Thread: does anyone have any info on injector pumps for 4BD1

the suzi benifits greatly from another 3-4 degrees of overlap as it improves the scavanging blow through from the turbo. the lift start times can be left as is but a sharper rise on the opening of the exhaust and a snappy close makes a fair whack of difference...

the changes to the pump youve outlined are correct they inject about 1cc more over500 strokes (in the lowest turbo spec pump) when on full tilt than the biggest non turbo pump and the rise rate on the torque plate is significantly sharper.

other than that I agree with most of your points other than the refuelling on the non turbo engines. if you leave it all stock I agree if you leave it planted and its labouring you will do bad things eventually, but if you clean up the breathing of the engine (its woeful as a standard design) then you can run a fair bit more through them. but nowhere near as much as a full boost engine...

Originally Posted by Blknight.aus

the suzi benifits greatly from another 3-4 degrees of overlap as it improves the scavanging blow through from the turbo.

That is very interesting.
I've run my 4BD1T with both boost and backpressure gauges.

On acceleration the backpressure (exhaust manifold) is often exactly double the boost (inlet manifold). So yeah 40psi transient backpressure to deliver my 20psi boost.
As the EGT's rise the turbo feeds more off the heat and the backpressure drops.

Steady state cruise at 100km/h, boost is 8-9psi, backpressure is 12-13psi, EGT's are 400-450 deg C.

Climbing a hill (slow increase in EGT's) you can watch the backpressure dropping as the EGT's rise. 600 deg C is the crossover point. At this exhaust temp at low enough revs (below 2000rpm) I have equal backpressure to boost.
20psi boost for 20 psi backpressure.

Run the EGT's higher and I get more boost than backpressure. But only if I keep the rpm down as my small exhaust (2.25") contributes backpressure at higher revs.

Of course there is a lot more happening in the individual inlet and exhaust ports than can be revealed by simply measuring the pressure. But it seems to me that almost all the time backpressure is higher than boost and scavenging isn't really possible. Zero overlap seems like a much better option for boosted engines to prevent internal EGR.

The reason my engine has a boost compensator on the fuel pump? It was a japanese import, probably sourced from a wrecked truck in Japan.

the secret Im told, lies in the ramping of the cams and the movement of the gasses.

I was skeptical about it being right for the same reason that you are... (I still am and Ive seen it working)

as I understand it the concept is similar to the one of using the backpressure on a 2 stroke to stall the flow of the gasses into the exhuast pipe while the fresh charge is still tyring to get into the chamber but your trying to go the other way.

you get the exhaust gasses moving out of the chamber at a rate of knots and then while they are still trying to go at a rate of knots you open up the inlet valve and the gasses there start doing their bit. in the 2 stroke this is the time you want the exhaust pulse to reflect and stall the inlet charge in the chamber. In the suzi your doing the opposite and trying to use the inlet charge to top off the pressure in the chamber to keep the speed of the exhaust gasses up and prevent them from stalling out... if a gas is flowing its exerting less pressure, its when it slows down that the pressure rises.

however......

get it wrong and it goes bad quickly and you wind up with exhaust gasses in the inlet and if your inlet is short enough and ugly enough its got the potential to stall off the turbo....

the stock cam is good, if not very good but there is that tiny little bit more to be had from it and it comes at a cost... the extra air your pushing though will help burn off any over fuelling youve got which A, makes the turbo work harder and B, will raise the EGTs like you wont believe.

anther problem I have with it is that as its working with pressure pulses to do its magic in theory it will have a "sweet" range and outside of that who knows what other problems you will get.

I also think that the extra overlap isnt so much more of traditional "overlap" but is more to do with the increase on the ramping, the valves close completely at more or less the same point but as the ramps are steeper then it appears that they have more overlap as they are open for longer...

Ive also screwd the wording of part of what I originally wrote so it might have been a little miss leading...

[QUOTE, Me]. the lift start times can be left as is but a sharper rise on the opening of the exhaust and a snappy close makes a fair whack of difference..[/QUOTE]

should read

The inlets lift start time can be left as is with a sharper rise with a snappier close and a slight increase on the exhausts open duration can make a fair whack of difference...


I was trying to condense about 8 lines into fewer to make it read easier got distracted and pooched it., My bad

Number of cylinders, valve timing, exhaust manifold, and exhaust energy to drive the turbine, all have complex interactions that are difficult to optimise.

I have seen results (but not for our Isuzu's) from engine modeling with Ansys Multi-Physics that illustrated what is happening very well.

IMHO, with the 4BD1-T, there is more to be gained from the exhaust manifold design, than there is from altering the stock camshaft. With the stock manifold, the exhaust pressure at the turbine is much less than is available at the exhaust port (because of the crankshaft design of a 4 cylinder engine). With care it is possible to make a manifold for a 4 cylinder engine that will realise improved turbo performance, but it is difficult to get right.

Originally Posted by Bush65

According to what is printed in the workshop manual IDE2140:

1. Valve open/close timing is identical for both 4BD1 and 4BD1-T. I'm skeptical about the cams being different. Turbo doesn't need more valve lift to stuff in more air, so what else beside timing would be different?

2. Injection nozzles and nozzle holders have same part no for both 4BD1 and 4BD1-T. Injection starting pressure is same for both 4BD1 and 4BD1-T. Over flow valve opening pressure is lower (18 psi vs 23 psi) is lower for the 4BD1-T.

The injection pumps have different serial no, but are basically the same. They are calibrated differently and I suspect the torque cams are different, but these are adjustments that a diesel injection shop can make. Also the automatic timing advance is different.

AFAIK, 4BD1-T's in Aus did not have the boost compensator on the injection pump as shown in Dougals pic. The boost compensator reduces the fuel/smoke as the turbo boost pressure reduces.

The nitrided crank in the 4BD1-T is slightly better for wear and to reduce formation of cracks at points of stress concentration. But how many Land Rovers with the 4BD1 (turbo'ed or not) have either of these issues?

The oil squirters (for piston cooling) give extra durability, but again, how many Land Rovers with the 4BD1 (turbo'ed or not) have any piston failures.

IMHO, if you are going out to by an engine, then get a 4BD1-T, but if you already have a 4BD1 fitted, then turbo it. As part of the turbo installation, torque the head bolts to 4BD1-T specs, adjust the maximum fuel screw on the injection pump and time the injection pump to 4BD1-T specs.

The lighter duty of our vehicles compared to Isuzu trucks makes a hell of a difference.

I wouldn't have the 4BD1 overhauled before fitting a turbo unless it was required because of wear.

Increasing fuel delivered from the injection pump, without increasing the air is worse than fitting a turbo and increasing the fuel.

Very well said John - thanks for injecting some facts!

Bushie
I do agree with you on turboing the N/A engine, much of the design on the engine is specificaly aimed at trucks, but the pumps are quiet different in the aspects of timing and advance, and the nozzels on the injectors are a different spray pattern also. If you like I can dig up the part no's for the different cam and injectors.
When at Isuzu "parts" they found that the cams were different between the two engines, which I suspected, you can't say that an engine built to have a turbo would have an identical cam to a N/A engine. It's just not logical. And the reason I'm getting a "custom" grind isn't for any other reason than they are $600 clams genuine of $160 for a custom grind to turbo specs.

Originally Posted by Larns

Bushie
I do agree with you on turboing the N/A engine, much of the design on the engine is specificaly aimed at trucks, but the pumps are quiet different in the aspects of timing and advance, and the nozzels on the injectors are a different spray pattern also. If you like I can dig up the part no's for the different cam and injectors.
When at Isuzu "parts" they found that the cams were different between the two engines, which I suspected, you can't say that an engine built to have a turbo would have an identical cam to a N/A engine. It's just not logical. And the reason I'm getting a "custom" grind isn't for any other reason than they are $600 clams genuine of $160 for a custom grind to turbo specs.

My Manuals agree with everything John has posted.

"Early" 4BD1s have some extra differences, but 1987-on 4BD1s are the same.

My Manual (N Series 4BXX 1985-on (printed Sept 1988)) concurs with what John has posted.

Valve timing (Camshaft) changed in 1986/87 for 4BD1 and 88/89 for 4BD1T, but they BOTH changed.

e.g: in 1986, both the 4BD1 AND 4BD1T had:
Intake opens at 28 deg and closes at 62 deg
Exh opens at 70 deg and closes at 28 deg

in 1989, both the 4BD1 AND 4BD1T had:
Intake opens at 19 deg and closes at 47 deg
Exh opens at 57 deg and closes at 15 deg

The injector nozzles are THE SAME between both tha NA and T models. However the T has opening pressures the same as 1986 and earlier NA models. 1987-on, the NA models had higher opening pressures.

By the sound of it, you have an early-spec engine, and someone is trying tyo sell you a later spec (cam) grind. However this has nothing to do with NA/T spec.

Please stop posting (mis)information, unless you are sure of the facts.

Originally Posted by isuzurover

My Manuals agree with everything John has posted.

"Early" 4BD1s have some extra differences, but 1987-on 4BD1s are the same.

My Manual (N Series 4BXX 1985-on (printed Sept 1988)) concurs with what John has posted.

Valve timing (Camshaft) changed in 1986/87 for 4BD1 and 88/89 for 4BD1T, but they BOTH changed.

e.g: in 1986, both the 4BD1 AND 4BD1T had:
Intake opens at 28 deg and closes at 62 deg
Exh opens at 70 deg and closes at 28 deg

in 1989, both the 4BD1 AND 4BD1T had:
Intake opens at 19 deg and closes at 47 deg
Exh opens at 57 deg and closes at 15 deg

The injector nozzles are THE SAME between both tha NA and T models. However the T has opening pressures the same as 1986 and earlier NA models. 1987-on, the NA models had higher opening pressures.

By the sound of it, you have an early-spec engine, and someone is trying tyo sell you a later spec (cam) grind. However this has nothing to do with NA/T spec.

Please stop posting (mis)information, unless you are sure of the facts.

So what differences do the advanced cam timing make to the operation of the later engine?
I'm thinking it'd bias it more towards high speed operation than the earlier cam, but I'm just guessing.

Zero overlap with both cams?