1993 Isuzu NPR - crawler hauler?

Tydes

Tydes

Battle Masher
Joined
Feb 24, 2021
Messages
224
Loc
Bend, OR
So a buddy posted one of his old work trucks on Craigslist with a couple issues. I fell in love and it came home with me a few days later. I plan to build a flatbed to haul my wheelers to some of our local spots. Both of my current trailers are goosenecks and haul two rigs and I would like something I can take just one. It’s a 1993 Isuzu NPR and has the 4bd2t/auto. What do you guys know about these? I would like to upgrade the turbo and increase the exhaust size. Currently it’s a non-waste gate turbo and runs a 2.5” exhaust through what they call a “Jake brake”. I ordered a boost and Egt gauge to help get a base line before I start messing with it.

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I have been hunting around here and the old place for different bed designs and here are a few I like.
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From what I have found people love or hate these trucks. Is this idea a waste of time or is it worth it?
 
4BD2T is similar to a cummins 4BT in layout and power delivery, but with a different style of injection pump and indirect injection. Solid engines for sure.

I'd recommend building out the chassis to be what you want it to be before messing with the engine. That way once the build is done, you can feel how much power it has at the weight it's going to be, and decide how much power you're going to have to add to be happy (double, triple the power, etc).

I'd definitely recommend "adding lightness", as Colin Chapman used to say, to your bed design. At the end of the day, it's going to be a heavy rig with a 4cylinder powering it.
 
To add, there are some good threads on 4BTSwaps. Basically any recipe you follow for a 4BT will get you the same or slightly better results with the 4BD2T due to the fact that the 4BD engines have slightly better volumetric efficiency than the 4BTs. IIRC that's due to the design of the runners in the head.

These threads can get pretty technical. Fun reads IMO

www.4btswaps.com

Power Recipes

Some have posted what amounts to recipes for a given amount of power. We've had a request to stick at least one of them, so here's the ones I find. I'm having difficulty locating them right now, if anyone finds power recipe pm me a link and I'll add it. 200 HP 4BT 250 HP 4BT 300 HP 4BT...
www.4btswaps.com www.4btswaps.com

www.4btswaps.com

300hp Single Power Recipe

300hp from a 4BT with a single turbo has always been a bit of a mirage. Sure you can do it with a dyno queen, but can you do it with driveability? I ran through the 250hp power recipe and cranked it up a bit to see what would stop us. I kept fuelling at the 180cc/1000 shot limit you get from a...
www.4btswaps.com www.4btswaps.com
 
GLTHFJ60 said:
4BD2T is similar to a cummins 4BT in layout and power delivery, but with a different style of injection pump and indirect injection. Solid engines for sure.

I'd recommend building out the chassis to be what you want it to be before messing with the engine. That way once the build is done, you can feel how much power it has at the weight it's going to be, and decide how much power you're going to have to add to be happy (double, triple the power, etc).

I'd definitely recommend "adding lightness", as Colin Chapman used to say, to your bed design. At the end of the day, it's going to be a heavy rig with a 4cylinder powering it.
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My only thought was swapping the turbo and building the exhaust while the bed is off. My buddy gave me a low mileage HT18 off a Nissan patrol that bolts to the 4bd2 manifold. I also have a bunch of 3” stainless laying around to build an exhaust. It’s not much bigger but has a waste gate and larger exhaust housing. To step up from 2.5” to 3”.
 
Tydes said:
My only thought was swapping the turbo and building the exhaust while the bed is off. My buddy gave me a low mileage HT18 off a Nissan patrol that bolts to the 4bd2 manifold. I also have a bunch of 3” stainless laying around to build an exhaust. It’s not much bigger but has a waste gate and larger exhaust housing. To step up from 2.5” to 3”.
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I hear you, go for it especially if it'll be close to free.

My point is that if you spend money on a small turbo upgrade now, then build the rest of the rig, you may find that it's not enough power and you'll be spending (turbo, injector, etc) money twice. That's all I was advising against.
 
Didn't Ian start a 4x4 conversion/crawler hauler build on the old FourWheeler TV Show?
 
rockota said:
Didn't Ian start a 4x4 conversion/crawler hauler build on the old FourWheeler TV Show?
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I have seen a picture of it started but nothing completed. Fred and Dave built one with divorced 205 and super duty axles.
 
rockota said:
Didn't Ian start a 4x4 conversion/crawler hauler build on the old FourWheeler TV Show?
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Here are the episodes of it: Crawler Hauler Izuzu Flatbed

He got the bed on it and the 'structural' work done. The last episode he talked about doing 'cosmetic' work to it next to make it look like a Dakar rally truck, but that was the last of it.

He started one on his Big Tire Garage with a GMC T6500, but didn't finish that one either.

 
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I’ve been working on one for a few years now. Mine will have a supercharged 6.0 LS. I’ve converted it to 4WD using a Chevy Dana 60 with push pull steering. Custom midship box and Dodge dually bed. Need to get off my ass and get it wired.
 

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akguy09 said:
I'm not sure Ian finish's a whole lot of anything :smokin:.... and this is going to be an awesome truck
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Well, I understand when he was with PowerBlock/Nation/whatever that the decisions weren't always fully his, but the T6500 was all on him. I think there it comes down to having the resources to dive into whatever crazy projects he can come up with before common sense takes over. :jester:
 
In high school I had an Isuzu Amigo and thought it would be cool to SAS it and tow it with an NPR. My understanding is that they are slow, and would be rough in the hills, but maybe not with the 4BT.

That Axial crawler is pretty hilarious, I haven't seen that one yet.
 
Here’s my old SAS VehiCross race truck. Very easy to do with a Dana 44 out of an old Jeep Wagoneer
 

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Diablo169 said:
In high school I had an Isuzu Amigo and thought it would be cool to SAS it and tow it with an NPR. My understanding is that they are slow, and would be rough in the hills, but maybe not with the 4BT.

That Axial crawler is pretty hilarious, I haven't seen that one yet.
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That’s the og wraith that axial built the crawler off of. He had one before that that looked similar that was rotary powered.
 
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Ive got one, but a little newer. 4he1 engine. Had plans to put a little crane on it but built another truck instead.

Pretty solid trucks. Grease the kingpins often because they like to seize up.
 
I wouldn't get excited about doing too much to the engine, it's going to be gutless no matter what, no sense in making slightly less gutless and unreliable.

Now, on the other hand, a cheap turbo upgrade and bit more fuel, probably wouldn't hurt. Look at he351cw's off of 5.9 common rail cummins. Way better than the an old non wastegate turbo. Although I know nothing about putting on 4cyl, maybe there is a smaller version?


Before you do anything, I'd figure out what trans it has, some trucks that size had terrible, loose, non lock up trans. Meant to never leave city streets.
 
Hx30w, super Hx30w, or I think a td42. He351 is too big as a single, but works well as an atmospheric turbo on a compound setup at that displacement. That's what I have as my atmospheric turbo (with a super hx30w) on my 4b.
 
Some guys saying He341 (03-04) works well.

But obviously depends on what you're doing. Towing up the mountains with an auto, a little lag probably won't hurt too much.
 
YotaAtieToo said:
Before you do anything, I'd figure out what trans it has, some trucks that size had terrible, loose, non lock up trans. Meant to never leave city streets.
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It has a JR403e which has a lock up converter and it was recently rebuilt.
 
YotaAtieToo said:
I wouldn't get excited about doing too much to the engine, it's going to be gutless no matter what, no sense in making slightly less gutless and unreliable.

Now, on the other hand, a cheap turbo upgrade and bit more fuel, probably wouldn't hurt. Look at he351cw's off of 5.9 common rail cummins. Way better than the an old non wastegate turbo. Although I know nothing about putting on 4cyl, maybe there is a smaller version?


Before you do anything, I'd figure out what trans it has, some trucks that size had terrible, loose, non lock up trans. Meant to never leave city streets.
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It is probably a Jatco with a lockup converter. Mine is in an 11k lb rv and I tow 6-8k behind it most of the time I have had it. Somehow, (knock on wood) it keeps going. Extremely slowly but steadily.

I literally keep the pedal to the floor nonstop for 3-4hours at a time. I manually downshift out of overdrive any time it drops below 45mph. I think it is only a 4 speed but you can hear the converter lock and it almost makes it seem like it is a 6 speed if you count shifts.

Next time I drive it the trans will go out since I talked so nicely about it. :flipoff2:
 
That's an exhaust brake not a jake brake.
Closes off the exhaust creating about 50psi backpressure on the engine.
 
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