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Old 08-09-2013, 12:24 PM   #1
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Default Learn me o-ringing blocks.

I'm about to do this on a couple of my spare motors, and a concern/thing i don't know is what ratio of wire sticking up vs. gasket thickness is ideal.

I figure for the relatively low price, there's no point in me NOT doing this, especially if it gives me another 5-10psi i can push without "lifting my head" or blowing the gasket due to pressure at this point.

This is NOT BP-specific, so i'm not real interested in hearing why you shouldn't need to do this on a BP.
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Old 08-09-2013, 03:19 PM   #2
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IIRC from talking to a good BMW engine builder, Paul Burke.....liked to do a .025" groove in the block and use a 0.40" wire.
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Old 08-09-2013, 03:32 PM   #3
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IIRC from talking to a good BMW engine builder, Paul Burke.....liked to do a .025" groove in the block and use a 0.40" wire.
Yeah, i read a bunch of threads on o-ringing M20s last night and saw that they were using .040" or .041" wire, but they were doing .030 grooves.

Didn't see much discussion as to what sort of head gasket they were using, looked stock.

I didn't know if there was some sort of ratio you'd try to hit ideally. For instance, i have .041" wire, if i cut a .030" groove, i've got .011" protruding. Is that enough for a stock gasket? Too much? What if i use a crazy thick copper gasket?


Basically i'm looking for the kind of boost levels that happen when you run a Holset HX35 without a wastegate.
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Old 08-09-2013, 03:41 PM   #4
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You say this is not BP specific. What specifically do you plan to o-ring?
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Old 08-09-2013, 03:55 PM   #5
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F2T.

We haven't found the point in which the stock bottom end will blow in terms of power/boost, but we have found that on stock head bolts the head gasket will blow out in the mid 30psi range on say... a 35R or a big Holset. It also won't make **** for power, relatively, but that's not the point.
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Old 08-09-2013, 04:15 PM   #6
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Basically i'm looking for the kind of boost levels that happen when you run a Holset HX35 without a wastegate.
+1 props for plans to run ALLOFIT!
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Old 08-09-2013, 04:17 PM   #7
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+1 props for plans to run ALLOFIT!
Having a stockpile of motors you essentially got for free is pretty liberating.
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Old 08-09-2013, 04:51 PM   #8
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Quote:
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Yeah, i read a bunch of threads on o-ringing M20s last night and saw that they were using .040" or .041" wire, but they were doing .030 grooves.

Didn't see much discussion as to what sort of head gasket they were using, looked stock.

I didn't know if there was some sort of ratio you'd try to hit ideally. For instance, i have .041" wire, if i cut a .030" groove, i've got .011" protruding. Is that enough for a stock gasket? Too much? What if i use a crazy thick copper gasket?


Basically i'm looking for the kind of boost levels that happen when you run a Holset HX35 without a wastegate.
He recommended using the stock gaskets, and ensuring the O-ring was still in the "fire ring" of the head gasket.

I had my hands on a nasty built M20 with plans of 450whp, but ended up selling it.

If you use an MLS gasket, I don't think I'd O-ring it.

However, you mention that the headbolts are breaking, not the gasket blowing out? Have you tried ARP studs?

If not, O-ring + ARP studs = ALLTHEBOOST!
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Old 08-09-2013, 04:57 PM   #9
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Props given for ambitious plans.

Is the f2t or whatever an open or closed deck engine? Cast iron? I don't know much about o-ringing but don't think its too common on a cast iron closed deck block..
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Old 08-09-2013, 05:03 PM   #10
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Quote:
Originally Posted by z31maniac View Post
He recommended using the stock gaskets, and ensuring the O-ring was still in the "fire ring" of the head gasket.

I had my hands on a nasty built M20 with plans of 450whp, but ended up selling it.

If you use an MLS gasket, I don't think I'd O-ring it.

However, you mention that the headbolts are breaking, not the gasket blowing out? Have you tried ARP studs?

If not, O-ring + ARP studs = ALLTHEBOOST!
Nah, headbolts aren't breaking. They might be stretching, but the end result is that the gasket is blowing out.

Most of these guys don't use ARP studs. I'm going to, because i think it's stupid not to when we're talking about this kind of boost level, and for $190, i'd just as soon throw 'em in there and see what they do.


Which is also why i'm interested in doing the O-rings. Broken down between the blocks i'd do it to, i'm looking at $100 or less per motor.

Cheap insurance when trying to see how far above 400whp i can get on a stock bottom end. Even better insurance if i'm unsatisfied and decide to do a head swap see how legit my Puerto Rican contact's claim of 540whp @ 20psi on a T4 60trim really is.

Quote:
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Props given for ambitious plans.

Is the f2t or whatever an open or closed deck engine? Cast iron? I don't know much about o-ringing but don't think its too common on a cast iron closed deck block..
Closed deck cast iron.
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Old 08-09-2013, 05:08 PM   #11
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Its gonna be funny to see the torque curve on this thing. I bet it will be like this /\ with some crazy spike to like 400-500wtq or something haha
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Old 08-09-2013, 05:15 PM   #12
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Its gonna be funny to see the torque curve on this thing. I bet it will be like this /\ with some crazy spike to like 400-500wtq or something haha
I'd be disappointed.



In those numbers, that is. I will seriously be disappointed if it doesn't break 500wtq.

I honestly don't give a **** what the curve looks like for now. It's never going to be GREAT as long as i avoid doing the head swap. But power is power, and this bitch is going to be fast as ****.

Don't get too excited too quickly, i'm still in the slowly-gathering-parts and planning stages, but i have my donor motor here already and a transmission for mockup and bellhousing is en route.
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Old 08-09-2013, 05:18 PM   #13
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Quote:
Originally Posted by 18psi View Post
Props given for ambitious plans.

Is the f2t or whatever an open or closed deck engine? Cast iron? I don't know much about o-ringing but don't think its too common on a cast iron closed deck block..
Very common in the BMW world.

The M20 engines in E30s came with forged rods from the factory capable of holding 500+ wtq. So pistons, O-ring, ARP studs is all it takes for big HP E30s.
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Old 08-12-2013, 07:02 PM   #14
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Why not just call cometic, order you custom head gasket and ask what the need to be machined to.
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Old 08-12-2013, 07:35 PM   #15
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Well that doesn't really answer my question and they don't make gaskets for this. :P

I already have a few gaskets sitting around. Two coppers.
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Old 08-12-2013, 07:40 PM   #16
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Hmm I was talking to someone this weekend about oring'ed blocks because they were asking me if I oringed the block in the miata. I swear he said he had his custom made by cometic but maybe it was another company. Though he said it only cost 80 bucks, which does point to it being not cometic. Much beer was consumed this weekend.
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Old 08-12-2013, 07:42 PM   #17
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I'm not talking about a Miata motor.

I dunno what's out there for BPs, don't have a reason to care about anything other than stock.
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Old 08-12-2013, 07:43 PM   #18
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Neither was he.
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Old 08-12-2013, 07:45 PM   #19
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Ok so what are we talking about Cometic for, then? I'm confused.
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