06 LJ Randy Rebuild

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Randy Bobandi
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06 LJ Randy Rebuild

Post by Randy Bobandi »

For documentation sake, I'll be posting status updates on the rebuild of a salvage 06 LJ. This was once a beautiful and bulletproof example of Jeep's finest. Well, fine except for the transmission (which will a significant focus of this build). Last spring I T-boned a girl at an intersection. I had a green light, she had a green light, but she failed to yield while turning left and the I plowed into her 2017 Grand Cherokee at 40 MPH. The LJ was totaled due to frame damage and a wrecked front axle. Insurance offered me $15K for it, I said fine as long as I get to keep it. They said sure, we don't care, keep it. I bought a 2000 Cherokee to daily and I built it up a little bit. Swapped the 0331 head out of course. So this summer, here in Maine, we build the LJ.

We strip it completely.
-Fix the frame while fabricating a one off mid arm suspension
-Remove any rust, clean and coat all ferrous metal
-Rebuild the NP231 with 6 Pinion Planet, Wide Chain and SYE, Custom Driveshafts
-Acquire AW4 core, rebuild it and install it with a standalone TCM/RADesign manual shifter
-Acquire HP30 Front Axle Housing, Rebuild it with 4.88 Gears and Eaton TrueTrac
-Engine Rebuild: Jeep 4.7L Inline 6 Stroker Engine, Clegg Fully Counterweighted Crankshaft, Scat Forged and Bushed Rods with .927" Wrist Pins, Racetec Custom 3.915" Pistons, Billet Speedworks Billet Main Caps, Fully Ported OEM TUPY Head with 2.00" Intake and 1.60" Exhaust Valves, 3/8" Pushrods & Roller Rockers. 9.9:1 Compression
-Haltech Elite Series 2000 ECU with 50-100 Shot N20 (We will be building a Turbo Kit this winter to install next summer featuring the Forced Performance FP7275 Turbocharger)
-Walbro 350LPH Fuel Pump, Fuel Injector Clinic 650cc 2JZ Injectors, F&B 70mm Throttle Body, ARH 1 3/4"-3" Header
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

The Engine looks beautiful at 200k Mi. All bearings look brand new, untouched. Lifters had zero signs of wear. Just some normal piston scuffing. Man I love these engines. I already sold the crank and rods to my local machine shop for one of their customers stock 4.0L rebuild.
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

Billet main caps came in today and I'm relieved by the way they came out. They are exactly as specified. They are not to be installed as they are in the picture. I just had to get them in place to take some preliminary measurements. These main caps are designed to be used with ARP main stud kit 146-5401 and the OE main girdle, without spacers to clear the rods. This means that they are .750" taller than the OE main caps. They are 2.700" in height and cut straight across. Our next step is to have them line bored and once we get the fully counterweighted, casting #3214723 crankshaft in place, we will determine if we can machine them down any shorter. Either way, oil pan clearance is not too far off with them as is. I will document any adjustments made along the way.

These caps are available from Billet Speedworks. They can also make stock height versions but I'd rather not run spacers under the girdle. They are machined from 1045 steel and are as strong as a two bolt main cap can get. Made in the USA in Barberton, OH.
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

Tucker Valve Seats to the rescue. This is for anyone looking for valve seats in the future.
These are true USA ductile iron valve seats that can accommodate 2.020" intake and 1.6020" exhaust valves. Tucker is one of the only valve seat manufacturers that can machine custom valve seats overnight for you. These seats increase the intake ID to 1.750" and 1.375" on the exhaust. 1.750" is nearly the exact height of the intake port after porting and 1.375" is nearly the exact diameter of the exhaust ports after porting. They have the same depth as stock so you don't have to grind half of the seat off to get it flush with the chamber.
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TJryder
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Re: 06 LJ Randy Rebuild

Post by TJryder »

Nice build. Looks like you are going to install all possible upgrades :D

Target HP?
°O|||||||O°
Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

TJryder wrote: June 11th, 2021, 10:18 pm Nice build. Looks like you are going to install all possible upgrades :D

Target HP?
Pretty much. Though the cylinder head work I think is necessary when increasing stroke/piston speed. I don't see how you can increase mass flow rate by installing larger valves on the stock seats. You would have to hog out the ID of the seats and then you significantly compromise the seat's durability.
I have the rough shapes cut for each port. My local machine shop will be taking care of the seats and the valve job. These TUPY heads have plenty of material throughout the chamber, ports and valve guide bosses. I don't see why they can't make as much power as the earlier heads. I have the exhaust ports opened up to 1.400" ID all the way through, that's perfect for a 1.375" ID venturi and a 1.600" valve.

This engine will eventually be turbocharged. It will start out as an NA motor with N20 on tap. We will be tuning it on a chassis dyno and we'll be shooting for anything over 300 WHP. Over the winter, I'm building a bolt on turbo kit with Forced Performance's FP7275 unit. That's why it's being overbuilt at the moment with billet main caps, main and head studs, 19cc piston dish, 350 LPH fuel pump, major axle/trans/transfer case upgrades, custom mid arm suspension and even frame strengthening. At that point we'll be looking for 600-700 WHP with 35" tires. BTW, the correct main studs for the billet main caps are ARP Part# AR4.750-1LB. You have to buy them individually. Today I'm cleaning up the junkyard HP30. I got lucky on this one as all of the factory mounts/spring buckets/tabs are in good shape. The ball joints were the only bitch. I need to upgrade my impact wrench.
Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

I got around to pulling the front axle and taking the crucial measurements to determine how bad the frame is bent. Turns out, the frame is not bent at all. The frame is dead straight. These Jeep frames are pretty strong. This thing took a pretty good shot head on. It looked way worse with the busted grill and bent up axle underneath it. I am going to Safe-T-Cap the bottom of the frame anyway. Plasma torch time this weekend.
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

Front axle is buttoned up. 4.88, TrueTrac and a little custom work. Was able to achieve a pretty much perfect pattern.
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

NP231 is done. This unit has everything you can get for an NP231; wide chain, 6 pinion planetary, 32 spline, 1350 output. I might polish it rather than paint it.
LJNP231.jpg
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I6FAN
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Vehicle Model: wrangler

Re: 06 LJ Randy Rebuild

Post by I6FAN »

Nice TC! Was this a kit, or did you piece it together yourself? I have a TC that got ruined by a bad/soggy tranny mount that allowed the transfer case to settle down on the skid plate. After a period of this, it chaffed a hole in the bottom of the TC, and all of the lubricant drained out unnoticed. Either fix or replace, but I'd like to do the mods you've done to yours.

On the main caps, how much are those if you don't mind my asking? And, there is an ARP main stud that allows for the girdle install? I thought the OEM bolts were the only way to use the girdle.

Thanks, I'm watching your build (and repair)!
Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

For the transfer case; it's the Advance Adapters SYE https://www.advanceadapters.com/5144
Master rebuild kit from East Coast Gear Supply and a 1 1/4" chain, sprocket & 6 pinion planet from Ebay. That kit, at the time, looked like this
np231kit.JPG
I don't think it's available from the same seller but I'm sure you can find a similar kit. The 1350 rear flange and front yoke are provided by Tom Wood's Driveshaft. If you ever need a pinion yoke or output flange, call Tom Wood's shop. Their service and shipping is leagues beyond the other driveshaft shops.

For the main caps, its $600 for the front 6. $250 for the rear main. That's from Billet Speedworks.

We won't be running stock bolts of course. The ARP studs for these main caps are part # AR4.750-1LB.

ARP 4.750" 1/2" studs. You simply drill out the girdle for 1/2" fasteners, not a big deal. The only significant mod that will be required is the custom oil pan.
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I6FAN
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Re: 06 LJ Randy Rebuild

Post by I6FAN »

Thanks for the reply! Gotcha on the girdle. I think Moroso or Milodon make an oil pan for the Jeep I6. Not sure if that would work or is still available(?).
Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

I6FAN wrote: March 22nd, 2022, 12:41 pm I think Moroso or Milodon make an oil pan for the Jeep I6. Not sure if that would work or is still available(?).
The issue is that the billet main caps are .750" taller than the stock main caps. They are taller so we won't have to use spacers with the studs and girdle to clear the rotating assembly. I know some folks just take a hammer to their oil pan but I'm going to cut out the sections that contact and weld in some 16 or 14 gauge.
Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

Cylinder head is all but cc'd, final assembled and cleaned. New Tucker valve seats are in...

Stock Jeep Intake Seat - ID 1.675 x 2.00 x .21875 New Intake Seats - ID 1.750 x 2.0365 x .21875
Stock Jeep Exhaust Seat - ID 1.285 x 1.5642 x .1875 New Exhaust Seats - ID 1.375 x 1.625 x .21875

Once the seats are in, machined and blended into the bowl, they provide a pretty much perfect throat to valve OD percentage. The valves are 2.00" OD Intake and 1.600" Exhaust. 88-93% is the range you'll hear which is an acceptable throat percentage. So with minimal blending the Tucker seats create a good throat percentage of 87.5% Intake and 86% Exhaust. Simple blending with a cartridge roll and some abrasive buffs can take the throats to 90% but I went with and intake throat ID of 1.76" which is 88% and a Exhaust throat of 1.405", also 88%.

Interesting that the stock (valves and seats) intake throat percentage is also 88% yet 85% on the exhaust. This suits the TUPY head pretty well with the small exhaust port cross section. This is where the heads with 2"/1.60" valves on stock seats meet their limitation. You have to remove so much material to get an acceptable throat percentage. This creates very weak valve seats that get way too hot. They start out at 84% intake and 80% exhaust. Also, the combustion chambers require a good amount of work to limit chamber shrouding. The common equation is 20% of the valves OD clearance at 25% of the valves OD of lift. So I need .400" intake clearance and .320" exhaust. I will have to revisit this once the block machining is finished. Right now I have .300" on both intake and exhaust and I've removed a good amount of material.
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Randy Bobandi
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Re: 06 LJ Randy Rebuild

Post by Randy Bobandi »

I've been working on oil pans and valve covers.

I cut the entire top off of the steel late model valve cover and welded in a 2.375"x23.5" piece of 13 ga. I'll be welding the baffle back in along with 3 bungs. -16 ORB for the oil fill, -10 ORB for the breather and 1/8 NPT for a crankcase pressure sensor.

I had to test fit the oil pan with the taller main caps. I welded in a mixture of 13 ga. and 16 ga. to clear the caps. I also added baffling as this was not a baffled oil pan. The Isihara Johnson crank scraper is 16 ga. and it was welded to the sealing surface. This required adding 16 ga. to the front timing cover sealing surface area as well as the rear main area. This way I can install and remove the pan just like any other pan and it will be compatible with one piece pan gasket. It won't have an uneven sealing surface that would require RTV rather than a gasket, like most folks resort to with this style of crank scraper. I will wait to weld in the turbo oil drain bung and I also plan on adding 3 1/8 NPT provisions to the pan for piston cooling oil jets. They will be deflected flat spray nozzles that will be fed from a NPT/AN manifold with a 1/4 NPT solenoid valve. Press a button and the jets spray oil on the rods, pistons and cylinders.
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