M20 aftermarket head bolts?

[MR 325]

If I stay NA, BMW bolts are the cheapest and strongest, but are ONE TIME USE? And if I go Supercharged (no boost spikes) they remain the best up to 10-12psi? And if I go turbo, get the ARP no questions asked?

Thanks guys...I'm an E36 guy and new to the E30 world...and I've never done a turbo build.

In my personal opinion ARP studs are a good choice with any boost.

You are correct that OEM bolts are one time use.

[planecraaazy]

Hey all...looks like there is a little tension on the thread, and if you all can refrain from blowing a head gasket, may I ask for a quick clarification? I am starting on a 2.7 M20 build with an 885 head and associated other differences...blah blah.

If I stay NA, BMW bolts are the cheapest and strongest, but are ONE TIME USE? And if I go Supercharged (no boost spikes) they remain the best up to 10-12psi? And if I go turbo, get the ARP no questions asked?

Thanks guys...I'm an E36 guy and new to the E30 world...and I've never done a turbo build.

[digger]

yep stupid cheap

[nando]

Dude, you're not going to beat $25 for stock bolts. Unless you're turbo, it shouldn't even be a question.

[Lugnuts]

Go with the BMW bolts. Used them twice now and they're good quality. I'm not a bolt guru, but they're straight* and seem to be holding up well (NA engine).

* unlike a pack of Victor Reinz bolts I received that had 2 bent bolts...roll it across the table and watch the ends lift up and down. Yeah, I didn't use those.

[digger]

id be wary about generic high tensile bolts, there are many around that are made in china that dont actually meet the specs they claim to. with work we test every batch of critical fasteners in our own lab and have a full time department specifically doing this.

a brand like UNBRAKO would be good but no cheaper or easier to get than OEM

as for ARP not specific to M20 that is correct its a bit of steel right length, diameter and with correct threads. nothing more than that.

OEM bolts are necked down in the shank so you get more stretch out of the bolt which improves fatigue life and better for retaining preload. the same reason why if you replaced the bolts with M24 bolts tighten to the same clamp loads as the small bolts you be more prone to failure of the gasket as there isnt enough stretch in the bolt

[15Michaeljoseph]

M20 aftermarket head bolts?

Well, the ARP have been specifically modified to fit the e30 specifically with it's specific length spec. Furthermore, and 'with the above train of thought' Raceware, Metric Blue, and Genuine BMW ARE e30 specific.

Look pal, I don't see what your problem is, you wanna use your hardware store bolts go right ahead, if it works, great, good discovery. If it doesn't, don't say you weren't advised to use the right parts. You have 39 posts on this forum, 7 of which are on this thread. I've seen your other posts about 'changing expansion tank cap O-rings' and swapping 'e34 cluster into an e30'.... I understand new people want to ask questions but you shouldn't be an instigating hooligan because someone's trying to help you. I'm getting sick of your fishmonger tomfoolery over HEAD BOLTS. we're trying to help you in your quest for the perfect bolt. what do you want us to do? make you a specific bolt to specifically fit your specific needs?

you wanted opinions, you got some. PLUS, you STILL haven't said WHY you need these 'stronger' head bolts.

--Mike

[Joseph~]

They ARE generic in the fact that they haven't been designed for the specific use of M20 head installation.

With the above train of thought;

....[SNIP}....ARP bolts for the m20 are the same bolts as some hondas and other makes, and they're just cut to size, so that's why there have been some issues with fitment, but this has probably been fixed....{SNIP]

ARP bolts / studs have not "been designed for the specific use of M20 head installation"

[15Michaeljoseph]

M20 aftermarket head bolts?

Has the OP made any reference to his car being turboed? no.

Now, I wouldn't know too much about turbos but after a little research, the stock bolts should be perfect for 5-8 psi. above that is a bit of a gamble, so you might as well go with studs. studs are better than upgraded bolts I've heard too, they get a more even, tight, grab. But whatever. Lot's of good things have been said ablut 'metric blue' head bolts.
Metric blue head bolts can be found athttp://www.mcmaster.com/part number 91303a306 (same as 91303a900) sold in packs of 5, so you'd need 3 packs. class 12.9, 8mm hex socket, (not 'generic' hardware store bolts!), blue coated steel m10x1.5mmx150mm, partially threaded, grade 12.9, 176,900 psi tensile strength.

ARP bolts for the m20 are the same bolts as some hondas and other makes, and they're just cut to size, so that's why there have been some issues with fitment, but this has probably been fixed. IDK you guys know more about this than I do.

And don't forget about the headgasket conundrums too.

HOWEVER JOSEPH NEVER SAID HIS CAR IS BOOSTED, NOR DID HE ALLUDE TO PLANS OF BOOST, SO I'M NOT SURE WHY I JUST DID ALL THIS RESEARCH. but it was better than homework so whatever. I'm going to go shovel now.


--Mike

[MR 325]

Personally, if I'm boosting an engine, I'm going ARP so there is no limit to worry about.

Plus they're reusable!

[whodwho]

I ran 12psi with the SC and no issues, maybe because the boost wasn't that high at lower RPM/loads or because no boost spikes.

[Ether-D]

So at what psi do the OEM bolts become inadequate? I've read that it's mostly about the tune. Let's assume that you have a perfect tune, how many psi can be safely run (ballpark)? I hear 10 being tossed around a lot. Is that just because it's nice and round?

[Joseph~]

[SNIP}..... do it in their memory, a tribute to the BMW elders. show your respect. light a candle....{SNIP]

--Mike

OK, I will light a candle.



Joseph

[15Michaeljoseph]

Boys! Boys!

Joseph, my esteemed and honorable friend, the fact is, the genuine BMW spec part is the cheapest option. They're not going to break. They're not going to be subjected to anything close to a 1220 Mpa. You don't need the 12.9 ASTM F568 certified bolt. Use the same part that the guys who built the motor in the factory used. do it in their memory, a tribute to the BMW elders. show your respect. light a candle.


--Mike

[MR 325]

They ARE generic in the fact that they haven't been designed for the specific use of M20 head installation.