Turbo size?

[Defcon92]

What's everyone think of a 63trim .68 for a 4.2l stroker? Not sure if its too big, maybe go to a .48 housing on the exhaust?
Just kicking this idea around as a buddy is willing to give me it. I would like to run my stroker and lock it up with a 5psi wastegate spring. It should never boost more than 7psi worst case.
And before this gets into a huge discuss about tuning and need this or that, let's leave it alone. Many people have now run 5-7psi with zero tuning outside of manipulating injectors & fuel trims. Hell a zj guy on jeepforum has 78000 clocked miles on a stock 4.0 with 7-10psi. Spikes 10, drops to 7 & creeps back to 10psi around redline on his internal turbo setup. He threw in 24lbs injectors and a adjustable pressure regulator & a water to air intercooler. Adjusted the AFPR to get his air fuel ratios in check. 1 step colder plugs gapped at .030. 78k and it ran flawless the entire time for him.


My setups a 4.2l. Big valve ported 7120. Mopar 229 cam & 1.7 Rockers. 9.05:1 static. 7.87:1 dynamic. Pistons are .017 above deck, .051 head gasket giving me a .033 quench. 91 octane. I could probably drop 1 heat range on the plugs, and if really needed drop the timing back a few degree's. Injectors are 703s which are 21.7lbs @ the stock 39psi. @49psi they are just over 24.
With 5psi I would probably be dynoing north of 200whp which is more than enough for me. And for tuning I'd probably go with christuned & see how good he could set me up. If not do as the zj guy and get an adjustable fuel pressure regulator.

If intake temps are an issue I'd would add in a meth injection kit with a 1gph for the sole purpose of helping cool things off without adding too much fuel.
Anyway what's everyone think of the turbo size? T63 .68ar. Looking at 5psi max.

[Defcon92]

Some more specs for you guys. I believe my compression is 9.05:1 & 7.9 dynamic with a .033 quench height. Running a mopar 229 cam with 1.7RR's. There's a unknown piston dish so it could be even lower..but that is the highest it will be. Pistons are cast speed pro 677's.
I believe I'll be good for my 5-6psi I'm actually after. It would be locked in on a 5psi wastegate spring.

Intake: 3 inch
Inlet: 2 inch
Compressor trim: .50
Compressor Wheel diameter: 50.16 / 76.84
Turbine Wheel diameter: 54.06 / 65.20
Exhaust Trim: .63A/R

Just picked it up. Yes its a knock off GSP (Godspeed) brand that has been rebuilt and spec'd. Saw mid 300hp on a honda series motor.
Grounding kit and anl fuse holder in the back ground waiting for the jeep as well. and the 80mm vortec tb I'm hoping to graft in as well.



.63a/r & its a 50 trim. Not 63 as advertised? Being a 50 trim it'll be about perfect..I wish it was a 57trim as the others using a 50 are spooling at 17-1900rpm. My cruise is 2400 @ 65mph. 4.10, 31s & ax15.


No play anywhere, nothing loose. Ran for 18000 mile before the setup changed. 0 miles on the rebuild.

[Defcon92]

I also picked up a BEGI rising rate fuel pressure regulator. The hard part is gonna be getting it setup as I got it second hand and I'm not sure what's what on it lol.
Just by read it has "onset" adjustments. Which means it can raise the fuel pressure before it even sees boost and you can adjust how much and how it ramps up ect. This will be great since I'm not going to be using a fuel engine management unit. Just a re flashed ecu by christuned.
Then once it's seeing boost you can adjust from there also how much it goes up and how it ramps up I guess. Gonna call their hotline and get more tech on the thing.

It will make it in the jeep as its a easy and effective way of helping me tune without going to crazy. Total I spent on it was only 20 bucks I believe its over 200 new.

[DaemonForce]

Every time I see a thread like this I think of the annoying Honda girl on my facebook and then I start thinking about what could have been with a 232 or 258 instead of a 199. Today I went up to Nisqually and found a cute little SAAB that still has the turbo, intercooler and everything. I don't see how or why it's a parts car but I'm wondering if I should snag the turbo while I still can. At the very least I know I'll need an intercooler since I won't be using a carb anymore. If I had the wiggle room I would probably be considering one of these about now. I'm only interested in the small 2.5" Outlet turbos since I don't want to be cramming more than that down the throat of a 60-63mm throttle body apparatus. I thought about putting on a Vortech supercharger but decided against parasitic equipment when I started thinking of blamming my belt driven P/S pump and thinking of ways to replace it with an electronic pump.

[Defcon92]

My engine builder is stating a turbo in the 5-6psi range would be too much for this motor. Stating compression is to high for the iron head & block. It'll blow ect ect.. Its 9.05:1 static 7.9 dynamic with a 229 mopar cam & 1.7 RR's. The quench is .033 should it should be much more efficient than a stock 4.0 in terms of detention?

I've been told single pattern cams were good for boost? The compression isn't much over stock, the dynamic is a bit more, but a better quench? Is it too much to worry about?
I'm thinking pull 1-2* base timing via the CPS. And 1 step colder plugs with a 5psi wastegate spring. Should never boost more than 6psi? Obviously running 91 octane.

[jeepxj3]

Dual pattern cams with more duration on the exhaust is usually better with FI.

I would think that 5-6 pounds would be fine but you need to be able to add more fuel under boost. What is your plan for more fuel?

[Defcon92]

Dual pattern cams with more duration on the exhaust is usually better with FI.

I would think that 5-6 pounds would be fine but you need to be able to add more fuel under boost. What is your plan for more fuel?

Well it would be tuned so to speak. As I said pull 1-2* of BASE timing meaning 1-2* across entire rpm range. I have a begi rrfpr. (Rising rate fuel press. Reg.) it can be set to raise before boost and while in boost.
On top of that christuned to tune my entire ecu..plug timing in certain spots if needed on top of the 1-2* add fuel where needed if the rrfpr isn't enough in certain areas.
Its hard to decide if I should leave well enough alone or push my motor? Idk if its safe for boost, as in if it'll be at the ragged edge with 5-6psi or will I be completely safe? The questions stuck in my head.