Best performance head gasket?
05-01-2014, 04:25 PM
#31
Drifting
05-01-2014, 05:36 PM
#32
Rennlist Member
Perhaps the stock headgaskets don't require the exactitude or precision of installation as do the metal versions? I'm not sure. It's not tune that is doing mine as far as we can tell. There are no obvious signs of detonation (although with E85 it may not have the same appearance as pump) but we've been on the dyno a few times and on the track as well. The motor is pushing hard against the mounts as it tries to turn in a clockwise direction. One of our semi solid mounts broke or at least the bolt inside did. A lot of torsional forces are being exerted.
What I used to think was with the open head motors we were getting just enough headlift that allowed the cylinders to shear at the sealing or embossed crush area around the metal gaskets. I thought the deckplate, large headstuds, pinned girdle etc would be a cure. Guess I was wrong. So the head is still possibly lifting or something is still flexing/moving enough to shear away at the gasket. Short of a billet block/head we have another option to try which involves a modified gasket and a type of O ringing. Not the same as the more traditional version mentioned previously.
In the long run, I'm not super bothered by it as I have grown to think of h/g's as a perishable item. You get used to it.
What I used to think was with the open head motors we were getting just enough headlift that allowed the cylinders to shear at the sealing or embossed crush area around the metal gaskets. I thought the deckplate, large headstuds, pinned girdle etc would be a cure. Guess I was wrong. So the head is still possibly lifting or something is still flexing/moving enough to shear away at the gasket. Short of a billet block/head we have another option to try which involves a modified gasket and a type of O ringing. Not the same as the more traditional version mentioned previously.
In the long run, I'm not super bothered by it as I have grown to think of h/g's as a perishable item. You get used to it.
05-01-2014, 07:45 PM
#33
Drifting
This is what we found. We were running our cars on the track, some cars running 1.1bar all the way up to the modified cars running 1.5bar boost. On 1.1 bar we would see 12-13 track day before the stock gasket gave up. On 1.5 bar we would get 7-8 track days before the stock gasket would give up. These track days usually consist of 6 sessions at 20 minutes each.
With the Cometic MLS we are now getting 15-16 track days on a car running 1.1 bar and 10-12 track days running 1.5bar. To us this is considerably longer and worth it. The benefit of the Cometic besides longer change intervals is the fact that when off boost they seal up completely. Meaning we were able to get the cars home with out a tow if we ha a breach.
Im not sure if some of you guys understand(this is not directed at you George) but track work is nothing like street work. We have street turbos here that have done years on come tics and will probably never need replacing before the head would need servicing next. On track is a different world, The constant extreme stresses the engine is under in 20 minutes would be comparable to 10 years of street driving. Everything wears out a lot quicker.
Another misconception is that the head and block need to be dead flat for a MLS to work properly. It simply isn't true. Its just been thrown about the internet for so long that its starting to stick.
There is a catch to use them correctly. Hylomar the gasket before it is installed. Also use a small amount of RTV silicone around the top water hole. No more leaking problems.
I would say currently for the past 3 years we have installed Cometics on all customer cars, no just track cars. Before that we did just use them for the track vehicles but we saw the benefit of the fact if they were ever to breach the customer can always drive the car back to us and not leave them stranded on the side of the road. We have installed them on perfectly flat blocks and not so perfect flat blocks. No difference. They just need to be installed using the technique above
Remember this is just our opinion and what we see works effectively for us.
Regards
Sean
05-01-2014, 10:50 PM
#35
Rennlist Member
Sounds funny but it was true George, In our Porsche club sprints the furthest track is just on 2 1/2 hours away. I have blown a HG there and it cost $600 for the tow home. Not really a fun way to end the day. Not to mention you usually had to wait around a few hours for the towie.
This is what we found. We were running our cars on the track, some cars running 1.1bar all the way up to the modified cars running 1.5bar boost. On 1.1 bar we would see 12-13 track day before the stock gasket gave up. On 1.5 bar we would get 7-8 track days before the stock gasket would give up. These track days usually consist of 6 sessions at 20 minutes each.
With the Cometic MLS we are now getting 15-16 track days on a car running 1.1 bar and 10-12 track days running 1.5bar. To us this is considerably longer and worth it. The benefit of the Cometic besides longer change intervals is the fact that when off boost they seal up completely. Meaning we were able to get the cars home with out a tow if we ha a breach.
Im not sure if some of you guys understand(this is not directed at you George) but track work is nothing like street work. We have street turbos here that have done years on come tics and will probably never need replacing before the head would need servicing next. On track is a different world, The constant extreme stresses the engine is under in 20 minutes would be comparable to 10 years of street driving. Everything wears out a lot quicker.
Another misconception is that the head and block need to be dead flat for a MLS to work properly. It simply isn't true. Its just been thrown about the internet for so long that its starting to stick.
There is a catch to use them correctly. Hylomar the gasket before it is installed. Also use a small amount of RTV silicone around the top water hole. No more leaking problems.
I would say currently for the past 3 years we have installed Cometics on all customer cars, no just track cars. Before that we did just use them for the track vehicles but we saw the benefit of the fact if they were ever to breach the customer can always drive the car back to us and not leave them stranded on the side of the road. We have installed them on perfectly flat blocks and not so perfect flat blocks. No difference. They just need to be installed using the technique above
Remember this is just our opinion and what we see works effectively for us.
Regards
Sean
This is what we found. We were running our cars on the track, some cars running 1.1bar all the way up to the modified cars running 1.5bar boost. On 1.1 bar we would see 12-13 track day before the stock gasket gave up. On 1.5 bar we would get 7-8 track days before the stock gasket would give up. These track days usually consist of 6 sessions at 20 minutes each.
With the Cometic MLS we are now getting 15-16 track days on a car running 1.1 bar and 10-12 track days running 1.5bar. To us this is considerably longer and worth it. The benefit of the Cometic besides longer change intervals is the fact that when off boost they seal up completely. Meaning we were able to get the cars home with out a tow if we ha a breach.
Im not sure if some of you guys understand(this is not directed at you George) but track work is nothing like street work. We have street turbos here that have done years on come tics and will probably never need replacing before the head would need servicing next. On track is a different world, The constant extreme stresses the engine is under in 20 minutes would be comparable to 10 years of street driving. Everything wears out a lot quicker.
Another misconception is that the head and block need to be dead flat for a MLS to work properly. It simply isn't true. Its just been thrown about the internet for so long that its starting to stick.
There is a catch to use them correctly. Hylomar the gasket before it is installed. Also use a small amount of RTV silicone around the top water hole. No more leaking problems.
I would say currently for the past 3 years we have installed Cometics on all customer cars, no just track cars. Before that we did just use them for the track vehicles but we saw the benefit of the fact if they were ever to breach the customer can always drive the car back to us and not leave them stranded on the side of the road. We have installed them on perfectly flat blocks and not so perfect flat blocks. No difference. They just need to be installed using the technique above
Remember this is just our opinion and what we see works effectively for us.
Regards
Sean
05-02-2014, 01:05 AM
#36
Racer
Join Date: May 2008
Location: Encinitas, ca PCA National DE instructor PCA San Diego chief driving instructor
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Another nice thing about Cometic is that they can rapidly produce custom gaskets, for near the cost of OEM gaskets.
We used them in our 400 hp/liter supercharged nitrous land speed engine with no problem.
We used them in our 400 hp/liter supercharged nitrous land speed engine with no problem.
05-02-2014, 01:19 AM
#37
Drifting
Love you guys. Truly, all input is relevant. My car is not track only. I get the difference. I'd be in jail now if I ran my street/track in that order, as it's wanting. Track duty from a 3.0 motor pushing against modern motors is for the faint of heart. I find this fun, and at times worthy of breed. A track only race car of mine wouldn't utilize these motors.
That said, I'm just stating observation of other motors. You know what I have in this car, and I'm a fan of the surprise.
Thanks for the folks that understand cost in racing, any venue, requires expendable cash flow. Head Gaskets are cheaper than modern brake pads, wear items. Cometic, 968TS, O-Ringed heads with matching dents in the block, etc. is fine.
Running 500whp in a small displacement motor is killer. I drove to my place in Greer from Tucson, 250 miles, and I put in ten gallons of 91.
Math is easy, spanking everything on the way is priceless.
Thanks for all input towards these cars.
Kindest Regards,
George
That said, I'm just stating observation of other motors. You know what I have in this car, and I'm a fan of the surprise.
Thanks for the folks that understand cost in racing, any venue, requires expendable cash flow. Head Gaskets are cheaper than modern brake pads, wear items. Cometic, 968TS, O-Ringed heads with matching dents in the block, etc. is fine.
Running 500whp in a small displacement motor is killer. I drove to my place in Greer from Tucson, 250 miles, and I put in ten gallons of 91.
Math is easy, spanking everything on the way is priceless.
Thanks for all input towards these cars.
Kindest Regards,
George
05-02-2014, 01:57 AM
#38
Race Car
I'm with Sean on this. I prefer to be able to drive home if it goes. I've blown both and I'd prefer to have MLS.
I am disappointed to hear Patrick is having issues, as that's the direction I went.
Pat, where is is breaking? In the usual spot on the cylinder side?
Maybe if it goes, I'll just Oring receiver groove it like the old engines I built. Problem is, those copper gaskets never seal coolant.
Darn it, I should have went with Dave's design.
I am disappointed to hear Patrick is having issues, as that's the direction I went.
Pat, where is is breaking? In the usual spot on the cylinder side?
Maybe if it goes, I'll just Oring receiver groove it like the old engines I built. Problem is, those copper gaskets never seal coolant.
Darn it, I should have went with Dave's design.
05-02-2014, 02:52 PM
#39
Rennlist Member
I was having problems getting my head to seal, motor is a 3.0 l block with Darton MID sleeves. 1st used an OEM gasket: lasted 1 time out, 2nd a wide fire with O-Rings: lasted 1 time out, next came solid copper gasket with O-Rings: lasted 2 times out, and finally ended with Cometic MLS: 6 months and counting (4 track weekends, one of which was a club race) 14 to 16 psi boost no problems.
Just bought a second MLS, as we all know the parts you have spares for never fail.
Just bought a second MLS, as we all know the parts you have spares for never fail.
05-02-2014, 03:05 PM
#40
Rennlist Member
Pics of ours. All for were stuffed.
Agreed on spares inventory.
Agreed on spares inventory.
05-02-2014, 03:29 PM
#41
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I ran 21-23 psi in mls, 21psi daily not a race car but it was on pump 91 daily
05-02-2014, 04:54 PM
#43
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05-02-2014, 05:27 PM
#45
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