Question : 4T60E converter selection

[3400-95-Modified]

Ok well in the 1/4mile thread I kinda had a discussion going but I think i should put it over here.

My build is a 3400/3500 hybrid setup with a 65mm TB headers, Ported 3 angle valve job, TCE intake spacers, Cold air intake, 216/232 dur .050 .517/.568 valve lift, Comp Springs, 4T60E with a 3.42 final drive, EP LSD, and 225/45/17 BF Goodrich Drag Radials...

I'm currently running a Yank Performance Converter, which was sold to me as a "3k" stall converter... Now when I get on the gas brakes to the floor the car will start to creep around 3200-3300 and I think thats a little aggressive. Car bested a 14.46 in humid conditions but I really feel this car should be a low 14 sec car with the cam thats in it.

Does anyone have any input on a better Torque converter selection? I know with my old 3400 I think I could get my FJ converter up to 2400-2500 stall... so with this motor it may be a little higher due to more torque.

What do you guys think? Everything I look at on line is referencing V8 duration and rear end gears and stuff like that and a small block and big block converter choice for those setups... I know it cant be that accurate to what we are working with.

[IsaacHayes]

What is stock? How bad does your motor bog when at low RPMs? I know you have shorter gearing so I'm not sure if you can tell when it locks at say 50mph how bad it bogs since you might have the RPM's up a lot more over stock. I know 50rpm locked TC is a pretty big strain on a stock engine, with your cam I wonder if it would be the same or worse. Might be able to get by just fine with a stock converter but once again depends on the cam. You do have more displacement and headers/etc though to help.

[3400-95-Modified]

It doesn't bog... I can hold 50mph locked up a decent hill and not strain it that much.

I wouldnt go with stock.. stock is 1630, thats WAY too low for my cam. I would think the 2095 would suite it much better.

Eric said he can reach 2300 footbrake stalling the car with a 2095 converter in there and possibly with my cam and whatnot I should be able to reach around 2500 or higher... the next converter is a 2375 or something like that so I dont know if I want to go that far because I might end up right where I am now approx 3300 footbrake stall.

[johnnymossville]

Maybe this will help you choose you converter:

The more torque you apply to the converter, the higher the stall speed is.

Say your 3400 puts out ~230ft-lbs @ the crank and you use a converter with the second digit D, that has a K factor of 180 with a 2095 rpm stall speed.

Take the square root of 230= 15.165 and then multiply by the K factor (180).

15.165 x 180= 2729.7 rpm stall speed

Here is the K factor on a few converters:

2nd digit/K factor/stock stall speed

D= 180 2095 rpm
E= 160 1865 rpm
F= 148 1720 rpm
G= 140 1630 rpm
J= 177 2060 rpm
L= 143 1895 rpm

I probably wouldn't go any higher than a 2095 rpm because that is around 2700 rpm. When Ben gave you an estimate of 290 hp, did he give you an idea of your torque numbers?

[3400-95-Modified]

Yeah both the HP and torque dropped down to about 275 on his newest simulation with his newer program, so yeah 275ft lbs square rooted then multiplied by 180 is around 2900... And I know now I can start creeping the car at 3400rpm with what I have so yeah I'm searching for a HD FD9B converter at the moment.

Thanks for the K-factor info.

[johnnymossville]

You're welcome. Ben just ran a sim. for me and it shows 275/274 with my build. I don't have headers yet , just ported 3500 front exhaust manis. and my cam is nowhere near big as yours. I think that I'll have to have somewhere around 2500 rpm stall as my power range comes in a little earlier than yours. Oh yea, nice vid of your 14.46 run at the strip.

[3400-95-Modified]

Oh yeah you got 11.5:1 compression... Damnit... I need to bump mine up, thats where I'll really see some more n/a HP.


Any ideas on what to do to bump the compression without changing pistons?

How much do I need to shave the heads to get 10.5:1 or 11:1?

[3400-95-Modified]

Just bought a Heavy Duty FD converter from Direct Transmission Parts in NY.

Base converter is 95, the HD upgrade was 100, and the Kevlar lockup clutch was 45, so all and all it was 266.04 shipped to my door. Should have it middle of next week.

I hope this will help with my setup a lot. I've been told what I have is a little too aggressive.

[torq455]

3300 rpm stall i feel it is too aggressive. my 97 lumina small port heavy car foot stalled at 2800 rpm. GM may have wanted a higher stall to get the bigger cars rolling.