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2.5 to 4.8 swap

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56K views 174 replies 42 participants last post by  Green LJRub  
#1 ·
Ok I am looking at swapping out the 2.5 in my 1997 tj. I could explain why but its long torturous road. :nonono:

I have been looking for a donor jeep with a 4.0 but in the back of my mind was this voice that said "if I was going to all that trouble why not bump up the power, and there are more parts available for the 5.3 locally ;)"

I have found a 2005 5.3 Z71 auto I can get all the parts I need for $1,500.00.

The question is will the transfer case work out ok.?
(Using it will save a $500.00 adapter and my 231 is in need of rebuilding.)

I know the drive shafts will have to be redone.

Ideas? or tips from someone that has done this conversion?
I have to tell the salvage guy somthing by monday


Thanks
Lowell
 
#4 ·
Its gonna be a lot of work and a lot of money for that extra 50hp. The only REAL difference I've noticed between the 2.5 and the 4.0 is when it comes to towing. I can't speak for the 5.3, but it seems a little excessive unless you plan on entering competitions. That being said, if you have the time and money, go for it! Sounds like a fun project!
 
#5 ·
I went back and forth between the gm, ford and dodge engines when I did mine. The magnum v8 is half the price to swap in and also half the work. The tq numbers are about the same as the 5.3 as well. The 5.9 puts out 245 hp and 335 tq. The factory gages all work right with the magnum and you don't have to worry about how to hook up the drive by wire and electronic gas pedal. All you will need to reuse your 231 is a new input shaft if you have a stick auto is already 23 spline! The factory auto shifter works fine with the 44re or 46re auto unlike the other makes.
 
#9 ·
Mine is a 5 speed. I didnt think about the throttle. So I should get that assembly also ?.

I agree about the magnum but this is just the best deal I have found sofar. I asked about a magnum and I was getting prices double or more of the 5.3

Here is some info I found. Im not sure how accurate it is.
Jeep 4.0 265 hp and 290 lb.-ft of torque,

1999-2007 5.3 are rated at 285-295 hp and 325-335 ft·lb torque. ...
2005-2007 extended cab 4WD pickup trucks which have 310 hp
The donor is the 4wd z71 extended cab :thumb:
 
#19 ·
Yes it will bolt up, but you will need a 23 spline input shaft if you don't already have an automatic in your jeep. Also the hemi is drive by wire , so you need the pedal assembly and the pcm uses a different bus , so the gages won't read right either without doing some work. like a dash and harness out of an 03 or newer tj, or you may be able to have hotwires reflash it for you to work with your display.
 
#20 ·
rda616 said:
Yes it will bolt up, but you will need a 23 spline input shaft if you don't already have an automatic in your jeep. Also the hemi is drive by wire so you need the pedal assembly and the pcm uses a different bus so the gages won't read right either without doing some work. like a dash and harness out of an 03 or newer tj, or you may be able to have hotwires reflash it for you to work with your display.
Click to expand...
Ok, I have read that the exhast manafolds need to be swaped out for more clearance. True?

On the spline change, cost?

Thanks
 
#23 ·
v8 on the way for Katrina

After alot of research and ebay searching I have a v8 purchased. I am to go get it monday. I was going to wait till I got it home to post but I couldn't. lol Its a 4.8 chevy out of a pkup with 12k miles. I have talked to Advanced A about converting the trans to fit the 231 and I have a quote from a local trans shop to swap the tail shaft. Yea I know thread says 5.3 but it came down to condition, price, and distance. I could have purchased a 5.3 with the same money but it was a 2006 with 78k. One of my goals is as high mpg, and im told the 4.8 would be a little better on gas. Its rated at 295hp and the 5.3 at 315. IDK but another source saaid the 4.8 may have a little more room at the sides.

I looking forward to the build :popcorn:but that means Im going to miss afternoon rides in the Katrina Jeep .

Because of this jeeps past my buds named it Katrina. It seems in its past it had spent alot of time underwater . LOl

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http://www.wranglerforum.com/attachment.php?attachmentid=62574&stc=1&d=1313241626
 

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#24 ·
I don't want to bring you down, but the 4.8 is exactly the same externally as the 5.3 (and 5.7, and 6.0, and 6.2... all 98-current GM V-8s), so no more room. It will be a huge upgrade in power for you!

When I picked up my 97, an LS engine swap was my plan. I since went to an 03 Rubicon. The V-8 swap is still constantly on my mind.
 
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#25 ·
subtlez28 said:
I don't want to bring you down, but the 4.8 is exactly the same externally as the 5.3 (and 5.7, and 6.0, and 6.2... all 98-current GM V-8s), so no more room. It will be a huge upgrade in power for you!

When I picked up my 97, an LS engine swap was my plan. I since went to an 03 Rubicon. The V-8 swap is still constantly on my mind.
Click to expand...
Yea I kinda thought that too as , dont they use the same heads?

Im thinking maybe what my source meant was the exhast manifolds IDK. Im prob going to use headers anyway. :) I have read on here that the rear dumps will not work. IDk but we will try stock first.
 
#30 ·
Lowell,

3 to 6 months is nothing to sit without turning over if inside a garage. Not much if any fuel will be sitting in those small fuel rails and that short line, not like the carb days of the past. That 4.8 is very popular in express cargo vans and half ton Chevy WTs so with the jeep going 1500 lbs less your TJ will fly. Let me know if you need any help I've done sb swaps in many different cars - even a 1966 Sunbeam Alpine!
 
#31 ·
Thanks, I'm sure I will hit several walls and will need all the help i can get.

Right now I am searching for a wiring diagram for a 2008 engine. I have found some for 07 and down, but not 08. Mine does not have the Throttle petal modual controler. It just plugs from the petal to the ..IDK.. . I know I could send the harness off but I dont really want to lol. Not if I can figure it out :D
 
#38 ·
Just starting to do the 4.8 into the TJ last night.

I have lots of question as Im just starting.
1. Power Steering lines, Anyone have a supplier info if there is a off shelf soluton to use the GM pump with the jeep steering box, or am I going to have to fabricate a line?
2. Exhaust Manifolds, It looks like the oem truck ones are not going to work. Anyone have a link to center dump type or other sujestions?

3. Fuel pump, looks like going to use Walbro 255 LPH Fuel Pump in tank pump. The question is does the 2008 4.8 have a fuel press regulator on the rail or in the tank?

4. Wiring , going to send it off to get it mod to four wire, but going to send the under hood GM fuse box also, and that may make for a more stock look. The same co can flash the vats also.

5. Advanced adapters for the trans adap and the motor mounts.

6. Rad from AA

7. Not sure route to go on gauges yet. I would like to try the GM cluster, but Im told thats a big PIA. SO I guess Im going to do the dual jeep and gm ecu idea for now

8. The vapor line from the tank to the intake. The oem gm one is about a 3/8 line the jeep tj had one also but its a 1/4 line. Ideas? Hook the 3/8 to the 1/4, cap it off, or run new line from engine to the fuel take 3/8? What about the carcoal can I dont have the gm one , get one, or delete that whole system? No smog checks were I live but I am wanting good MPG ( idk if vapor sys has anythig to do with MPG)

Thanks , any help appreciated
Lowell
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end of day one
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#40 ·
Sure, and thanks and hey I would have got more done but had two birthday parties to go to in the middle of the day, LOl

maybe Katrina can do a TB trip soon. Bring on the Gauntlet!:punk: I felt bad knocking her in the head so to speak. I took one last trip through the woods first LOL

:popcorn:Next step is get the AA stuff coming and take the trans to the shop for the change over. The mech stuff does not worry me, the elec and and emiisions do however.:confused:
 
#41 · (Edited)
Well I got the adapters ordered today, Im going to go ahead and tear into the 231 and have it ready to go when its shaft gets here.

Does anyone on here have an idea about headers for the v8? type , style, anything?

And the program guy is going to flach the ecu to remove vats , rear o2, egr valve, and said to cap the vapor line purge line to the tank. Is any of that going to help or hurt MPG? and is capping the tank purge line a good idea or bad? I have a pic here of the purge valve (if thats what its called lol)
Image



The line on the left goes into the intake, the line on the right I think when to a charcoal can and then to the top of gas tank. I think?
 
#44 ·
So far
A. 08 4.8 Chevy engine pull out complete with 4l60e $2,500.00 Could have found one for more than half that but I wanted one with low miles.

B. Adapter Trans to jeep 231 $525.00 Advanced Adapters, These guys are great, I call them a lot and ask a ton of questions. J

C. Engine mounts $157.00 advanced adapters

D. 4l60e output shaft conversion from 2x4 to 4x4 $32.00
Labor fee local transmission shop to swap output shaft $150.00, It can be done DIY but it didn’t what to.

E.Junk yard acquired auto shifter and center console $15.00

F.Master rebuild kit 231 transfer case from rompalicious.com cheaper and free shipping $109.00

To do
Fuel pump walbro swap in tank. $99.00 ( I may have to get a external pressure regulator as the IV chevy uses a in tank type and I will have to bypass the oem jeep as it is set at too low psi, IDK yet on that) Im told the 4.8 will run fine on 45 psi IDK I will try and see

Ecu flash and rewire harness $275.00

Radiator Advanced adapters $500.00 ( I may try the stock rad IDK yet will see)
New elec fan $250.00 Could also use a fan and shroud pulled from wreck $30
1.25 body lift $125.00
 
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