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I'm constantly asked for a build thread whenever I post videos or pictures of my jeep, so here it goes. I'll start with a general overview of my jeep, and follow with individual posts about the engine, drivetrain, electronics etc. And I will answer any questions anyone has.
It started as a bone stock 1997 Cherokee Sport, 4.0, Auto, 4x4
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The 4.0 has been rebuilt, modified and turbocharged. It's a 4.0 bored .030 over, with stock rods and cast pistons. An Edelbrock aluminum head and a mild cam help it breathe better, and a Borg Warner S363 force feeds it with a little over 20psi of air. Most of the power is generously absorbed by a GM Turbo 400 transmission and some of the power makes it to the 242 transfer case where it is split (sometimes) to Dana 30 and Dana 44 axles. All this drives a cinder block shaped and colored Cherokee weighing 3875lbs with me in it (I only account for about 1000lbs of that weight, depending on what i had for breakfast). It's pretty quick for a Cherokee, but the project is not finished and is constantly improving. In the next post I'll talk more about the engine and turbo setup in detail.
As a stated before it's a 4.0, the engine we all know and hate love.
I'm not sure of the year of the block, but its not a renix block, its definitely 91-01. It's been decked, bored .030 over, and honed.
The crank is from a 98 4.0 and it has been reconditioned and balanced.
The rods are stock 4.0 rods with ARP rod bolts
The pistons are .030 over Speed Pro hypereutectic pistons. They are cast units, not forged and what i believe to be the current weak point of this engine, but it has not been an issue yet.
The Cam is a Comp 68-232-4 cam, which is relatively mild and therefore not a dramatic improvement over stock. Had I known the Jeep would make it this far I would've picked a hotter cam.
Standard pushrods and lifters, Harland Sharp Billet roller rockers, non adjustable.
Edelbrock Aluminum head, unported, with the included valves, springs, and retainers.
ARP head bolts and factory Chrysler steel headgasket.
Horseshoe intake manifold from the newer 4.0s, and a stock throttle body.
The exhaust manifold is a custom piece i made using a Renix manifold as a base. I heard that the port height of this manifold is .125" lower than the newer head, but I haven't seen any issues relating to this. I chose the renix manifold due its log style, which was easier to make and much stronger than the '98 manifold I previously used, which was prone to cracking in the collector area.
The turbo is a Borg Warner S300 63mm, T4 flange, .88 A/R.
The Wastegate is a precision PW39, 39mm.
**When I first built the engine I was rocking an eBay GT45 turbo, not the BW S300 i currently have. You will see it in the following pictures**
Last edited by akaxauto; Nov 25, 2017 at 11:22 PM.
Most people know that its pretty damn hard to tune the OBD2 Jeep ECUs, so most people resort to piggybacks or MAP adjusters. I decided go with a standalone ECU and settled on the Megasquirt MS3x, due to it's support for the 91-up 4.0 crank and cam trigger pattern, and its support for all the other factory Chrysler sensors. It controls both fuel and ignition as I no longer have the factory ECU at all. This was my first time installing a standalone in any car and it turned out to be pretty straight forward. The Megasquirt community is very DIY oriented and therefore very helpful with unconventional setups like this.
The MS3x gives me seqential injection and sequential ignition, which allows me to run individual coil packs. The coils are GM LS2 round coils. The Megasquirt allows me to run a wideband o2 sensor, electronic boost control, digital dash, etc. It also as many race oriented features such as launch control, antilag, rolling antilag, rotational idle, etc., which I can use and abuse at my leisure. Megasquirt is awesome, I highly recommend
The fuel system consists of a Walbro 255 fuel pump, -6 braided steel feed and return lines, an AEM adjustable rising rate fuel pressure regulator, a custom aluminum fuel rail, a GM flex fuel sensor, and a set of Bosch 850cc fuel injectors. Yes this Cherokee is tuned for both gas and E85 and the Megasquirt seamlessly blends the maps so it truly is a flex fuel vehicle.
MS3x, installed in the glovebox.
So many wires!! This was after the factory ECU was removed, and where the Factory harness will merge with the Megasquirt Harness. The original turbo setup is visible in the background.
Cam and crank pulses visible on my laptop, the light at the end of the tunnel.
GM LS2 ignition coils mounted on the Renix-era aluminum valve cover.
Drilling injector ports in the fuel rail
Aluminum fuel rail next to stock fuel rail. Notice the clearanced portion so the rail doesn't interfere with the factory throttle cable bracket. Mounting tabs will be welded on. Both end holes are tapped 3/8NPT. Fuel is fed in one end and there is a Radium Engineering fuel pulse damper currently installed in the other end (not pictured). Fuel pulse damper is important due to a harmonic with the injectors causing a lean spot on the fuel map at a certain RPM.
I will start off by saying the AW4 is a fantastic transmission, but it's downfall is that it's expensive to build. I have an automatic Supra transmission that I was going to swap some parts from, but I decided to go with the tried and true Turbo 400. Novak adapters adapt the 4.0 to the TH400 and the TH400 to the NP242 transfer case. I went with an NP242 because I thought i wanted full time 4x4, but my front locker makes that feature pretty useless. The front axle is a Dana 30 high pinion with a Spartan auto locker. The rear axle is a Dana 44 with an Auburn limited slip differential. Both axles are geared to 4.56, pretty insane on 31" tall tires and no overdrive. I will regear to 3.73 to make it more street friendly.
The TH400 has a 3000rpm stall converter, which allows me to build about 8psi of boost before launching. The trans originally had an automatic valve body, but it did not shift under boost, so now it has a reverse manual valve body.
All the components hold the power well, but the Turbo 400 definitely robs a bit more power than the AW4 did, but at least it shifts now.
Dana 30, with Spartan Locker
Dana 44 with Auburn LSD. This axle came from an 87 Cherokee Chief, I rebuilt it outside of the truck and installed the assembled and painted unit in my truck.
NP242, rebuilt
Rebuilt Turbo 400, Novak tailhousing and output shaft installed.
Novak transmission adapter installed on the 4.0
Turbo 400 ready to install
Turbo 400 Installed in the XJ with the NP242. I was able to use the factory cross member by drilling some new holes. Front driveshaft not installed. No transfer case shift linkage yet.
All that and I would have just dropped a Diesel Turbo charged engine in there. Good job though and I like the approach just too much work for my brain!!! But when you got those tools and shop to your disposal your thoughts are probably easy to become reality.
Finally found a crank, ironically at a local machine shop, already machined. I'm going to get some forged 4.0 rods, and custom forged pistons. Compression will be low, around 6 or 7 to 1. I'll use my current Edlebrock head and valvetrain with the exception of the cam which will be more aggressive, but appropriate for the lower displacement, lower compression, and higher rpms and boost.
Turbo 4.0 Cherokee
