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Discussion Starter #1
Has any one played with the pump to get some more power manly tq? or is there any thing else with these engines I am planning on installing one in my astro with a nv4500 to tow my camping trailer.
 

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Discussion Starter #3
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.
Is that the twin turbo set up you are working on? And how much power do you can get from playing with the pump?
 

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Hey Dougal,
Can you post a couple more pics of your setup. My swap is for a '93 RR LWB. What turbos are planning on using for your compounds? Boost levels? anticipated hp&trq?

Thanks.
 

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I too am interested in which screws to turn. I bumped my timing a little and reset the valves last year and it made a world of differance but I have a felling once i add the turbo I'm going to need to do a little tweeking on the pump.

Thanks in advance,
Anders
 

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Hey Dougal,
Can you post a couple more pics of your setup. My swap is for a '93 RR LWB. What turbos are planning on using for your compounds? Boost levels? anticipated hp&trq?

Thanks.
I've got a PDF I can email you with some more pics. But there's not a lot more to see in the other views as the piping hasn't all been drawn in yet. There's an air\water intercooler going over the other side.

The turbos I plan to run are quite small, the intention is high boost at low rpms. A Garrett GT2256V (from a mercedes 2.7 diesel) and a GT2860 from a Nissan Skyline. T28 is the big one.
I'm going to set it at 30psi for a start, I only intend to get 200hp from it, but around 500Nm. I don't expect to get it dyno'd though so I won't be able to confirm anything. The plan isn't for big power, the plan is for the widest possible boost curve.

Is your rover LHD or RHD?
I have all the mounts drawn up to bolt this engine into a RHD rangerover, for LHD the factory power steering box is in the way. You can see in the picture above the Isuzu gearbox grafted in where the LT77 was. The LT230 bolts to the back of what you see there, I haven't drawn it yet.
 

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Discussion Starter #8
I've no idea what power levels are possible as no-one has pushed one of these engines then dyno'd it.
I am just hoping to get more performance than the old 4.3 in the van now I was thinking about getting it in there first then play with the thing, just whant to pull the trailer easilly with this engine the 4.3 struggles a little now up long hills:(
 

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Is your rover LHD or RHD?
I have all the mounts drawn up to bolt this engine into a RHD rangerover, for LHD the factory power steering box is in the way. You can see in the picture above the Isuzu gearbox grafted in where the LT77 was. The LT230 bolts to the back of what you see there, I haven't drawn it yet.
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We're LHD over here. The steering box wouldn't be a big deal as i would probably be swapping that also. What are using? I think TroutRover used a Scout box in his swap w/ the 4BT.
About your liquid intercooler, what are you using for fluid and where's your cooling rad located? Have you ever measured the temp drop. I'd rather a water to air since it takes up much less space up front.

Thanks.
 

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We're LHD over here. The steering box wouldn't be a big deal as i would probably be swapping that also. What are using? I think TroutRover used a Scout box in his swap w/ the 4BT.
About your liquid intercooler, what are you using for fluid and where's your cooling rad located? Have you ever measured the temp drop. I'd rather a water to air since it takes up much less space up front.
I run the usual water/antifreeze mix in my water/air cooler circuit. I have run before with a homemade heat exchanger in it, the new large one I haven't fitted before. The radiator is out front just behind the grill.
I have monitored water temps, but the last heat exchanger couldn't get enough heat out to make the system run hot, the hot side of that radiator would be medium warm to the touch, the outlet cold.

I'm RHD and running the stock steering box, it works great for me and I have no reason to swap.

You may want to edit your post and remove your email address, I've sent the PDF.
 

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S-10 Diesel

Has any one played with the pump to get some more power manly tq? or is there any thing else with these engines I am planning on installing one in my astro with a nv4500 to tow my camping trailer.
Have you started this project, yet? I would like to see pictures of it.
I am planning on putting a diesel into my 1999 S-10 ZR2 4X4.
If it will fit into a Astro, I should be able to fit it into my s-10 with no problem. A lot of guys are going with the 350 vortec's but I want the mpg and torque of the diesel.
 

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Discussion Starter #13
Have you started this project, yet? I would like to see pictures of it.
I am planning on putting a diesel into my 1999 S-10 ZR2 4X4.
If it will fit into a Astro, I should be able to fit it into my s-10 with no problem. A lot of guys are going with the 350 vortec's but I want the mpg and torque of the diesel.
Might be a while till I get to it I still am looking for a engine that runs good so I don't need to do much to rebuild if at all. I thought agout a sbc. in the van but whant milage to go with the tq.
 

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Hi,

I'm new to the forum, an engine builder by trade & specialize in airflow development.

You have certainly picked on a nice engine for the forum. I had no idea that there are so many wanting info or conversions etc for these mighty little engines.

I have a 4BD1T in my isuzu NPS 4wd truck, it's time i rebuild the engine & make her perform better. In the coming weeks i will be dismantling the engine & making several performance modifications to it before rebuilding & modifying the head.
If there is anybody interested i can proceed step by step on rebuilding & modifications done for the forum.
It should be an interesting project, i can post pictures etc as well.

Let me know if there's interest i can take the time to do it if there is, not sure if anybody is interested or not?

Someone will have to inform me on how to post pictures though?

Thanks, Great Forum!!!!
 

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I have a 4BD1T in my isuzu NPS 4wd truck, it's time i rebuild the engine & make her perform better. In the coming weeks i will be dismantling the engine & making several performance modifications to it before rebuilding & modifying the head.
What are the performance modifications you're planning on making?

I last rebuilt my engine about 18 months ago, got it out now for a clean up and paint.
 

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Hi Dougal,

The 4BD1T has a few oiling issues that need correcting for pushing these hard. The big ends have a few issues but once modified the reliability under extreme conditions is enhanced, i will tackle these sorts of things with the rebuild modifications.
Basically i will be blueprinting my engine much like a race engine & reworking the ports with a cam change etc etc etc.
There are some good gains to be had with these engines & with the right work reliability goes up as well.
My NPS truck works hard here in Australia & it's a long way between things if you break down so reliability is paramount.

Thanks
 

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Hi Dougal,

The 4BD1T has a few oiling issues that need correcting for pushing these hard. The big ends have a few issues but once modified the reliability under extreme conditions is enhanced, i will tackle these sorts of things with the rebuild modifications.
Basically i will be blueprinting my engine much like a race engine & reworking the ports with a cam change etc etc etc.
There are some good gains to be had with these engines & with the right work reliability goes up as well.
My NPS truck works hard here in Australia & it's a long way between things if you break down so reliability is paramount.

Thanks
I'm interesting in these oil problems.

My engine was balanced several rebuilds ago (it's had a long and rough history), it made a huge difference, heaviest conrod bigend had 17g more than the lightest.
But what do you mean by "blueprinting"? This particular term means different things to different people who're building engines for different purposes. Some take tolerances to the tight side, some to the loose side.

IMO there's not much to be gained from many of the factory tolerances. The cranks are nitrided, if you grind that coating off you're in for a world of hurt. and the factory matched piston/ring/liner set won't be improved on either. That only leaves bearings to play with.

I also question the cam and porting. The inlet ports on this engine are huge and the rpm is low. Removing material from the head will weaken it, possibly causing problems later.
A cam change to enhance VE will have very limited benefits compared to simply pushing more boost. Getting cylinders full of air in a turbocharged engine isn't too much of a problem. I'm quite sure that if there was a cam change that had no bad side effects, Isuzu would have found it.

My biggest question is how much fuel can the factory pump deliver?
This is going to be the single biggest influence on performance and I haven't found anyone who has opened one all the way up yet.
 

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Oiling Issues

Hi Dougal,

The 4BD1T has a few oiling issues that need correcting for pushing these hard. The big ends have a few issues but once modified the reliability under extreme conditions is enhanced, i will tackle these sorts of things with the rebuild modifications.
Basically i will be blueprinting my engine much like a race engine & reworking the ports with a cam change etc etc etc.
There are some good gains to be had with these engines & with the right work reliability goes up as well.
My NPS truck works hard here in Australia & it's a long way between things if you break down so reliability is paramount.

Thanks
I am also curious about oiling issues that you refer to. I haven't read anything that would indicate that there are big end problems with the 4BD1/2T engines. Could you elaborate. Also, what mods specifically are you proposing to address these oiling issues. Any input would be appreciated as I have almost no first hand experience with these engines.
 

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There are a few questions to answer here, i'll give it a go. This will more than likely put most of you to sleep.

quote
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My engine was balanced several rebuilds ago (it's had a long and rough history), it made a huge difference, heaviest conrod bigend had 17g more than the lightest.
But what do you mean by "blueprinting"? This particular term means different things to different people who're building engines for different purposes. Some take tolerances to the tight side, some to the loose side
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Every engine should be balanced properly if good running & reliability is needed. Like mentioned 17grms is a lot of unbalance.


Blueprinting is only making sure that each cylinder, deck height, combustion chamber, rod & main clearances etc etc are the same as each other. This is only so each cylinder, journal etc is operating in the same manner & not differently to each other.
Of course if one cylinder differs from the rest it will operate differently.
The term blueprinting doesn't differ but the engine application will require differing blueprinting clearances.
Eg, for street engines--gasoline, we can run tighter clearances than say for a 8000rpm race engine.
Blueprinting is application based sort of thing but the term means the same thing.
Most people wouldn't worry about it for Diesels though but at least you know what you have if you do it properly.

quote
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IMO there's not much to be gained from many of the factory tolerances. The cranks are nitrided, if you grind that coating off you're in for a world of hurt. and the factory matched piston/ring/liner set won't be improved on either. That only leaves bearings to play with.
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Your right there is never much to be gained in bearing clearances, just make sure there right. Usually reading the old bearings can tell a lot as to what is needed in the next rebuild.

There is much to gain from piston modification, a piston deck, dome or dish is the "bottom" of the combustion chamber & anything that improves combustion is going to lead to more power.




quote
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I also question the cam and porting. The inlet ports on this engine are huge and the rpm is low. Removing material from the head will weaken it, possibly causing problems later.
A cam change to enhance VE will have very limited benefits compared to simply pushing more boost. Getting cylinders full of air in a turbocharged engine isn't too much of a problem. I'm quite sure that if there was a cam change that had no bad side effects, Isuzu would have found it.
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Anything we can do to make an engine breath better is going to increase power, hence race engines or Turbo engines. With this increase in air & fuel creates more power to do the work.

Yes the rpm is low & the ports are big a BAD combination for responsive power.
I have spent years on my flowbench porting heads for diesel, street & race engines & like anything it is application based. Heads are made with an excess of material & as long as common sense is applied you will never run into trouble especially for diesel porting or street car use. Porting doesn't mean hacking out the ports but tuning them for the application.

A factory camshaft can always be improved upon no matter what engine be it a GM or Ford etc etc etc.
Every mass engine manufacturer for normal highway use vehicles can't spend the time to develop huge power gains.
They are more interested in Cost firstly & then Emmisions & Fuel economy. With these things in mind std cams can be vastly improved upon for HP & Torque figures. Just like any old chevy engine, tame as a baby in std form from factory but F me do they wake up screamin with the right work. Just an example only of course we don't want the Isuzu with performance gains of gasoline engines & won't get it because the fuel burns to slow--unforunately!!


Cylinder filling is a problem even with a Turbo, i haven't got the paper work with me at the moment so don't hold this as gospel.
It takes from memory 150cfm of air for 100hp so if we just look at the "Theoretical CFM" for this engine it is roughly.
Approximate only:
3.9ltr = 238cu/in & just say 3500rpm at the engine
238cu/in X 3500rpm/ 3456 = 241cfm

241cfm equates to around 160hp.
This is for a Normally aspirated engine & not Turbo.

The engine in reality only makes around 120hp in Turbo form about 25% less than the Naturaly Aspirated Theoretical figure because of the VE & so about 180cfm with the Turbo.

As you can see even with a Turbo the Actual VE is much less & the power figures show this at around 120hp or so. A cam & a port job done correctly will not only increase hp but also improved torque where they so badly need it.

Increasing boost is easy but the results won't change much due to many factors. To increase boost we need the exhaust gas to drive it as well, before we increase boost we should increase the engines airflow capability & configure the ports accordingly to do so.
This doesn't mean hacking out the ports but "tuning" them to the application because in reality we are only getting around 120hp with the Turbo due to the Actual VE of the engine.

I think the 4BD1 Normally aspirated engine only gets around 105hp or something so you can see by the Theoretical CFM figure of the engine they don't breath to good from std.
Because there diesels meant for long life they are under tuned & not configured at all for High output figures.

Of course we are not chasing race engine statis with this with 100% VE & up, but we are chasing a nice gain in performance though.

The 4BD1T injector pump will handle a lot more than the engine can deliver std, normally you could expect this to be able to cope with at least the Theoretical CFM figure of the engine & then some. It wouldn't make sense for the factory to make something that only just does the job.
In fact if you could see the black smoke pouring out the exhausts of some Isuzu's up long hills etc here in Australia you could see the pumps are wound up & far to much fuel being delivered. Don't make sense really!!


This next part is written by someone else, my words exactly but saves me writing it out, it's not copying but more agreeing with the person from personal experience. It's in plain English.

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There are many misconceptions about "turning up the boost." Boost pressure is only one part of a complicated balance of getting more power from an engine. Boost is developed by the pressurization of air that is NOT going into the engine.
If all of that air was going into the cylinders, there would be no boost pressure.
It's like trying to cut off water flowing from a garden hose: the more you restrict the water, the higher the pressure. If you don't restrict the water, the pressure doesn't rise. The boost pressure in the plenum is caused by the restriction of air entering the cylinders and the turbo attempting to force more in.

We are trying to get a greater volume of air into the cylinders. That air, along with a greater amount of properly proportioned fuel, will result in more power. Our four valve per cylinder engines are nearly 98% efficient at filling the cylinders. The only way we can get more volume of air into the cylinders is by pressurizing the air. But just because you put twice the "pressure" of air into a cylinder, doesn't mean that you have twice the volume. Pressure ratios aren't linear.

Back to the garden hose. If you had a hose with a good nozzle on it and 30 psi of water pressure, you might be able to fill a bucket in about 30 seconds. If you were able to increase the water pressure to 60 psi, the bucket would fill in about 22 seconds, not half the time. That same hose will squirt farther across the lawn, but doesn't actually get much more water to the plants.

This brings into play the pressure ratios and volume. We often think of pressure as "boost pressure." Remember that we are sitting at atmospheric pressure, typically around 14.7 psi of "boost" (29.92 in. Hg or 760 mm Hg), so any pressure that we want to develop really needs to be referenced from absolute pressure. We are at 14.7 psi, so if we want to run 14.7 psi of "boost," it is really 29.4 psi, or a 2:1 pressure ratio. Again, as mentioned, twice the pressure does not mean twice the volume of air.
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Cylinder filling is a problem even with a Turbo, i haven't got the paper work with me at the moment so don't hold this as gospel.
It takes from memory 150cfm of air for 100hp so if we just look at the "Theoretical CFM" for this engine it is roughly.
Approximate only:
3.9ltr = 238cu/in & just say 3500rpm at the engine
238cu/in X 3500rpm/ 3456 = 241cfm

241cfm equates to around 160hp.
This is for a Normally aspirated engine & not Turbo.
Unfortunately everything you've written above is straight from the petrol engine school of thought.
Petrols run a 10lb/min of air = 100hp rule of thumb. At atmospheric pressure that's approx 150 cuft/min.

It's irrelevant to a diesel as excess air is already present. Even at peak power they're still shifting between 1.5 to 2 times the petrol volume of air.
At cruise my 4BD1T is processing enough air for 150hp in a petrol engine, but is only producing about 40hp.
It produces 40hp because that's what my right foot has dictated the fuel pump to deliver. Not because the VE is poor.

In stock form a 4BD1T has exhaust temps of around 400 deg C pre turbo. It is not air flow restricting power, it is fuel.
You can add roughly 50% more fuel without running out of air (but you will hit smoke).

VE is not the problem restricting power. These engines are massively detuned so they'll last for 500,000km between rebuilds.


As you can see even with a Turbo the Actual VE is much less & the power figures show this at around 120hp or so. A cam & a port job done correctly will not only increase hp but also improved torque where they so badly need it.
A cam and port job might increase VE from 80% to 85%. A 7% increase in boost (3psi) will give the same air volume increase in the cylinders and will not weaken the head.
Have you had a look into the intake ports on this engine? There are no big gains to be had.

Increasing boost is easy but the results won't change much due to many factors. To increase boost we need the exhaust gas to drive it as well, before we increase boost we should increase the engines airflow capability & configure the ports accordingly to do so.
This is wrong.
Extra fuel and the boost required to burn it are the main factors in diesel tuning.
Extra boost simply requires a wastegate modification. If you're running a freefloat exhaust housing then more fuel will automatically give you more boost.

In a diesel more fuel = bigger exhaust volume = more power spinning the turbo.

Again the VE is not the problem. It is not VE restricting the power of the NA version, it is fuel atomisation.
Modern common rail engines get much higher power from the same airflow because they can burn more fuel without smoke.


The 4BD1T injector pump will handle a lot more than the engine can deliver std, normally you could expect this to be able to cope with at least the Theoretical CFM figure of the engine & then some. It wouldn't make sense for the factory to make something that only just does the job.
In fact if you could see the black smoke pouring out the exhausts of some Isuzu's up long hills etc here in Australia you could see the pumps are wound up & far to much fuel being delivered. Don't make sense really!!
Blowing black smoke can be for many reasons, a clogged air filter is usually the main culprit, a malfunctioning turbo is another. None of which indicate the pump can deliver more fuel than the healthy engine and turbo can burn cleanly.
I'm still hoping some one can tell me what the max fuel delivery of the pump is (per cylinder, per injection).

There is already a lot of experience on this forum in diesel engines and turbocharging. We get a lot of people here trying to apply petrol engine tuning theories to diesels without success.
There is a long thread about cams in the cummins performance section which I think you should read.

A long badly written analogy on boost pressure is not any help. But earlier you mentioned oiling issues which we would be greatly interested in learning more about.
The

I hope this resource is useful to you modifying your engine and I hope you will help add to the knowledge base here. But please take the time to read and research first.
 
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