SR20DET ARP main studs

[gaz_moose]

why do people fit these? is there a rough power level where the stock main bolts become a problem? or is it just a 'belts and braces' type mindset.

I am in the process of working out a spec for my new engine and have been on the fence about these for days,

I understand that they would stop the caps from 'fretting' in a regular engine but the DET has the big girdle/ladder frame bolted to the main caps which should go along way to eliminate that.

I know if I go for them I have to get the caps line honed and mod the rear studs/alloy sump pan.

cheers,
Gaz

[Kingtal0n]

when going from bolts to studs you want to machine the engine with a deck plate, using the same studs torqued to the same way they will be used on the final assembly.

If you switch from bolts to studs without machining it may/will distort the cylinder walls and create issues with blow-by gasses.

similar question/thread regarding other engines with similar situations.

http://ls1tech.com/forums/generation-iii-internal-engine/1841690-5-3-head-studs.html#post19356463

I am always worried if I swap from head bolts to head studs on an engine, it would need to be bored with a deck plate first. Else the cylinder wall will distort and the engine will pass more oil (blow by).

Valid concern I think. Most of the LS engines are not torque plate honed, so they're not very round or straight to begin with. However, after you put miles on the engine and the walls wear in, going to a different fastener may change the shape of the bore and reduce ring seal. At least I think that's a possibility.

As far as if a torque plate changes the bore, that is a definite yes. Especially with aluminum blocks.

[hanzbrady]

Builds that are going to be living in the >400whp we recommend going with the ARP or our hardware. they help keep the main journals from distorting from abuse, the factory bolts move a considerable amount. Also once you pass into the 600-800whp range we also recommend billet main caps as the stock ones crack right down the middle, these are also accompanied by 1/2" main studs.

[gaz_moose]

I would put my this build in the 350 - 400hp category. i was planning to use a gtx2867r.
I had made my mind up to reuse the OEM main bolts as they measured up ok but then I picked up some new ARP mains off a local guy in a package deal with some other parts.(I've also got ARP head studs to go in)

I don't have a deck plate is that a real deal breaker for line honing these main caps? I thought I could just send it to the machine shop with the main caps and girdle/ladder torqued upto spec for them to machine.

the block will be bored out to 86.5 and decked at the same time its at the machine shop.

the engine is to go in my drift car so will get its head kicked in regular and wont be daily driven etc..

that ls1tech thread just had people bitching about ebay head bolts, I don't see the relevance???

[hanzbrady]

Torque plates are used to simulate the force that the torqued head applies on the block while machining.

Every aluminum block that we machine is fine with a torque plate to ensure that the cylinders stay in round during assembly.

They're an exspense, however the $80 charge on a $8,000 engine build is cheap peace of mind.

[gaz_moose]

hmmmn
I don't think my local engine machine guys are going to have an sr20 torque plate knocking around. getting one knocked up may prove costly as its not something im going to get much use out of I hope.

cheers for the advice, I will see if any England people have a plate knocking around.

[hanzbrady]

Ask around on Driftworks!

[gaz_moose]

if I measure the main journals in the block with my dial gauge and they have gone oval due to the ARP's what do I get the machine shop to machine them too to make them round again?

the workshop manual does not state a spec or tolerance that I can see??

[hanzbrady]

if I measure the main journals in the block with my dial gauge and they have gone oval due to the ARP's what do I get the machine shop to machine them too to make them round again?

the workshop manual does not state a spec or tolerance that I can see??

You give them your crank, a set of H bearings and tell them to hone your mains to size.

[gaz_moose]

thank you for clearing that up for me.

[gaz_moose]

With the torque plate fitted and the main caps torqued up to ARP spec my mains are coming out as being 1.5 thou out of round. what would be the tolerance for these main caps?? would I be within spec for out of round or are they proper egg shaped??

should I get them machined? or am I good too go???