So planning on refreshing and replace all my bolt but need some help finding the part number. Looking for the 18 header bolts and the 6 nut and studs that connects to the turbos (3 on each side). Any help much appreciate!

 

8mm x 28mm for the header to heads and 8mm x 22mm studs for the turbo to exhaust. no need to pay porsche prices any grade 5 bolt and studs will work

 

My experience with other cars is you can use standard USA or metric fasteners. Obviously you want the right diameter and thread pitch and bolt grade. I've even used stainless steel fastener hardware.

However, you have to be careful. What I have found over the years is while one can match the diameter and pitch no problem the factory hardware length is sometimes not standard. The factory fastener is a bit shorter than standard.

If you get an off the shelf fastener and find it a bit longer than the factory fastener be sure the hole is threaded deep enough you can properly tighten the longer bolt down without bottoming it in the hole.

 

aluminum heads. DO NOT USE stainless steel bolts. they will cut right thru the aluminum threads in the heads if crossed.

use 25mm black oxide allen bolts grade 5. long enough and found at lowes. studs can be replaced with 20mm grade 5 hex head bolts for the exhaust.

 

Picked up some grade 10 hex bolts from mcfaddendales. All for under $10. Black ones are 30mm and silver ones are 20mm, will that work?

 

20mm are fine for the exhaust. 30mm are 2mm to long for the heads. you might get away with using a flat washer and a lock washer under the head . try a test fit and see

 

Well, I used stainless steel fasteners on various aluminum motorcycle and automobile parts, including heads, and didn't have any problems.

'course, I avoided cross threading the bolts/fasteners.

Grade 5 seems a bit under spec'd.

Generally for any fasteners other than for body/trim I used grade 8 hardware, especially for the exhaust. Lots of heat expansion/contraction, vibration, etc.

 

look at the oem hardware torque specs for the exhaust. no need for stainless grade 8 . grade 5 is fine. and nobody starts out to cross thread a hole in the head. but when it happens stainless is the clear winner of that battle and you are the loser.

 

I've had stainless bolts seize badly in aluminum, I'd be very careful about using stainless and certainly use a nickel based antiseize whatever bolt went in there.