Well, we dont have Porsche engines. Those cars are built to a much higher standard from top to bottom. Our blocks go into everything from minivans, to mom's SUV and to sedans. The way the VQ35DE is designed, there is alot more side load on the cylinder walls. Simple putting larger studs and torqing them down more to sandwich the gasket is a bandaid imo. The way the engine is designed plays a huge roll in what we can get away with in the aftermarket. I hope the HR motor is a huge step up.

 

Drilling and tapping of the vq DEFINATELY needs to be done right...we have a very tight setup that makes the process very accurate...

But, IMHO and experience, the hks headgasket + 1/2" head studs on a open deck/unsleeved block is very very capable...even with extreme cylinder pressures, when those heads are torqued to 100ft lbs with the stopper headgaskets, this setup is extremely forgivign and durable...I am running a conservative 16-18psi on a unsleeved block, making a little under 600whp and over 600ft lbs of tq, and it is loving it...

for power levels above 700rwhp, sleeving may be necessary, always good insurance for those of you that can't pull a motor out in a few hours (like me )...but we are really pushing the limits of the unsleeved block with greater sealing of the heads- and have yet to see a failure (knocking on wood)

-TODD

 

no one has proven that the open deck cylinder is actually moving...all of the failures I have ever seen have been a result of headgaskets blowing out because of cylinder head lift due to inadequet clamping force- studs stretching

...not trying to argue, but do you know of anyone that has PROVEN that the cylinder is actually shifting? I know of a handful of guys who are pushing close to 700whp on the unsleeved setup with no problems....

I don't think the 1/2" headstuds + improved headgaskets is a bandaid, this seems to be a SOLUTION...sleeving is great, may just not be necessary for these power levels

 

Like Julian is saying, the stud design is stronger than a bolt...the simple explanation, without getting into to Gurgen math is: a bolt will thread into the block as it is tightened, putting lots of stress on the threads and tensile force on the bolt as you are rotating it/tightening it...

a stud is fixed into the block, it doesnt spin as you tighten it, the tensile force is better distributed throughout the length of the stud as it is torqued, a washer and nut on the top end verses the head of a bolt....

THERE IS A MUCH MORE COMPLICATED explanation that is not necessary to go into for the current topic

We use 1/2" head studs on 95% of all the engines that we build...relatively cheap insurance, as we charge a $550 upgrade price on any of our engine packages - to add the ARP 1/2" head studs (involves maching the block, timeserts steel inserts, and machining the cylinder heads to accept the larger stud)

-TODD

 

Good info!

 

Todd
So with my setup you think it will be ok with the L19 if I ever decided to turn up the boost to get somewhere around the 700whp to 800whp? I know It's hard to get those numbers but it's just an if
Thank you all for valueable advices.

 

IT HAS BEEN DONE, BUT then again, people have pushed the limits on a stock block too and eventually experienced failure- 550rwhp completely stock internals!!!!...is it advised, definately not, can it be done, absolutely...how long will it last, that's the question of the hour!

 

IMHO, until somebody cracks an OEM sleeve, we're just making WAGs about what power level they're capable of handling. Same goes with the L19 head studs. I've never heard of anybody lifting the heads with L19s. We need somebody to make 700-800whp on the stock sleeves using L19 head studs. If that setup could last a year without problems, we would have our answers. Heck, maybe I'll try it myself this summer.

 

I have heard a few cases of head lift with L19's actually, and with 12mm headstuds..it can still happen even if you have 4" headstuds

The point of this advice is that there a certain precautions that can prevent these failures, int he abovemnetioned cases, they were when a lean condiition was present, or installationerror/tuning issue

No one, to my knowledge has cracked a sleeve, I agree, but I still stand by my abovementioned recommendations, they have been tried and tested and have worked...

I'll be going to a dyno day here tomorrow, I'll post some numbers at maybe 19-20 psi, unsleeved block, should be well into the high 600's..maybe mid, as I am not going too crazy on the ignition timing advance.