5.4 to 6.8 swap; Is it worth it? - Ford Truck Enthusiasts Forums

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5.4 to 6.8 swap; Is it worth it?

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Old 11-15-2018, 11:41 PM
351WTF
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5.4 to 6.8 swap; Is it worth it?

I have a 2002 F350 SRW 4X4 std cab 8' bed that is rapidly approaching the 200K mile mark and i am currently running the motor on Rotella to keep it happy. It idles smooth and still has a decent amount of power but it has the head gasket mating surface defect and keeps pissing oil out of the back of the passenger's side cylinder head at a steadily increasing rate. This truck is my livelihood, i plow snow, haul firewood and just about everything else with it. I can't afford to jump wrong with it. My question is, aside from the obvious fluctuations in HP/TQ & mileage numbers, is it worth it to grab a cheap lightly used V10 off of marketplace and dunk it in there? If so, what modifications, if any, need to be done to accomplish this or is it just plug and play with reduced clearance at the fan shroud?

 
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Old 11-15-2018, 11:59 PM
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I'm of no use to you, but do you have cheap and common V10's where you live? I searched extensively here and rarely found one under 180K+ miles for sale in a functional truck. They just aren't here. I found mine and it was clean and solid and paid more than I should have, but I was so happy to have found what I wanted that I didn't and don't care. I've never swapped in a V10 to a 5.4 truck, but I'd guess there are tranny issues. I'd probably look at trading it in on a V10. It will probably take some searching (based on my experience) but, there are clean ones out there to be had. For everyone that loved them there is still going to be that guy who occasionally pulled a trailer, but drove a civic to work because he didn't want to buy the gas. No clue if you have your truck all set up with a goose neck, air ride etc. But assuming it's reasonably stock... I'd just look at trading it out. The upgrade to 6.8 is worth it. I've had 4,6 and 5.4. I love my V10's
 
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Old 11-16-2018, 12:19 AM
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Good to know. I live in the northeast and there are quite a few that can be had for about $1000-$1800 with between 60-120k on them. I know that it's really the same architecture as the 5.4 just with two extra cylinders. My concern was more with how it would fit in the engine bay. As well as if the extra torque & HP, at the sacrifice of a few less MPG's, would be worth the aggravation?
 
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Old 11-16-2018, 12:30 AM
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Short answer - my opinion - not worth it. Not if its your livelihood and you can't afford to have it down for a while to do the swap properly. Its not just an engine swap, you'd be swapping a lot of required electronics as well. Plus the 5.4 engine will be much easier to find and probably a lot cheaper.
 
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Old 11-16-2018, 12:38 AM
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The v10 is definitely a worthy upgrade but it’s not as straight forward of a swap as you think it is. You would pretty much need an entrie donor truck. You need the engine motor mounts complete wiring harness pcm and transmission and I want to say the radiator is different too along with the fan clutch. The v10 will bolt up to the 5.4 trans but it won’t last long behind the v10. The fuel mileage between the two motors is negligible maybe half a mpg I’ve had both. In your situation and the fact you depend on the truck I would either just replace the 5.4 or get a different truck with the v10 if that’s the motor you want as it doesn’t sound like you can afford the down time and the swap is quite a bit more involved than you were anticipating.
 
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Old 11-16-2018, 12:41 AM
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I can do a week down, but not any more than that. From what I've already done under the hood it doesn't appear to be much more than the ECM and engine harness that would need swapping. Don't get me wrong, i'm happy with the 5.4's power and reliability. I love that it's based off of the legendary SOHC motor from the 60's. I'm just looking for as many opinions and personal battle/success stories on this topic as i can get before making my decision. Thank you for weighing in though, much appreciated!
 
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Old 11-16-2018, 08:26 AM
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I think you'd be better off getting a replacement 5.4. If it's already working fine for you, the swap would be easier and cheaper. Also, the trans on a 5.4 is not built quite the same as the 6.8 even though they're technically the same. I forget exactly what's different, but there are more robust parts in the 6.8 trans.
 
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Old 11-16-2018, 10:27 AM
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With a week allowed down-time, Why not rebuild original engine?
 
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Old 11-16-2018, 03:47 PM
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Yeah, rebuild a 5.4 or get a supercharged 5.4. Them stock lightning engines produce 100hp more. Throw a magnum powers blower or something else on there and gain another 100 with a 6lb lower. I wish I would have never sold my old 5.4L supercharger parts... Would be fun to have a 5.4L supercharged Superduty. Well, except for the gas mileage. :P
 
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Old 11-16-2018, 08:21 PM
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The 4R100 on the 5.4 will get torn to pieces by the 6.8L. If you are going to swap, you need to do both at the same time.
 
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Old 11-16-2018, 09:17 PM
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DO IT!
all you'll need is the motor, harness or the engine which should come with it and the v10 pcm (must be an automatic pcm)
radiators are the same between the v8 and v10 super duty.
the 5.4 trans will bolt up, it is however slightly weaker co pared to the v10/7.3 transmission.
it has less clutches in the torque converter, and forward bands. It's only one less clutch though
 
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Old 11-16-2018, 10:16 PM
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Originally Posted by johnfist View Post
Also, the trans on a 5.4 is not built quite the same as the 6.8 even though they're technically the same. I forget exactly what's different, but there are more robust parts in the 6.8 trans.
The 6.8L trans has more friction plates in the clutches. I would expect the 6.8L to tear up your trans in a short time.
 
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Old 11-16-2018, 11:34 PM
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Thank you for the info guys! Putting a supercharger on it would be awesome if $$$ were no object but that is not the case. Good to know about the differences in the 4R100 though. I had no idea Ford would deliberately build them different for gas motors. Rebuilding the 5.4 that i have is again, a budget issue and where i live i'd be lucky to get everything back from the machine shop in less than a week. Keep the comments coming though! It'd be great to hear from someone that has actually pulled this off!
 
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Old 11-17-2018, 12:19 AM
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Originally Posted by 351WTF View Post
.. i'm happy with the 5.4's power and reliability. I love that it's based off of the legendary SOHC motor from the 60's....!
Suggest you have your motor rebuilt or find an identical 5.4. But realize the 5.4 and the '60s SOHC have NOTHING in common other than being SOHC V8s. Not a single part or design element interchanges other than the 90 degrees between banks.



 
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Old 11-17-2018, 02:55 AM
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I don't see a successful 5.4 to 6.8 swap happening. Call me negative?

(I like to plug and play)
 

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