I am surprised that no one has mentioned upgrading the stock head gasket. I would consider a Cometic head gasket as well. I do not think the OEM one will be holding up at 650whp with or without sleeves.

 

t32gzz, I agree and am looking into the metal head gasket plus the ARP bolt and studs to hold it all together along with some engine dampeners.

So, Sharif.... I have been learning the hard way how this is going to work and you were more correct then even I anticipated in the cost of the build. While the actual engine might be running about 15k the extra's are costing me over 10k... UGH, that is even more then the 20k I had sort of budgeted for.

Anyway, I guess I am about done with the spec’ing of the engine and parts. This next couple of weeks I will start seeing what is optional and what is mandatory to get the car as reliable as possible and increase the longevity of the engine/drivetrain.

Thanks for the advice and I will probably be asking more questions in the coming weeks/months.

Regards,
Brent

 

Tim,

What kind of head gasket are you using?

 

sharif,
do you think that he might need to build his tranny? is yours upgraded? especially if he plans on drag racing, i could foresee him having some problems with it in the future.

 

We've discovered that there is an issue with one of three things, as it relates to high boost/high powered VQ35's.

There is a weakness in one of these three things...or all of them...only time and further experimenting will tell.

In high boost situations..usually greater than 18psi and 600whp....the headgasket is not holding very well. It could be one of these three things.

1) Stock cylinder walls and their open deck design
2) Weak OEM head gasket (althought other shops have reported to me that the Cometic head gaskets were also failing)
3) Inability to retighten the head studs after heat cycling the motor...or maybe larger diameter head studs are needed.

What is happening, is that as you approach 20psi, combustion gases are eventually pushed past the head gasket, and you end up overpressurizing the cooling system with air, and then the engine overheats. Once the boost is retuned to a lower level, and the cooling system is re-purged, the problem goes away,and no damage is done.

The fist signs of this are an overflowing coolant resevoir...FYI.

 

Sharif,

there is a member here (who I will keep anonymous...he can chime in if he likes) who blew his built motor. when they took apart the motor the ARP bolts did not need to be retorqued. There were fine.

 

There was one other member..not sure if its the same one...and he mentioned a couple of the studs were a little bit loose...but not VERY loose.

I just wish there was an easier way to figure this out. I'm doing the Darton sleeved block with Cometic head gasket, so I'll be putting that package to the test. I am leaning towards cylinder wall issues....but its only speculation at this point.

 

Jorge, I am running the stock head gasket. As Sharif said, there is no proof that the Cometic is more reliable. I would like to see someone with Darton sleeves push over 600 and report back as to what may be floating in their overflow resevoir. I believe there will be a forum member doing this in the not so distant future.

 

I am going to have SGP check my studs when they tear apart my motor next week. I let you know what they find.

 

That would be great...before they remove the studs, have them retorque them and see if they, indeed, required some additional tightening.

 

Would it be possible to o-ring a sleeved block??

 

I think Sharif said this was where he was headed and to be honest that is the direction I am headed also. Darton MID's with the Cometic metal head gasket and expecting to be pushing around 650.