Isuzu 4BD1-T swap into a '92

[Wheelingnoob]

That's great news!

How much boost are you hitting now before you back out? What size down pipe do you have? I had to run 2.5" for about 13" then flared out to 3" from there back.

Glad you are in the fun stages now!

 

[jtaylor]

I am making a solid 15-18 lbs, but if I put too much right foot it doesn't hold the gear, so there is potentially more to be had. I am running 2.5" all the way.

Jeremy, what is the highest I want to see my egt's pre turbo?

 

[Wheelingnoob]

I am making a solid 15-18 lbs, but if I put too much right foot it doesn't hold the gear, so there is potentially more to be had. I am running 2.5" all the way.

Jeremy, what is the highest I want to see my egt's pre turbo?

Well you want to keep it at or below 1200f pre turbo sustained. Meaning if you are on a grade with a loaded truck that the EGT's at full throttle does pass that after 3-4 min of full throttle. If the EGT's quickly shoot up to 1200f its too hot and would continue to climb as the exhaust manifold heat soaks.

Also need to make sure the probe is in the middle of the exhaust flow, meaning the tip is in the center of the exhaust stream.

For the exhaust try disconnecting the exhaust after the down pipe and see what it does. What sort of muffler are you running is it straight through?

 

[jtaylor]

It shoots up to 1200 fairly quickly, the probe is in the center of confluence of the gasses.

The muffler is actually pretty small, like something you would put on a honda or similar, it seems, it is not straight through. I told the exhaust shop I wanted it quiet, maybe they went a little overboard? What might be a better choice?

Thanks!

 

[Wheelingnoob]

It shoots up to 1200 fairly quickly, the probe is in the center of confluence of the gasses. The muffler is actually pretty small, like something you would put on a honda or similar, it seems, it is not straight through. I told the exhaust shop I wanted it quiet, maybe they went a little overboard? What might be a better choice? Thanks!

Sounds like the probe is placed well. I would try removing the muffler for a test and see what it does. Maybe have the muffler shop make a test pipe for you. For mufflers on Turbo engines you want as free flowing as possible. Any back pressure after the turbo is lost power and efficiency (High EGT's is one indicator).

Any black smoke under hard acceleration? If there is no black smoke (slight haze is ok) then I would bet its a restrictive exhaust making the EGT's climb. If its smoky then turn down the fuel a bit.

 

[jtaylor]

Sounds like the probe is placed well. I would try removing the muffler for a test and see what it does. Maybe have the muffler shop make a test pipe for you. For mufflers on Turbo engines you want as free flowing as possible. Any back pressure after the turbo is lost power and efficiency (High EGT's is one indicator).

Any black smoke under hard acceleration? If there is no black smoke (slight haze is ok) then I would bet its a restrictive exhaust making the EGT's climb. If its smoky then turn down the fuel a bit.

Absolutely zero smoke when the throttle is down

 

[Wheelingnoob]

Absolutely zero smoke when the throttle is down

I would look very closely at the exhaust then. Could be pump timing too but if you did not fiddle with that it should be ok. Hard starting can be contributed to pump timing as well I just cant remember advanced or retarded. It may correlate with EGT's too I think its a retarded timing but you would need to make sure.

 

[scottryana]

Yeah too much retarded timing will cause very high EGT's

 

[cjmoon]

Yeah too much retarded timing will cause very high EGT's

And white smoke at least an old ford IDI that was the case I don't remember high egts but my guess is very restrictive exhaust. Advanced timing will lead to hard starts but pretty extreme advances to affect it

 

[jtaylor]

One little bit of info about the engine - it is a 4bd1tH, from an '86 NPR. From what I have learned it is the same but has retarded timing 0-3 deg. if I am not mistaken, while later models used I think 12 deg. or so. So I am thinking of bumping up the timing to a later model standard, and I will try pulling the muffler and running a straight pipe and see what happens.

And I will do it one at a time, don't want to change too much at once, HA!

Thanks for the input guys!

 

[Wheelingnoob]

My engine was at 8deg when I spill timed it, I adjusted it too 12deg. I think the slightly retarded timing was for CA emissions.

Once you get your head wrapped around the spill timing its fairly easy and precise but man its messy.

I would not think that 3 deg retarded would make a huge difference in EGT's. Did you turn the fuel up at all yet? I would try the muffler first and go from there since you can visibly see its a restriction.

 

[jtaylor]

Currently the fuel is cranked, that is one thing I am going to mess with soon.

 

[Wheelingnoob]

Currently the fuel is cranked, that is one thing I am going to mess with soon.

I would back that off then so under sustained high load the EGT's peak at 1200F once its all heat soaked. Going up a 6% grade for 30 sec at full throttle will not give you an accurate reading. You need something long 2-3min that you can keep your foot into it and then at the end not have exceeded 1200f. Boost is also a great way to cool the EGT's since you are forcing in more air leaning out the AFR's.

If you do not want to touch the fuel then I would highly recommend finding that restriction, muffler sounds like a good bet. The engine is so quiet with nothing off the turbo Ill bet putting a test pipe where the muffler is now will tell you if its the culprit. Probably will not be loud with out it too.

I got an AeroTurbin for mine think it was $78 for a 3".

 

[jtaylor]

A little update. I had some time this morning to fiddle with some stuff. I cut off the muffler that was on there and put on a magnaflow that is straight through with a slight curve, it matched up well and I could tell a difference in the flow. The other muffler was so restrictive it was as loud as the magnaflow but sounded like s***. Now it is a little more peppy.

I also took out the filler restrictor and got a full tank of diesel from the pump.

I then messed around with the air intake. I went from the conical, to nothing, to the factory with no change in how the engine ran. It runs good under load when it is warm, otherwise it runs like s***. Misses and belches smoke like crazy when cold and on startup. I turned down the fuel a smidge, dropped egts a little and with a freer flowing exhaust it barely pulls over 1200 deg. on the egt's on long climbs.

I put about 80 miles on it today, mostly highway and freeway. It runs good when its warmed up, it is a little quicker than the 3fe, but you can feel that there is more torque down low. It pulls long grades pretty good, I had some quality time between 55 and 65 today on the highway, worked well. I also took it up to a local trailhead to go for a little ride with the misses and the pups. There were some steeper sections and the torque was very noticeable. I haven't filled back up so no economy report yet, but I don't think it will be very mindblowing considering it is not running 100%. I still need to fiddle with the tv cable placement, but where it is at isn't too bad, but it can be better.

So one pic of this thing finally back where it should be!

Overall I am getting more and more pleased with how this has turned out, I still have many little things to do, but at least it is running and driveable. I shall carry on........

 

[jtaylor]

Update

Wanted to give a little update, I have been putting some miles on this rig and so far am really liking it! I still have some things to work on (I know I keep saying that), and now that I pulled the injectors to send them off to get rebuilt I will tackle them!

First thing - send off injectors to get rebuilt, this is the first step to correcting the running problem. I have been led to believe this should fix it, but will see.

Second - replace a couple leaking AN fittings

Third - y-link steering upgrade, so I can actually drive this thing off-road for real, pussy footing in the dirt has been a test of my self control - not a bad thing?

Fourth - wrap up the wiring for good, just needs to get packaged away neatly

Fifth - second battery tray is on the way, need to integrate that back in to the IBS and hook up the fuse panel and get the fridge back in.

I have recorded so far a little over 13 mpg. But keep in mind it has not been running properly. After the injectors hopefully that should go up.

Got out to Gooseberry last weekend, finally got to try out the new tent.

 

[half k cruiser]

whoa, that is one badass pinstripe you have on the side of your rig. I'm guessing that's not a sticker ?

 

[jtaylor]

the ding on the rocker or the artwork on the back?

 

[jtaylor]

Injectors are back, two had bad nozzles, all were rebuilt and had new nozzles installed. I got my 94 battery box and got the battery wired in to the IBS. And I have started working on the steering conversion. Pitman arm is getting re-tapered today and everything else is off and the new is ready to go back on. Getting closer!

 

[cody c]

Not sure why you need to upgrade your steering to y-link before you wheel it, are your steering links worn or bent?

Lots of folks wheel the piss out of their 80's without fear nor damage to their steering linkages. I've had zero issues with mine with a heavier powertrain and 37's and now 38's.

 

[lostih]

Thanks for the write up on your swap. I'm leaning the 4bd1t direction after spending days and days reading about them. I'm curious about more information on the differences you found with the early 4bd1t? I may have found a lead on a motor from an early US NPR and want to understand any differences with the later engines. Dougal mentioned they have a different cam pre-'88. Sounds like the timing is different per your earlier post. Do you know of any other differences?

How are the new injectors treating you?