I am looking into getting a custom turbo kit done, and having the pistons switched to 8.5:1. Anyway I was wondering if anyone has an idea of how much boost I could safely run, and about what hp numbers it should be putting down at that psi.

 

With just the pistons done probably only a fraction more than on a stock bottom end..So maybee if you run 8-9psi on stock..you can go 12psi on pistons only...You are talking about an aluminum open deck block..to get any serious HP you need to get the whole block sleved and decked...Then do Rods and pistons and now your stock heads and valves are the weak link..So now you have to get the heads done..your looking at about $8000-10000 on the engine alone..But is should handle 25-30psi no prob good for about 600-750HP..JMHO...

 

so lets say...darton sleeves and SGP 8.5:1 pistons. could you safely run 12 psi?

 

With that cost and risk, you got to ask yourself at what point would it be better to just wait 1.5 years and get the Z06 vette with 500hp stock and a warranty?

 

$13,000 more or less for just the motor.......I know cause thats what I'm paying.

And yes, thats sleeved decked, rods, pistons, bearings, and completely redoing the heads. Running 20 psi......could go to 35 if need be.

Sure you can wait.......why not wait 5 years there will be all kinds of good stuff out by then.

Isnt the whole idea is to have a fast G35 or 350Z that can blow the doors off a Z06???

Robin

 

Hi Robin, I want to build the best Z I can like many. Sometimes i get frustrated seeing all the problems we are having getting reliable hp.

Jeff

 

Tell me about it, my car is sitting in the garage(with a hole in the block) gathering dust right now..........gives me time to work on the sound sys. I guess, lol

Robin

 

Well there is no such thing as 100% reliable HP..Even a stock Z06 can have issues..The cost's do seem to outway the end result..But Man is it priceless to see the look on a Porsche owner when his $90,000 car gets walked by a NISSAN!!!

 

Forged internals and a properly built block will take 12 psi no problem. Your only limiting factor at that point is the petrol you use and how well you tune the car.

I have run 22 psi on 93 octane w/ 8.8:1 forged JE pistons. No problem.

 

There's a TT kit available here that uses 8.5 pistons amongst a whole lot of other stuff. IIRC it's setup to run 1 bar (~15psi) boost. They posted some info on it here a while ago. Do a search for nizpro.

 

This engine doesn't have any more issues than any other. The recipe is fairly simple:

1. Sleeves (Darton's Modular Integrated Deck series should be great)
2. Rods (forged)
3. Pistons (low compression ~8.5:1, forged)

then add boost. It should hold more boost than you (or the rest of the powertrain) know what to do with.

If you want a raised redline, look into balancing the crank and upgrading the cams, valves, springs, retainers, etc.

All of this is very common if you want to push serious boost through a stock street engine. Even factory boosted motors have their limits (although much higher, obviously).

Yes, you can go to Chevy and buy a faster car from the lot, but eventually you'll want more power.. and the LS series small blocks don't handle boost well either.

 

What about blueprinting the block?

 

From what I understand Subaru uses open deck blocks on all their cars, and they're running 14.5 psi on the STi. So what I don't get is why I would need to get the block decked. I am not looking to ever push more than 15 psi on the stock block. Also I am not ultra familiar with open deck blocks beings that I have always driven a closed deck block, but what exactly is getting it sleeved?

 

Sleved and decked is simply reinforcing the cylinder walls and block...You should be fine with the pistons and rods and 12-18lbs of boost..Go any higher and you may need to sleeve and deck..I am just gonna do it once so its all getting done right the first time..

 

reinforcing the cylinder walls.

daking, dude, why do you have my picture in your avatar?

 

Thats the reallife BEAVIS!!

 

Isnt the VQ block steel sleeved anyway? Therefore re-sleeving it wouldnt get you that far, since steel is a harder metal than iron, isnt it? Decking, however, should make the block stronger.

 

I think you're right.

 

How much do you think it will cost to do steps #1-3 above?

Jeff

 

I would estimate about $2800 for parts (forged pistons, forged rods, rings, wrist pins, etc) and machine work / assembly. I cannot find any info on the sleves so I'm not sure on that. I have 0 experiance with sleved motors.

I am thinking about just pulling the heads and installing some forged internals without pulling the block. Chances are the rings wont seat very well. I dunno..