A Proper V8 Swap

SeaPro

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My 2005 v6 is perfect underneath, no rust. My 2003 v8 is mechanically perfect, but the rear end is shot where the sub frame bolts to the body. I was going to repair the frame mounts, but the deeper I look, the more rust I find. It's a major restoration project.

I don't need two cars. One is always stored.

The v8 is a perfect mechanical donor. I realize wiring from the firewall forward will be different. I realize the suspension is different, but plan on doing a complete upgrade anyway.

Are there engine mounts for a V8 on the v6 frame, or will it all need to be swapped? Will the v8 transmission bolt up where the v6 transmission was?

I plan on swapping the entire drive train and exhaust. I'm doing all of the work on my own, what are the nasties waiting for me?

I'm planning to remove the engines from the top, so I'll have to tear apart the majority of the front end.

Any insight? I wish restoring the v8 were possible, but it's quite far gone. This isn't one of those fishing threads of a hopeful 18 year old. Both cars are ready to go. I plan on stripping the v8 to its shell and towing it away, keeping anything of value.

Thank you,
Sean
 

Kumba

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Frame mounts should be the same. The real problem is going to be putting the V8 ECU into the V6 car. These things can be notorious for finicky electrical issues. SO probably going to have to swap quiet a few things over.
 

SeaPro

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I'm planning on doing a complete electrical swap. I realize it's going to be a pain, but it's looking easier than rebuilding a rusty car lol. I can't bare the thought of throwing away both of them, and buying new isn't practical right now. I work offshore and have lots and lots of free time when I'm home. I'm going away for 6 weeks, and plan to do it as soon as I'm back. Just trying to set up a game plan for what to expect when I start. Has this even been done? Most of the engine swap threads on here seem to be people dreaming big, using different engines... I mean, other than a bunch of work, this should be a pretty straight forward swap right?

Thanks.
 

Kumba

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Pretty much what you've already laid out. Do a complete drivetrain strip-down of both cars, transplant the V8 ECU/PCM/wiring-harness and relevant wiring to the good chassis, then transplant the engine/transmission/whatever else to the good chassis.

Not really much of a game plan other then just stripping everything down and keeping the better components.
 

joegr

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You'll have to swap the cluster and the keys too.
 

SeaPro

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Yeah I read about the cluster. Why is that? My v6 has the extra screen for the v8s message display ( it's non functional on the v6 ).

They appear to be identical, and I noticed the v8 spedometer lagging a while back in some heavy rain. It showed me doing 110 kph on the highway buy I was passing everyone. Opened up my GPS and I was doing nearly 140 lol. Could be the sensor in the transmission?

It's been fine since but that same day it was off even at low speeds, and very slow to increase/ decrease with actual speed changes.

I was hoping to keep the v6 cluster.

Thanks for the info! I'm going to fully document the transplant, lots of pics and maybe some video. Believe it or not but I'm actually excited to do it. The idea of basically rebuilding the v8 rust damage did not sit well with me.
 

joegr

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PATS is in the cluster. If you don't swap the PCM, Cluster, and keys all at the same time, PATS will prevent the engine from running (won't even allow an attempt to start it) until you "marry" the PCM, cluster, and keys together. Some scan tools can do this. If yours can, then no problem.

Speed data all comes from the ABS controller, which uses the wheel speed sensors. The sensors in the transmission are only used for shifting and diagnostics.
 

Kumba

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That makes me think that you'll have to reprogram the transplanted ECM/Cluster to accept the old keys for the chassis you are keeping. You could probably use a regular (non-pats) key to turn the ignition and then just hold the old transplanted ECM/Cluster key up against the dash to get it to recognize it. If this works then hopefully you can marry the PATS in the keys that fit the chassis to that ECM and make life easy.

IF not any real key shop should be able to reprogram the keys for you. They did that for an Escape I had when I lost the spare key. He didn't even charge me anything since I bought they key there but I imagine they wouldn't be ridiculous.

The whole reason for all this mess is so that you still only need 1 key that fits the whole car.
 

04_Sport_LS

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Frame mounts should be the same. The real problem is going to be putting the V8 ECU into the V6 car. These things can be notorious for finicky electrical issues. SO probably going to have to swap quiet a few things over.

Agreed. You are asking a car that was wired one way... to be something it is not. Kinda like asking your wife or girlfriend, (or both), to instantly change their personality.

Nuff said??? It can be done,,, but with alot of counseling, (for you).

I hope your laughing at this point!!!
 

04_Sport_LS

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You'll have to swap the cluster and the keys too.

Thread intrusion,,, but Joegr... do you know any way of making this work to the point of making a stock 3 valve 4.6,,, "play nice" in an LS. In Theory,,, I have most of the rest of the swap worked out, (sketch diagram in my mind).
 

04_Sport_LS

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I know... But IIRC it doesn't go into details on how to marry all of the wiring. I might be wrong though. It's been a while since I looked at it.
 

SeaPro

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I plan on swapping the ignition and using the original v8 keys. Really shouldn't be too hard to swap the wiring harness. *Famous last words* ...
 

04_Sport_LS

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Thanks for the info Cam. My main concern,,, is trying to figure out how to trick the LS into thinking it's a 2005 or so Mustang GT,,, without having major breakdowns, (both the LS and me :) ). But again,,, this project is at least a year away, (hopefully).

No superchargers or turbos... just NA,,, with different cams and TB change. Hoping for 350 horses in the end.
 

cammerfe

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:) Just as a 'by-the-way', 350 HP is VERY easy to get with a day's effort to install a bottle. And almost all of them come with a selection of jets so it's easy to get 400 or 450 or...

There was a study some years ago that said that going down the road on a 60 MPH steady-state basis takes a modern (post 1950) car about a 30-40 HP expenditure. You only need more on the odd occasion. I've commonly driven around for several months between bottle fill-ups. I own 5 bottles simply because I take them all to a week-end's racing. And I don't go through half of it, usually.

KS
 

04_Sport_LS

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I appreciate your efforts... but no bottle for me. I don't want a race horse... just a pony with a little extra pep than what the 3.9 offers. Keep the exterior stock,,, but when the Mustang GT pulls up next to me.... they will be in for a surprise.

Already done this...

On wet roads at a stoplight,,, I have the advantage. On dry roads,,, the Mustang has the advantage... because it can use all of its earlier torque curve.

Remember the old saying??? "There's no replacement for displacement." To me,,, the "cats a$$" ... is a 4.6 LS.
 

1LoudLS

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Remember the old saying??? "There's no replacement for displacement." To me,,, the "cats a$$" ... is a 4.6 LS.
well if that was the case, then there would be little beating a 7.0 LS7, but honestly, there IS a replacement, and it comes in the form of a snail and makes a lot of whooshing sounds. hell even the 2.3L ponys are making 427 Z06 power with a few mods. #EcoBeast
 

cammerfe

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There are versions of the AJ engine that make 500 HP and with much less effort than the swap, they can be run using the electronics that already exist in your LS.

KS
 

04_Sport_LS

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There are versions of the AJ engine that make 500 HP and with much less effort than the swap, they can be run using the electronics that already exist in your LS.

THAT... is something I might be interested in. Willing to learn,,, but the 4.6 seems more plentiful to adapt in a cheaper method, other than the electronics "playing nice". Part of my choice for a 4.6... comes down to eliminating some of the "quirks",,, of the 3.9.

I guess it comes down to me wanting a 4 door "sleeper". Kinda like the old days.
 

04_Sport_LS

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well if that was the case, then there would be little beating a 7.0 LS7, but honestly, there IS a replacement, and it comes in the form of a snail and makes a lot of whooshing sounds. hell even the 2.3L ponys are making 427 Z06 power with a few mods. #EcoBeast


Yeah... kinda wanted to stay away from turbos. They left a bad taste in my mouth in the 80's. Previous research has shown that the V6 ecoboost will fit... but it seems to be an electronics nightmare for a "retofit". 365 HP would be nice though,,, from a "factory" engine.
 

cammerfe

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Among other arguments regarding a 4.6, the engine is at least somewhat larger and weighs somewhat more. I can carry an AJ engine block under one arm. One of the benefits of an LS is the EXCELLENT front-to-rear balance.

KS
 
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