Hello all, new to this board and nice to meet all of you. I have an '87 SE that I am transplanting a 4.1 Buick V6 Turbo into. Save the flame comments, not interested in them. I know nothing about the rotary motors and don't care to. The car was originally purchased for $200. I bought it b/c it was rear wheel drive, stylish, light and had a large engine compartment to it. I bought the car with the sole purpose to drag race it, yet maintain a sleeper appearance on the street. The car will reatain A/C and Power steering. I am looking for some heavy hitters that have actual experience with putting a ton of HP & Torque to the original Mazda rear ends.

I believe I have a LSD out of an '88GXL. It's a 5 lug rear with big brakes (compared to the SE rear).

I am not sure of the ring gear size.

Question is, how much HP & Torque has someone put to these rears before they break? Looking for approximate HP/TQ or E.T./Quarter mile times of when people started running into problems.

The half-shafts look pretty dinky and I worry the most about those. I plan on initially having 500HP and 650ftlbs of torque available and the car will be drag raced (slicks).

Anyone with real world experience in this department?

Thanks for your time.

Mike Savino (Orlando_87GN) http://www.TurboBuicks.com

http://www.grandambition.com/misc/misred/

 

put narrowed nine inch in it then you won't have to worry

 

About 500rwhp.... and more importantly that much Trq. (which as you know is what kills driveline parts)

To tell you the truth, the sick f***s over at www.v8rx7.com would be a better crowd to ask about your conversion.

Watch you *** over here. We dont like them there pissss-ton engines in RX cars.

If this is an all out drag car you already know IRS sucks for drag racing, so you should just look at building a racing rear setup with a 9 bolt and ladder-bar 4-link setup or something and ditch all the stock parts.

 

Why does everyone frown on the IRS? All I will need are consistant 1.4x's, 1.5x's short times to support my E.T. goals.. (low 10's).

I have seen 240z's do 1.5's on drag radials...Buick Powered of course.

More importantly though, I am going to have my hands full with the rest of the conversion. The last thing I want to think about right now is major rear end fabrication.

 

hey, dyre, I love the peoples rebulic of california tag..hehehe

 

There are a lot of piston haters, here, but just as many who respect all engines. If you are using an auto tranny, you wont have a problem with the stock diff. Manual, I would do a switch to the TII rear-end. It should hold up fine for a 10 sec car.

 

The rear-gear is a 4.10

 

great

 

Dude, get outta here. You make me sick, fricking "pistoners".

 

I broke a piece off of either my ring or pinion at only 376 rwhp. It did though, have over 150k miles on it.

 

I was more worried about that trq than the hp granading the rear end. 10 sec rotary with stock TII rear end. Yes
10 sec 4.1 Turbo Buick with stock rear end.... i dont know.

Like i said, ask the guys at v8rx7.com... they will know for sure.

 

I was putting out roughtly 450 at the flywheel, with 160k miles on my last n/a 90. Held up fine. CJ

 

I bet its gonna run a 200R4 auto out of a GN.

 

Yes, it will be using a race built 200R4 and eventually a 9" converter. The 200 trans is a compliment to the Buick motor in the fact that it's a 4 speed auto. It also utilizes a Torque converter lockup feature which improves gas mileage. I'll have to sit down and figure out how bad these 4.10 gears are going to kill me. The Buick motor is a low reving engine making most of it's power around 4000rpm. The 4.10 gears are going to force me to use 4th gear at the track, which I would rather not do. This is the last thing on my mind though, and can be addressed later.

 

grab the IRS out of a corvette if you want to still have IRS. If not I don't think it will take any of that power.
Go domestic for it.

 

What does the stock converter stall at? If its a relatively low stall speed, you can probably get by. You'd still need an LSD rear out of a 5 lug car, since yours is an SE and probably doesn't have limited slip.

 

Stall speed is around 2800-3000rpm, nothing wild. I am using a rear out of an '88GXL. It's already in the SE at this time.

 

I think it will hold up fine.

 

While the thought of a ****-ton engine in an RX-7 makes me wanna kill... :p

FWIW, the auto tranny'd RX-7s had 3.90:1 rear ends. I'm not sure about LSD, though. They also used a different length driveshaft, but since you're using the TR tranny it shouldn't be an issue (you'll already be fabbing a custom shaft).

B

 

Barely 300lb/ft for an NA rear end.&nbsp 400lb/ft for a turbo rear end.
Unless you baby the launch (1.3-1.4 60' times are pretty stout launches!), it's going to break pretty easily...

MaybeGNX7 can comment since he'e running almost the same mods?&nbsp I read on some web page that he's running an NA drivetrain...




-Ted

 

The GXL posi unit you have should be fine.... and if you break it the GXL unit they are pretty cheap to replace. If not email me and I'll sell you a T2 diff/halfshaft setup for a good price. The flange on the T2 diff however will not mate up to the driveshaft created for the GXL diff.

A guy with a 2nd gen RX-7 with a 350 and NOS went 10's@125mph on a 7" SE differential and M/T slicks. These halfshafts aren't as thick as the GXL ones and not as beefy as the T2 units (the strongest).

There is a company that makes chrome-moly halfshafts for our cars. But why should you when replacement halfshafts are about $100/pair.

MisRed and GNX7 (me) will be competing for who gets in the 10's first.... and lowest et/ highest mph. All a question of who is crazier with boost levels and who has a bigger turbo/injectors. Pretty much same setups.... not sure if he is more racecar oriented or street car. Turbo selection will dictate that and torque convertor.

Run the GXL setup and if it fails I'll set you up with a Turbo 2 setup. If that fails you should contact Chris "Speed" Anderson in FL and have him do a Mopar 8 3/4 solid rear diff and ladder bar setup like he has in his mid 9 second RX-7 and choose whatever gearing you desire to go through the traps in 3rd.

Guys with homebrew Mustang twin turbo setups run 3.08 gears and maybe even 2.73's and are in the 9's......

You will be required to go into 4th gear. Mine shifts into 4th a little after the 1000ft marker..... unfortunately.

GNX7 (boinger...... not a spinner anymore)

Mungo like turbo boinger setup for simplicity/cost/and reliability

 

Ok... I will also say that I don't like piston engines in an RX-7... now... here's something that may help. The differential in an 88 convertible, or ANY automatic 2nd gen RX-7, is a 3.909:1 instead of the 4.10:1 that you have. They are NOT LSD though, so you will need to swap the gears from the auto differential into the one you have now.


Brad

p.s. you are probably gonna break it.