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Discussion Starter · #1 · (Edited)
Need Opinion on Overbore Head Gaskets
My OEM head gasket 2.0L (86mm) Modified by AMS to 2.2L (90mm) failed. AMS claims to have had best results from OEM Mitsubishi gasket in this configuration... The modification alone looks and seems a bit risky from what I can tell however for the sake of this thread does anyone have any input on a "better than OEM" head gasket regardless of modified or not??

I am looking at Cosworth and Brian Crower thus far...

Cosworth
http://www.cosworthusa.com/store/pc/viewPrd.asp?idcategory=71&idproduct=867

Brian Crower
http://www.briancrower.com/makes/mitsubishi/4b11_misc.shtml

Here is a couple shots of my new replacement modified AMS gasket... My concern is how close to the sealing ridge the modification may sacrifice... I also ssee some small burs from the machining that also could cause some hot spots around the inside edge of the gasket...


I am not trying to cause any riffle with AMS here just looking for alternatives as a head gasket issue on this car has cost me some coin and a lot of time... Were all here to learn from eachother after all... And this issue is NOT something I want to keep revisiting...!

Opinions??

Thanks in Advance!
 

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I used a cosworth in my build. So far, its all good. I am stock bore though. Maybe some 90mm guys will chime in on options. However I can tell you upon initial inspection the Cozzie HG did appear to be a very high quality.
 

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I bought the Cosworth FLS for my 2.2 and I'm using standard ARP's for clamping, but I'm only using pump 93. What are you using for clamping? Standard ARP's, ARP 8740's or H11's? My personal option, if I were going to run e85 or race gas with high boost, I woud look into larger diameter H11's.
 

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Sorry to hear about your head gasket failure.. From the looks of that first picture.. It almost looks as if they used a dremel.. Doesn't look like the material was evenly taken off.. Just my opinion.. I use many of there products and am in no way judging there ways.. Maybe someone from AMS will chime in to tell us the method they use to enlarge the gasket to accomidate the larger bore.. I've used cometic head gaskets for many honda motors I've built without a single failure.. I think if I ever do a build I will definetly be using a cometic..
 

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The gasket has probably been waterjet cut. The problem with Cometics, is the block and head RA finish needs to be perfect for correct sealing. I agree though, if you have the money for the machine work, Cometic is the WTG.
 

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Discussion Starter · #6 ·
I called Cometic and they do have an over bore option for the X. It's actually the cheapest of them att at $120. Brian Crower is the most at $226. At this point price is not my concern, just the best result...
 

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I'm running the AMS bore out for my 2.2...time would tell if it holds up.
 

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As far as clamping yes the standard ARP's torqued to 90lbs... I am not aware of other arp options... Do the H11's require machine work?
No machine work need, Coswoth L19 head studs for the X, here is the description:


Made with H11/L19 alloy steel - Tensile Strength: Up to 260,000 psi - Maintains stock stud dimension and thread pitch for ease of installation - Larger .90" washer size increases clamping surface on the cylinder head - Includes a Hex broach on the top of the stud enabling you to install the studs with the head on the car if necessary.

ARP makes custom age 625+ for the X - tensile stength is also 260,00 psi
 

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Discussion Starter · #12 ·
I did look up my ARP's they are rated to 200,000. So the H11's w old be a bit of an upgrade. Do you know what he recommended torque setting is on the H11's? The ARP's I'm running is 90lbs.
 

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More than likely the reason for the success for the stock gasket, is the finish doesn't need to be perfect for installation. Cosworth FLS is 20-30ra, cometic is 50+ra which is almost a mirror finish or any newer MLS type gasket the mating surfaces need to prepped to spec; flat and smooth.

If I were to guess, I would say clamping wasn't sufficient in this case. A race car on c16 or ethanol, I'd for sure do the H11's.
 

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I did look up my ARP's they are rated to 200,000. So the H11's w old be a bit of an upgrade. Do you know what he recommended torque setting is on the H11's? The ARP's I'm running is 90lbs.
It's probably the same, between 80-90lb/ft
 

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Discussion Starter · #17 ·
I have just ordered the H11's... I'll sell my old ARP'd I suppose along with all my other extra parts ;)

I have a Coseworth, however may also order a Cometic and let my builder decide...
 

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I am running the ERL one, seems to work.

ERL helped Cometic finish their development on the 2.2L headgasket and that is what they use.
 

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Discussion Starter · #19 ·
It is interesting that the H11's are rated to 260,000psi and the ARP's I have are rated to 200,000psi. However the ARP torgue spec is 90lbs and the H11 is 85lbs... Less is more?? Wonder what the deal is here...? I posed this question to Cosworth, they did not respond. I was hoping this spec may increase with the upgrade...
 

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It is interesting that the H11's are rated to 260,000psi and the ARP's I have are rated to 200,000psi. However the ARP torgue spec is 90lbs and the H11 is 85lbs... Less is more?? Wonder what the deal is here...? I posed this question to Cosworth, they did not respond. I was hoping this spec may increase with the upgrade...
Working with a lot of diesel's, ARP's we torque to 245lb/ft, but with tool steel there isn't any "stretch", so we torque to 175lb/ft. We prefer tool steel in those high cylinder pressure situations.

Looking at the ARP install guide for 625+ for the 4b11t, you torque to 100lb/ft.

I'm not familar with the 625's.
 
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