I posted a couple days ago about hardened head bolts, well i made some phone calls to some guy's i went to school with and found out they do exists( i think), a local guy from around here sells them but i can't find them anywhere else I've searched the internet and called a couple shops but i can't find them. The guy's from school told me they are grade 12 and that they had a allen head on them. I was just wandering if anybody else knows about them and where to get them.

Thanks

 

Mteric bolts do not use the same grading as fractional

Bob

 

mine are allen head , and they guy i got them from is running twins ( around 100 psi) and n/x and pulls it every weekend there is a pull .

 

That's what I thought it should be something like 8.8 or 10. something i don't know grade 12 would be equivalent to but either way i was just wandering if any body had heard of these

 

flippy what was the guy's name you got them from, i noticed that you live in Ohio i might know who you got them from.

 

This is easy-

SAE bolts are grade 0,1,3,5, 8, 8+. ASTM are a little different, but all american UNC/UNF thread. I'd assume headbolts are yield critical. Fty for a grade 8 bolt 130ksi., Ftu=150 ksi. that's 150,000 lb/in^2

Metric bolts are done in Mega Pascals (MPa). The SAE class (8.8) tells how the strength.
common strengths: 4.6, 4.8, 5,8, 8.8,9.8, 10.9, 12.9

A 10.9 metric= Grade 8
8.8 metric= Grade 5
12.9 = 177 ksi which equates well to a high-strength allen bolt. Generally in UNF/UNC they are called "grade 8" but is a misstake as they are stronger.

If you want to find sizes- go to Holokrome's website.

hope this helps

 

Maybe i misunderstood the guy that told me, he might have meant 12.9 instead of grade 12. Well anyway it doesn't seem like anybody knows about these things except for Flippy1974 & In the red, I'm starting to feel a little dim for asking about them. The reason i don't just go and get them from this local guy that sells them is i can never get him to answer the phone and i don't know where he lives (the guy from school tried to give directions but they didn't know the names of any roads, just the usual turn here turn there) that's why i'm looking for another place to get them.

 

Alright i got a hold of the local guy and found out the phone number to the company he get's these bolts from. They are not head bolts they are just harder allen bolts and he said that with a .020 head gasket you could run 60 psi of boost all day and not blow the head gasket, so i ordered a set (70 $) and I'll see how they do and if anybody would like to have the phone number to this place let me know.

 

I'm currious on how those will hold up.

Bolts to be strong, need to be the correct length. General practice is no threads in the shear plane. Higher strength SHCS have very little between yeild and failure as the metal is fairly hard.
I'd guess he is just selling you SHCS from hopefully- HoloKrome. See if their is a name on the head when you get them.

Michael

 

I'll let you know when i get them, I guess there is several people around here running them and a couple i know pretty good but I never knew about there head bolts before today and they run pretty high boost levels and one guy run's nitrous with a s300 on a 2nd gen pushing i know at least 60 psi and never had any head gasket problems that i know of