3 7875.

 

My 2cents..... I've been down that road and decided to go with the Powerslide and I HATED IT ! If you are only going to see the track a couple times a year AND you want it to be a summer time car that you will enjoy driving on the street then DO NOT GO GLIDE Seriously! I had a 77 Datsun 280z with a smallbock chevy, the car weighed 3100 with me in it, everyone said my car was perfect for a Powerglide. That may have been true if it was a track only car, but I drove it around town and only having 2 gears was NO FUN!!! (I think it harder on your engine too, especially if you plan on cruising around town) The glide stayed in my car for about a month before i SNATCHED IT OUT in favor of a TH400.

 

It will suck riding around with that powerglide. The 400 isn't nearly as bad as some make it out to be worth the "little rules". You can downshift all day long at freeway speed with the 400, it just about takes a moron to tear up a 400. And yes, you can peddle a 400 in 2nd.....as long as you are deft with the paddle. Aside from all that, I really don't think your motor has enough beans at that weight for a glide. You really need to be making some steam to make a glide worthwhile imo.

 

I run a glide in my nova and have no issue with it. if your local track is slick and you do any street drags the glide will help the car leave with a more predictable launch. . I removed a 350th and went glide and it helped the car. car runs 9.80s at 3500 lbs. 10" ptc convertor, 3.42 gear ,28" tire.

 

In the end the first gear ratio is the same between a th400 and a glide, so it comes down to starting line ratio and what you are doing with the car.

Everyone is going to have a different opinion and everyone's car is different. I went glide because its simple, its one shift, its lighter, and can leave on more power at line.

It will take 9-11lbs for my 3800lbs car to 60ft 1.3x with the glide with 3.25 gears, and with the 80e ( same planetary as a th400 ) couldn't leave on more than 8lbs without smoking the tires.

Its all about what your intended goals are and how you plan to drive the car. Both transmissions will work for you.

 

9-11 SLR range is usually targeted for a good working chassis. Turbo car or not...

With a glide and 28” tire the OP’s SLR 5.72. (with the standard 1.76 glide gear set) Which is horrible.

With a TH400’s 2.48 first gear he would be at an 8.06 SLR. Still not “ideal” But MUCH better.

As mentioned either CAN be made to work and either CAN be fast. But the Th400 is better suited gear wise for 600hp street car at that weight IMO. It will give you better launch SLR while retaining street friendly rear gearing for cruising.

Dropping any trans into a low gear from a high speed roll and “Stomping on it” isn’t good for it. Likely to shear off the case lugs. Good news is with a turbo car it usually isn’t necessary. With a standard radial tire you should be able to blow the tires off at will, regardless of the gear it's in.

I have a 2.73 gear in my TH400 “Street car”. It’s a mild 5.3 twin setup on 15lbs. Likely around 600whp. It will do 140 in 2nd gear and I use 3rd as overdrive. In town I cruise around in 2nd and treat is as “drive”. It will blow the tires off at will anytime I want in 2nd. And thats with a drag radial. With a standard tire I bet I could do the same in 3rd.

My “street race car” is a glide with a 30” tire and 3.25 gears. It’s a different animal and around 1000 crank hp going by trap speed. I can’t leave it in 1st all the time, and if I have it in 2nd it drives like a minivan. Spooled up on the trans brake at the track It will cut 1.3X 60” times and run high 8’s just under 160 on a good day. But I have to be mean to it to get the turbo spooled up high enough to launch well.

It’s just my opinion.... but between the 2, the TH400 is 10x more fun on the street. I like the simplicity and lighter weight of the glide and would suggest it for a more track oriented lighter weight setup for sure.

 

600hp RMVB TH400 turbo street fox body here. Nittos and 3.08 rear gears. My first to second shift is so harsh and annoying when cruising that I usually just start from second. I'd say anything above 45mph in 3rd, I just floor it and the car hauls...nothing but a rolling burnout lol.
So I really never have a need to downshift when I shouldn't be, if I am going slow enough to need 2nd, I just click down then slowly bring the RPM's up then lay on it...most always though I just leave it in 3rd and go as mentioned above.
I'm with the others, get a TH400 and absolutely a PTC converter and be happy! I never believed in the "good converter" thing until I swapped to a PTC...I now know how a converter truly makes or breaks an auto combo. They just know how to make them work right on a turbo combo. Tightish down low for nice cruising then hit like a ton of bricks when you smack it.

 

have you drove this around yet? If so how is it? Weight?

 

Well this pretty much sums it up for me. Stick with my original th400 And PTC converter plan.

so, anyone look at the FTi th400s fmvb with brakes? "Rated for 900hp" just a thought. I thought I heard good things about them from somewhere . But is there a go to place for a th400 to get shipped to my door ...lol

 

9-11 SLR ? That is pretty aggressive for a high horsepower radial (1200-1500rwhp) car IMO. I found that around that the higher SLR the harder it is to make the car consistent at the track. Lot of fast radial guys over on bullet said low to mid 6s is ideal for radial cars ( 275 PRO ).