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01-28-2009, 11:30 PM | #1 |
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What headgaskets are people using that last at 25ish psi
Just wondering what people are using and actually having success with over any period of time
cometic- failed cosworth- failed oem- havent used since stg2 tomei just write your thoughts
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01-28-2009, 11:59 PM | #2 | |
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I know of more than one car locally running 35psi with no issues with the head gaskets. It will be interesting to hear from others what they are using and at what power levels. |
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01-29-2009, 12:13 AM | #3 |
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OEM + arp headstuds correctly torqued
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01-29-2009, 01:04 AM | #4 |
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Using OEM STi HG's with ARP headstuds...
Know someone running 30lbs on that setup as well... |
01-29-2009, 06:58 AM | #5 |
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Call Cometic and see if they have the "fuzion" in the Subie application. It's diesel technology in that there's a gas ring incorparated into the design to perform as an O ringed block/head would, without the machine work involved. 60+ psi on some applications.
I also think that at some point you may have to look at possible issues outside of headgasket type. Jay |
01-29-2009, 09:47 AM | #6 |
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Cometics + ARPs. I milled the heads flat and very smooth and I hand lapped the block very smooth + the ARPs I torqued to 82 ft lbs back in the day.
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01-29-2009, 11:01 AM | #7 |
Citizen Mick
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Cometic's, no issues.
Looking at your signature may explain why you are popping head gaskets, 464/505 on a dom3. That's a tiny turbo for such large numbers which says to me you are pushing it way past it's efficiency range which means you are blowing hot air. Not only hot air but also very high cylinder pressures. If you have any det in this situation the cylinder pressures will go off the scale, easily high enough to pop a head gasket. Turn down the boost and make the tune more conservative or get a bigger turbo if that's the power you want to run day in, day out. |
01-29-2009, 02:13 PM | #8 |
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^^^that's some great advice, a 35r on an average pump gas tune makes those kinds of numbers, an would probably last longer than a dom 3 engine at that power level
your making everything work really hard with that smaller snail I agree, with the above..but I also think that 465 is pushing it on most any build for the street without having at least some pistons people like mick have built motors that an withstand 500+whp and the same torque, but he for example only runs ound with ~400whp (as per some quotes I have read of his...and he is a tuner/builder/etc. that says a lot to me right there about wanting to have longevity |
01-29-2009, 02:28 PM | #9 | ||
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I was going to say the exact same thing. Consider some relatively obvious and observable trends: If you take a close look at threads related to power producing setups, you might observe that head gasket failure is not that common. It happens, but not at an alarming rate. You might also observe many other people making power levels similar to yours without head gasket failure, using a variety of different brands. Further consider that you have had two head gasket failures (or perhaps more). It would seem logical that you might want to first explore the cause of the failure before jumping down the path of looking for a better part. Perhaps some exploration into what kind of cylinder pressures you are experiencing? what kind of intake air temps (past turbo/ic of course) are you seeing. What kind of timing, and how does that timing relate to torque. What is the rate of torque gain/degrees of timing at your current timing ( effectively what is the dTrq/ dTim). These questions and observations will likely help you more than a random sampling of user head gasket failures. Also, you posted before about this:http://forums.nasioc.com/forums/show...0#post25242070 Did you come to any resolution about the shop you were using? Did they have a recommendation? And explanation about the failure? Datalogs from the tunes? Jeff Last edited by sponaugle; 01-29-2009 at 07:13 PM. |
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01-29-2009, 05:38 PM | #10 |
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Noting wrong with cometics. Use the HG to give you the compression/quench you want combined with your pistons and just torque the studs right.
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01-29-2009, 05:42 PM | #11 |
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do you use the same factory torque sequence with a cometic gasket? i know its a MLS like stock, but ive heard some people blame their cometic going out on the step where you back off 180* then re-tighten... any ideas on that? or is the stock steps fine
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01-29-2009, 06:13 PM | #12 |
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Use the ARP torque spec but utilizing the stock sequence. Ie, middle, middle, corner, corner, corner, corner
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01-29-2009, 06:39 PM | #13 |
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i am using 100 percent meth and 93, and am only tuned to about 25/26 psi with wiseco pistons, and arp head studs and have about every mod possibly done to max out the turbo, plus i was pulling 70 degree temps that day
so i appreciate everyones thoughts but the setup and tune were well thought out and my afr is 11.3-10.8 (going from 1st to 6th) so very conservative in my opnion using 100 percent meth |
01-29-2009, 07:11 PM | #14 | |
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First, did you read my post, as well as Micks? (hint, the question marks are a great opportunity for you to reply) Are you familiar with adiabatic heating, and how the efficiency of the turbocharger effects the compressed air temperature? What measures have you taken to assure even distribution of the meth you are injecting? Port injection with individual sprayers, measurement apparatus to determine ratios? DDS3? Injection pressure? You could start by posting some datalogs. How did changed in timing effect the output torque? Did you determine the dTrq/dTim I mentioned in the previous post? Which cylinder broke in each case? How did the spark plugs compare from each of those experiments? Did you change around the injector order? What EM? Are you using the stock EM per cylinder injector and timing offsets? What knock detection? What other primary head gasket failures have you seen in other cars that leads you to believe the problem is the head gasket itself? You are implying it is not your 'setup'. That is, as is obvious, a direct statement that you believe the problem is the head gasket. As you can also obviously imagine, that does not seem to be a popular view here. That unpopular view may in part be due to the lack of common failures. Indeed information is the part most lacking in this discussion. Fortunately you have a excellent array of experienced engine builders and tuners that can help out. All we need is information. Cheers, Jeff Last edited by sponaugle; 01-29-2009 at 07:17 PM. |
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01-29-2009, 07:23 PM | #15 |
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wow lots of stuff to answer i dont even know how to but the point of the thread is to verify that these headgaskets are in fact working for other users because my belief is that it is my shop that is the problem in their engine building and NOT the actual headgasket
so now i am going to try for a 3rd time with a different shop and wanted to determien which headgasket i should use this time use one of the ones ive used or try something new as for the meth injection, i only have one large nozzle a few inches up from the throttle body tapped into the intercooler piping as for the tune, i tried briefly just to seem, and with the meth turned off completely my afr only when up 1 point or fraction (11.0 to 12.0) so as important as it is its not like im using the meth to gain all that much power, im using it somewhat conservatively |
01-29-2009, 07:30 PM | #16 | |
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Indeed there have been head gasket failures from time to time. It is always possible to have a bad one, and some brands may have a better/worse track record. (although I have not seen a convincing study of this topic) However your instinct is correct that that is only part of the story. There are many factors that can contribute to the head gasket failure. Unfortunately these are things that your competent tuner would need to talk to you about. The HP you are producing is high, especially with that turbo. As a result, there are certain problems you might experience. Why don't you have your builder/tuner read this thread (if they are not computer capable, print it out), and have them provide comments about the potential failure causes. EDIT: I see you are going to another shop... However it would be even better to have them comment.. Best of luck in finding a solution, Jeff |
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01-29-2009, 07:35 PM | #17 |
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Last edited by Stiguy34685; 01-29-2009 at 08:43 PM. |
01-29-2009, 08:57 PM | #18 |
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01-29-2009, 09:46 PM | #19 |
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There is an 18 page thread about head gasket issues on STi's on iwsti.com. hardly a rare thing if you ask me. Mine seems to not be sealing correctly anymore and I am just protuned stg 2 (intake, exhaust and tune). I run less than 18psi max and a/f's are around 11:1. Not 100% sure on timing but at 275whp and 308wtrq I am sure I am tuned fairly safe.
link to thread: http://www.iwsti.com/forums/2-5-lite...d-gaskets.html I am not sure if the stock head gaskets failed on me or if it was the stock head bolts that are allowing the heads to lift under high heat/pressure. Just wanted to let everyone know this is more common than you may think. |
01-29-2009, 10:21 PM | #20 |
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I was talking to my local Subaru senior master tech about this recently. He sees all kinds of failures at the dealership and handles 99% of their "big" engine failures. He said it was common in some of the earlier Subarus but not on the newer ones. Like others have said, a good tune is required.
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01-29-2009, 11:12 PM | #21 |
Citizen Mick
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01-29-2009, 11:15 PM | #22 | ||
Citizen Mick
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01-30-2009, 01:12 AM | #23 | |
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The problem in the iwsti thread is either bad head gaskets or bad head bolts. |
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01-30-2009, 10:10 AM | #24 |
Citizen Mick
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Sorry, I do not agree. The overheat IMO is the source of the issue which leads to a cascade effect as the heads warp and then the gaskets fails causing more issues.
I know from experience that if you do not correct the source of a problem it will just keep happening. In this case it's my opinion that the source of the issue is not the head gaskets themselve but something else. |
01-30-2009, 10:23 AM | #25 | |
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