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Hey fellas so I have a 2jzgte with manley h tuff rods and pistons arp main and head studs new Toyota head gasket gsc s1 cams and gsc springs and retainers I'll be running 93 pump gas and using aem meth injection with 50/50 boost juice how much boost can I safely run and what kin of power do you think it will make thanks
 

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what turbo-- specifically the compressor size and exh turbine size/housing

how large are your engine injectors and what nozzle/flow cc will the aem 50/50 deliver ?
 

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S366 turbo and id1000 injectors walbro 450 pump
I'm assuming you're on a 3.0L and around 9.0:1 compression, and assuming your meth setup is spot-the-fuck on and works correctly.

Still some variables with the size of your downpipe, your intake manifold, and your turbine housing size, but I would expect it to make low-mid 500's around 18-20psi on straight pump premium (if you're on a 10:1 bottom end or have a small hotside and/or downpipe, you may be capped at 15-16psi and high 400's/low 500s') and on meth you'll be creeping into low-mid 600's around 24-26psi. I wouldn't push it further than ~25psi on meth but that's just my preference. On a properly set up 50/50 meth system you can certainly run 30+psi of boost but the margin for error is really, really small and bad shit happens FAST when the meth fails. If you've got a good aftermarket intake manifold, a good turbo manifold, a larger exhaust housing, and a 4in DP/MP/exhaust I'd expect numbers on the higher end of that range. Vice versa if you've got a 3in DP/MP, crap turbo manifold, small turbine housing, and stock intake manifold.

If you haven't already, consider some of the fail-safe setups that can be tied into boost control or your standalone if the meth tank sensor goes too low, or EGT's go too high, etc.
 

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and a 4in DP/MP/exhaust
Hi Jeff,
hows things?

Without getting off topic too much, I just wanted to ask how crucial the 4" mid pipe is in all of this, and if a 4" DP that goes to just below the start of the flat floor pan would give decent benefits in back pressure reduction?

Cheers 🍻
 

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Hi Jeff,
hows things?

Without getting off topic too much, I just wanted to ask how crucial the 4" mid pipe is in all of this, and if a 4" DP that goes to just below the start of the flat floor pan would give decent benefits in back pressure reduction?

Cheers 🍻
Mr Ree! Good to see you here and glad you're still enjoying your NA-T beastie! Thank you for the kind words in that other thread - I'd meant to reach out afterwards but my current situation (working in the mid east) doesn't have the most consistent internet access.

The 4in DP part immediately after the turbo is by far the most important part. You want the most volume possible with the least flow resistance immediately outside of the turbine housing. The further away you get from the turbo, the less crucial it is.
Ground clearance turns into a real issue with midpipes and catbacks that are much bigger than 80mm or so. The good news is your 4in DP is getting you the majority of the gains to be had from a 4in exhaust system, but obviously more 4in is better for HP and spool, but not so good for ground clearance and street-friendly, police-avoiding noise levels.
With your ~550hp setup I'd estimate that you may gain another 100rpm of spool and perhaps 15-20hp going to a 4in MP and 3.5in catback with no other changes. Not a whole lot of value considering the cost to change it all up. If you wanted to double your HP, though, it'd almost be mandatory as the restriction would be more and more significant at elevated boost and exhaust flow levels that come with that kind of HP.

If I ever have the time, I've been intending to experiment with a balloon-style downpipe of sorts that puts a basketball-sized shitload of volume right behind the turbo and then teardrop-funnel streamlines down into the MP section. There's diminishing returns somewhere with spool and torque especially when you're taking away from the air gap that insulates everything else from the DP heat, but hey, that's why it'd be an experiment.
 
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