1997 - 2003 F-150

Swapping wheezy 4.2 liter V6 for brawling 408 cubic inch V8 stroker!

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Old 11-28-2023, 11:55 PM
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Swapping wheezy 4.2 liter V6 for brawling 408 cubic inch V8 stroker!

Hello fellow F-150 owners,

Back in 2008 I bought a 2002 F-150 XL equipped with a 4.2 liter V6 and an M5R2 5 speed manual transmission. The "story" was that grandpa had passed and the 18 year old that inherited it had put on a set of aftermarket wheels, skipped about four oil changes, and plowed it into a pole.

So said the guy that sold it to me, that bought it from the kid. He was a good bodyman but didn't know engines. The truck was clean and pretty but the lack of maintenance had caused the V6 to spin a rod bearing.

I bought it from him, via a local ad paper, for $1,800 bucks. Besides teaching math at the local university I am a part-time construction contractor (and longtime gearhead), so I needed a good work truck. I pulled the engine and bought a "crank kit" from the local AutoZone and purchased a connecting rod and gaskets (etc.) from Rock Auto and.... Bob's your uncle, had the beast back on the road for under 2 grand.

Fast forward 15 years of serious work truck duty and the old V6 is making some bad noises. I could probably freshen her up and get another 10 years of work truck duty from the venerable 4.2 liter V6, but to be honest, I'm damn tired of LS V8 Chevy and GMC pickups and Hemi Rams kicking sand in my V6 Ford truck's face.

It's time for a righteous, high horsepower Ford V8 to show those redneck "Brand X" clowns what an old school Ford V8 can do.

Now, I know there are a bunch of forum "know it alls" just waiting to stomp my V8 swap dreams into the dust. Let's address those "objections" one by one.

1) It's not worth it! Just sell the V6 truck and buy a V8 F-150.

The body and interior of my truck are VERY clean. But even so, a clean 2002 F-150 with a tired V6 goes for about 2 to 3 grand. A clean V8 of similar vintage sells for MUCH more and those V8s (4.6L and 5.4L) only put out 210 to 250 hp.

No thanks.

2) You don't understand the challenges you face. The trans, the electronics etc.

Well, one of the reasons I chose a 351 Windsor based swap is that the 4.2 liter V6 is, basically, a 302 Windsor V8 with 2 cylinders lopped off and a balance shaft to quell primary V6 imbalance issues. So the M5R2 tranny will bolt right up to the 351 Windsor block (soon to be a 408 cubic inch beast). .

So, I'm not looking for reasons NOT to do it. Don't waste your keyboard strokes.

I've already bought a 5.8 liter (a.k.a. 351 Windsor) "roller block" engine from a local junkyard.

The disassembly is complete and the block is in pristine condition. I could just hone the cylinders, put in new bearings and rings, a high lift/duration cam, a set of aftermarket heads, a pair of long tube headers, a Super Victor intake and a carb and send it. That would easily make nearly 500 lb/ft of torque and 500 horsepower; but that's not enough to completely humiliate a 6.2L LS Silverado or a 6.4L Hemi Ram.

That's why I'm building a 408 cubic inch stroker with an internally balanced forged steel crank, forged pistons and rods and a solid roller cam. This should push the engine to close to 550 lb/ft of torque and nearly 600 horse pressure.

So, here's what I am asking from the forum: Has anyone done a similar swap? I'm, probably, going with an aftermarket ECU (Mega Squirt?). Does anyone have experience using an aftermarket ECU in the 1997-2004 F-150?

I'm sure lots of issues will come up, so if you have any POSITVE suggestions I'm all ears. If you think I'm wasting my time, go post on your Facebook page, I'm already committed.

Pictures and updates will be coming as I proceed.
 

Last edited by BossGuy; 11-29-2023 at 12:12 AM.
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Old 11-29-2023, 08:48 AM
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This will be an interesting build.
 
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Old 11-29-2023, 10:17 AM
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No way can the M5R2 handle that kind of horsepower. You need to find a different transmission.
 
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Old 11-30-2023, 09:40 PM
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Originally Posted by glc
No way can the M5R2 handle that kind of horsepower. You need to find a different transmission.
now now, he’s a gonna do it unlike all the others


and yeah I highly doubt the OP is more than talk
 
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Old 11-30-2023, 09:41 PM
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Originally Posted by ManualF150
This will be an interesting build.
IF it happens
 
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Old 12-01-2023, 01:22 PM
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Originally Posted by stoffer
IF it happens
x2

 
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Old 12-04-2023, 06:33 AM
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Originally Posted by glc
No way can the M5R2 handle that kind of horsepower. You need to find a different transmission.
M5R2 is used in the supercharged T-bird Super Coupe. Guys in that forum say it will survive so long as you limit shock loads

If it breaks I will find another trans. Maybe a Tremec TKX.
 
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Old 12-04-2023, 06:47 AM
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Originally Posted by stoffer
now now, he’s a gonna do it unlike all the others


and yeah I highly doubt the OP is more than talk
I guess you missed the " POSITIVE suggestions" part of my post.

The V6 gets pulled this weekend. If the damage is minor I may rebuild it (again) and sell it to help fund the project.

The V8 is at the machine shop getting hot tanked, decked, and bored 0.030 over.



p
 
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Old 12-04-2023, 07:01 AM
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Originally Posted by ManualF150
This will be an interesting build.
I'm very excited to get going. 5.8L (351 Windsor) block is at the machine shop getting hot tanked, decked and bore 0.030 over.

Pulling the V6 this weekend.
 
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Old 12-06-2023, 10:19 AM
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Originally Posted by BossGuy
M5R2 is used in the supercharged T-bird Super Coupe. Guys in that forum say it will survive so long as you limit shock loads

If it breaks I will find another trans. Maybe a Tremec TKX.
We have a member who Procharged a 5.4 in a F-150 of your generation, and he's gone through 5 of them. The Super Coupe had a 3.8 V6 with 210 HP and 315 torque. Your 408 will have a LOT more than that.
 
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Old 12-11-2023, 03:13 PM
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Good luck! I will be following along living vicariously through your adventure!! Please share tons of pics!! Let's gooooo!! 💪🏻
 
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Old 12-11-2023, 03:44 PM
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Originally Posted by glc
We have a member who Procharged a 5.4 in a F-150 of your generation, and he's gone through 5 of them. The Super Coupe had a 3.8 V6 with 210 HP and 315 torque. Your 408 will have a LOT more than that.
It is the "weak link". I originally figured I would have to replace it and was encouraged by the posts at the T-Bird Super Coupe site. Some people said things similar to the guy that Procharged the 5.4, having gone thru multiple numbers of them (three was the number mentioned by a T-Bird guy).

I wondered, why would you keep replacing it wit hthe same trans if they were breaking?

If (when?) the tranny breaks, I'll put in something more robust, like a TKX, but the guys on the T-Bird site said that if you don't put high shock loads on the trans (like clutch drops and power shifts) it will survive.

The 8.8 in my truck is an open dif (have plans to buy a helical conversion kit). So one thing at a time.

If the trans breaks first I'll buy that first.

 

Last edited by BossGuy; 12-11-2023 at 03:48 PM.
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Old 12-11-2023, 03:46 PM
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Originally Posted by 4Dnut
Good luck! I will be following along living vicariously through your adventure!! Please share tons of pics!! Let's gooooo!! 💪🏻

I'll post some pics of the pulled V6 once I tear it down to see what was making the "bad noises".

Then I'll fab up some motor mounts and take shots of that.
 
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Old 12-11-2023, 04:24 PM
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I wondered, why would you keep replacing it wit hthe same trans if they were breaking?
He said next time it breaks he will replace it with a ZF out of a Super Duty. That needs a 3" body lift to clear the tunnel. He hasn't posted here in quite a while so I don't know what the situation is now.
​​​​​​​You may want to put a 9.75" rear in it.
 
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Old 12-11-2023, 06:27 PM
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Thanks 4Dnut.

It's going to take all of the winter and a bit of the spring, since it's a weekend project.

And I have to space out the expenses. Just the heads are going to be over 3 grand.

Photos to come!
 
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