E36 rear end and 500hp

[schwerdt1]

Completed the 302 swap, added Super Sniper EFI and an On3 70mm turbo. 1st week, blown head gasket(found that my builders tech didnt know about the water jackets and proper gasket placement on passenger side). Replaced gaskets on both sides, upgraded to ARP at same time. Then came the manual boost controller issue, doing test run, boost jumped to 20psi. Now I have mocha frappe in my oil pan again. Believe we may have a block issue, or could be another head gasket issue. Bit the bullet and ordered a short block from Crebs. Cleaned up to 306, forged pistons with ring gap set for up to 11psi boost. Have Twisted Wedge 170 61cc heads and an F303 cam ready to go with it. Going to have HPP racing do the tune this time, try to keep her around 450-500hp. Rear end, going to have fab shop do the reinforcement plates for me, as I am no welder. I see the 750 swap recommended on some sites. At this horse power level, do yall think that would be necessary? Would be a good idea in general im sure, but think it could be put off for a while? I do plan on some trips to the 1/8th mile now and then. 1993 325is with the winter package, so 3.91 rear. Has anyone had the spiders welded on theirs for a full locked rear?

[R.Thomas]

Torque is the limiting factor for the rear end and should be considered.

Here is a good reference thread: https://www.bimmerforums.com/forum/s...hlight=188+lsd

[schwerdt1]

Thank you.

[nvrtoofast]

While welding the spiders is an inexpensive alternative, It usually ends with a destroyed rear end. You may never have an issue but when you have an issue it will be a big one. Lockers and LSD's are expensive for a reason. They are built to take a LOT of abuse. Also get the right one to fit your driving style and need. Drag, Road, or Track. All use different types of solutions.

[schwerdt1]

Thanks. Any good recommendations on someone who sells lockers or mini spools for this application?

[pbonsalb]

If you have 500 lbs rwtq and run drag radials at the drag strip, you will probably break 188mm diff output stubs. Might twist a stock driveshaft in two at the strip as well, but I assume you have a stronger shaft as part of your conversion. If you run street tires, they will just spin so there is not as much stress unless the axles start hopping. Hopping is bad and breaks stuff because it is abrupt traction, no traction cycles. You may break your 25 year old axles as well.

The E32 750il diff is rare and now that it has become popular, expensive unless you get lucky at a picknpull. A few people have done custom Ford 8.8 conversions, but I don’t know what it takes. I did the 750il 3.15 LSD in 2014 and have had zero issues even at the dragstrip with drag radials.

A 3.15 might not be a good ratio for your conversion. There is an E34 M5 diff that is similar to the E32 but shorter ratio. And even more rare and expensive. You can build one but setting it up is not for most DIYers.

[schwerdt1]

Prob be closer to 400rwhp with the boost. Got in my reinforcement plates. Going to take her up to the fab shop and see what he thinks we can do to reinforce the subframe. Axles, what do you recommend if just swapping those out? Have thought of a 8.8 or 9" swap. Seems like that would be a very large undertaking.

[pbonsalb]

Ideally rebuilt M3 axles but those require M3 diff output stubs and M3 rear trailing arms. Maybe just clean and regressed yours and see whether they last. The grease is probably soup at 27 years. Messy, time consuming job.