Performance upgrades for BJ40 & BJ42

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Jun 25, 2003
Rixeyville, VA
I'm currently looking at a bj40 or 42, forgot which one it was. by the way what is the difference between them. it has 60k on a rebuilt diesel engine. what kind of performance upgrades can i do. any turbo? also how much HP does the B engine put out.
ok i found an axt turbo kit goes from the original 90 hp to 132. i think it going to cost 3k though. does that sound right. is it worth? is the stock diesel really slow for a daily driver? should i scrap the idea of diesel and just stay with gas?
BJ40 has 1B and BJ42 has 3B.

I can do second gear starts on level ground without excessive slipping of the Clutch. :D

The advantage with the B over the 2H is that you can buy an Exhaust Brake(Like what was on a similar aged Daihatsu Delta). 8)

With a 2H you can do second gear starts on a slight hill. :)

The BJ42 LX also has Airconditioning, 5 speed Gearbox and other stuff.
Go with the AXT turbo. It is worth it and it does make a large difference in raw pulling power. Diesels are never going to perform like a V8 for off the line acceleration though. I use my '84 BJ60 w/o turbo as the daily driver. The only caution with the turbo is to GET A PYROMETER and don't run over 1200F or you'll blow the engine (piston meltdown and/or crack the head).
If you have more money than mech. and engineering skills, go for AXT (available for 3B but not B... I'm not sure but I seem to remember the kit is made for the 3B-II with the rotary pump as found on the 60 & 70 series, and might need a few adjustments for a 42). Their customers sound very pleased with the performance. If you have more skills than money, build your own turbo setup... :D
If your engine is a B, then a low pressure turbo would be OK, but don't look for big power if you want your engine to last...
I had an AXT turbo fitted to my BJ42 3B cost $3500 best money i have ever spent on the old girl. When i got the dyno report back the figures not really up to the advertising bull but still well worth it. My truck had 201'000km when it was fitted............Dazz
Cruiserhead, my B-engine has 76 HP according to the specs; not much and it's not fast (max 120kmph). Accelerating from 70 to 110 kmph may take a minute. But the engine is reliable.

Denis, you mention a 'low pressure turbo' for the B-engine. Do you have more info on this?

The turbo will give you more torque for pulling up hills but it will NOT give you any more speed. I'm not sure that it would be the best upgrade for you in the Netherlands. Have you considered an H55 5 speed transmission? I can hit 140kph with my '82 BJ60 with the H55 tranny. :D
Cruiser_guy, I am not really looking for more speed. But a little more torque would be nice for going uphill (I know Holland is flat country, but we are planning a holiday to Spain and there are hills), and also less noise when on the highway. So I guess I want a 5 speed transmission AND a performance upgrade. Does a H55 tranny fit on a BJ40 without adaptions? Do I need expert mechanical skills for that?

I can't say much about the B engine as I have no experience with it. Our 'Cruisers are both 3B engines but the H55 is available for the 3B so if the bolt pattern/output shaft size etc. is the same then I guess it would work. The H55 will give you a quieter ride on the Autobahn (less RPM for the same speed) and the AXT turbo will definitely give you more torque. I live in British Columbia and I can pull up hills at 90kph that I used to need to do at 60!!
You can swap a tranny on your own but it is a lot of grunt work, I've done it once to replace the clutch and once to install the H55. The tranny won't help your torque any though.
I also installed my AXT turbo on my own as well it was a little more involved mechanically but easier as it was not as much grunt work.
Where are you in Holland? I have relatives in Maarn and Nimegjn (sp) as well as in Germany.
if its a B engine, its not worth your while strapping anything to it. It cant handle high boost turbos or supercharges, and mediums take a huge toll too, or so they say. if its really a big deal, better off getting a whole new engine, turbo 3b or 13bt or something. while your at it get that 5speed, and split transfercase.
[quote author=Ton link=board=1;threadid=3797;start=0#msg28249 date=1058822888]

Denis, you mention a 'low pressure turbo' for the B-engine. Do you have more info on this?


Well, not really, (I'm no expert about it) but IMO when you think hard about your turbo sizing, you can get pretty much what you want.. i.e: a small turbo for low-end torque should work OK, but will not give such a high boost in the high revs (you hardly ever rev. a B series over 2800rpm anyway) and may actually restrict the exhaust flow quite a bit... the max power might not be greatly improved, but torque would be... OTOH, a bigger turbo might require some more time to spool up and give boost, and give a far better efficiency on the high end... Now I guess you need to find the right balance for youir own application, then it's a matter of trial and error I guess... you can estimate the behavior of your turbo looking at the factory/tweaked specs of your donor engine : capacity, typical powerband, boost pressure, peak power...

I think a conservative setup on a B engine could work fairly well if you make sure you know what you're doing, and don't expect drag-racing power... the engine will remain a tractor engine anyway... ;) :D

Re: 5sp

the H41 (most likely) in your BJ40 and the H55F have almost the same ratios but thr 5th overdrive gear in the H55F. Also, the 5sp is longer than the 4sp by 60mm or so IIRC, and you would need to relocate the crossmember, and modify your driveshafts accordingly... also I'm not sure you can bolt an early T-case on the back of the 5sp, so you would need to swap both cases in... Also remember that 40 and 60-70 series don't have the same shifter, so you need a BJ42 tranny if you don't want to have the shifter coming right through the heater box...

IMHO it's not really worth the effort. bolt a turbo on the engine, as well as an ontercooler while you're at it, and put some bigger tires for overdrive, and you should have a decent setup...
i sort of meant for the cost of turboing an engine, the B wasn't the best starting block, and for the same price or a bit more, you could get a much nicer engine.
I totally agree if we're talking about an AXT or similar kit, but the DIY approach could bring good results with less money ;)
It's definately a challenging endeavour, but I don't think it's really THAT hard...
granted, if I could have a turboed B or a 13BT for about the same price, I'd obviously go for the 13BT ;)

say US$150 for a used turbo in good shape, $100 for a new EGT gauge, $75 for an intercooler, and another $150 for misc stuff and homemade fabjob...
so that's $500 if you do everything yourself :D

I guess a bigger exhaust (say 3") would be nice as well...

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