More power from 4D3?

[Oilburner]

I am looking for info on getting more HP from this engine. A few have posted that boost can be increased, I am looking for any info or experience from those that have done this. The engine has a blow off valve that releases at 15PSI and the wastegate seems to open around 12, I also imagine that the computer reduces the fueling once the MAP sensor sees something over 12 PSI. I am thinking of putting in an adjustable wastegate, putting a plug in where the blow off valve is (it's an automatic so not really required and I watch my boost gauge), and a boost controller for the sensor to fool the sensor a bit.

Any comments?

The engine also has a fuel rate resistor, can i get more fuel by changing this out?

This particular engine is in an 80 series Cruiser so it does not work as hard as the Fuso/Canter would, and I think the engine can handle a lot more boost than 12 PSI, judging by how it is built, with thick rods, big bearings and oil squirters!

Cheers

JL in Canada

 

[Amesz00]

A few have posted that boost can be increased, I am looking for any info or experience from those that have done this. The engine has a blow off valve that releases at 15PSI and the wastegate seems to open around 12, I also imagine that the computer reduces the fueling once the MAP sensor sees something over 12 PSI.

my FG currently runs at around 16psi flat out. the 1st thing for you to do (if not already) is the exhaust, should have at least 3" as close to the turbo as poss. i dont know anything about this blow off valve, but when i pulled my watsegate tube off the diaphram it didnt really make much difference, full boost was reached about 100rpm sooner and went up to 13 instead of 11psi. so i just left it at that. my guess is that the restrictive dump pipe on mine, together with limited (stock) fueling, it was just leaning out. i then installed a DPchip, still with the WG line unplugged, and it now boosts around 300rpm sooner and goes to max of 16. the turbo setup is defenitly not great, but anymore than this and IMO the turbo (both compressor + turbine) would be seriously choked.

I think the engine can handle a lot more boost than 12 PSI, judging by how it is built, with thick rods, big bearings and oil squirters!

this engine, as well as the isuzu 4bd1t, are almost carbon copies of a cummins 4bt, which has many documented cases of people running 30+psi with no apparent ill affect.

The engine also has a fuel rate resistor, can i get more fuel by changing this out?

from my understanding this slows the input from the accelerator pedal to the IP. your better bet for more bulk fuel is probly a power chip. the injector pump also has some weird injection timing control (retarded at low rpm, then advances at around 2k), i started looking into this but am now selling the truck, so not worth stuffing around with for me.
Andrew

 

[Oilburner]

Thanks for your reply... That helps a lot.

One of the problems is that the original wastegate actuator was leaking, so I replaced it with a universal model that is rated for 14 PSI. I think that this is too high as I now see the stock wastegate opens around 10-11 PSI.

I am working on a no-restriction 3 inch exhaust, I think that will help, but I am really surprised that I can't get the boost to exceed 10-12 PSI. The turbo on these engines is so small that I figured it would spool up quick and rely on the wastegate not to choke out the engine. I disconnected the wastegate entirely (always wide open) last night and went for a drive and I can still get 4-5 PSI with the wastegate fully open, so this seems to be a very small turbo that really needs the bypass. With the wastegate closed it really should spike, that's why I figure the computer must be de-fueling based on the boost pressure.

My next step is to get a proper 8-10 PSI wastegate actuator and try it again.

Anyone else have experience with boost pressures and these trucks?

 

[JRhetts]

Oilburner

You might want to try getting together with a Fuso dealer. From my personal experience, they have software and interfaces that can monitor and record as many as 200 variables in real time as you drive around in real-world circumstances, enabling extremely accurate diagnosis of what is actually going on with the engine, etc.

Doing this might allow you to pinpoint areas of sub-par performance and give you very specific ideas about what to do about it.

John

 

[Oilburner]

JRhetts thank you for the recommendation but my local dealer only started selling Fusos in 2004 and they apparently do not have diag. equipment for the 4D3. I have not really pushed the issue but I suspect that they would have a problem diagnosing a Mitsubishi engine fitted to a Land-Cruiser, although all the OEM wiring is intact.

Progress - I fitted an adjustable wastegate and have found that the factory one was experiencing boost creep (the exhaust gas pressures were opening the wastegate, overcoming the actuator spring) at 10 PSI regardless of boost pressure on the diaphragm. I can now get 15 PSI easily in 3rd gear (until the pop-off valve opens) and a solid 12-13 PSI in overdrive. The engine response has improved dramatically and I can only hope that finishing the 3 inch exhaust will help as well.

It does need more fuel. I am reluctant to put in a chip, and am still convinced that the fuel rate resistor adjusts the fuel injection rate incrementally to allow for different altitudes and variances in the pump. I am contemplating swapping the resistor out for another one, to see if I get a difference. I will also block the pop off valve in the intake to see if the computer will continue to increase fueling past 15 PSI.

 

[Amesz00]

I will also block the pop off valve in the intake to see if the computer will continue to increase fueling past 15 PSI.

you mean by itself? it wont.

It does need more fuel. I am reluctant to put in a chip, and am still convinced that the fuel rate resistor adjusts the fuel injection rate incrementally to allow for different altitudes and variances in the pump.

if your talking about the resistor i think you are, its in the line from the throttle posi sensor to the ecu. to my knowledge, it doesnt affect overall fueling but just slows the input from TPS to ECU. the injector pump on these is controlled by a 'pre-stroke actuator'. this acts basicly like a boost compensator pump, as i said before it retards the injection timing (alot) at lower rpm. its this that makes the engine feel very lethargic under 2k rpm. i think its this that you want to be playing with. it also wont however, affect fueling at full rpm full load. i have a complete engine manual (somewhere) that goes into lots of detail about how it works, but i forgot most of it (this is off the top of my head so dont quote me...)

 

[Oilburner]

I was under the impression that TICS advanced timing and shortened injection time at lower speeds, and retarded timing and lengthened injection time at higher RPMs, but there is little information available online, and my factory manual is pretty much silent on the TICS system. If yours is better and you wish to sell it (since you are selling your truck) please let me know.

I have a spare pump and will pull the governor apart to see if there is a full load adjustment built into the governor, but I think I am stuck (if indeed the resistor is for a control circuit function as opposed to fuel rate).

 

[Oilburner]

A bit of an update. I finished most of the 3" no restriction exhaust and the difference is unbelievable. The muffler I was using was apparently a huge restriction. The mid range and top end power increase is huge, and I am seeing 18-20 PSI max boost, with the pop-off valve in the intake screaming away (it opens at 15 PSI). I am not sure how this relates to O.E.M. power levels in the original vehicle, but for a 2500kg Land-Cruiser it's quite nice and will happily run north of 130 km/h without much coaxing.

I will keep posting as I continue to upgrade and tweak as I am sure there are a lot of 4D3 owners that would not mind an extra 20-30 hp. I should note that I am fitting a pyrometer before I start adding any fuel.