LS1-450

iTrader: (33)

Have read several posts regarding ARP bolts & still ask why they are needed for motors in cars making up to 500 RWHP? My opinion is that using a stretch bolt limits the load on the threads tapped into the aluminum block. Where as using hardened ARP bolts makes the threads in the block the weak point.

-Has anyone actually blown a head gasket on stock bolts on an engine w/ up to an 11:1 compression ratio or 500 RWHP because of the stock head bolts?

-Has anyone using ARP bolts or studs had a thread failure in the block where the bolt tore the tread out? Not from over torquing, but, from engine operation?

-Anyone know the strength of the threads in the block? For sure they are the weak point when using hardened forged bolts.

Please comment

TTPMatt

iTrader: (18)

We are using stock bolts on a lot of applications up to that range, but only in N/A motors. I have the motor that dyno'd 505rwhp with a t56, stock bottom end, still running gm head bolts. This motor has seen over 70 dyno passes and 50+ track passes this season with no reasons for concerns (C/R is about 10.9:1).

Any forced induction or heavy N2O application (Even within the 500rwhp range) I'd use ARP head studs, 12-pts usually.

For a major application 700+, I would use the 1/2 head studs, have a good machine shop machine for the stud application.

LS1-450

iTrader: (33)

Thank-you for the comments. Glad to have confirmation that in NA applications stockers are good.

How is 500 using FI or N2O (low compression ratio) different than 500hp high compression ration NA? Would think that the combustion chamber pressure would be similar between the different applications. Or are you saying FI or N20 applied to a high compression chamber? Just curious.

Any block thread failures in the 700+ applications or does the use of studs (compare to bolts) take care it? I can understand how the block threads would be loaded differently by using studs.

Xtnct00WS6

iTrader: (8)

One thing to keep in mind is the installation of both the head bolts. ARP has the stockers beat 10 fold in my opinion.

I couldn't get the last bolt (on the bottom) out on the passanger side because the 15mm bolt was too big and didn't have the clearance so I had to pull the head with the bolt in. To get a stocker back in, I would have had to put the bolt in the head and install the head with the stock bolt in it. With the slightly smaller 13mm heads on the arp bolts, you have enough clearance to get it in and take it out quite easily. It can get tight in there and that little extra clearance helps a lot.

There's also a specific torque sequence needed for the stockers that sucks. You need to mark a line on each bolt and then turn it 90 degress after it's torqued to 22? ft/lbs. On the last bolt in each head, I couldn't even see the bolt so how are you supposed to be able to draw a line on it after it's torqued down to 22ft/lbs? It's possible with a mirror, but just a REAL pain. With the ARP's, you can pretty much just torque them down.

So basically ARP's are stronger, easier to install, easier to take out, and easier to torque down. They're worth the extra money in my opinion!

EDIT, I see you have an LS6 in a miata so some of the clearance problems might not apply. You could have more of a clearance problem too with a tiny miata. What I've mentioned applies to an F-Body though.

LS1-450

iTrader: (33)

I understood your point & thanks for the post. Clearance isn't an issue in the Miata only because we planned for it & made some access areas for the head bolts. Otherwise, they would have been a freakin' nightmare.