my motor i have dynoed 400whp in the camaro it was in.. its going in my fd.. on street tires should i worry about the rear end shelling.. i wont be drag racing it

 

400whp is fine with the stock rear end. Hinson didnt go to a KAZZ until they were deep in the 10s and didnt get new axles until the 9s. Besides, those street tires are just going to spin in 1st anyway... I only have 360whp (LS1) and 1st is basically useless with the street rubber. . . on r-compounds that is a different story....

 

a local ls1 FD broke his rear with less HP. if you get axle hop, it can really do damage.

 

Do you have carb or fuel injection

 

im fuel injection and i have bout all the suspension mods i can think of... springs, shocks, trailing arms, tow arms, stiff mounts for the diff, diff brace etc... so i shouldnt get any wheel hop if any.. i just dont wanna snap it... i wont run sticky tires like slicks or drag radials.. but only street tires.. i doubt i will but better safe than sorry...

 

i drove my ls1 fd for the 1st time 2 days ago. with my skinny 225 tires i spun 1st,2nd, and 3rd. it was also very cold out so.....im currently looking into some wider rims/tires. oh...its a stock engine with custom cold air intake and long tube headers.

 

No secret here but tire compound makes all the difference, pick well.

 

so if id run drag radials with that much power with all the correct braces and launch kit and tuned suspension to eliminate 99% of wheel hop.. would the rear snap with 400whp?

 

It will be pushing it. The torsen seems to break apart inside, get jammed and then explode outwards destroying the casing. Switch to a clutch pack style for more insurance (turbo II, Kaaz, Cusco, Carbonetics, etc).

 

understood.. however if i would switch to a kazz lets say would it affet normal driving? would my fd be as nible as it was before?

 

Heidihi, Where did you get your motor and trans and how much did you pay for it? I have about 30k into my 13b with parts and labor and I have only 340 miles on it and i am thinking I am going to make the swap. I am just tired of the hassles with these things. It's not even through the break in and I am thinking about selling the whole set up....(if there is any buyer out there) to go V8. I spared no expense on this thing and it's probably one of the most efficient 13b's out there but I just think it would be nice to just drive the car, make some decent reliable power and still get half decent gas mileage. I should have done a V8 from the start.

 

what kind of welder did you use on that hood scoop?

nice work, I burn holes through sheet metal, but am starting to thing I need some heat venting at the very least.

 

I dont have any power in my FD, but I did switch from stock Torsen to a USA spec OS Giken Super Lock.

Using the Motul oil the previous owner bought for it there is absolutely no loss of nimbleness with this set-up. It barely stutters backing up and is silent. It doesnt lock when I three wheel up my driveway though- have to pull ebrake to get up.
A different oil would probably give it more noiae and more aggressive lock-up.

It does drive different than Torsen though.
Throttle on spin it always drives straight or toward the steering input.
Also I noticed I could get on the gas before the apex and easily rotate the car under throttle- the slip angle is just easier to manipulate.

When I autoxed my TII with its stock clutch type the rear would lock way to easily and cause on throttle understeer till you overpowered the rear tires into oversteer. Hated that and swapped in a FD Torsen.

Which was great till I got 420rwftlbs torque then it acted like an open diff- spin one tire up way too fast and hook you random direction in 4th on the freeway...

I recommend a clutch type diff with as many plates as you can afford and a differential cradle to shore up the thin cast FD rear end housing.

 

Or 8.8 swap for more low rev V8 compatible rear gearing.

3,000rpm down the freeway will be miserable in a V8. Better inder 2,000rpm.

 

Detroit TrueTrac for the 8.8. Basically a bulletproof torsen. I love mine. Super predictable and controllable when the rear steps out under power.

 

This thread is from 2009 but nonetheless, would anyone recommend the truetrac in an 8.8 for a street car? Is it noisy?

 

I just recommend it. It is silent, and in my opinion will be the best street car diff bar none.

 

Thank you, I was hoping to hear that from someone with truetrac experience.

 

I know they do consider some alternative oils to be acceptable, but imo you should only run the specified OSG 80W250 oil in it.

 

No problem. You’ll like it.

 

Yeah, the Motul I used is on their "select few" fluids one can use,

https://osgikenusa.com/blogs/tech/us...il-and-os-250r

but your point is taken that if I want the exact lock-up properties they engineered i to the LSD I should start with their fluid.
I will try the OS Giken fluid next fluod change- wasnt going to pass up free Motul.

 

it was more than that, sorry to go OT in the thread

https://www.rx8club.com/rx-8-racing-...3/#post4920237

.

 

I'm at about 450whp with a T-56 Magnum and KAAZ 1.5 way and am happy with the setup.

 

Found the data sheets-

OS 80-250R=
422 mm2/S kinetic velocity @ 40C
50.1 mm2/S kinetic velociry @ 100C

Motul 300 75W-90=
72.6 mm2/S kinetic viscosity @ 40C
15.2 mm2/S kinetic velocity @ 100C

Thanks for the heads- up.

That cold viscosity though.. is this why Japanese always warm rear end 4 wheels up in pits with engine idling in gear?

 

don’t worry, it won’t stay anywhere near that temp once you’re getting on it.