That right there is the rev limiter. Nobody.....here let me repeat,.. Nobody has a stock block that has survived more than 500 WHP. It is a constant topic of discussion, and it always ends the same way.
The turbo waste gate, or SC pulley combo will not be the power limiter decision,...( so, no " the sky's the limit") it'll be how many pieces do you want to pick up off of the road/track if you try to make anything more than what it will handle.
And that has proven to be slightly less than 500 WHP.
Once you get a realistic expectation for that, then you can focus on the rear
suspension.
A full on purpose built drag car typically gets the axle tubes welded to the center section. Some sort of tube braces that tie to the holes in the center where the existing vibration damper may still be, out to the end of the tubes as far as possible.
A rear end girdle, and either one of two ways to keep the axle in the housing should one break. And in big power applications, an anti-roll bar.
- C clip eliminators
- Small/big bearing 9" axle housing ends welded on in place of the standard ones currently on the rear.
A spool has no place on the street..it'll screw you if you ever get caught in the rain, and it's murder on axles if you have a sticky tire when trying to drive it through the parking lot. And you can forget about ever being able to push the car if the steering wheel isn't pointed straight. At your intended usage, I'd use the T-loc, or one of the aftermarket " better" differentials out there ( Detroit locker, Detroit True-track)..if your axles are some aftermarket hardened 31 spline like a Moser or Strange...then you're good there.
I have QA1 single adjustable struts on the rear of the monster,...and maybe a 130lb, 12" spring. And a fairmont, while lighter than a notch, has way more rear overhang than any FoxMustang. That said, Spring rates are gonna be different for each car...and the right spring for a notch, will not be the right spring for a hatch. If you are gonna spend 90% of the time driving the car on the street, a spring that is too stiff will be about the same as no spring at all.. So I'd go as soft as you can get that will not compress past half of the strut compression when the chassis is fully loaded, and start from there....springs are cheap. Getting a double adjustable strut will be a waste unless you intend to spend the time at a track sorting out 60' times, so you'll have to make that call. Regardless of which strut you choose, Choose to use it. There's no point in mini-tubing the car if the inner frame rail limits how big of a tire you can use because there is a big, stupid factory coil spring stopping you. If the shop you're using is worth the money to cut up your car, and install a pair of mini tubs,...you'd think they'd know something about recommending a strut.
Good American made upper, and
lower control arms ( read,...no SVE) and serious attention to reinforcing the torque boxes finish out your drag race options.
Be advised though,...guys get on here all the time and build rear suspensions biased for big power drag race set ups,..then regret how harsh and punishing it will be to drive the thing after doing it. Again, it just depends on how you intend to use the car. A factory rear
suspension with uca/
lca's, a girdle, an air bag in the passenger side factory spring, and torque box reinforcements will allow the car to lay down some freakin' low et's with slicks. But sooner or later...the tubes will start to bend, or twist.
I had a friend that had a sub 7 second 1/8th mile drag car with a similar set up,..that the axle tubes had pulled so far forward, it had to be cut apart and straightened over an inch on each side.
