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How to blow up a 4.0 ( a turbo Cherokar build)

Gunhand1

Well-known member
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May 21, 2020
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880
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Hi, you might remember me from the Dana 50 build thread I did (dumb). Being know for that level of ignorance wasn't good enough for me so now I am turbo-ing the Cherokar.

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After my axle build thread this thing has seen a lot of action, some flops, and lots and lots of rev limiter......and it didn't break any drivetrain components. BORING. What I need is more power, I need that carnage every now and then to really make me feel like I was trying.

I was visiting a buddy and dropping some stuff off to him and we stood around bullshitting in his garage looking at his fresh 6.0 swapped TJ one day. The conversation eventually landed on the ebat turbo that was sitting on his shelf collecting dust. After a while he says that I should take it with me and use it as it is too small for anything he owns now, I'm a sucker for free parts so I do just that.

I stand around a bit drinking some miller's and pondering ideas on how best to stuff this free Beijing block buster under the hood (as cheaply as possible, of course). Eventually I decide its gonna go right about where the factory airbox sits.

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All that fleshed out I set to work building a (sort of) cage, because I wouldn't want to take the most direct path here. I picked up a Hughes model 1 (jd2 before the name change) bender for a little bit of nothing a while back and converted it to air over hydro and bolted it up to an engine stand. I'm hoping in the not too distant future to build a more hardcore rig out of a TJ tub that I have laying around, but having never don't tube work in my life I decided I need some practice. And if I am being honest this whole XJ has been practice from day 1, I had no idea what I was doing when I started down this road. Begin the "cage" build:

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So I just ended up doing some B pillar uprights and a crossover that ties into the pipe (yes, pipe) rain gutter "tree sliders". And basically the same in the rear to tied into the shock towers and a little X bracing there so I don't smash the roof in on my kids head. It's not the best tube(pipe) work, mistakes were made. But I feel a little more secure now and I think I can do better on the next build, and I definitely need a notcher, or at least a better drill press and a X Y table.

But I digress. With the looming possibility of a new job being offered ( distant possibility, as I asked for a pretty crazy amount) I decided ot was the perfect time to start a turbo build.

I got to work disassembling all of the engine bits that guide fresh air in and guide expended gasses out so I could chop up the perfectly fine not cracked at all stock manifold. The plan here was to make a log manifold that was pretty low profile and with extremely questionable flow characteristics.

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Pretty straight forward, just cut straight across and notch them a bit to cradle the pipe (yes, pipe. Again). All except #6 were smooth, the angle of the factory header for this was wonky so I had to cut another section off and graft it in.

Lots of test fitting to make sure it all cleared happened, but so far it looks like it will all fit with room to spare.
 

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After I was satisfied With the fitments welded up the turbo log. It's not beautiful, I'm not a welder by any means. But my welds don't break (unless it's on cast, but I don't count that :flipoff2:). I may do some work to smooth the flow into the runner to the T3 flange but I am a a bit crunched for time now.

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Why am I pressed for time? Well that job I mentioned in the OP was offered to me, and it was good enough that I couldn't say no. So I'm starting at a new place soon, also it's 4 hours away from my house :homer:. So I not only have to finish this shitbox up, or at least make it move under its own power, but I also have to prep my house to sell it. The bright side of all this is I will be back in my hometown where the wheeling opportunities are MUCH better, and trips will be more frequent.


I got a move on and built a downpipe that connects to the remaining factory XJ exhaust, for simplicity and because the common hood stack method is a little too hoodrat even for me.


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Intake bolted up to check for clearance, I'm fairly pleased with it. I will probably make a bracket to tie the turbo to the intake as well just for extra support. Though it feels very solid as it currently is.

This is where it is currently sitting. I am waiting on the 10AN bulkhead fitting for the drain line to arrive so I can drop the pan and get it installed. Also waiting on the turbo jacket and header wrap, I want to try to keep heat down as much as possible on this thing since it gets so humid here in summer that AC is a necessity.

Also ordered the cold side piping and one of those little mushroom/dick shaped turbo filters.

Turbo is supposed to be wastegated at 8psi, which I think will be ok with no intercooler.

I'll update in a few days hopefully when shit arrives.
 
Yours looks to be 97+. What are your plans for tuning?

That's the neat part, I don't know.

For the time being I'm just gonna have to get it running until we relocate, even if it runs like shit.

But HP tuners works with the JTEC ecu now, so I will probably go that route eventually.

However some guys have said that the factory ecu will do ok with 7 or 8 lbs
 
you could make a simple bracket and go to the engine mount if need be to support the weight off to the side. another idea is all.
 
Had a lot going on this weekend between looking at property for a new house, driving 8 hours, and working on my house and didn't get as much done as I would've liked. But some progress was made.

Got the fiberglass header wrap in and wrapped the up pipe and down pipe to try to keep heat under the hood under control. Threw the manifold in and the turbo on and realized that I needed to rotate the turbine housing to get the oil drain line to clear part of the inner fender.

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I didn't get many pics, but I dropped the oil pan to clean it up and pop a hole in it for the 10AN oil drain hookup bulkhead fitting.

Noticed this little guy while I was in there:
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Should be fine........I hope.


Changed the filter and added oil and hooked up the last few sensors. I also added the, apparently mandatory, check valve in between the manifold and MAP to keep it from seeing boost.

Kind of hard to see in the pics, but I rerouted the fuel line to be above the intake, normally it runs below but there's no room for that now. I will eventually build a bracket to hold it up off the manifold, but for now it will just get some tape or foam in key spots to keep it from rubbing. ( it's getting to be crunch time and this junker needs to be on a trailer to be relocated soon)

Anyway, all that done I couldn't resist cranking her up to test the sound.


Not too bad if I do say so, I'm sure my neighbors were thrilled at the new boosty noises I can now make :homer:


According to ebay the silicone elbows and charge pipe should be here today. So I might just get to see what happens when I feed it a few PSI. I still have no idea what the actual size of this turbo is, the only numbers I could find on it brought up nothing when searched for online, it does seem to spool really fast though.


Also of note: fiberglass header wrap is super shitty to deal with. I've heard the volcanic/basalt/Rockwool type is much better, being that itchy is not worth the 20 dollar savings of fiberglass.
 

I was thinking more like this
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I started this knowing almost nothing about turbo/boosted builds. Now I know just a lottle bit more than nothing.
Can somebody tell me if a BOV is necessary or not or is the internal wastegate sufficient for 6-10 psi? I can't seem to find a real concise answer as to whether it's necessary or just nice to have.
 
BOV and wastegates are 2 different things.

BOV is nice to have.
Wastegate is mandatory.

PS : I want to see this thing at 10psi. You're looking at big problems.
 
BOV and wastegates are 2 different things.

BOV is nice to have.
Wastegate is mandatory.

PS : I want to see this thing at 10psi. You're looking at big problems.

Understood on the wastegate. I wasn't sure about BOV. Thanks.


10psi off the get go will for sure be problems. I'm going to have to try to keep it pretty low for now until I can get a tune done or figure some other way to control fuel/timing
 
You need injectors, fuel pump and a bunch more shit.
 
You need injectors, fuel pump and a bunch more shit.

I've got a lot more research to do to make it right for sure.

I figured on needing injectors for sure and it'll need a srt4 MAP when I go to get it tuned. From what I can remember reading a while back with injectors and a tune it should be able to handle low boost (8ish, some say 10psi) with the stock fuel pump.

Another thing I considered is changing it over to a return style system and running a boost referenced reg to dump more fuel at higher boost. I have heard this can be hard to tune though.


If you've done this before though I'm all ears, boosted stuff is all new to me
 
I think the blow off valve is a pretty mandatory. It prevents you from blowing boost through a closed throttle body. From my understanding, if you don't have some form or surge protection, you will have a hard time tuning and will be ruining turbos pretty consistently. Waste gate it optional depending on turbo size. It's function is to let you use a tighter exhaust housing for quicker spool, while limiting top end pressure / heat. There are plenty of non gated turbos out there. They will take longer to spool but will usual out perform a gated turbo of similar size.
 
This guy Richard Sawyer has one turboed for a couple years now. His setup when I asked him about it,

A year now. Not 1 problem. I didn't skimp on anything.
255 walbro in tank pump
61lb bosh injectors
Boostworks turbo manifold
Rev9 turbo
Rev 9 intercooler
Fans on the intercooler ect...
Stock ecu tuned using hp tuners.


 
This is not low boost at all


I've done it "right" (tunable ECU, proper fueling etc) which explains why I didn't have issues.
I can't really help you on doing it wrong.
I'm not really trying to do it wrong, there's not a lot of info and some of it is pretty questionable.

Plan right now os just to get it mobile under its own power( which it pretty much is with no charge pipe hooked up) so I can load it on a trailer and move it to the new place. After that I will have to work on tuning/ getting it running right.

We converted a late model XJ fuel sending unit to return style and used it on a LQ9, so I really think the pump will support a turbo 4.0, the reg may be the choke point. Injectors will be swapped, I'm just not sure what ones to use just yet. After that's all said and done I'll get somebody with HP tuners to look at it.



This guy Richard Sawyer has one turboed for a couple years now. His setup,





I'll have to watch that later, looks interesting
 
There was a guy on the old site that built a decent looking setup for a YJ. I remember a lot of extra widgets to get the tuning right though.
 
We converted a late model XJ fuel sending unit to return style and used it on a LQ9, so I really think the pump will support a turbo 4.0
Boost is much different than N/A when it comes to fueling.

As an FYI, this is the flow diagram of a Walbro 255, which should be enough for you. OEM will be worse.

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Injectors will be swapped, I'm just not sure what ones to use just yet.

After that's all said and done I'll get somebody with HP tuners to look at it.
How do you handle the MAP ?

the reg may be the choke point
The fact it's not pressure referenced is the problem.
 
Boost is much different than N/A when it comes to fueling.

As an FYI, this is the flow diagram of a Walbro 255, which should be enough for you. OEM will be worse.

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How do you handle the MAP ?


The fact it's not pressure referenced is the problem.
I think I still have a walbro 255 in a box somewhere from an old project. If I need to stuff it in the sending unit I'll do that.

As far as MAP I believe the common swap is to get a sensor from an SRT4 Neon. You have to adjust the MAP reference range (or something like that, I'm no tuner) to allow the JTEC ecu to read positive pressure. When I get closer to needing all this done I will probably get with FRP and see what he recommends, he seems to be the 4.0 tuning guru.


Is a boost referenced full reg really necessary on a tunable OBD2 system? I was under thr impression that was a bandaid for older stuff that couldn't be tuned. Not trying to argue, that was just the impression that I had. And honestly swapping to a return style system would probably be beneficial anyway with the heat soak issues the 4.0 in XJs seem to all have.
 
Is a boost referenced full reg really necessary on a tunable OBD2 system? I was under thr impression that was a bandaid for older stuff that couldn't be tuned. Not trying to argue, that was just the impression that I had.

It's not because you can that you should.



The whole series is worth watching.
 
It's not because you can that you should.



The whole series is worth watching.

Excellent. I didn't take into consideration the differential pressure under boost that you don't have NA.

I'll have to try to find the rest of the series and watch it
 
Well finally took it down the street just to see what it would do.....and the answer is not much besides sound cool. Definitely running out of fuel and/or ecu is pulling power ( I'm sure I'll get some" I told ya so" comments :flipoff2: )



At any rate it sure seems like it will be a good time when I fix the fueling and timing issues, but for now it will probably drive itself on the trailer and go off to the new place until I can get moved and settled in and continue. I may pull the turbo off and throw a factory manifold back on in the mean time since I am going to like have to build a new shop.
 
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