So finally I blew the HG's in my DE...word from Z1 and JWT is to use HR headgaskets with a mod to the block and use Nissan turbo Juke headbolts....changes cooling flow in the heads providing better cooling...

Anyone done this in a Z over 550hp and with success?

Thoughts?

 

heard good things about the dynosty spec'ed head gaskets.

can't help you on the juke bolts. That is the first time I've heard of those.

gl

 

I got a dynosty head gasket and I'm close to 550 who according to that vette I ran, I put 7000 miles on my car so far no problem.

 

Yes. I'm currently pushing about 640 ft. lbs. of torque and just shy of 600 whp, as measured on a Mustang dyno, in my G35 (my exhaust and turbine housings are a little restrictive - making changes soon to hold the torque better at high rpms and get more top end hp).

Anyway, I have about 6 months and 2000 miles on the motor, and so far no issues.

 

FYI, I am using ARP L19 head studs.

I don't what the Juke bolts are, but if they are the same as the HR head bolts, they probably are OK for 550 whp. A few years ago, though, somebody in the forum using the HR head bolts and running up near 700 whp had a problem with head lift. At that time I was considering using the HR head bolts but, based on his head lift issue, stayed with the ARP L19s for my new motor.

 

Check out XKR's build. I think he is running HR head gaskets and L19s, but double check. There is an entire thread on his build from a few years back. He finally made somewhere around 1000 whp.

I don't know anything about Dynosty's head gaskets, but they are very knowledgeable. Call them and get some info on their gaskets.

 

Dynosty headgaskets are very similar to the HKS gasket. Basically the same thing, $100 less. Go for that. Good for 1000hp neighborhood. The limiting factor with the hg at that point would be your head bolts... Jukes are fine, but if you have the money go for l19's, torque them in stages to 90ish pounds and stop worrying about headlift or Blown gaskets

 

So my Z has been boosted over 40K miles and currently has L19's..this is what tripped me out about them saying to use the Juke Turbo head studs...I need to understand more about the torqueing down process....basically what JWT was telling me is that they thought it was better to use a factory headstud that was torque to yield over the L19...and they said they have had great success with the factory HR gaskets..

http://www.jimwolftechnology.com/tech_details.asp

scroll down to "VQ35-37 COOLING, HEAD GASKETS & HEAD BOLTS"

Very interesting stuff...

 

So are YOU going to build your own engine.....or is Z1 ??

If someone else I, personally, would go with their suggestion just hoping they would help you out if the Juke bolts failed.......

 

JWT's a great shop, and have good products, but in this case don't listen to them. The l19's have been well proven as the best studs for this engine.

Beyond that Studs>TTY bolts all day every day.

Beyond that l19 (tool steel) has incredible tensile strength. There's a reason you find only l19's on all the biggest hp engines (even outside vq land).

As for the torquing process, it's stages;

Divide end torque by 4 or 5. So for 93 you'd go in 22 or 23 lb increments.
First stage, torque all studs in pattern for 22 lbs, then when you're done, bump the wrench up to 45, then do all the studs in the same patter, then up another 22lbs, then up another 23 or whatever it would be to get to your target #.

Does that make sense?

The HR gasket is great, any stopper style gasket is good. But if you're planning for over 600hp the extra cost for a good gasket shouldn't be an issue. If you're going for sub 700hp an HR gasket it's self should be fine as long as you're torquing above 80-85lbs imo. The only kinds of studs or head bolts that can handle that safely (without stretch fatigue) would be l19's.

Head bolt has the torx head on the actual bolt. Studs, are just that studs. Which have washers and NUTS that screw on separately. The issue with TTY bolts is as you torque them you naturally loose torque to the friction in the threads (as you are spinning the whole bolt while you torque them). Where as Head STUDS you only loose torque to friction on the nut (a very small surface area). So you have a much more accurate torque measurement to start with, as well as a better, stronger, less fatigue-able loading structure.

If that doesn't explain it for you, you'll need to do some searching about head BOLTS vs head STUDS. This is universal for all engines. And the same idea can be applied for any place you bolt something in for the most part. It's just most things don't need that much strength/precision.

 

Resmarted..THANK YOU..I knew in my mind what i was trying to say, but you clarified it for me...I agree wholeheartedly about the L19's..that is what is in the engine right now...I understand that head gaskets are going to eventually fail..I have a fully built and balanced forged internals engine..the gaskets finally let go is all..so was looking for opinions on the replacement hardware. My engine lasted over 40K boosted over 550rwhp...I will still do the cooling mod with the HR gaskets but will use the L19's again...I do understand correctly that even the L19's are a 'One time use" item correct? I need new hardware when I pull the heads...

 

BTW I just called ARP and their tech support told me that L19's are RE-usable? I though this hardware ALWAYS had to be thrown away and new stuff used....

 

Just throw away and buy new.

 

Torque to Yield bolts, such as the HR bolts (and I assume the Juke bolts) are not reusable.

L19s, however, are not torque to yield, and thus are reusable. But, you cannot leave them open to the air while you store them. They must be stored in oil. If you don't store them properly until you again use them, and they get exposed to air/humidity over a long period of time, they will rust.

That happened to my original L19s. Apparently, according to my tuner, they were stored in oil, but the oil leaked out of the container somehow, and they rusted. He bought me new ones.

 

FYI

"A torque to yield fastener is mounting hardware which is torqued beyond the state of elasticity and therefore undergoes plastic transformation, causing it to become permanently elongated." (http://en.wikipedia.org/wiki/Torque-to-yield_fastener)

This is why they are not re-usable.

L19s are a completely different type of fastener. As opposed to a TTY fastener, they are not torqued beyond their state of elasticity, which is why they are fine to reuse.

If you have L19s, store them so that they are completely immersed in oil, and reuse them.

 

Interesting. Dyno style HG have failed before unfortunately. Just a lit FYI




Dynosty ^^

 

Thanks That'll save me $450.00!

 

All headgaskets can fail.

They're still a good design however.

Do you have any info on how they failed? What were the heads torqued to?
Things that come to mind are if the person didn't have the heads/block machined properly, if the heads weren't torqued properly, etc


OP: And yes the L19's are re-usable, don't toss them. Just have them checked by a machine shop if you don't know how. I'm actually using l19's that came from another motor.

If any are bad, you can just buy one or two new studs to replace them and new nuts and you're ready to go. Most likely though, they're fine.