I know this is a question that doesn't really have such a straight forward answer but going on the following spec, and using STANDARD head bolts, what sort of limit should I be looking at with:

V3 sti
2.0ltr
Cosworth pistons
Cosworth rods
Cosworth bearings
v9 nitrided crank with modified oil galleries
MLS head gaskets


I have an sc42 which is not mapped to full potential as I am waiting for the 6 speed fitting at end of month.
I was hoping to reach 420


Having read up it looks like CR plays a massive part in concluding a safe limit when it comes to head bolts, but I have absolutely no way of finding the CR out, and tbh its too technical for me to properly understand anyway.


Anyone out there able to advise?

 

Should have no worries at that sort of power level really.

 

wicked!! cant wait to get the six speed now hahaha

 

Hi there

Stock head bolts should be OK up to 1.6bar,maybe bit more(seen few cars running on stock head studs 2.0bar without the single issue),but beyond that I would go with ARP headbolts or Cosworth High Tensile 260k head bolts

Hope this helps

Thanks,Jura

 

Yer I don't plan on getting it mapped much past 1.6bar so will take that into consideration.

Cheers Jura

 

Hi there

Many people run OE head studs beyond 1.6bar without the issue,I know my friend running on his STI 1.8bar on older MD321T without the single issue and he clocked already on this turbo around 20k miles without the single issue

Hope this helps and good luck

Thanks,Jura

 

if you have gone to the trouble and cost of buying those components why not simply spend another £200 for a decent set of ARP/RCM 180psi studs and job done.........

 

Unfortunately It was built by previous owner, otherwise I would have.

 

Where does that mentality stop?
You could get very carried away

 

agreed to a point but if you have paid top dollar for Cosworth branded items then personally i would want the full benefit - to be fair if you bought a stronger & cheaper piston then the head bolts would be a no brainner anyhows as you would probably have change left

the best components in the world wont stop the std headbolts stopping play

 

The build will only be as good as the weakest component. why try to save £150 on a £5k engine rebuild to then limit the power/reliability because of it.

I keep seeing people trying to save here and there and sure enough they get bitten down the line.

 

nicely put @Tidgy, that was what i was trying to say but maybe not as well.......

 

Next you will be saying he needs to use new head bolts lol.
Agreed in this instance that the engine has cost lots and lots of money so what's a wee bit more. Obviously way over specced for 420bhp. But prepared for the GT35 in the future....

 

Again comes back to the saving for saving sake, can you gaurenty they are 100% fine?

Personally i'd rather spend that little bit more and make sure i'm not worried about it.

But that said cheap jobs tend not to last, so make of that what you will

 

Did you read what I said? I agreed in this instance

 

yeah yeah, was agreeing as well lol

 

The engine was built by previous owner, and I'm not sure if its worth stripping the heads back to fit uprated head bolts/studs If they aren't needed.

Ok so I should be ok at 420bhp with standard head bolts?

Not going much past that

 

It'll be fine.

 

no i was simply giving "best advice" as anyone that knows me or our companies reputation will be aware of - in this instance with a previously built engine then it is what it is but thats not to say i would recommend this way as the "norm"