I was pushing my twin turbo setup this week, and we discovered real fast that the heads were lifting and spewing coolant into the reserve tank.

Good news is we found the weak link (head gasket) and are working to fix the problem. We maxed out the Dynapack dyno at 3k rpm load - aprx 500+ftlbs at 15psi - that was just awesome to see!

Bad news, we now need to pull the motor, replace the head gasket before we can continue to push again…

From what I'm gathering in speaking with people that are pushing the limits as well is keeping the heads from lifting is the 'big' and still unsolved problem! It seems like this topic hasn't been discussed or talked about much here. This is not an issue under say 600-650hp or when not loading up the motor...

This issue will not show prejudice – i.e. it doesn’t matter what kit you have, what engine management you’re running, etc… it’s a limitation in the current design. I believe the stock head gasket is 37 thousandths and it just isn’t cutting it.

I welcome thoughts, and feedback from people that also have experienced this – Let’s keep this thread productive, and not specific to any brand… Once we find a solution, it’ll help the community push past this barrier and hopefully we’ll soon have 900hp street cars.

 

let me guess AEBS block?

 

NO - and like I said, let's not get BRAND specific. This is not the topic, and is not the problem. This occurs at the upper hp limits and you will not see signs of this at sub +/- 550hp levels...

 

Anyone with a Cometic head gasket failure on the board? I know I have heard rumors of the Cometic failing, but have not heard of a member having this issue. Also, curious to know the thickness of the Cometic if anyone knows.

Are there other aftermarket options?

 

Not 100% certain, but I think the Cometic stock style gasket is 65 thousandths and still has they same type of behavior at these power levels.

 

Just to make sure . Is this head lift with stock head bolts ? Or ARP after market head bolts ?

 

The stock Head Gaskets are .024" and the Cometic gaskets are .030".

Cosworth and Nismo also make head gaskets but I do not have the specs on them

 

It's happened with stock bolts, and stock & 1/2" ARP studs...

 

Buy bigger turbos for less streching inside and more egual boost-less torque then to push the heads or maybe the crankshaft bearings to spin

 

sharif wasnt having this problem until he was in the 600s IIRC. good luck, seems like this is gonna be the next obstacle to overcome with these motors.

 

I'm pretty sure phunk was having a similar problem with head gaskets way back when he first started pushing the boost. I'm not positive though. He'll chime in here I bet.

 

we are all doomed.

 

Chime!

 

Maybe ill try out the cosworth since all the failures are happening with the nissan/nismo gasket.

 

We carry the Cosworth headgasket, and they are made by Cometic...so no differences between the two. The failures people are seeing usually happen in situations where you are seeing very high boost at relatively low RPM. This can also happen during 5th and 6th gear, where there is extreme load on the engine, and lots of boost.

An upgraded headgasket should help, as well sleeving. IMHO, anyone pushing for 575whp+ should strongly consider sleeves. It's also important, especially when tuning, to avoid putting too much boost on the motor at relatively low RPM. Load based dynos are awesome, but they allow you to put the motor in a situation that it would never experience on the road...ie...15lbs of boost at 3000rpm. The extreme load, and very high cylinder pressure, and very low RPM, can result in headgasket damage, regardless of the precautions taken.

I am now 100% convinced, that these failures are not a result of cooling system deficiencies, but are a direct result of very high cyliner pressure, and inadequate stability around the head gasket. Whethere the failure is the result of cylinder wall distortion (open deck), weak OEM headgaskets, or maybe the ARP hardware backing out, is anyone's guess at this point.

If your coolant resevoir is overflowing, you are more than likely experiencing head gasket failure.

 

I've got NISMO ones I can measure Tuesday if anyone is interested. Some have said its the same as the Nissan gasket, though I have never seen them repackage a stock part in a NISMO package and call it a NISMO part..something about them would almost have to be different to warrant it being a NISMO (Japan) item)

Anyone have specs, pics of a new Nissan OE headgasket? If not, I can order one Tuesday and do a comparison myself

 

Has anyone thought about having the bolt holes being drilled and tapped to accept thicker rod bolts?

Jermaine~

 

I totally agree. The stock bores and sleeves are fairly thick, but if you can go to a thicker sleeve then you would in effect give a wider crush zone for the headgasket and a larger surface area for the cylinder gases to cross to get to the cooling jacket. This would also give much more stability to the bores....they would be more square to the headgasket surface and minimize any bore "tilt" under pressure. New and much thicker sleeves, and a better type of gasket may be the only real way to keep the pressure in the cylinders in these motors.

 

I was thinking about that too.....but I think the larger bolt holes would have to be cast into the block. I am fairly sure they are an iron insert at the bottom of each headbolt channel.

 

The stock Head Gaskets are .024"

I have several sets of stock gaskets in stock and can take a picture on Monday if anyone would like one. I sold my last set of Cometics last week and won't have them in stock until the 2nd but I can take pistures of them also if someone wants them.