Geo Tracker Kubota Diesel Engine Swap

[Christ]

Diesel's don't overrev on factory settings because they literally run out of fuel.

If you have a Bosch pump, you can get more fueling through the RPM range by shimming the thickest of the springs on the governor shaft inside the pump. You can get more fuel advance (generally) by adding an inline fuel pump, which may make a little more power for you as well.

If your gearing is wrong, you could go up a tire size or two, but you won't gain much. Consider your differential gears. Many junkyards sell complete rear ends for around $75 or so, and they're VERY easy to swap between vehicles.

[DieselDrewski]

Originally Posted by Varn

The rpm that the PTO is made to run at is 2400. When I get these engine warm, I adjust the rpm to 2400 and leave it there. 3000 is not the usual unless doing some road travel. I was surprised that the engine could not be pushed any further.

The governor cuts the fuel back gradually as the rpm builds. This starts above 2400rpm. My 19 hp is a one liter 2 cylinder my 21hp is a 1.2l 3 cylinder. Pretty similar to yours.

I doubt if adjusting a single screw on the fuel pump is anything that you should try without much investigation.

Your best option in my opinion is to not push your engine harder but consider taller gearing, taller tires. Something to make the engine run about 2400.

The single screw is an external hard stop on the throttle lever, and I'm pretty sure its meant to set max RPM within the governed range. I'll check the service manual to be sure, though. The owner's manual from the donor lawnmower states the no-load high idle to be 3100-3200 RPM. I'm not sure what accounts for the difference between your engines and mine.

I guess maybe the tachometer circuit should move up on my priority list. How many pulses per RPM is the tach going to be looking for on the tracker gas 4 cyl? Is it one or two?

[v2squared]

tiny tach has a desiel tach that bolts to one fuel line from pump to cylinder. about 90 to 100 usd with shipping. the order form lets them know what engine you are using it one they will make sure you get what you need.

again taller gearing will work to a point I have a set up to adjust is to the the rpm of 2400 and did not have the guts to get out of 2nd gear.

[Cobb]

Any idea of the mpg without the turbo? I just bought a sidekick ljx this year and keeping with traffic and a few eco mods managed 32mpg. I lowered mines 2 inches, blocked the upper and lower grills, removed the roof rack, spare tire, spare tire carrier, installed front skid plate, inflated tires to 40psi, serviced all gear boxes and put synchromesh in the tranny.

I just recently got the ac working by using a shop vac to remove 5 gallons of pine straw and other yard waste.

[pete c]

Originally Posted by Christ

Diesel's don't overrev on factory settings because they literally run out of fuel.

Ever look at an old Benz diesel tach? There is no redline.

I read somewhere that the reason Mercedes didn't bother with painting one on there was that their engine simply could not rev high enough to do itself any damage. You could put it in neutral, drop a brick on the accelerator and walk away. Diesel plain and simply can't burn fast enough to get it past a certain rev point. I think it was somewhere between 4-5K revs.

I have seen other diesels that did have redlines. I don't know if these engines actually were capable of spinning that fast or if the manufacturer just decided that all tachs should have a redline.

[skyking]

there is a governor built into the mechanical pumps. When you press on the accelerator, you are not moving the fuel rack itself. you tell the governor you want to go faster, and it moves the rack.

[Cobb]

I had a 81 mercedes 240d stick shift. It was my dads and 3 other people before I got it with 470 thousand miles on all original parts.

I drove it like him, which turned out we were lugging the hell out of it. I too later found out it cant be over reved and not to be afriad to push the gas petal to the floor. I did however adjust a screw on the injector pump to put in more fuel, which made it smoke under load and installed a kn air filter.

Before I had the junkyard tow it away I did just that, I picked a gear, took off and did not shift. The engine started to howl like a typical v8 at 4 grand with flow master mufflers. Being use to the clattering the roaring noise took some use to. I think not having a fan clutch caused more noise from under the hood too.

Man, it wasnt a bad driving car after that change in shifting. I am pretty sure I wasnt getting 32mpg. I basically drove to highway speeds in 2nd and third gear and treated 4 as if it was an over drive gear. I shifted out of first at 40 mph, 2nd at 50, 3rd at 65.

Still if he cant past 50 mph in the stock configuration I am sure any mods will push the engine beyond the designers original design and shorten its life or cause some extra mods needed.

[Christ]

Originally Posted by pete c

Ever look at an old Benz diesel tach? There is no redline.

I read somewhere that the reason Mercedes didn't bother with painting one on there was that their engine simply could not rev high enough to do itself any damage. You could put it in neutral, drop a brick on the accelerator and walk away. Diesel plain and simply can't burn fast enough to get it past a certain rev point. I think it was somewhere between 4-5K revs.

I have seen other diesels that did have redlines. I don't know if these engines actually were capable of spinning that fast or if the manufacturer just decided that all tachs should have a redline.

I can tell you right now, that's the hugest load of bull. Diesel DOES and WILL ALWAYS burn fast enough to spin engines VERY MUCH faster than 5k RPM.

In fact, the biggest cause of blown engines in the VW IDI family is modified governors and over-revving. You can safely take a 1.6D to 6-7K, but much more, or a quick snap to that speed, and you're gonna grenade it.

The reason that engines have a rev limit has nothing to do with fuel type, and everything to do with component and build type. An oversquare engine will never be able to rev as high safely as an undersquare engine will. R/S ratio, B/S ratio, and several other factors I won't bother explaining here, including airflow and cam specs, as well as dynamic compression ratios (determined by the former) all play parts in redline on an engine.

Diesels are literally kept within certain ranges by the engine manufacturers installing governors in the pumps, or in the case of common rail and most DI style engines, electronic limiters which literally just cut the amount of fuel being injected at certain RPMs.

On my VW 1.6 IDI, I only get about 50% of the available fueling (that the pump can provide) at 2500 RPM, and it's cut by 80% at 4,000 RPM, which is basically the rev limit of the pump (It'll go slightly higher, but not enough to matter). Simply removing the throttle plunger and shimming the fat spring (main fuel cut) increases fueling available (so you have manual control over it, via the pedal), but also removes the rev limiter to some extent (depending on how much you shim it).

[Varn]

Hi Christ,
Why is the fastest diesel vehicle in the world tuned to a max of 3800 rpm. The vehicle has done 350mph. JCB Dieselmax.

If it isnt the flame front then surly it is something else. Probably run away heat.

I am not about to modify the governor on my IDI VW. What would be the purpose?

[Cobb]

I think in its oem un fooled around with design most diesels are safe in that regards. I have seen a youtube video where an old diesel seeked an alternative fuel source (ether and crank case oil) it ran away and spun a few bearings til someone choked it off, but as a newbie I cant post it here.

Its my understanding most engines have a sweet spot and really the lower of an rpms you can dial it in the more power and efficiency you will have. I heard back on my shop days inthe mid90s that it took 75 hp alone to spin a tradational v8 push rod lifter/cam shaft over 5000 rpms.