2003 Jeep Grand Cherokee Overland Build

[tjZ06]

I prob should explain the longblock you see *in* the Jeep in the engine mount pics is a bad 5.7 junkyard motor for mock-up. There are no additional inspection holes in the 5.7, so when the project is all done I might just refresh it to sell... or a future project? I sure would like to find a 2-door JK or JL with a bad motor to do a 5.7, junkyard tons and 42"s on... you know, just for those flooded mall parking lots and such.

-TJ

 

[Haggy]

This sounds hot!

 

[orange01z28]

I prob should explain the longblock you see *in* the Jeep in the engine mount pics is a bad 5.7 junkyard motor for mock-up. There are no additional inspection holes in the 5.7, so when the project is all done I might just refresh it to sell... or a future project? I sure would like to find a 2-door JK or JL with a bad motor to do a 5.7, junkyard tons and 42"s on... you know, just for those flooded mall parking lots and such.

-TJ

That 5.7 needs a Duster around it

 

[tjZ06]

This sounds hot!

It should be decently spicy... as mentioned I'm running the stock 6.1 SRT8 heads, cam (which is small for the 426 cubic inches this thing is, but should be a torque monster, it's 221/225, 0.571/0.551 on around a 117 which is actually bigger than Comp's first couple aftermarket cams for the 5.7s), exhaust manifolds and intake manifold. Stock these motors did 425 horsepower and 420 lbs-ft of torque if I recall at ~372 cubic inches. Just on the cubic inch change it should make ~485 hp, but it'll have a freer flowing exhaust than the factory stuff (factory manifolds, but less restriction after them) and a bit more compression it might make around 500 hp which is MORE than enough for this thing. What I'm more interested in is the torque.

That 5.7 needs a Duster around it

You're not wrong, but then again I'd maybe want to start with another 6.1, they're 4.055" x 3.58" bore and stroke, so they could be made into a real high-RPM screamer...

-TJ

 

[tjZ06]

The holiday stalled-out assembly, the pistons rods are all together but waiting on the proper ring compressor for the somewhat unusual bore (well, for us former LS-junkies):


We also threw the stock 6.1 cam in a cam-doctor, if you recall the internets says it should be 221/225 at 0.571/0.551 on around a 117 and what we found is:

The intake rocker ratio on the 6.1 is 1.6, and the exhaust is 1.66 so that works out to .5456 intake lift and 5478 exhaust lift, so overall 208/213 at 0.050 and .5456/.5478" pretty far off the 221/225 at 0.571/0.551 but I'm still leaning towards the stock cam. We threw data into engine analyzer starting with a base 5.7 data sheet, then modifying it for the 426cui bore/stroke and the 6.1 head flow numbers and cam.

6.1 head flow:


Theoretical numbers for the 426cui build (playing with intake center lines of 125, 121 and 117) vs. a stock 5.7:

As you can see it's really going to run out of breath up top with this cam, also this is figuring the 5.7's intake, TB and exhaust manifolds. We'll definitely be running the 6.1's intake and TB (but IIRC the 5.7s and 6.1s both have 80mm TBs).

Next up sticking with the 125 ICL but a theoretical 1-3/4" x 24" primary long tube header:

It pics up power everywhere, including torque the whole way across (teal vs. pink) with the headers.

Next up playing with some cams:

Of these I'd say the 223/228 114+0 would probably be the pic, still pretty mild and really not far at all off what we *thought* the 6.1 cam was. The TSP Stage 4 is very very close too and specs at 226/235 .582/.582 114+3 but that's starting to get pretty rowdy for a low-stall setup (remember, this is still going to be wheeled, not hot-rodded so the ATS billet converter is pretty low-stall).

Next, playing with some runner data. I can't find real solid numbers on the 5.7 intake vs. the 6.1, but it seems like they both have about a 12" runner so this is really just mental masturbation. The 6.1 is said to flow better though, and changing engine analyzer's intake CFM setting from 650 to 750 did pick up power across the board but it still really didn't want to run out much past 5800. Anyway, this is just messing with intake lengths, not the CFM:

If I was going to pick, I'd probably actually take the short 6" runner setup to mellow the torque out (yes, I said that, lol) but let it run some RPM. But like I said w/o going aftermarket (I'm already too much $ into this thing) and doing a single-plane style w/ a 4150 style throttle body I'm pretty much stuck w/ the 12" runners.

Playing with another cam option (you can kind of ignore the other plots):

This cam 226/232 116+5 would bring it daaaaam near the 500/550 numbers I was guessing at and shouldn't be too rowdy for my converter and use case... maybe.

-TJ

 

[tjZ06]

A little progress on the exhaust...



-TJ

 

[tjZ06]

Exhaust work continues. And I'm happy to report the exhaust guy is actually getting the exhaust pretty far back and out vs. just dumping under the rig at the end of the belly skid, as I expected (he asked me about the change, of course). Hopefully between this and the cats fumes on the trail getting back into the cab won't be too bad.











And yes, there is a X-pipe up above this cross-member:


-TJ

 

[tjZ06]

Finish welding starts tomorrow:



-TJ

 

[Trail_pilot]

Awesome! I still need to find time to route my exhaust it just does a turn down right after the cat lol.

 

[MrWilsonWJ]

Project looks awesome! Only question I have is how long before it gets 1 tons and 40's? Maybe a hybrid exo cage?

Jokes aside, when you had your trailer how much did it weigh and how did the 4.7 handle towing? I know you're running 35's with different gears and axles so it's kind of an apples to oranges comparison to my drivetrain but did the motor feel under powered or get hot? I recently had a kid and now the WJ is looking to be on the small side for camping since we also have a Great dane/Mastiff mix we take with us. I'm thinking I need to either upsize the camping/trail rig or build an off road trailer that can haul our gear into camp and allow us to keep using the WJ. If I built a trailer I would try to stay around 1200-1500 lbs. loaded, but I'm still running stock gears with 33's so a gear change might be needed. I've been holding off on a gear swap because I would much rather change out the axles than put money into the weak stockers. I think either way I go there will be some build projects in my future, I really like the WJ but they just aren't real spacious for family camping with a dog and a weekends worth of gear.

 

[tjZ06]

Awesome! I still need to find time to route my exhaust it just does a turn down right after the cat lol.

That's how it was when the 4.7 was still in it, which wasn't too bad. I honestly didn't get noticeable fumes in the cab, but still figured it'd be worth doing the longer exhaust w/ the 426cui Hemi.

Project looks awesome! Only question I have is how long before it gets 1 tons and 40's? Maybe a hybrid exo cage?

Jokes aside, when you had your trailer how much did it weigh and how did the 4.7 handle towing? I know you're running 35's with different gears and axles so it's kind of an apples to oranges comparison to my drivetrain but did the motor feel under powered or get hot? I recently had a kid and now the WJ is looking to be on the small side for camping since we also have a Great dane/Mastiff mix we take with us. I'm thinking I need to either upsize the camping/trail rig or build an off road trailer that can haul our gear into camp and allow us to keep using the WJ. If I built a trailer I would try to stay around 1200-1500 lbs. loaded, but I'm still running stock gears with 33's so a gear change might be needed. I've been holding off on a gear swap because I would much rather change out the axles than put money into the weak stockers. I think either way I go there will be some build projects in my future, I really like the WJ but they just aren't real spacious for family camping with a dog and a weekends worth of gear.

Haha, obviously there are times I think "why didn't I just do tons 'n forties?" I told myself I was building a "Rocklander" not a true rock crawler. This thing is clean and straight inside and out, it's far too nice for a crawler build. I wanted to stay with a reasonable tire size for the WJ that didn't mean hacking it to bits, and that really only necessitated (built) D44s. In theory 35"s and D44s will ride nicer too with way less un-sprung weight vs. tons and forties. But then, who the heck needs triple bypasses and hydraulic bumps on an Overlander? Obviously things snowballed a bit out of control, and if I'm being brutally honest I'm not exactly sure what the heck I built. ;)

Anyway, IIRC my trailer weighed around 2600-2700, in fact from earlier in the thread here are weights:



Let me explain them real quick, since it might be super obvious. The first one is mostly what you'd expect: trailer hitched up to Jeep, Jeep's front axle on "Steer" pad, Jeep's rear axle on "drive" pad, and trailer axle on "trailer" pad. The second one I unhitched, and the entire Jeep (both axles) are on the "steer" pad and the trailer axle AND tongue jack are on the "drive" pad. In other words, the 2nd one are the weights of the Jeep and trailer individually. This was with a full tank of fuel in the Jeep, full water/gear/food in the trailer ready to go on a trip.

With a fresh 4.7 HO (with '08 intake manifold swap and a more minimal exhaust that dumped just after the belly skid), 4.88 gears and the 35"s. In short, it wasn't great. The power was mostly okay, but the 4.7 likes to rev. But in high ambient temps I couldn't keep it cool if I was rev'in the heck out of it. And if you look back in the thread I have a big all-AL radiator, the highest flow dual e-fan/shroud I could find (arguably the stock hydraulic fan would have been better to keep) and all fresh cooling parts like water pump etc. I would pull over if it started to hit 220, and never saw more than 225. It cooled down nearly instantly when pulled over, which tends to tell me there was some aero problems going on, as an undersized cooling system/fans typically suffers when stopped and idling yet mine would pull the temps back down to the 180s (running a 180 t-stat) in a matter of minutes stopped but idling.

Still, I drove the setup w/ the trailer all the way from Northern CA to Idaho (North of the Boise area, Payette National Forest if you know it) in the peak of summer and made it work. I had to run w/ AC off a lot and pull over here and there, but that included big passes like going up and over Donner Summit on Highway 80 as well as long, steady but shallow grades like the vast open stretches between Winnemucca and the Oregon border. It's been a few years, but I think I could actually hold 40-50 over Donner Summit but I timed it to be doing it early-AM when it was cool out. And even 40 is still WAY faster than the big rigs (in sections they are literally doing 10-15) and faster than things like the RVs and trailers I've had in the past. If I could have kept it cool I think it would have been fine, but not ideal. FWIW I am trying to remember, but that trip up to Idaho I think I actually got 12 MPG towing which really surprised me with how much time I was at high throttle openings with high RPM.

So, all of that said, should you tow with yours? "Maybe." I suspect your WJ itself is nearly 1k lbs lighter than mine. As you see above mine weighs 5,360lbs whereas the internet tells me a stock '03 Overland was ~4k lbs. So even if yours weighs ~300lbs more than stock it's still 1k lbs less than mine. So if you keep your trailer to 1,800lbs you'd be another 1k lbs lighter there - meaning all-in-all you'd be 2k lbs lighter. If you stay on the 33"s but gear to where I am (4.88s) I bet it'd actually do pretty well overall.

-TJ

 

[MrWilsonWJ]

Thanks for the info. I figured heat would be a possible problem, I've done cooling system upgrades but like yours it would still come up a bit on long grades or going over a pass when loaded down with gear. I think if I were to go with 4.88s I could get away with towing but I think putting gears in those axles is just polishing a turd and I would end up wanting to do an axle swap and all that goes along with it. At this point I'm leaning towards building a full size rig for family camping/trails and keep the WJ for solo trips and more of a wheeler. I have a little time since this year I'll probably only make it out solo but I'm trying to get a game plan together so I can start shopping for parts or a vehicle. Been checking out some builds on first gen Sequoias and '00-'05 Tahoe/Yukons with SAS and thinking that might work well for a family rig. Also I got a wrecked 1 ton GMC sitting around with a good 70k mile LQ4/4L80E combo in it, maybe I can find something cool to drop that in. Anyway I'll stop hijacking your thread. Keep up the good work, that thing is gonna be a rowdy beast when it's done!

 

[tjZ06]

Thanks for the info. I figured heat would be a possible problem, I've done cooling system upgrades but like yours it would still come up a bit on long grades or going over a pass when loaded down with gear. I think if I were to go with 4.88s I could get away with towing but I think putting gears in those axles is just polishing a turd and I would end up wanting to do an axle swap and all that goes along with it. At this point I'm leaning towards building a full size rig for family camping/trails and keep the WJ for solo trips and more of a wheeler. I have a little time since this year I'll probably only make it out solo but I'm trying to get a game plan together so I can start shopping for parts or a vehicle. Been checking out some builds on first gen Sequoias and '00-'05 Tahoe/Yukons with SAS and thinking that might work well for a family rig. Also I got a wrecked 1 ton GMC sitting around with a good 70k mile LQ4/4L80E combo in it, maybe I can find something cool to drop that in. Anyway I'll stop hijacking your thread. Keep up the good work, that thing is gonna be a rowdy beast when it's done!

No worries on the hijack, I love kicking around build ideas. ;) As for building the D30/44A honestly I think if you're not going too wild it's not bad. Sticking with your 33"s, doing trusses (and sleeves/gussets up front) and good axle shafts and of course lockers there's no reason that combo shouldn't last. Now, that is a lot of $ into the 30/44A, but still a lot less than it ends up being to put anything else under it. If you score some JK Rubicon axles cheap, stick with the 4.10s (keep in mind not all JK Rubis had 4.10s, later auto JKRs went to 3.73s standard w/ 4.10s optional, my set for example were from a JKUR Recon and it had the 3.73s) and e-lockers so you're not putting any extra $ into them and do the minimal stuff to make them fit/work it might come out cheaper than building the 30/44A - but it probably depends on how much of the work you can/will do yourself.

As for SAS'ed full sizes, well I love my SAS'ed '11 Silverado 2500 so I can't say I don't suggest it. Or maybe get a square body Suburban and put that LQ4/4L80E into it!



As for my turd, here's the cam we landed on working with Modern Muscle:

(lift is 0.561 on both sides)

It shouldn't be too aggressive since it's feeding 426cui, but should have a little chop. Obviously I wanted to retain drivability, torque, and get something that works well w/ a stock stall converter.

-TJ

 

[tjZ06]

More exhaust progress:









-TJ

 

[AggieOE]

Oh I'm excited to see this!

 

[tjZ06]

Finally, some progress, nearly a complete short block:





-TJ

 

[tjZ06]

I'm enjoying the journey ! nice build

Thanks! It certainly has been a journey, lol.

-TJ

 

[tjZ06]

BTW, here are the cam specs:

 

[tjZ06]

OEM crank was undercut on the snout, aftermarket has a big radius:


Chamfered the crank gear for the timing set to ensure it fully seats and the alignment with the cam gear is spot-on:


-TJ

 

[tjZ06]

Engine bay cleanup/paint:



Engine detailing/paint:





-TJ