I've got a PTE sitting here with two of the four turbo-to-manifold bolt holes tapped for a larger size on the exhaust flange. The banjo bolt that goes into the head for the oil-feed line screws right in, so I guess it's that width. (M12?) Problem is, who sells bolts that size and length that are heat-treated?

I know some people use "strong" bolts from Home Depot and similar places, but if someone's used something like that and had it last a long time for such a high-stress spot, I'd like to hear about it.

deusxmachina said:

I've got a PTE sitting here with two of the four turbo-to-manifold bolt holes tapped for a larger size on the exhaust flange. The banjo bolt that goes into the head for the oil-feed line screws right in, so I guess it's that width. (M12?) Problem is, who sells bolts that size and length that are heat-treated?

I know some people use "strong" bolts from Home Depot and similar places, but if someone's used something like that and had it last a long time for such a high-stress spot, I'd like to hear about it.

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i've never heard/seen of bolts locally that will withstand the weight, and heat/stress

I really wouldn't use hardware from Home Depot on a high heat, high stress application.

I would order from mcmaster.com

a stainless steel m12 bolt should be a couple of bucks each.(not rated)
or you could get zinc plated steel, for about the same.(class 10.9, DIN 931)

Yep, nothing local so far. Had a hardware guy tell me metric 10.4 (or so) is equivalent to SAE Grade 8. The grade 8's look like the stock ones, but I know they're not as strong. Didn't find any metric of that size and fine pitch anyway.

Mcmaster.com is good to know. I just read a thread yesterday saying how brittle stainless steel bolts can be, but maybe the zinc ones will work, or at least something from their catalog.

The holes are threaded for the bigger bolt and are now too big for a normal helicoil. For the record, I screwed up, the oil-supply banjo bolt is the same size as the turbo bolts. It's an M12 exhaust bolt or something I happened to have that fits in the hole.

Let me know how long of bolt it is that you need and I should probably have something that is the right size and of the right grade hardness for you. I have a large supply of mitsu bolts taken off the cars that I have scraped out. I use sub frame bolt in my exshust housing (o2 to downpipe)instead of the studs. I think that these are the same thread size that you need. If not, Ill try and find one in my junk yard.

Steve.

Thanks for the offer, fivestardsm.

Someone on my state list told me to go to the local Fastenal. I told the guy to order me the strongest heat-treated bolt in that size he could get. Even after getting hit with a surprise $7 shipping fee at pickup the price was still cheaper than Mitsu bolts, so I took them.

They are only grade 8.8. But, looking around, including at McMaster, so far I can't even find an M12 heat-treated bolt with 1.25 pitch rated any higher. Anything stronger is a higher pitch or not heat-treated.

So, I guess I'll use them and hopefully won't have to curse later. They are weaker per square inch than the stockers, but they're twice as big, so we'll see.