isuzu 4BD1T swap?!

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I spoke with Isuzu a few weeks ago and was able to obtain a dyno chart for the U.S. version of the 4BD2-TC. I've attached a copy below. It's also in my Jeep build-up thread on Pirate4x4: Build-up: Jeep YJ w/ Isuzu diesel.

Between IH8MUD, 4btswaps.com, and Pirate, there's too many Isuzu diesel threads to keep track of! :)
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iroc86 said:
I spoke with Isuzu a few weeks ago and was able to obtain a dyno chart for the U.S. version of the 4BD2-TC. I've attached a copy below. It's also in my Jeep build-up thread on Pirate4x4: Build-up: Jeep YJ w/ Isuzu diesel.

Between IH8MUD, 4btswaps.com, and Pirate, there's too many Isuzu diesel threads to keep track of! :)
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Hey thanks, that's really interesting.
The torque curve is much flatter in the top half and the fuel consumption curve shows about 5% higher fuel consumption than the 4BD1.
 
Here's where it gets really interesting... a comparison between the 4BD2-TC and the Cummins 4BT. I interpolated the data from both official dyno charts and made a new one. The Isuzu clearly has the advantage after 2000 rpm.
torquecurve3.webp
 
iroc86 said:
Here's where it gets really interesting... a comparison between the 4BD2-TC and the Cummins 4BT. I interpolated the data from both official dyno charts and made a new one. The Isuzu clearly has the advantage after 2000 rpm.
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And more is just a few turns away.
I've got around 500Nm, that's about 370 ft-lbs.:)
Running 20psi boost with no intercooler.
 
ozwallaby said:
20lbs and no i/c.....do you hate this motor Doog..... or is this all part of your finite stress analysis.... :clap::clap:
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I'm testing it.:grinpimp:
I plan some even harsher tests in the future. If no-one tests the limits then we won't ever know where they are.

Plenty of people running Cummins 4BT's with up to 35psi boost and stock internals, I expect the Isuzu to take similar abuse.
 
A/C Hook-up

Is anyone running A/C on theirs yet? I'm wondering space wise if it will fit in the stock location or if it's going to butt up against the frame. I haven't seen an engine with A/C hooked up to it but it looks like it sticks out as far if not a little farther than the starter.

Also, the shop that's putting this all together for me found an Isuzu starter that is actually turned up snug against the engine so you don't have to off-set the engine.
 
andrew.fletcher said:
Is anyone running A/C on theirs yet? I'm wondering space wise if it will fit in the stock location or if it's going to butt up against the frame. I haven't seen an engine with A/C hooked up to it but it looks like it sticks out as far if not a little farther than the starter.

Also, the shop that's putting this all together for me found an Isuzu starter that is actually turned up snug against the engine so you don't have to off-set the engine.
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I have that other Isuzu starter on my engine. The downside is it draws a lot more current than the geared version, so make sure your starting system can handle it. Mine draws around 300 amps peak on 24v.

I'm running the stock Isuzu AC compressor, I think I have a modified tensioner bracket which tucks it in a little closer (protrudes less than the starter) but it still uses the same factory mount as the alternator.
 
There's always a downside, I'll have to look into how to overcome that. I'm pretty dense when it comes to electrical. Is it just a matter of bigger battery, thicker wires and stronger starter relay?
Does your AC compressor protrude less than the OEM starter or the "other" starter? Can you post or send me a picture of your tensioner bracket? I have no brackets right now so I want to make sure I get the right ones.
 
andrew.fletcher said:
There's always a downside, I'll have to look into how to overcome that. I'm pretty dense when it comes to electrical. Is it just a matter of bigger battery, thicker wires and stronger starter relay?
Does your AC compressor protrude less than the OEM starter or the "other" starter? Can you post or send me a picture of your tensioner bracket? I have no brackets right now so I want to make sure I get the right ones.
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This is the best I can do for a photo right now.
The AC compressor is just visible underneath the alternator, it actually sits just above the chassis rail in my truck. I guess it protrudes as much as the original starter.
IMG_0573.JPG
 
andrew the AC in stock locale wont fit, it will need to be raised or otherwise relocated. i want the GR starter and offsetting the engine was not a problem, the stock cruiser engine is offset to the D side and now i'm offset the same amount to the P side.


IROC i was reading some of your other posts on other forums, nice build.... i dont understand the oilpan on the 2 series engine, i havent had one apart so there must be a reason its like that. i dont think though that it would pose any issues, looking at mine with P side diff i think it would still clear, i have the engine forward off the firewall some and SOA,, but if the engine were all the way back as it looks like your doing i think it will be completely behind the front axle,, no??
 
RHINO said:
andrew the AC in stock locale wont fit, it will need to be raised or otherwise relocated. i want the GR starter and offsetting the engine was not a problem, the stock cruiser engine is offset to the D side and now i'm offset the same amount to the P side.
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Do you think modifying in the existing location will work, ie. like Dougal's modified bracket. I guess it depends on how far it will bring it in. If I remember right, you said you have about 20mm each side with the stock starter so there isn't much room left to move it over any more to accomodate. That and I don't think there is any room on the other side to mount any components.
 
Thanks for checking out my Jeep build, RHINO. The only reason I can think of for the 4BD2's unusual oil pan is capacity. That bulge is big enough to hold about two extra quarts of oil. Maybe the Isuzu engineers found that extra oil capacity and a big, single filter was better than the 4BD1's setup? When I get my motor mounts done, I'll pull the pan and let you guys know what it's like in there.

I'm also going SOA with my Jeep, but I'm keeping the lift fairly mild to lower the center of gravity. Because of this, I have the engine mounted low --- it's probably about five inches below the hood line. That's why I'm afraid the driveshaft won't fit without oil pan modifications.

Andrew, I'm not sure if this picture will answer your A/C question, but it's worth a shot. This is the compressor location on the 4BD2 between my Jeep's frame rails. The engine is not offset to any side and the rail centerlines are 31" apart. I've never actually seen an A/C compressor for these engines, so I don't know how big it is. It almost looks like a Harrison R4 would fit.

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andrew.fletcher said:
....Also, the shop that's putting this all together for me found an Isuzu starter that is actually turned up snug against the engine so you don't have to off-set the engine.
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How about posting a picture of this starter. I've only seen the one starter that is geared and is quite wide.
 
andrew, the compressor gets into the frame about 20mm or so,,, this is with clearance for the GR starter, so you'll be into it more if you do go with that cough crap cough non GR starter:p. so yeah raising it will work, i have been thinking of a mount to hold the alt and a/c in one and raise them both, plenty of room to go up.


IROC, the comp is a nippondenso radial, just like a harison, delco ect. my SOA is low also, i put the engine in the frame so the oilpan gasket is about level with the top of the frame, and its still a good 3" below the hood.
if that bump is capacity then by all means chop it off if you need clearance!!! the pan holds 7 or 9 qts, thats plenty of oil for an engine that doesnt run real hot and has an internal oil cooler.

also my engine isnt offset per say, the starter and oil filters are centered in the frame which sets the engine to favor the P side a little. most straight engines favored one side or the other, no biggie
 
I've been lurking around this thread for sometime now taking in all the info.
I did some calculations for a cost benefit analysis, and from what I've taken in from the 4BD is the way to go. My 80 with a 3FE is getting around 10 mpg (i know it should be getting better) and the Isuzu can get around 32mpg. See below.
Comparing the installation cost with the improved mpg will determine when you start actually seeing the improvement from the petro cost difference.
3FE_4BT_4BD2T_Comparison.webp
 
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