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Stock Hard Part and Rotating Assembly Limitations?

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I finished up adding Microsquirt to my 1986 GLHS. Made 195hp and 245ft/lbs at 13psi on E85. I figured it would be a good idea to ask some questions before I go and slap a bigger turbo on, or turn the boost up further. I want to know what stock hard part limitations there are. I have a completely stock block (TI?), turbo, and transmission (A525?).
  • What are the piston, rod, crank, and block HP/TQ limits before failure?
  • Any typical bolt failures to look out for (rod, main, head)?
  • Head lift / head gasket issues start to occur at what PSI?
  • Any valve spring or lifter limitations with a bigger cam?
  • Stock clutch, Axle, and Diff TQ limits? (I heard the diffs like to explode)
I realize that every car is different, and a bad tune can window a perfectly good block, but I figured that this community has been around long enough to have an idea as to when these hard parts need to be upgraded with aftermarket. Sorry if this has been requested before, as I couldn't find the info I was looking for. I'm not exactly going the typical "bolt on" route so most of the advice I found doesn't exactly fit. I'm open to brand and vendor suggestions as well.
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IMO, the a525 tranny is the weakest link. I have found all bets are off after engine dynos 240-250 WHP. Followed closely by the LW rods. Of course the factory exhaust is a joke. The turbo could stand a compressor wheel change around 240-250 HP too. After 300 HP the turbine wheel becomes a restriction. You can baby the a525 tranny by never bolting on a sticky tire, but eventually it will fail, sometimes with catastrophic results. Same with those LW rods. They're just fine... until they're NOT!
The early block and stock Mahle pistons can support 300+ WHP, but your walking a tightrope. That is why the factory upgraded the tranny, block, and why TII engines had stronger rods and steel cranks. They knew back then, and you will too eventually when you are constantly replacing broken parts. Some people just seem to enjoy misery though, and do things the hard way, most of the time because of budget constraints.
Of course the valve springs will need to be changed out with a bigger cam. They're marginal at best to begin with!
The clutch; same with the other parts, well they work until they don't. They will start slipping in 5th gear under load (boost), then 4th, then 3rd, etc., etc., etc., At least when a clutch fails it typically doesn't take other parts with it unlike the LW rods and the tranny. Axles will hold fine until you bolt a sticky tire under it. On the street they will work fine, as the tires will just break free instead of the axle. The really good thing is this is an l-body which is a light car. The heavier the car, the heavier the load on the axles become (providing you have traction). Wheel hop is really bad on trannys and axles, lift immediately if you feel or hear it, or that tranny will be toast in short order.
In a nutshell, if you want to go faster, you pay to go faster, or you will just be changin out parts on a regular occurrence. Most everyone will tire of pulling the top half of the engine apart everytime they pop a head gasket, crack a ring land, lose a turbo, lose a clutch or a tranny. Pullin trannys on L-bodies is no fun....
My advice if your want to go a lot faster and this is a nice GLHS, is build a proper powertrain first, then pull the original powertrain and mothball it. That way you'll minimize your downtime, and you can enjoy your GLHS rather than have it sitting in a million pieces in your garage for months or years. Then with the original powertrain intact, down the road you can have a #'s matching powertrain for your #'ed car when it comes time to sell or restore it.
Good luck!
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