greynolds17

welp i got a free engine and its about time to send it off to the machine shop to get bored and decked and all that fun stuff. however there are a few questions that need addressed.

1. looking to get about 10-12 psi out of a turbo on this engine, should I stroke it as well? or just build it as a 4.1 or 4.2L. I know I need forged internals and a stronger head gasket but should I also O ring the block? not positive how these engines like boost above 5 psi

2. what should I do about tuning it? i know jeep ecus dont like to be tuned so would i have to go aftermarket?

3. what compression ratio should i go for and what pistons should i order for it?

4. i see lots of people use the 68-232-4 cam on the stroker builds...would it work for a turbo? or should i keep it stock? or custom grind?


5. can i expect equal, if not better gas mileage from the stock 4.0 to the turbo?

6. should i buy a turbo kit or custom fab one? the banks turbo kit looks promising but im not really fond of running my exhaust under the engine and back up through the passenger side. was thinking of a way to make a custom turbo manifold.

Cummins93

I am running about 12psi with an m90 on a stock engine with colder plugs and methanol injection. I will always recommend an MLS head gasket and studs.

Assuming you are 1996 and up i think the ecu tuning options are Chris tuned, flyin Ryan, and syked ecu. Then you can full tune with megasquirt which is non emissions compliant or if emissions are a must you can use an AEM FIC 1913. there are other options but I haven't used them.

I am using stock pistions and cam which are what SCR 8.8:1 DCR 8.5:1? Good numbers for boost. They won't last long with detonation. Keep and eye on the AFR gauge.

I haven't used anything other than the stock cam. Someone will be able to get you a good answer.

I get the same mileage with the supercharger...as long as I am out of boost.

If this is not your daily driver that you depend on to make an income, which I hope it's not, you can fab up a manifold or a crossover pipe providing you can weld. There was boostwerks on naxja that would make a manifold for 600 or 800?

What turbo are you considering? is this Jeep auto or manual?

CobraMarty

All the above.

We use Victor Reinz/Mahle MLS head gasket and new head bolts.
Can get custom forged 4.0L pistons, about $500 with rings, and with different pin height for 0.000" deck height which with MLS head gasket will give 0.043" quench and about 9.0:1 CR which is fine.

Have had great luck with Harland Sharp 1.7:1 roller rockers which fit under the stock valve cover, can use stock cam, valve springs and pushrods. Adds about 0.025" lift and 2-3* duration to the stock cam.

Must have some sort of intercooling and MUST have a tuning solution like above suggestions.

greynolds17

its auto and it's my daily for now, after I get a new car then the engine will be dropped in and it will become my backup...looking at a t3 or t4 turbo also i hear flyin Ryan doesnt tune anymore

and yes I have to pass emissions otherwise I would just do a hood exit exhaust

also do you run yours on pump gas? Because I'm probably still gonna put maybe 6k miles on it a year when I'm done. And should I get forged pistons as insurence? And did you get a bigger fuel pump and injectors or did you use the 7th injector method

Cummins93

T3 or t4 is vague. I like the Mitsubishi Super 20g/TD06H. I mapped a few different turbos. I believe the GT35R was also a good candidate* Look into a transmission cooler inline after the stock cooler and placed in front of the radiator on the mechanical fan side.

Do just have to pass obd2 plug-in emissions with a visual cat check? If so even the megasquirt can be piggybacked. A change over to stock injectors and ecu would be required every emissions check.

I run my setup on 93 at sea level. Forged pistions are a good idea if this is your first time tuning or just for added insurance as they are more forgiving. They are not indestructible though.

I have the stock pump with 36 lbs@3bar injectors. I am also injecting water meth through the M90. Detonation is the killer. The more steps to prevent it the more oops room in tuning.

*A suggestion that is based on how I would use my personal Jeep. Your requirements may differ.

greynolds17

as far as turbo goes i haven't decided, just looking for one that spools quick but not too quick

emissions wise there is an IM240 test for 82 through 06 vehicles, idk about anything else they do. so as long as it passes a sniffer test i think ill be fine

im not very familiar with meth injection although i have heard of it, is it kinda like intercooling that also prevents detonation? and im planning on having it professionally tuned so as far as detonation goes i think ill be fine. and im thinking of running close to, if not, the same injectors you are. but if you could enlighten me a bit more on what you did to prevent detonation that would be cool

and would you recommend a turbo kit? or scratch build or modify a kit? ive been looking at 505 performance and they seem to have a good one with the exception of low boost numbers, but im assuming i could swap the wastegate out and change the tuning a bit for more, but it comes with all the goodies for the most part and makes it easy, with the exception of having an exhaust pipe running under the oilpan

indianaXJones

I wouldn't chase a psi unless you have a turbo in mind already. It is largely a useless number. For example here are some flow numbers for various turbos at the same psi:

20G ------------------ 650 CFM at 14.7 PSI
SR 50 ---------------- 710 CFM at 14.7 PSI
GT-30 ---------------- 725 CFM at 14.7 PSI
60-1 ----------------- 725 CFM at 14.7 PSI
GT-35R -------------- 820 CFM at 14.7 PSI

For an apples to oranges comparison I am running a GT35R on a 4.0 V6 and find it to be the perfect size for that application. Spools quickly, but not uncontrollably and at the 12 psi I'm running isn't producing huge amounts of heat.

Just to beat the dead horse, tuning is the most important part of any turbo setup. So this would be the first thing I would figure out if I were you.

Follow that with maybe a power goal which will make selecting a turbo and injectors a bit easier.

Then you'll have to figure out cooling the air. Meth is probably the easiest for packaging, but I personally don't like it for things that will see a lot of miles. Got to keep juice in it. W2A are efficient and can fit into smaller spaces than A2A, but will require a heat exchanger and pump. A2A is the easiest to do, but fitting one on an xj might be tough, unless you aren't wheeling it and are cool with letting it hangout under the bumper a bit.

houstonchapman1

You have helped me tremendously, I have a 20g, brand new. Ftc 201 with the extra injector. It's not connected but I have it.

Cummins93

The 4.0 with an estimated efficiency of 85% at 5k rpm on a super 20g with no aftercooler spinning that turd to 130000rpm within the 68th? Percent efficiency island.
Here is what I got with colorful markers. I wish I knew how to turn these attachments to make them upright...

CobraMarty

You can't go wrong with the 20G for 8-16psi on the 4.0L

greynolds17

sounds like ill go after the 505 package (which comes with split second and access+ for an extra price) and just leave out the turbo if they can make a flange to fit one of the above options, ill see about the g20 as well as the turbo off the 3.9 cummins and add a few other bits.

gonna need a w2a intercooler since i will be wheeling and the engine makes too much heat for a top mount

Cummins93

So the 505 kit is $4275 without addons and gets you 104ft/lbs. I did a rough look at the Garrett S60 compressor map and at a pressure ratio of 1.68 (10psig) on the 4.0 at 5000rpm it is at the far right of the compressor map? So if you want more power it doesn't have much more to give. Also the 505 site states that the kit can only pass a tailpipe emissions test? Does the FTC throw a DTC?

greynolds17

not sure but all I'm aware of is that I have the tailpipe test and more power isnt much of the issue at the current time