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Another SRT Swap (This one's real)

74K views 192 replies 28 participants last post by  XK0611 
#1 · (Edited)
Hello everybody!

I've been eyeballing this forum for a few years now but haven't signed up until just a couple days ago, because now i have a project!

I own the 2008 Jeep Commander Sport 4.7. It will soon be a 6.1. About a week ago I ordered a remanufactured long block from 3rd Strike Performance, and a number of other parts. I still have more to get but I could use some help. The most I've done on a vehicle was a rack and pinion replacement on a foxbody mustang, I've never taken on a task quite like this one, but I'm mechanically inclined, and I'm a nuclear mechanic in the Navy, so I'm confident I can get it done.

Here are the parts I know I need and/or I'm using:
Long Block (ordered)
Valve Covers
Coilover Covers (ordered)
Fuel Injectors (ordered)
Alternator 5.7/6.1 (ordered)
Compressor 5.7/6.1 (ordered)
Power Steering Pump
ECU 5.7 Commander (ordered)
Wiring Harness 6.1 GC (ordered)
Intake Manifold (ordered)
Exhaust Header (ordered)
Throttle Body
Fuel Rails
Oil Pan 5.7 Commander (ordered)

I've got a little over $2k left in my current budget until I have to start going from paycheck to paycheck. If I'm missing anything or anyone has any suggestions, it would be greatly appreciated. I intend on documenting as much as I can and updating this thread as much as I can with lots of pictures when I start this undertaking. I am serious about this project, it's not going to be a dud where I just say "HAHA! I wanna do a SRT swap, into mah Mander!" and then not follow through. I've wanted to do this for a WHILE, and I can finally afford it. I have read the other SRT swap threads by Saturate and whatnot, and while helpful, didn't have everything I needed. I'd like to know more from a technical standpoint.

Thank you all in advance!
 
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#2 ·
Holy smokes! Ballsy move tackling this project. Hope you keep us updated. Good luck.
 
#4 ·
But does the 4.7L transmission bolt up to the 6.1L engine? I don't know, I suspect yes, I think they kept the same bellhousing pattern for all the V8's.


As long as they've been doing engine swaps, people have been using transmissions rated for the less powerful engine. Usually with an Automatic Trans, the damage that comes from using more power than its rated for is that the trans wears out much faster.


Definitely add more cooling for the trans.


I'd think the biggest problem may be, can the front drivetrain (driveshafts and axle/diff) handle the power of a 6.1L?


The only option I see, if you want it to bullet proof, is transfer the entire drivetrain of an SRT Grand Cherokee. It had a different XFR case and driveshaft's to handle the 6.1L power, as well as the trans.


The biggest problem that you may encounter is incompatible software and communications between the different control modules for Engine, Trans, Drivetrain and Body.
 
#6 ·
That simplifies the swap though, you just have to worry about the driveshaft to the rear. That might be one thing to consider, getting a stronger custom rear driveshaft.


Most auto trans can easily handle more power than they are rated for, but it gets them hot and wears them much more quickly. If the stock 545RFE is factory rated for 450 ft-lbs or HP, what ever, that rating likely means it can handle that power and last 100k miles or more. You increase the power 25% over the factory rating, it might NOT snap anything in the trans, but it ain't going to last 100k + miles. Adding more cooling will reduce the extra heat from the extra power that will shorten the life of the trans as well. Also, fluid and filter changes on the trans more often will help it live longer under the higher stress.


Since the Commander Stock recommends only Synthetic Axle fluid and changing it every 15k miles for severe usage, but lasts the life of the vehicle for normal usage, I'd consider rear axle fluid changes often, and using the best Synthetic Fluid, like AMSOIL in the right viscosity. The pressure on the ring & pinion must be pretty high if they recommend changes that often for severe conditions, and adding a more powerful motor is just going to increase the pressure on the gears.
 
#8 ·
This is good info, thank you. Hadn't thought of all this nor did I know about these kinds of things. I already have a transmission cooler, but I guess I could upgrade soon. Just got the 5.7 ECU yesterday. got it for a steal at $65 off car-part. Ordered used fuel injectors (for now) off a website for $120 the other day. I'll upgrade when my budget builds back up. I know I've got to finish the project at hand first, but next year I'd like to supercharge this thing!
 
#7 ·
Oh, and yes, I've seen that strategy about re-using the PCM for the old engine on the new bigger engine, if they are compatible, to keep the communications working properly. Especially if use a tuner program to alter the tables in the stock PCM to adapt it better to the new motor it should work out better than trying to splice a PCM for another vehicle into the data network, you can get yourself into a corner where only a Chrysler lab could develop a fix to get you out of.
 
#9 ·
Does anyone know if the odometer info is stored on the gage cluster or the ECU? I hadn't thought about it until a couple days ago, and I hadn't looked up the applicable laws in WA yet about any possible issues.
 
#10 ·
Hmmm, the PCM does store the mileage in its non-volatile memory. But it varies from vehicle to vehicle, many the mileage in the PCM is just for maintenance and calibration reference. I have swapped out PCM's in a '99 Neon and it did NOT change the mileage in the odometer, but it had a electro/mechanical driven odometer. In most cases its stored in the instrument cluster, but it is possible it could be read from the PCM.


The Dealer has the tools to program the mileage into the PCM, I'm sure they can do the same Instrument Cluster as well. You're going to have to take it to the Dealer or someone with the tools to program those things anyway, so I wouldn't worry about it.


The PCM has an anti-theft measure where it will refuse to start unless the VIN# programmed into it matches the VIN# on other control modules. So, if you do this work yourself, you're going to have to either get it towed to the dealer, or try to drive on the 4.7L PCM controlling the 6.1L hemi motor to the dealer. Just tell them to do the mileage in the PCM and odometer also.


Look at the title transfer section of your title or registration, it usually will talk about the State Law about Odometers. Every state I have registered vehicles, (never WA though) it talks about the penalty of perjury to misrepresent the actual mileage of the vehicle, and an check box option saying the odometer is accurate or is inaccurate.


I take that to mean, its NOT illegal to have the wrong mileage on the odometer of "your" car, its just illegal to state the mileage on the odometer is accurate when in reality it is NOT.
 
#11 ·
Hmmm, or should I say, in most states its illegal to intentionally alter your odometer; it is NOT illegal to have an inaccurate odometer because of an innocent reason, other than intentionally altering the odometer to misrepresent the mileage of the vehicle, but its still illegal to NOT disclose that the inaccuracy of the odometer during the sale of a vehicle.
 
#12 ·
So I contacted my local dealer and they said the Odometer reading IS stored on the ECU, they're gonna get back to me on what I can do. we briefly discussed bringing in my commander in WITH the installed ECU, and they can flash the new 5.7 ECU with my accurate milage and just swap the ECU's then I'll tow the jeep back if I need to. BUT! I'll have accurate mileage on the Jeep.
:grin2:
 
#13 ·
Something new I thought of. Spark plug firing order. Would it be the same as my 4.7? what about the coilpacks and wires? should I replace those as well?

And just an update cause it's been a few weeks... I was told a turn around time of 2-3 weeks to receive the long block, aaaaand I still haven't gotten it. I ordered the Mopar cold air intake for the grand cherokee SRT8 though, I hope it fits right! But I will be ON IT when the block gets here. thanks guys.
 
#15 ·
Something new I thought of. Spark plug firing order. Would it be the same as my 4.7? what about the coilpacks and wires? should I replace those as well?
I thought you were going to use a 5.7L PCM (ECU)?


Have you checked to find if the wire harness is the same between the 4.7L and the 5.7L, I would think they are different and if so, you're going to have to swap out the wire harness with the PCM and Engine.


If the wire harness is the same between the two engines, and the firing order is the same for the SRT motor, then I think you would NOT have a problem. Even if firing order was different between the 5.7L and 4.7L engines, but the wire harness's are the same, then that means the wire harness just completes the circuit between the PCM and coil, thus the PCM will fire it in the correct order.


Thing to worry about is if they changed the firing order between the 5.7L and 6.1L (which I doubt) but if they did, your 5.7L PCM won't work, unless you start swapping pins around on the connectors to the PCM.


I would keep the coils intended for the engine in the vehicle, they are designed to produce the spark strength the engine needs. If you use different coils, they may NOT make the necessary spark strength and thus you might have problems.


I believe the PCM fires the coils by grounding the primary when its needed. And it probably has a constant 12+VDC applied to the primary of the coil. I could be wrong on this, confusing it with the fuel injectors. So, a different coil than the PCM was designed to use, probably won't be a problem.


Of course, I think that grounding is done with solid state driver circuits and they do have a limit in the amount of current they can carry, so although unlikely, its possible a hotter coil might burn out the PCM (in at least the driver for the coil). But that's the risk you take doing a hi-tech engine swap like this.
 
#19 ·
Alrighty, well I planned on getting the 6.1 Harness, from what I hear, the 5.7 harness is only slightly different from it, and I didn't want to dead with it. I had a 6.1 harness lined up, but the guy sold it before I tried to buy it from him. and I don't know the difference in harnesses between years for the 6.1 GC. I'm trying to research that now, but I'm not having much luck. I can get new ignition coils, that's fine, and the money isn't an issue. I accounted for possibly spending more than I anticipated, as anyone should with ANY engine swap.
 
#21 ·
So, as of the middle of last week, I called my guy and my engine should ship by the end of the week, worst case scenario, Monday. it's Saturday night and I've got no word. If it's not shipped by the end of next week, I'm getting a refund... one way or another.


Meanwhile...

Enigine's out!
 

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#23 ·
No problem. couple more updates:

Engines almost finished and will soon be on its way. Apparently they had to special order rods...

I also may have found a buyer for the old engine, who'll give me more than if I return for the core and heads, so I'll have a little extra breathing room for getting this thing together.
 
#24 ·
Alright, sorry guys, It's been a while. I got my engine yesterday. It came just a little less complete than I expected, and they stood it up on its side so I had a hell of a time getting it off my Uhaul, but it's here. I'll post pictures soon, But I've got an invasive doctor's appointment today., So I'm gonna be out of it all day today.
 
#26 · (Edited)
Alright, I didn't get much done today as I have to run errands, so I had until 11, and most of my morning consisted of running back and forth to Lowes for bolts to lift and put this bad boy on a stand. I ended up having to settle with 3 bolts on the stand, I couldn't get the 4th on.

I tried seeing if my 4.7 pickup and oil pan would fit, it doesn't. So I need to hunt down a 5.7/6.1 oil pan and pickup tube.

AND BOLTS! how the hell do I find bolts for accessories and some components. I've gone through the MOPAR parts drawings and found some for things like valve covers, heads, and internal engine bits, but none for things like, let's say alternator mounting bolts, etc.

My engine was also supposed to come with a harmonic balancer, water pump, and timing cover... It didn't. So I have to contact 3rd strike and ask WTF. he's also holding my intake manifold hostage until I return the core, even though I already paid a core deposit. I RECOMMEND NOT EVER GOING THROUGH 3RD STRIKE PERFORMANCE. I've had tons of problems with them since day one that I haven't even brought up.

Hopefully tomorrow I can get more done.


Update: Ordered the oil pan and pickup tube
 

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#27 · (Edited)
Sorry it's been a while, I had to file a dispute with paypal on my engine purchase for a partial refund, and things haven't been going well overall here. But, i could really use a little help. I installed the oil pump, however, I couldn't find ANYTHING, that mention an O-ring/gasket in between the pump and the block, only between the pump and the pickup tube. not even my service manual mentioned anything. I just wanted to make sure before I let it go. It's currently solid metal to metal contact with the outside of the joint being inside the timing cover (It's the joint circled in red). Anyone replace their oil pump notice or know anything?

Thanks in advance guys
 

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#28 ·
Small update. Got my partial refund, returned my core to UPS, Got my oil pan and pickup tube and many bolts, and painted the heads and oil pan purple. I need to clean up and press the new seal in the timing cover, then I can get the engine much more complete looking. Will include pics when I get home from work.
 
#31 · (Edited)
woo, forgot I said I was going to include pics. lol

Well, I got more complete anyway I'll just include them now.

I'm starting to get the hang of getting all my bolts, I've ran to the dealership a few times now after special ordering many, but still many more to order. I'm also thinking I'm gonna need a 5.7 hemi radiator at least, the hoses come off the same side of the engine, which was not the case for my 4.7, and then there are some other lines that are supposed to come off the water pump then go under the intake manifold, I believe they are for the heater core? if anyone can confirm? either way, I'm thinking I'm gonna just go with braided hose to solve that issue.

Also, there's an extra stud on one of my main caps, that "doesn't work with my application", so Promar engines is sending me another bolt to replace that stud. until then, I cannot fit the oil pan gasket, therefore the oil pan itself will not go on, until that is replaced.

But onto the good stuff.
Pictures!
 

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#34 ·
hey quick question guys, I don't know exactly how different the 5.7 is to the 6.1, or if it even matters, but I'm gonna need to install my crank hub/harmonic balancer soon, and I don't know if there's a specific clock to it that it needs to be at. everytime I try to look it up on google (universally, no one works on hemis), they just say make sure the keyed slot lines up, because that's what holds it in position, however the 6.1 hemi isn't keyed, it's a pressed fit. and I'm pretty sure the 5.7 is the same way.
 
#35 ·
small update, got my replacement main cap bolt, had a time getting the other stud out. I backed off on the other side, inserted the new bolt and torqued them both to 20# +90° in increments on each side, hope i did it right, but anyway...

The oil pan needed 16 bolts, I had 15 from my old engine, so I ordered 1 to compare and finish installing it, turns out, the ones I need are longer. Mine thread enough to hold the oil pan on, but I'll just replace them later and then torque them. Got my crank hub/harmonic balancer bolt, It's a big SOB. but I still need the crank hub... so it's just sitting there.
 

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#37 ·
I really wasn't sure if it would be able to me seen or not, plus, I might not be doing coilover covers for a while. as for the color purple, I intend on getting the commander painted sometime after the project's done. 2-tone, satin black on top, satin silver on bottom (similar to the current factory shade silver, just satin). It'll have purple accents here and there, brake calipers, badging, under hood bits, etc.

I want to take a set of grand cherokee srt badges and do them up on the commander, but I found a website that can do custom chrome/billet badges that can match factory if you want, but I'd replace red coloring with purple. So it'll have very slight purple, and not excessive amounts of it, on the jeep.

I've got some satin black srt replica rims on my mind i found on CARiD I want too.
 
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