It's just the limit of most builds today so that's a well tested range in my mind. Could be much higher actual limit...

 

Z community is progressing. When I did my build last September it was believed by many reputable shops that to reliably hold 550+whp sleeves were reccomended/needed. That doesnt mean we had stock cylinder/forged internal blocks failing at that power levl, thats just what most agreed upon would be a good idea. Now we have 600+whp no sleeves doing just fine. Back in September if you ran 10+psi on any stock block turbo car you were insane, now many shops are doing this successfully.

 

You are right, I guess we dont know cuz we havent seen many HIGH hp JWT builds...

edit-Ive never seen one out of a Z I know its a long IC but how thick is the core?

 

+1... I've heard rumors of 700whp on our stock sleeves. But it's rumors at best. The guys in PR and Japan have been pushing crazy limits for years on these blocks and I'm under the impression that sleeves are really only needed for those looking to pass down the 1/4mi track at 1000+whp.

Much to the contrary of popular belief, open deck motors can hold up to a ton of abuse at the RPM's that we're running. If we redlined at 10k, then I'd see it, but for 7-8k, I really don't see sleeving as a necessary piece of the puzzle.

 

Oh, I think it'll hold at least that. Even moreso with methanol injection.

Hopefully someone out there will be willing to push it to it's limit (and possibly failure).

 

What was your old turbo kit?????? Tell me your selling it..

 

I agree. Someone needs to do that.

 

I wish intercooler efficiency (temperature drop and pressure drop) stats were published with the turbo kits. I'm sure someone actually collects this data during kit design, so why not use it as a marketing tool...

 

Bert hit it on the head. It's easy to say that stock sleeves can hold 600whp+, but when you own a shop, and work on other people's cars you can't take chances or guess on things based on speculation. I have always run my business in a conversative fashion, and avoided suggesting parts or strategies unless I can stand behind my decisions. The customer determines our level of chance-taking, or aggressiveness. As such, sleeves were a good precaution, and that is always how I have suggested them, in conversations with customers.

RCDash touched on the cooling concerns with big bore sleeved blocks. Sleeves have always been designed, as a raw block strengthening device, in order to contain maximum pressure in the block. They are perfect for road use, drag racing, and brief periods of heavy load. But for sustained track sessions in the 20-30min range, an unsleeved block will provide better thermal cooling capacity, and allow the engine to run cooler.

George, I think your stroker 3.8L unsleeved package would be a terrific road race engine for me. I am just trying to keep this buildup simple (and cheap).

 

Good point and question. Even if it were discovered to be inadequate, fabbing up a little piping and dropping a more traditional and larger intercooler should be a fairly straight forward operation.

 

It's already been pieced out, and it's somewhat incomplete now.

 

First, we're really talking about dry-sleeved vs. wet-sleeved, not unsleeved vs. sleeved, right?

Second, why do you think wet-sleeved blocks (or, at least, wet-sleeved VQ35 blocks) do not dissipate heat as well as dry-sleeved? I have seen the claim repeated numerous times, but never with any explanation why this must be true.

 

This would be a terrific idea. A 15psi, I am seeing comparable air inlet temps, when compared to Greddy and APS, so the intercooler appears to be doing a good job at those power levels. We'll have to see how it goes at 20psi.

 

Wet sleeved blocks offer better cooling control but aluminum is a much better conductor of heat, when compared to cast iron. And when you bore it out to 100mm, things get worse.

 

And one last thing. I hope I am not giving the impression that I am anti-sleeving. Darton wet sleeves serve an important purpose for very high powered engines, and are required for the big stroker kits. But sleeving isnt required for what I am planning for my car.

 

That's good to know!

I gotta agree with Alberto though on the "looks" - the 350z JWT IC looks like they took the two for the G35 and smashed them together. Having the return pipe come out at 90 degrees does not look optimal either but the unseen internal ducting might be better. I think the design is much more optimal than a large, partially obstructed IC (because of front bumper restrictions) as part of the airflow would remain superheated...

 

Sharif,

Motor looks great. How are the L19 head studs working out after 25k miles?

 

Ah, I forgot to mention that. The L19 studs looked absolutely spotless. Zero signs of contamination. The threads still had our moly lube on them.

 

The larger bore part I can understand, but the rest I don't. In the stock, dry-sleeved block, the cylinder heat must transfer through the cast iron cylinder liner (dry sleeve), the aluminum/cast iron interface, the aluminum, then into the circulating coolant before leaving the block. There is much more involved than just the aluminum block material, so I'm not at all convinced that the better thermal conductivity of aluminum vs. ductile iron guarantees better heat transfer through the whole system. Do you have any engineering data to back up the claim?

 

The combustion event occurs inside the cast iron sleeve, and the next contact point is coolant, which surrounds the sleeve. So the heat does transfer directly from the sleeve to the coolant, and then to the aluminum block. Our OEM cylinder walls are made from aluminum, and have a thin cast iron liner that interfaces with the piston rings, but the rest is aluminum. Aluminum is a better conductor of heat, when compared to iron.

I'll have some track data shortly to support the claim.