Build Mitsubishi 4D34-3AT3B diesel swap into 94 FZJ80

[Fromage]

A little bit of Zexel trivia - Zexel is now Bosch but it wasn't merged into the Bosch corp until 2005. It was started as Diesel Kiki in 1939 (part of the Isuzu Motors Corp) and fabricated under license from Bosch - just the same way the Denso rotary IP is made under license from Bosch using the VE design. In 1990 it changed its name from Kiki Diesel to Zexel (BTW, same time the Y60 went from an inline to rotary IP). In 2000 the company was reorganized from Bosch KK (recognizing the Kiki Diesel) into Bosch Automotive Systems Corp. In 2005 it fully merged with Bosch Corporation, although it continues to manufacture using the Zexel name.

Good information. It's funny that the american-as-apple pie Cummins, the 2000 Jetta TDI and the Cruiser will ahve an injection pump from essentially the same manufacturer!

This pump is HUGE. That's a standard plastic folding lid bin and it takes up almost the entire thing. The pump must weigh 50 lbs.

And a pic of the transplant recipient. 150K miles, e-locked, on 295/75R16s, TJM bar and absolutely positively no rust. It is definitely not mint but it's pretty good for Western Quebec/Eastern Ontario. I had it krowned last year and will continue to do so for as long as I own it, I figure I might be able to get a solid 10 years out of it if I can keep the rust at bay.

 

[lshobie]

Jesus that thing is huge!

If anyone can make this project happen it is JL, he has a wicked amount of patience - but it is fun to see him snap once in a while I usually just laugh when he loses it.

JL, I'll need that steam cleaner, you going to be in this area any time soon???????????? I have beer, and bell housings!!!!!!

 

[96r50]

Wow that pump is massive! I've seen your truck around before but didn't know who it was.

Awesome build!

 

[canucksafari]

Wow, that IP is really overkill big.

Let's see a close-up of where the engine mounts are on both sides.

 

[Fromage]

I will get some better pics of the mounts.

I believe they will be very close to the stock location. I think they will be too low (meaning that the engine mounts on the frame will have to be lowered) but I don't see any interference issues between the ancilliaries and the engine mounts. This was figured out with a tape measure so it's not exactly super exact.
As you guys have probably gathered, the whole point of this swap is not to have to alter any driveshafts or the location of the rear crossmember. I'd really like to keep everything totally stock underneath so that all the driveline is stock length and in the stock location.

The bellhousing length of the 450-43 is about a 3/4 inch longer than the A442F so the engine will be slightly ahead of where the 1FZ is located. As the engine is fairly large but has 2 less cyls than the 1FZ, I will have about 5 inches of additional space between the front pulley and the radiator, which works out great as I will be moving the (custom) radiator backwards so as to give me some room to run the transmission cooler and intercooler ahead of the rad, but behind the rad support. As the 80 series rad support is not very conducive to intercooler pipes running through it, I'm going to try and hang everything on the inside of it. This may change quite a bit once I have everything apart.

Right now my biggest issue is that I need the truck for the next three weeks. I'll be resealing the Mitsu engine and probably giving it a coat of paint in the meantime, but until mid August I can't lay a hand on the Cruiser.

The other issue is whether or not to run AWD or 2WD. Since our driveway is so steep 4wd is required every time we come home,about 9 mos out of the year. If I run 2wd I would probably never disengage the hubs, but I would anticipate that the fuel mileage would still be better. However, the viscous center diff is absolutely unstoppable in the snow and that's this truck's primary claim to fame - It's called the sno cat for a reason...

I'm getting the new rad tonight along with the trans rebuild kit and some other little bits. It's a universal fully welded aluminum rad from Speedway Motors. I picked it because it's the right dimensions and since it's fully welded aluminum and furnace brazed (no epoxy) I can alter the outlet locations to fit the odd hose routing of the Mitsubishi. And any day I get to use the "Yellow Submarine" in anger is a good day (more on that later).

 

[Dougal]

The other issue is whether or not to run AWD or 2WD. Since our driveway is so steep 4wd is required every time we come home,about 9 mos out of the year. If I run 2wd I would probably never disengage the hubs, but I would anticipate that the fuel mileage would still be better. However, the viscous center diff is absolutely unstoppable in the snow and that's this truck's primary claim to fame - It's called the sno cat for a reason...

I'm not sure where the indecision is coming from. There's no difference in fuel economy between 2wd with hubs in and fulltime 4wd, but there's a big difference in traction, handling and tyre wear.

 

[Tapage]

There's no difference in fuel economy between 2wd with hubs in and fulltime 4wd, .

it is .. if you compared a similar HDJ80 with the HF2AV t.case and other HDJ80 with the HF1A the part time 80 it's faster and ant the end you will got 4km/g difference .. not big difference, but exist ... ( comparing stock cruiser with same tires and more less same overal engine shape )

 

[Dougal]

it is .. if you compared a similar HDJ80 with the HF2AV t.case and other HDJ80 with the HF1A the part time 80 it's faster and ant the end you will got 4km/g difference .. not big difference, but exist ... ( comparing stock cruiser with same tires and more less same overal engine shape )

You're comparing them with the front hubs unlocked, but Doug720 would be driving around with them locked. This means all the same parts are still turning so mileage has to be the same.

Even the difference between hubs locked and unlocked is only the difference between the front diff, cv's and driveshaft turning. I don't think there is 4 km/g (about 1km/litre) difference there.

 

[Tapage]

Even the difference between hubs locked and unlocked is only the difference between the front diff, cv's and driveshaft turning. I don't think there is 4 km/g (about 1km/litre) difference there.

trust me it is .. and even more if you spend the complete tank rolling around the city in heavy traffic ..

 

[Fromage]

I can see the VC eating up some energy whe you are in traffic or any time you are turning a lot of corners. I will probably leave it alone at first and see how good the mileage is, and if it is still not good enough I will swap it out for a part time setup. Even if it was locked in for most of the time, having the option of leaving the hubs unlocked for long highway trips or for 3-4 mos of the summer would be nice. The only issue is I lose the VC, which works so well in the snow. I need a T case that does all three, 2wd, 4wd VC and 4WD locked!

 

[astr]

I've always considered getting out to lock hubs, typically under the worse conditions, a real pain the a** but I was concerned about the reduced fuel economy that might result from leaving them locked so I did a little test a few years ago using my Samurai as the subject. I drove three tanks of gas with them locked and three tanks with them unlocked over the same route (5 miles each way) to and from work. This was during a typical Michigan winter. Never during this test period did I have to use 4wd. The difference in mileage was minuscule, easily attributed to other factors. The reason that I say this is the "locked hub" mileage actually calculated out a tad bit better than the "unlocked" mileage, certainly not what I had expected.

I realize that this test was not done under the strictest controls and even if all the random factors skewed the results toward favoring the "locked hub" situation, I think any mileage gain from running with unlocked hubs is insignificant. Probably a more significant factor would be the addition wear that you might get in the front end with all the parts always turning.

For myself, I lock the hubs when the first snow flies and unlock them (if I remember to do so) when winter is over.

 

[Dougal]

Probably a more significant factor would be the addition wear that you might get in the front end with all the parts always turning.

Surely it's better to keep them lubricated and turning. Many jap import trucks have never had their front hubs used, they're often gummed up with dried grease and won't go into lock (especially if they're auto hubs). I've heard of people finding the top half of the crownwheel has corroded because it's never turned into the oil.

 

[astr]

Surely it's better to keep them lubricated and turning. Many jap import trucks have never had their front hubs used, they're often gummed up with dried grease and won't go into lock (especially if they're auto hubs). I've heard of people finding the top half of the crownwheel has corroded because it's never turned into the oil.

If you never use them, then it really makes no difference.

For the readers of this forum, "never locked" probably doesn't apply.

I think we are getting off subject a bit - sorry fromage!

 

[Fromage]

Not off topic at ALL! No apologies necessary. This is all good stuff. The AWD vs RWD debate is bt a debate at this point because I am not planning on doing anything about it until the conversion has been tested for a while. Once I've gotten some numbers for fuel consumption I will revisit it.

The next big issue I need to sort out (and I need your help with) is gearing. The A442F has an OD ratio of .765. The AW450-43LE has a 0.703 gearset. That means that, by keeping the AW ratios, I end up with a 9% reduction in RPMs in overdrive. I am a bit concerned that it's too much gear for my engine, but I think that the higher gears might help mileage, and I would rather keep them if I can. Here is my analysis so far:

I paid close attention to the RPMs on the way in this morning. I usually cruise at 65 mph uncorrected,which equates to roughly 70 mph. I noted a cruise RPM of roughly 2200 RPMs, in lockup.

Using this calculator:

Gear Ratio Calculator

I obtain roughly 2200 RPMs as validation.

Now, here is the logic. The torque curve for the 4D34 starts getting interesting around 1500 RPMs with a PEAK at 1600 RPMs, and is flat through to 2400, where it really starts to taper off. Subsituting the .703 gears into the calculator, I obtain:

1600 at 55 MPH
1880 RPMs at 65 MPH
2027 at 70 MPH

There is the lockup torque converter, which will open and bump up the revs if necessary, and dropping into 3rd is also possible. The worst case scenario I can see is dropping off of the torque curve at around 55 mph and being stuck there, but this is not a speed I usually cruise at, and the torque converter can merely unlock to raise the revs, or 3d gear is not far behind (at 2260 rpms at 55 mph) at the touch of a button.

This happens often with the 1FZ that I will use 3rd to get moving and hit the OD to cruise. Also, hald of the year, the truck has smaller tires on it, so the gearing effects are lessened.

I think I will stick with the higher gearset, but I would really appreciate your opinions. Comparing performance to the 1FZ is kind of a moot point as the torque characteristics from a TD to a gasser are quite different, bu the 1FZ has a torque curve that it is fairly flat, but it does not get close to the torque generated by the diesel until about 2200 RPMs. This also makes sense from a seat of the pants feel, as the 1FZ falls into a hole around 1800 RPMs that it won't climb out of.

Also, the Fuso FE-SP truck has a rear end ratio of 5.714 on 30 inch tires. That works out to a maximum speed of 73 MPH at redline. This worries me, but these cube trucks would push so much air that they probably need such gears just to move that fast. At higher speeds the massive reduction in frontal area should make a huge difference in the ability to push the truck along without having to spin like crazy. Also, teir "delivery truck" pedigree probably values low gears and more chutzpah around town than long legs on the highway.

 

[Muleysam]

Nice find on the gear calculator

What is your tire size and do you still have the 4.1 gears

 

[Fromage]

I run 295/75R16s summer and studded 265/75R16s winter. Stock 4.10 gears.

 

[Muleysam]

someone told me that you get the best mileage out of a diesel at peak torque. That would put you at 55 mph. that doesn't sound rite because you would have to shift into third if the speed dropped. I think Profits puts 35 inch tires on theirs to get the gearing right.

 

[Dougal]

someone told me that you get the best mileage out of a diesel at peak torque. That would put you at 55 mph. that doesn't sound rite because you would have to shift into third if the speed dropped. I think Profits puts 35 inch tires on theirs to get the gearing right.

Peak torque is a very good compromise for drivability vs fuel economy. You'll get the absolute best economy running the engine as slow as it can to deliver the necessary power. But drivability sucks at that point.

 

[Fromage]

I think I am going to stick with the higher gearset. I think it will be fine, and since I'd much rather get excellent mileage than lots of get up and go, I think I will be happy with the result. I can always change it out later if I want (although that would be a LOT of work).

Still getting ready for D day. I was hoping to pull the engine last weekend but I still need the truck so it will wait another week or so.

 

[crushers]

interesting read...
i loved the old 2.7L that came in the Mits J53 and if that engine is anything like those you will enjoy the fuel economy. i did find the tight operational RPM range to be ... irritating ... and limiting for highway travel.

best of luck on the install. i would love to go for a ride once you have it buttoned up.