With my JWT ECU and other mods, I'm currently running at 15lbs of boost without any detonation problems. So my question is, how much higher can I crank up the boost before I need to start modding/reinforcing the internals to handle the pressure? And what internals would need to be, or able to be, changed out to make it more sturdy?

 

what head gasket you have? do you have head studs? and what kind of pistons do you have? what head do you have to help the flame front not detonate? start with those

 

Also what turbocharger are you using? The stock one becomes inefficient above 14-15psi.

 

if you dont want to do forged pistons you can always go with methanol injection. thats my play when im at 20lbs of course i will also have forged pistons

 

I run 26psi with a felpro hg/arp studs with an h trim compressor, .82 stage 3 hotside. I also use methanol injection.

 

damn 26 is alot, but also i guess the turbo motors are pretty low compression already...

 

^^^ That felpro head gasket isn't going to last 50k miles on 26psi boost though. Felpro HG's suck.

 

Like the others have said, it depends on your turbo. You really don't want to be out of its efficiency range or you'll end up making more heat than power. Is your JWT setup the 4bar or 3bar program? I've got the 4bar setup. With an HKS hg and ARP studs, I've had my Z up to 1.3 bar (I think ~19psi) of boost for short bursts. My daily driver setting is anywhere from stock to 1 bar depending on the weather. These motors are really stout from the factory, and the limiting factor seems to be the tune of your ecu, and how well your head flows.

 

It's been just as reliable as the stock turbo gasket I had on it before. I don't expect anything on a stock L engine pushing 500+hp to last 50k miles when it already has over 120k on it.

 

turn it up till it blows piston parts!

 

lol, its always fun when the engine starts vomiting itself out the exhaust. thats when you know your REALLY making power

 

The internals are stock. The turbo is a Garrett GT35R, so I'm barely giving it a workout right now. That being the case, how many lbs of boost do you guys reckon the stock internals can handle?

So I see mention of forged pistons. What make of pistons are these, and where's a good place to get them from?

 

you should look into reading BOOST and how to modify you NISSAN L

 

^^^ Indeed.

HeatRave... there's no definite answer. Each motor depends on it's miles, how well it's been taken care of, etc. When you start to max out the stock injectors (12-14psi) that's a pretty good sign not to go farther.

I'm sure the internals will take 15-16psi as long as you keep the A/F ratio rich... it's the "other" things that will likely go first: head gasket, bearing, valve spring, etc... which will promptly bring on damage to more significant parts.

Several places sell L-Series forged pistons, such as MSA. Prepare to shell out $600-$800.

 

I second that. I still don't know if you're 4 bar or 3 bar, but anyway, both maps from JWT are very conservative. I would guess you could get away with more boost on the 4 bar map. I've ran ~15-16 psi for a couple months now after fixing my head gasket (and prior to blowing it too), and I don't have any issues. You could probably run about 20-22 on stock internals daily if you really wanted, but like stated, it depends on your tune. Every motor is different. My engine has 135K on it and still has good compression, so I don't feel iffy pushing 1.3 bar every now and then.

One thing to remember though is your turbo is a heck of a lot more efficient and larger than my T3/T4. You could probably make the same hp at a lower psi than me. Dyno your Z and go from there for your boost levels.

 

when there is a rod hanging out of the block and pistons in the oil pan, only then will you know that you have reached maximum boost.

 

I've got about 104k miles on my engine right now. And I was considering an engine rebuild this year, and then while it's disassembled, do some fettling around (ie headwork, P&P, etc). I forgot to mention that I did dyno it already, which is how I know there was no detonation, even after all the heat soak from repeated runs. And yup, JWT tuned it conservatively rich on the high end.

Do the forged pistons from MSA change the compression ratio, or otherwise add any power on their own?

 

What boost pressure did you dyno at, and how much did you put down?

From what I see in the catalog, the MSA pistons are flat tops, so you'll probably have an increase in compression. Increased compression = increased power, but less ultimate threshold for boost.

 

pffft... says you. ever see the high HP DSM's and supra's and crap? they rock near 40psi on 11:1 internals. sure they are built to hell but a higher comp forged piston will take boost its all about the tuning. also the high comp = much better turbo spool

 

Higher comp = more power, but you can compress fuel so much before it can't be compressed anymore. You can run more boost on a lower comp piston setup for the same motor given equal factors. Those high hp Supras and DSMs that I have seen run on methanol or C16, none of which is available for the average Joe on the streets driving from city to city... If you want a dragster, fine, but for those of us with a more realistic build, we will stick with pump fuel. There is a reason why people who turbo S2000's tend to use a thick headgasket to lower the compression from 11:1 to 9.5:1 when they boost (see RSR).

 

i know where to get C16 out of a pump around here... soooo..... suck it! hahahahaha.... and usually on a high boost a methanol injection sure.