more power from a 4bt1t/2t

[Dougal]

both of those are a bit different,, and they are both a bit different from mine hmm. ok so we have the max fuel screw, now in those pics on the back of the pumps, the top one has a big "thing" and the bottom one does not, however under that big "thing" is a big nut looking debacle,,,, mine has that with what i think is a high altitude bit attached? ibelieve i can screw it in or out to change altitude performance but i'm still working on that info, however, behind that piece and under a cap, (on mine) is another screw with jam nut,,, i though that was max fuel, but maybe its pressure?? anyone know?? in the FSM it shows a pretty good reference to what i'm talking about with a cutaway showing whats under the cap.
does any of this make any sense??

I know what you mean.
The photos on www.isuzudieselswapper show a pump with what looks like a big pressure can on the back of the pump at main shaft level.
Inside the pumps at that point is the main spring that the governor works against, I haven't spent enough time thinking about those to figure out what the effect of playing with that spring will be.

The pump you see with the big nuts out the back is from my 86 4BD1T, the cylinder above with a hose attached is the aneroid (boost compensator).
The other pump (no nuts, no aneroid) is a rebuilt one I bought from a guy who knows nothing about it other than Isuzu 4BD1T/4BD2T. I tried to fit it to my 4BD1T but the shaft sizes have changed and the drive gear doesn't fit.

But I learned a lot in the process. I actually swapped the aneroid and several internal governor parts across before finding they didn't fit and had to swap it all back.

[bush65]

... however under that big "thing" is a big nut looking debacle,,,, mine has that with what i think is a high altitude bit attached? ibelieve i can screw it in or out to change altitude performance but i'm still working on that info ...

Sorry I'm not familiar with high altitude bits.

... however, behind that piece and under a cap, (on mine) is another screw with jam nut,,, i though that was max fuel, but maybe its pressure?? anyone know?? ...

The hexagon cap screws onto the guide screw. The thin nut that the cap screws up against is the guide screw lock nut.

The guide screw guides the govenor shaft. The guide screw is adjusted so that it's inner end is flush with the inside of the govenor cover - when adjusted correctly the distance from the back of the govenor cover (the surface under the lock nut) to the outer end of the guide screw, should be 14mm +/- 0.5mm.

I don't know if this value may be different on your pump with high altitude bit.

The screw you are referring to, in the center of the guide screw, is the threaded end of the govenor shaft. There are 2 nuts (lock nuts) on the govenor shaft.

The adjustment of the guide screw and govenor shaft determine the govenor spring force apposing the flyweights. Screwing the govenor shaft out (from the govenor cover) increases the spring force.

As the pump speed increases, the flyweights move out and pivot the tension lever against the govenor spring. As the tension lever pivots, it turns the torque cam. The profile of the torque cam acts as a limiting stop for other mechanisms in the govenor. The rotational position of the torque cam and it's profile (specifically designed for the engine the pump is fitted to) determine the position of the control rack.

The position of the control rack, determines how much fuel is injected.

[bush65]

...The photos on www.isuzudieselswapper show a pump with what looks like a big pressure can on the back of the pump at main shaft level.
Inside the pumps at that point is the main spring that the governor works against, I haven't spent enough time thinking about those to figure out what the effect of playing with that spring will be...

I may be wrong, but it looks to me that, what you call a pressure can, is not at main shaft (pump cam shaft) level, but at the level of, and to one side of, the govenor shaft and spring.

...The pump you see with the big nuts out the back is from my 86 4BD1T, the cylinder above with a hose attached is the aneroid (boost compensator)...

The big nuts (hexagon cap and locknut) are inline with the pump cam shaft and the flyweights. The screw under this cap adjusts the force of the idling spring.

...The other pump (no nuts, no aneroid) is a rebuilt one I bought from a guy who knows nothing about it other than Isuzu 4BD1T/4BD2T...

That pump looks the same as the one on my 4BD1-T.

[rhino]

the one on dieselswapper site is the same as mine, there seem to be differences in countries..
that "pressure can" is what i was refferring to as maybe an altitude thing. looks like whats on the toyota pumps.
so it looks like there are many adjustments to be made, but the main two are timing (rotate pump body) and fuel (screw/cam on side of body) is that about right??
i dont care for needing to get in and start messing around with all the other things unless they are improvements over stock as well.
on my pump it didnt get a "blob" on the fuel screw instead it has a nice cap that is semi permanent, like the caps on carbies. so i think my pump is all stock from the factory and unmolested, thats a good thing.
seems to be a bit of a dead spot between 1st and 2nd gears, not a big deal and i can compensate by revving up a bit more in 1st gear before i shift, what do ya think about that? i have the non wastegate turbo so i am thinking i dont have a boost adjustment eh?

[Dougal]

Let us know when you get gauges hooked up to it Rhino. I'm interested to see what factory boost and EGT's numbers come out like.

The other adjustments which may interest you are on top of the pump (two limit screws on one lever). They are idle speed and max speed.

[Dougal]

I may be wrong, but it looks to me that, what you call a pressure can, is not at main shaft (pump cam shaft) level, but at the level of, and to one side of, the govenor shaft and spring.

Here's the pic and you're right it's not at main shaft level.
http://www.isuzudieselswapper.com/images/dsc00066.jpg

It appears to be in the exact same location as the aneroid pushrod. So altitude compensator quite possibly. The aneroid works by restricting the rotation of the cam which the max fuel adjustment acts on. Essentially moving the max fuel limit.
Looks like the altitude compensator works the same way.

When you're feeling brave Rhino, pull it off and tell us what's there. It is external to the main pump function, so not that many bad things can happen.

[rhino]

you got it dougal,,, i did point an infra red temp guage at the turbo exhaust body under load at brisk acceleration, didnt quite get to 900 F, of course that just the body and it will be a little less than the actual tamp of the air flowing inside, but its a pretty good estimate. i have played with the idle screw, lowered idle a bit to what sounded good to me, the engine runs tops and i dont want to goof it up so tinkering will be a slow deliberate process. but i will be keeping updates and my impressions.

BTW that can thing our version of what you guys got for altitude compensator, its cool bacuse i can adjust for altitude manually buy loosening the jam nut and turning the body of that cylinder.

[bush65]

...BTW that can thing our version of what you guys got for altitude compensator, its cool bacuse i can adjust for altitude manually buy loosening the jam nut and turning the body of that cylinder.

Sorry in my earlier post, I had misunderstood the nut you were talking about.

Seeing the pic that Dougal linked to and your last post have cleared it up.

I don't have a pump with the boost compensator, and neither the boost or altitude compensator are mentioned in my engine workshop manual or injection pump service manual.

In the pic of the pump with altitude compensator, that Dougal linked to, the govenor shaft (and spring) are under the welsh plug above and to the left of the altitude compensator.

Some pumps have external adjustment of the govenor and idling springs. The adjustments have a hexagon cap over them.

The hexagon cap over the idling spring adjustment can be clearly seen on the back of the pump with boost compensator in Dougal's 1st pic. It is in line with the pump camshaft and flyweights.

[bush65]

Some people think of boost compensators as devices to increase fuel as the boost pressure increases.

But it is valid (perhaps more so), to think of them as devices to reduce fuel and hence black smoke/particulate emission, when the boost pressure reduces.

An altitude compensator probably works in a similar way, to reduce the fuel when the barometric pressure reduces at higher altitudes.

[bush65]

...I'm still hoping some one can tell me what the max fuel delivery of the pump is (per cylinder, per injection)...

I was looking at the technical instruction manual for the VE pump (4th edition 1999), and table 1 gives properties and characteristics data for different bosch diesel fuel injection systems.

Some of the data for the 'A' type pump (like that used on 4BD1 and 4BD1-T) are:

- injected fuel quantity per stroke 120 mm^3
- maximum nozzle pressure 750 bar
- maximum speed 2800 rpm
- maximum power per cylinder 27 kW

The power per cylinder appears conservative. 4cyl x 27kW = 108kW (~145 hp). But I assume the injected fuel quantity is determined from the plunger diameter and stroke.

FWIW, the values for the P7100 pump that the performance cummins people like are:

- injected fuel quantity per stroke 250 mm^3
- maximum nozzle pressure 1,200 bar
- maximum speed 2500 rpm
- maximum power per cylinder 55 kW

And for the VE pump:

- injected fuel quantity per stroke 120 mm^3
- maximum nozzle pressure 1,200/350 bar
- maximum speed 4500 rpm
- maximum power per cylinder 25 kW

[rhino]

In the pic of the pump with altitude compensator, that Dougal linked to, the govenor shaft (and spring) are under the welsh plug above and to the left of the altitude compensator.

i have no facts that that IS an altitude compensator, i just suspect it may be cause it looks just like the toyota equivalent. i am trying to find out, i have gotten some good info from the dealer,,, then he reffered to a diesel guy that would have heaps more info, i look forward to talking with him next week.

[Dougal]

I was looking at the technical instruction manual for the VE pump (4th edition 1999), and table 1 gives properties and characteristics data for different bosch diesel fuel injection systems.

Some of the data for the 'A' type pump (like that used on 4BD1 and 4BD1-T) are:

- injected fuel quantity per stroke 120 mm^3
- maximum nozzle pressure 750 bar
- maximum speed 2800 rpm
- maximum power per cylinder 27 kW

The power per cylinder appears conservative. 4cyl x 27kW = 108kW (~145 hp). But I assume the injected fuel quantity is determined from the plunger diameter and stroke.

You're an endless source of knowledge John.
Taking a BSFC of about 250g/kwh (best point is approx 220), delivery of 120cc/1000 strokes should be about 550Nm. A figure that makes 200hp almost possible.

Here's a cutaway I found on the zexel site. You can order these in poster size.

[Dougal]

Isuzu has a marine 4BG1TC engine which puts out 147kw. The industrial 4BG1 engines use the type A pump, I wonder if this one does.

http://www.isuzu.co.jp/world/product/marine/4turbo.html

[rhino]

now if we could just find a cutaway like that for diesel kiki pumps,,,,
so what about boost? when do we begin to bring that into the power discussion. without a wastegate to adjust, how do we bump up boost pressure? i need to get a gauge on and see what mine is stock.

looks like these guys will have some good stuff comming up on there web site, maybe good for some info.http://www.realdiesel.com/injectionpumpservice.html

[Dougal]

now if we could just find a cutaway like that for diesel kiki pumps,,,,
so what about boost? when do we begin to bring that into the power discussion. without a wastegate to adjust, how do we bump up boost pressure? i need to get a gauge on and see what mine is stock.

looks like these guys will have some good stuff comming up on there web site, maybe good for some info.http://www.realdiesel.com/injectionpumpservice.html

Diesel Kiki changed it's name to Zexel in 1990. They are Bosch's japanese arm.
The pumps are all the same. That type A cutaway is what we've got. Minor changes over the years and markets.

For you with no wastegate, more fuel will give you more boost. What the stock or even upper limit of that turbo are I don't know.
I've got one here I picked up secondhand, the compressor on them is a 45 Trim T25. Same as the Nissan CA18DET T25 turbo I've got going back onto mine.

[rhino]

wow dougal, awsome info. i am comming to the game pretty late here so excuse my rather newbie questions somtimes.
so zexel type A is where to look for info, cool i'm on it for my own info if nothing else.

[jwt27ta6]

Okay then



These are the fuel pumps you'll find on a 4BD1T or 4BD2T.
The cam on the side is the maximum fuel adjustment. The screw on that (with the lead seal blob) is the one you adjust to change the maximum amount of fuel you'll get. Winding the screw out (lets cam move clockwise) gives you more fuel.

Tweak at your own risk and always wear an EGT gauge.

&

Governed to 3600rpm.

Yes it can be adjusted higher very easily (adjustment screw). But running these engines near max RPM isn't a pleasant experience.

My EGT's climb quite quickly above 3000rpm, I suspect dropping volumetric efficiency is the cause. It feels like aroudn 3200 is peak power anyway.

If you set your max fueling for max EGT at max revs, then you start to lose more as you increase your maximum engine speed.

Sir, I am so happy to finally find a forum & thread where people know what they are talking about with the 4BD2T diesel!!!

Could you please help me with the following? I have analyzed this post & "isuzu 4BD1T swaps?!", but need some more details on the 4BD2T 3.9L turbo intercooled diesel, since I'm new to this engine. I know it is a lot of questions...sorry.

1) Governor: Where is this screw? From stock, how many turns in or out do u recommend, since I don't want to over rev? U have pic of this screw location?

2) Screw for fuel pump: In the above photo, is it the screw that is sitting sideways, adjusting that cam w/screw coming sideways out of pump, in about the center of above pic? Could u mark in the pic the fuel screw & any other pertinent adjustable items? And what is the "the lead seal blob"?... cause that doesn't fit the screw that I'm thinking is the fuel screw. How many turns out would u recommend?

3) Diaphram for wastegate boost: Where exactly is the diaphram? How adjust for more boost, if possible? How adjust to maintain boost longer?

4) You said, "Recently I've increased my gearing to drop cruise to 2000rpm, saving around 10% in fuel compared to my old gearing of 2500rpm cruise." What gearing did u change? manual tranny or rear end? Mine is an auto w/OD, which BTW is in an RV, built on Isuzu NPR chassis. I'm thinking it would be easier/cheaper to change ratio of gears in rear end for better MPG & less engine noise on HWY. Do u know what the stock ratio is? What ratio to aim for? Or would it just be easier/cheaper to replace tranny?

5) I know this diesel is known to lack power, so maybe I'm just experiencing the norm, but it seems really flat @ the bottom end. Any mtn items that I should check, ie...fuel filters, air filters?

I know this is a lot of questions, but I know it will help me & maybe many others in need.

Xnks so much....in advance!

[Dougal]

Sir, I am so happy to finally find a forum & thread where people know what they are talking about with the 4BD2T diesel!!!

Could you please help me with the following? I have analyzed this post & "isuzu 4BD1T swaps?!", but need some more details on the 4BD2T 3.9L turbo intercooled diesel, since I'm new to this engine. I know it is a lot of questions...sorry.

1) Governor: Where is this screw? From stock, how many turns in or out do u recommend, since I don't want to over rev? U have pic of this screw location?

The speed limiter?
Those are the two screws on the top of the pump. The black pushrod that you can see on the pump in the bottom of the picture. They're not far from that.
One sets idle rpm, the other sets max rpm.
I'd recommend leaving it at the 3600rpm factory setting.

2) Screw for fuel pump: In the above photo, is it the screw that is sitting sideways, adjusting that cam w/screw coming sideways out of pump, in about the center of above pic? Could u mark in the pic the fuel screw & any other pertinent adjustable items? And what is the "the lead seal blob"?... cause that doesn't fit the screw that I'm thinking is the fuel screw. How many turns out would u recommend?

Yes that's the one, just to the right of the bracket with the bend in it. The lead seal blob is just visible if you look closely on the wire through the bolt.

I recommend getting an EGT guage (exhaust temperature) before playing with the fuelling screw. Fit the EGT probe before the turbo.

3) Diaphram for wastegate boost: Where exactly is the diaphram? How adjust for more boost, if possible? How adjust to maintain boost longer?

Wastegate is the can mounted on the turbo (only certain year 4BD1T's have wastegated turbos, 4BD2's have no wastegate on the turbo).
With a non-wastegated turbo more fuel will give you more boost. If that isn't enough then a turbo swap is necessary.

4) You said, "Recently I've increased my gearing to drop cruise to 2000rpm, saving around 10% in fuel compared to my old gearing of 2500rpm cruise." What gearing did u change? manual tranny or rear end? Mine is an auto w/OD, which BTW is in an RV, built on Isuzu NPR chassis. I'm thinking it would be easier/cheaper to change ratio of gears in rear end for better MPG & less engine noise on HWY. Do u know what the stock ratio is? What ratio to aim for? Or would it just be easier/cheaper to replace tranny?

I changed my 4wd transfer case. I agree that a diff ratio will be the easiest for you to change.

5) I know this diesel is known to lack power, so maybe I'm just experiencing the norm, but it seems really flat @ the bottom end. Any mtn items that I should check, ie...fuel filters, air filters?

I know this is a lot of questions, but I know it will help me & maybe many others in need.

Xnks so much....in advance!

Definitely check your fuel and air filters. The 140hp or so they have stock is plenty for a light vehicle, but wouldn't go far pushing an RV. I recommend fitting EGT and boost gauges before any fuelling mods.

Some 4BD2's have altitude compensators, but I know little about them. They have been mentioned in this thread.

[jwt27ta6]

Wow! Xnks for that quick response....must be in part to your NZ residency. I work nights. So, seems we in sync, which is good for me! Xnks for all the answers! Yeh, I've printed these pages for my reference & have taken note of the alt comp. I can't remember if mine has it or not.

Since u are up, how do I adv the timing of pump that I see referenced? Does that involve the alt compensators? Is the alt comp the can thing on back of pump in top pic?

I've seen in other forums about advancing the timing. Are they talking about the pump? Or something else?

U also mentioned u adjusted the lower end of non-boost fuel pressure. Where & how did u do that? I read it, but still a bit fuzzy.

It isn't a big RV, only 26', & obviously not carrying freight, so I'd think it not too much for it.

[Dougal]

Wow! Xnks for that quick response....must be in part to your NZ residency. I work nights. So, seems we in sync, which is good for me! Xnks for all the answers! Yeh, I've printed these pages for my reference & have taken note of the alt comp. I can't remember if mine has it or not.

Since u are up, how do I adv the timing of pump that I see referenced? Does that involve the alt compensators? Is the alt comp the can thing on back of pump in top pic?

I've seen in other forums about advancing the timing. Are they talking about the pump? Or something else?

U also mentioned u adjusted the lower end of non-boost fuel pressure. Where & how did u do that? I read it, but still a bit fuzzy.

It isn't a big RV, only 26', & obviously not carrying freight, so I'd think it not too much for it.

Somtimes the time diff works well, but often it doesn't.

The timing is changed by loosening the four bolts holding the pump on and tilting it towards or away from the block. To be honest I can't remember which way is advance and which is retard.

My fuel pump has an aneroid which reduces fuel when off boost. That's the cylindrical housing on the back of the top pump in the picture.
I can adjust the pushrod the aneroid pushes on. But to my knowledge the 4BD2's don't have them.
I don't know exactly how the 4BD2's restrict fuel when off boost. It may be done on an RPM basis inside the pump. But if so it's not something that's easily changed.

[jwt27ta6]

Ok, xnks very much. I'll keep all this in mind next time I get a chance to mod it. Take care. U've been most helpful!!!

[Dougal]

So if we can get between 500-600Nm of torque from a 4BD1T, how much air do we need to burn clean?

Iveco do a commonrail 3.9L which is factory rated at 560Nm, it runs 25psi boost and is specified at max intake temp (after intercooler) of 50 deg C.
Since our engines are mechanical injection and won't spray as well, I think 30psi boost is good initial target to avoid smoke.
http://www.ivecomotors.com/uploads/I...P1D04N001E.pdf

[astr]

So if we can get between 500-600Nm of torque from a 4BD1T, how much air do we need to burn clean?

Iveco do a commonrail 3.9L which is factory rated at 560Nm, it runs 25psi boost and is specified at max intake temp (after intercooler) of 50 deg C.
Since our engines are mechanical injection and won't spray as well, I think 30psi boost is good initial target to avoid smoke.
http://www.ivecomotors.com/uploads/I...P1D04N001E.pdf

Interesting engine! Other than displacement, it appears similar to the Isuzu 4HK1 which superceded the 4HE1 which superceded the 4BD1/2 series, at least here in the uS. In addition to common rail injection, it is overhead cam and 4 valves per cylinder. It also seems to have the gear train for the cam at the rear of the engine, like the 4HE1 and 4HK1. I wonder why manufacturers are going to this layout?

[Dougal]

Here's part of my plan.

But in stock form they can offer a lot of improvement with the turn of a screw. The EGT's from the factory don't go much past 400 deg C preturbo.

I've gotta retract that statement.
The guys who did the last rebuild on my pump were nowhere near factory settings.
The 400 odd deg C I was getting was the result of a worn out aneroid diaphragm (that's the boost device on the fuel pump). I fixed the aneroid and now the EGT's easily run past 750 deg C with 19psi of boost (no intercooler).

I cannot stress enough the importance of a good EGT gauge fitted before the turbo.

[carcrafter22]

Has anyone tried to add an intercooler to a non intercooled 4bd? I wonder what kind of temp drop we could get out of a factory ford power stroke or cummins intercooler? obviously we could up the fuel and boost if we could control the egt's.

[Dougal]

Has anyone tried to add an intercooler to a non intercooled 4bd? I wonder what kind of temp drop we could get out of a factory ford power stroke or cummins intercooler? obviously we could up the fuel and boost if we could control the egt's.

Yes, plenty of Aussies with these engines in landrovers which are turbocharged and intercooled. Take a look:
http://www.aulro.com/afvb/isuzu-land...iasts-section/

I have an intercooler for mine, but I haven't installed it as I need to upgrade the axles before getting any more power.
I think my engine is currently running close to 500Nm of torque. That's with 20psi boost, no intercooler and EGT's up to my 750 deg C limit.
At 20psi the air out the turbo is above 130 deg C, so an intercooler is a logical step.

[scatsihc]

giezy,contact me im in london on. im putting 4bd2t in a 59 panel.its sitting in chassis just making up mounts.

[love-horsepower]

im overhauling one now. im going to be doing a little porting, ceramic coating heads ,valves ,chambers and pistons and balancing the assembly. what are you planning on? rod

[carcrafter22]

Has anyone made a custom header for the 4bd engine yet? I am thinking of doing one very soon for my particular conversion so that I can set the turbo where I want it to be. I am installing a different alternator to gain clearance for the HY35 turbo and think it will be easier to make an air intake and exhaust system if I can move the turbo.

I only have experience with headers and turbocharged diesel engines in a duramax application. I know there you dont see much gain until you get into big power ( ie 650+ at the wheel) besides a drop in egt. This is however a diffeent application all together what with different ports and cam timing as well as engine size. Most of the dmax engines with headers are more of a max effort engine due to where the gains are seen, I wonder if this will be the case with the 4bd? Maybe I need to stop asking questions and just build something lol

What do you guys think would be a good size for the primary tubes?

I would make it out of mild steel for some short term testing then out of stainless in a later version of course.

[Dougal]

Has anyone made a custom header for the 4bd engine yet? I am thinking of doing one very soon for my particular conversion so that I can set the turbo where I want it to be. I am installing a different alternator to gain clearance for the HY35 turbo and think it will be easier to make an air intake and exhaust system if I can move the turbo.

I only have experience with headers and turbocharged diesel engines in a duramax application. I know there you dont see much gain until you get into big power ( ie 650+ at the wheel) besides a drop in egt. This is however a diffeent application all together what with different ports and cam timing as well as engine size. Most of the dmax engines with headers are more of a max effort engine due to where the gains are seen, I wonder if this will be the case with the 4bd? Maybe I need to stop asking questions and just build something lol

What do you guys think would be a good size for the primary tubes?

I would make it out of mild steel for some short term testing then out of stainless in a later version of course.

Looks like you're going to be the first.
For the tube size I'd get a round that can be hammered to the same square as the exhaust ports in the head.