running_sideways

I've got some arp main stud figured what the hell! Can't hurt! The more and more I read is that if you go by they're torque spec you will more than likely need to get line board...and 80ft/lbs! Dose anyone else think that's a bit outrages for what it acutely is? Can I get some input on what some of you guys did or if it turned out fine with the arp main stud spec? I've seen a few little voices out there on forums saying just perform stock spec...if the thread pitch is completely different from oem. Would you get the same clamping force?


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Croustibat

More clamping force = chances to need a line BORE. You can't have one without the other. If you need it but don't do it, you will build a great load of bearing bits and kill your engine in 500miles, basically. You are going to need plastigauge to check.

I think this is the most common mistake when an amateur or a cheapstake (re)builds an engine (although it may compete with inverted bearings). I have seen the results if this quite a lot of time. You won't like it.

Bottom line, either use stock bolts and do what nissan says, or use arp bolts and do what arp says.

KAT-PWR

What motor are you using? I believe ARP is 65 ft/lb for KA main studs. If it is a KA make sure you don't have the girdle in backwards.

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MRP Manufacturing

running_sideways

Sorry for got to include its for a sr20det

I understand especially with aluminum bock and caps there more room for distortion. in return gives you a tighter clamping force and less of a oil gap for the bearing(witch factory spec is .02 to .045mm) witch is a big no no.

I was guess I was curious to see if anyone input on thinking this was a little excessive on the torque if they ever tried a different maybe stock spec and be fine or just go and get it line bored and ratchet that bitch down

I've built a few engine to a stock oem platform form gas to diesel platforms just never a performance aspect and I wanna do my homework before I even start


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KAT-PWR

I just torqued my next KA builds studs the other day to 65 and it spins like butter

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MRP Manufacturing

dbeiler

Whenever rebuilding an engine, the main bore should be checked. This doesn't usually happen for garage built engines. It's not usually off; thousands of people have had success without ever checking the main bore. If the main bore is off spec with ARP studs, it's also off spec with OEM hardware. Changing hardware has no effect on the main bore.

Think about it for a second. If changing hardware actually warped the main bore, the damage wouldn't stop there. The cylinder walls would become deformed and the block deck surface would warp also. If changing hardware warps the main bore, you have a seriously fucked up engine block. The main bore would be the least of your concerns.

If it really bothers you, purchase a straight-edge and feeler gauges. Remove the crankshaft and main bearings, reinstall the main caps, torque to spec, and check the main bore.

Align boring/honing is NOT a requirement with ARP hardware. If the main bore is incorrect, using OEM hardware will remedy nothing. CHECKING THE MAIN BORE is the ONLY method used to determine necessary align boring/honing.

Kingtal0n

there is a reason they make these,


and similar devices. A true performance application is ALL about the finite attention to detail, every thousandth counts. It is more important that the parts fit together at a molecular level that is comfortable with the intended application. If your goal is street performance, you use an OEM bearing on the tight side with a thin synthetic oil, and everything gets bolted down and checked before you perform the final install, i.e. you bolt the deck plate down and dial bore gauge the cylinder roundness and piston/wall clearance, using the exact hardware and torque spec/lube you will use during the live assembly, and do the same thing with the crankshaft out, bolt down the caps/girdle with the bearings and bore gauge the roundness and micrometer the journals for an exact specification you can depend on once the engine is finally assembled.

Cleanliness is also an enormous factor. The engine needs to be put together in a doctor-clean surgery style as much as possible for best results. Performance improvements can be made to the engine in terms of oil flow, head and valve work, and so forth should be done by a reputable machine shop. there are a host of sr20 failures for other reasons as well; pay special attention to what the FSM says regarding thrust washers.

FWIW I would stick with oem bottom ends unless you can afford to build a couple. If you nail the cleanliness part and the measuring and use all the right torque, there is still an unfortunately high chance for failure due to something beyond your control (machine shop errors and inexperience during assembly). for example practically every sr20 ever built I have ever seen leaks oil at the front cover between the head and block, and over HALF of the machine shops forgot to replace the bolts in those locations, and failed to set the chain timing correctly. I have also seen them "pre-bleed" the lifters, something you might do on a Honda but NOT an sr20det. One silly mistake like that will cause serious trouble, inexperienced as you are with these engines, you might not catch it.

Tuning is a whole other problem. Even tuners who have been "tuning" for years punch incorrect numbers that are too aggressive for daily drivers. I've posted quite a few maps and numbers you can find, used with great results on over fifty engines across fifteen years of service, not a single failure.

Croustibat

You are wrong, and clearly have never even investigated this. No matter how hard you try to think about it, it happens. I have seen it on a couple of RBs, a 2JZ and some CAs and SRs. My tuner even got a legal expert confirm it as the cause of an engine failure.

BTW ARP clearly write on its website to check for the need of an align bore.

running_sideways

Soo...torque it down the mains to arp spec and check with snap gauges or dial bore gauge? Then mic the bearings and the crank and make sure I'm in the .02 to .045 mm oil gap for the bearings if not get it line honed to get to proper spec...


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jr_ss

Correct, trq ARP mains, measure with a bore gauge, calculate, address if necessary. You'll also have to trim down the rear two main studs or clearance the upper oil pan if this is for a RWD install.

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My SR20VET

running_sideways

Thank you! Everyone for your help! And I set the bolts down for the oil pan issue and looks like they well clear.


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running_sideways

Surprising enough


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Croustibat

tbh you will need a gearbox before that extra clamping

running_sideways

That's also what I was wondering. Could you use the stock sr20 specs with arp main studs so you don't need to get it reline bord it's a really dumb question


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dbeiler

Let's clear up some confusion here.

The main bore is the alignment of the bearing bore centerline.
A misaligned main bore means that one or more of the main bearing bores are not perfectly in line with the other main bearing bores. This creates stress on the crankshaft as it would need to flex to spin. Main bearings would wear prematurely. The alignment of the main bore is checked with a straight edge and feeler gauges.

The main bearing bores are the individual bores in which the main bearings are located. These inside diameters can become out of round, elongated, and stretched. This will also wear bearings at an accelerated rate. The main bearing bore diameters are measured with a bore gauge (or indirectly, with T-gauges and inside micrometer)

Either one of these issues is fixed with a machining method called align boring/honing.

To answer your question: No, using OEM torque specs does NOT guarantee your main bore or bearing bores are correct. If it bothers you, buy the measuring tools and check them. Or send it to a machinist. Takes them like ten seconds.

running_sideways

Thank you! That's what I wanted for an answer! Much appreciated. Looks like i check the bearing specs with it tighten to 80ft/lbs and if there not in spec I'll send it in and have them line hone it till I get the correct measurement. All of you guys helped out ten fold of what arp studs said over the phone


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Croustibat

I already told you can't.

Fasteners need to be in their elastic zone when tightened. Overtightened = stretch / break, undertightened = come loose / no clamping.
Which is the reason their manufacturer give you a torque to tighten them. Torque the ARP bolts to OEM spec and they won't enter that elastic zone, meaning they won't clamp anything.

You MAY need a line BORE when using any fastener giving extra clamping force, in a general way. You NEED to check for this, because installing the fasteners and relying on luck is the best way to kill an engine.

Just install oem fasteners ... you don't need more clamping force

vipergtsr1000hp

The cause for the oil leaking between the head and block is because people do not know that you are suppose to RTV that area (says somewhere in the FSM). I did this for all my rebuilds and no leaking oil. Back in the day, I never did this and remember seeing oil leaking from the cover between the head and block. Now I know why.