Hello all!

I have a question that I think is pretty much impossible to answer over the internet, but why not give it a try?

Some background, I have a F-250 7.3 SCLB 4x4 year 2000 that I bought a couple years ago. Searched for the right truck to buy for a few years, I don't live in the US and the 7.3 is kind of rare here and I absolutely wanted a SD 7.3 SCLB 4x4. Parked the truck after running it for some time since it's in need of an overhaul / restoration. Now I'm able to get started with all the work. The truck is an auto but I always wanted a manual, doing the swap with all the work isn't something I'm afraid of so that wasn't a big factor when buying the truck. As of recently when I've begun looking around sourcing parts for the truck I've started to think about building the engine to 500 hp or thereabout. That power goal is further in the future, I'll probably do some engine work when the cab is off but nothing too serious, I want it back on the road first. If I were to keep it stock-ish I'd absolutely do a ZF6 swap but I'm not sure anymore with that "new" power goal. Unfortunately I don't have the possibility to test drive a manual diesel truck of any kind, that would maybe have made it easier to decide.

And so to the question, what is it like driving a 500-ish hp PSD 7.3 with a ZF6? Do you prefer an auto or manual when upping the power? Is it nothing but changing gears and waiting for boost with a manual? Some of the turbos available today seem to have really nice spool so maybe it isn't too much lag when shifting? I plan to use the truck as a daily driver and do anything between going to work and longer roadtrips. I probably won't do much pulling or hauling with it but it would likely be fun to pull a friends boat or something just for the giggles. Since I'll use the truck for "normal" driving most of the time I'm still leaning towards a manual swap, but maybe it's worth it with an auto for those times I do decide to put down some power?

 

A built auto would be more fun for a truck like that. ZF is a good workhorse transmission that holds up better than a stock 4R100 and would last nearly forever with a proper pilot bearing and used carefully, but it’s not as good for a high HP fun truck. More likely to break stuff or at least wear stuff out quicker shifting it hard. Plus a ZF won’t fit in the transmission tunnel on a 4R100 with cutting the sheet metal which adds to the headache, but it’s been done before

 

The ZF6 is not the sporty option if that was part of the motivation. Nothing at all like snicking thru a BMW 6 speed.

IIRC 500ish is pretty much upper limit on a 4R100 so it will need to be built to take it. Same for a streetable 7.3 far as I know, but I am far from expert on HP builds.

Got any pics of the truck?

 

I have driven many manuals in the years back but i love the comfort of the auto.
You should be good with the 4R100 up to 500 but personally I wouldn't go higher than 450. I had mine built up some years ago when the OEM died at 80K. All Bully Dog HD insides and now at 368k she still pulls the boat, flatbed and horse trailer without issue.
For additional HP tho I did go DP Tuner for a programmable chip and then added a 38R from a buddy who bought it from ATS then changed his mind so I got a deal on it.
Stage 2 injectors finished my setup.
I have semi retired the truck now tho... the most I pull is the boat to the lake and the occasional hauling a neighbor's tractor somewhere local for repairs or whatever. I did use it for some time as a daily driver and it was fun. Nice to have to power to just get up and go when you want to do 90 at the top of the on ramp. 😁

 

Personally, I wouldn’t be looking to do 500hp when living in a country where these trucks and parts are rare. I would lean towards a mild build that would be fun and dependable. “Hot” street vehicles can be a pain in the butt with the compromises that come with them.

My opinion is a KC Stage 1 Gen 3 turbo, bellowed uppipes, Hydra tuner. Just those will really wake it up. Then if you want more swap in some larger injectors (200/30 or 180/30) which will still pair well with the KC stage 1.

 

We haven't heard from him in awhile but paging @FinnishStroker to the white courtesy phone please.

 

Lots of good answers, thanks! Now I got a little more to think about and factor into the decision.

It’s a very good point made about building it to a little lower power, I’ve built some high hp (compared to stock atleast) euro gas cars and it’s always something that needs to be fixed with them, and then the extra headache from having to import pretty much any part will probably lead to the truck being parked a lot more than I want. I’ll take that into consideration, thanks for the reminder!

I’ll try to attach some pics.

 

I swapped the ZF6 into my Excursion about 7 years ago and have put probably 35k on the swap. In 2023 I upgraded the injectors and turbo etc like you see in my signature. Its a lot of fun but if you're looking to make your rig into a sports car, youre wasting your money, and a lot of it. The ZF6 is a medium duty truck transmission and it is fast shifting compared to other comparable gearboxes but it is not a sports car transmission and you might be disappointed. I'm a die hard manual transmission enthusiast so I love it. I think I should be in the high 300s to 400hp range, and I can surprise a lot of fun cars on the highway but it'll never make an impressive 60' time at the drag strip. 1st thru 3rd are very short so you're shifting a lot just to hit 40mph. Once you get into 4th it starts to get fun and before you know it you're out of gear and out of revs at 100mph!

 

Thanks for everyones input this far! I've decided to do the swap and probably run a little less hp when the time comes. After all, this truck with a manual trans is my dream truck.

I'm also a fan of manual boxes, but a few youtube videos of boosted launches with all 4 wheels spinning brought out the kid in me... But driving like that is also a sure way to start breaking stuff so even if I could do it I'd probably only do it once or twice and then be too afraid to break stuff. And it's still possible to do boosted launches with a manual, just keeping in mind that with a clutch I'd run on the street I can probably count the launches on one hand before it's time for a new. I have no vision that this truck will be quick and responsive to drive. As you say they can probably move surprisingly fast when they can stay in gear a little longer and put the power down. But I don't want to brake late and aim for the apex though. But that's also why I like it, it's a little like driving around in a tiny big rig more than a big car. I've had fast cars and I don't think they are very fun to drive on the streets anymore, the better you build them the faster you have to go for them to be fun. With all the added risk from the police and accidents that come with higher speed, I can't afford to go to jail... I'd rather drive around in my truck and listen to the engine and turbo and have the handling of a refrigerator on wheels. And in that scenario rowing the gears myself is what I've wanted pretty much since I saw and heard one of these trucks as a kid.

So if anyone has any tips on where I could find a used ZF6 and surrounding parts in decent condition online, I'd sure be glad to hear it!

 

Sounds like you have the right idea for the swap then. If you're going for the mini big rig vibe, you'll get it. I bought a used trans from a flood truck and used it as a core on a reman unit. Back then I paid about 2500 for the box in total and I got it for cost thru a shop I know the owner of.

 

Hmm I hadn't thought that far! A reman would be nice but not if I also have to pay for the core charge. I'll have to look into buying a not so good trans to use as a core, it shouldnt be impossible to make it work with shipping and everything despite not being local. Thanks!

 

Mine is 2wd so I havent paid attention, but back in the days I did my swap the 4x4 guys I don't think had figured out how to get ESOF to work so look into that and or consider buying one with a manual transfer case.

 

I’ve not done it but read others on here say that a manual swap requires floor board mods for the trans tunnel which they usually cut out of the parts truck. Just something to keep in mind since sourcing spare parts will be more difficult where you’re located. You may end up needing to go with a custom made trans tunnel. Sounds like you’re getting a good plan together.

I’ve also had a hot street car. Eventually they become too much hassle and you end up jumping in the easier vehicle 99.9% of the time. At least that was my experience.

 

At first I planned to change the input shaft on the transfer case and try to make it work with esof and the vacuum hubs. But I'm leaning more and more towards trying to find a manual transfer case and changing the hubs to manual. It would be nice to get rid of some wiring and not have to diagnose and repair any faults in some of the wiring and the vacuum stuff. Plus it would put another stick on the floor and clean it up a little under the hood, not by a lot but less stuff is less stuff. It would also be nice to not have to worry about if the hubs or transfer case have locked / unlocked properly.

Yeah if I can get my hands on the bit of the floor it'd be nice, but otherwise I'll cut the original floor and fabricate something out of sheet metal to lift the floor. I'm not a fan of body lifts otherwise that could probably have made it a bit easier. It would for sure make it easier to have the bit of floor though, if nothing else so I don't have to figure out where to put the hole for the shifter.

 

Maybe you'll get lucky like me and find a whole truck and get the trans, clutch pedal, brake pedal and floor from the same place.

Watch out for the brake pedals when sourcing the skinny pedal. The V10 trucks have a mechanically different pedal that makes up the difference between vacuum boost and hydroboost and doesn't bolt up to the hydroboost. It has to come from a 7.3 truck.