Does doing a 4.0 to V-8 conversion have any major downfalls or advantages? - JeepForum.com
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Go Back JeepForum.com > General Technical Discussions > Engines & Drivetrain > Does doing a 4.0 to V-8 conversion have any major downfalls or advantages?

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Unread 02-05-2014, 12:10 PM   #1
dazmanion
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Does doing a 4.0 to V-8 conversion have any major downfalls or advantages?

Been thinking about doing this. Does anybody have any thoughts?

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Unread 02-05-2014, 12:15 PM   #2
kaitlynsdad
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better have some deep pockets for the swap to do it right and for the parts youll break later
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Unread 02-05-2014, 01:17 PM   #3
mike_dippert
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I have a lot of thoughts, but you're going to need to be a lot more specific.

You basically just said "I'm thinking about moving, what do you think?"
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Unread 02-05-2014, 01:42 PM   #4
uberxj92
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Lots of work. Lots of money. Lots of fuel.
There's the added weight, custom Fab work in frame stiffening, Fab work in mounts, wiring, accessories, cooling. Whew. I've done it. It was a ton of fun on the strip. But I have access to a machine shop and still spent over $2500. In parts. Over cost of the motor. Mine was in an xj. Have fun.
What year model is the rig? What engine are you planning? What tranny and Drivetrain are you planning?
IMO you can stroke a 4.0 and get as good performance out if it as most stock 350's.
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Unread 02-05-2014, 02:05 PM   #5
vadslram
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Looking back past my YJ, 304 V8s were fairly common in CJs.
the conversion isn't any more than stroking and adding FI to a 4.2.

For me the only real downside of putting big cans in a wrangler is the weight addition. For an XJ it's not as bad, the longer wheelbase will balance out easier.
It will have more power and make it easier to break stuff but the engine won't break anything..you will using the engine.

Uber
Stock engines of the same year the 4.0 I6, 185 hp and stock 4.7, 230 hp.
Both have been in Jeeps. To get 230hp out of an I6 you need to put quite a few dollars into it. Put the same money into the 4.7 and you would be making close to 300 hp (guesstimate based on my work on Mustangs, I've never hopped a Jeep V8)
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Unread 02-05-2014, 02:33 PM   #6
uberxj92
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The Chrysler pos 4.7 isn't worth putting money into. Its a valve eater. The ford motor is a good engine except the plastic intake which is easily remedied.
I was just thinking that stroking the stock engine us easier because if the Fab work and other costs and work.
I still love my v8's. Got a 426 hemi built that I need a vehicle for. Nothing really beats American muscle. The sound the feel.
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Unread 02-05-2014, 04:41 PM   #7
jeepdaddy2000
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Quote:
Originally Posted by dazmanion View Post
Been thinking about doing this. Does anybody have any thoughts?
I always have two questions for this inquiry.....

1) What are you doing with your Jeep (IE what is wrong with the existing engine).

2) What are working on? To include any modifications, tire sizes, gearing, etc....
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Unread 02-05-2014, 07:12 PM   #8
Demp
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Biggest downfall is upfront cost and potential to consume more fuel. Parts and Labor can be very expensive to do any engine swap, much less one that doesn't fit the factory mounts and control systems.
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Unread 02-17-2014, 04:33 PM   #9
durrettcustoms
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If you are going to do this swap you should look at a LS engine. 5.3L LS engines can be had dirt cheap and places like Advance Adapters make all of the adapters needed to bolt it to your tranny or bolt a GM tranny to your transfercase.

I'm working on a JKU to 5.3 LS with 4L60e trans swap right now. Adapters are around $600, controller another $1500. Everything else is time and labor. The JKs can use the factory radiator and fuel system so Im not sure if that stuff would need to be swapped on yours.

On the JK fuel economy should go from 15 to near 20 and Horsepower will go from 210 to 350+.
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Unread 02-17-2014, 10:19 PM   #10
Wheelin98TJ
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Quote:
Originally Posted by uberxj92 View Post
Lots of work. Lots of money. Lots of fuel.
There's the added weight, custom Fab work in frame stiffening, Fab work in mounts, wiring, accessories, cooling. Whew. I've done it. It was a ton of fun on the strip. But I have access to a machine shop and still spent over $2500. In parts. Over cost of the motor. Mine was in an xj. Have fun.
What year model is the rig? What engine are you planning? What tranny and Drivetrain are you planning?
IMO you can stroke a 4.0 and get as good performance out if it as most stock 350's.
Added weight is not always the case. The 4.0 I6 is a heavy pig. Weighs more than a 4.7L V8. Also weighs more than a Gen III Chevy V8.

Frame stiffening is not always necessary either.

I'd like to know the answers to your questions too. What kind of Jeep are we talking about to start? Very little info here to go off of.
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Unread 05-06-2014, 02:24 AM   #11
theGiantPanda
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wow.. interesting posts on both sides of the fence...:-)
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Hospital? What, are you suffering from Overextended Jeepaphelia or something? :)
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6.1 HEMI Ultimate LJ Rubicon Build http://www.jeepforum.com/forum/f9/6-...ayhem-1013800/
2.5 to 4.0L swap and build up http://www.jeepforum.com/forum/f9/he.../#post14946167
4.0 to 2008 5.3L GM LS in the Taco'd TJ [frame off build].....http://www.jeepforum.com/forum/f9/5-...28/?highlight=
My new DD Build, lift, 4.0 motor swap, done in 6 days?....http://www.jeepforum.com/forum/f22/6.../#post15716292

the new shop... http://redrockwiring.com/ conversion, parts and wiring systems
shop email.... info@redrockindustries.net
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Unread 05-06-2014, 05:24 AM   #12
GPXJ90
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I know a big down fall alot of jeeps on jeep forum talk about electrical problems heck all my problems with my own 1990 jeep XJ 2.5l what i am saying is you gotta replace alot of the electronics such as the ecm which is programed to run a 4.0 and many of your other electrical sensors such as throttle position sensors will tell the wrong computer for the v8 and youll be underfueled might not even run without spitting and sputtering keep that in mind good luck
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Unread 05-06-2014, 07:45 AM   #13
mike_dippert
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OP must not be thinking about it too hard, 3 months and he hasn't been back.
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Quote:
Originally Posted by HurricaneRZA View Post
JF taught me that the 2.5L, Ax-5 and D35 together are so powerful that angels weep when I shift into 4LO.
Quote:
Originally Posted by mrblaine View Post
The only thing a bicycle inner tube is good for, is tying a knot in the end of when you run out of condoms.
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Unread 05-06-2014, 11:58 PM   #14
theGiantPanda
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must have gotten real...real quick LOL another dream fizzled out it seems
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Quote:
Originally Posted by CCJ View Post
Jesus. This is what heaven on 4 wheels looks like.
Quote:
Originally Posted by Deacon View Post
Hospital? What, are you suffering from Overextended Jeepaphelia or something? :)
I've never been poor, only broke. Poor is a state of mind. Broke is a condition brought on by Jeep ownership and a heavy right foot.

2006 Unlimited Redicon Panda Edition
RRI Long Arm...14" Fox CO's Front and Rear...D60 KP Front and D60 FF Rear... 5.38s spooled...40" Maxxis Trepadors...
6.1 HEMI...Atlas 5.1

5.7 HEMI 400 hp TJ Build http://www.jeepforum.com/forum/f9/ye...17/?highlight=
6.1 HEMI Ultimate LJ Rubicon Build http://www.jeepforum.com/forum/f9/6-...ayhem-1013800/
2.5 to 4.0L swap and build up http://www.jeepforum.com/forum/f9/he.../#post14946167
4.0 to 2008 5.3L GM LS in the Taco'd TJ [frame off build].....http://www.jeepforum.com/forum/f9/5-...28/?highlight=
My new DD Build, lift, 4.0 motor swap, done in 6 days?....http://www.jeepforum.com/forum/f22/6.../#post15716292

the new shop... http://redrockwiring.com/ conversion, parts and wiring systems
shop email.... info@redrockindustries.net
LIKE US on facebook..... https://www.facebook.com/redrockindustriesinc adding more daily
redrockindustries.net
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