Mileage before boost
 

:driving: I have a friend who has this great looking PW '12 right at 68k miles and considering to boost it. How much of a risk is it to boost a high-mileage Z? I know the Z has good internals but what are the risks? I'm telling him no but he insists it is safe and doable

That is not that high of mileage. If the engine is sound and not burning oil, he should be fine. A rebuild will be in his future though.

If it has good compression and leakdown numbers and an oil analysis comes back clean, go for it.

There are sooooo many variables. How much boost? How hard will it be pushed? What kind of shape is the engine in now?

As mentioned above, if the engine is in good shape, 68k miles is not that much for a modern engine. But it still has 68k on it and an engine only has so many miles it can go. If your friend doesn't plan on putting many hard miles on it, I'd say go for it (assuming engine checks out good). If he has a lead foot, I'd say no.

Ok. Determine engine health first with a good compression and leak test move forward if all is good or fix issues first if not so good. Because of the mileage and driving style there is a slight possibility of a rebuild along the way. Outside of the aforementioned tests, is there anything else? Thank you gentlemen.

Yeah, make sure he has enough saved to replace the motor if he has to.

A UOA (as per Chuck33079) will tell you a lot about the condition of bearings.

Comp/leak you can do yourself and UOA is easy to send off. I can't think of anything else that can be easily checked. I'd spend some money getting someone that knows hi-po engines to check things out.

If the dude wants a boosted Z then why not? He could blow up a low-mileage car or a high-mileage car or he could get lucky and run this one for another 100K. Probably not, but we can dream. :)

Point being, I wouldn't boost a Z with 5K miles without money set aside for a rebuild, you know what I'm saying?

I boosted my previous Z in the mid 70k miles and she still running today.:driving:

I agree with the others. If the guy has a lead foot and will beat on the car he is probably asking for trouble. If he plays with it on occasion and takes care of it he will be fine.

Today's cars are pretty dang good, if you take care of them. I remember doing valve jobs on Chevy 396 engines at 60K miles. It was pretty common. Now days a valve job is done at 250K along with a rebuild. By then the rest of the car is gone so it really doesn't matter. My two daughters drove a V6 Maxima that had over 200K miles all through high school and beyond until the tranny gave up. The engine was still fine.