Possible driveline update OM352A to OM906LA

[Christian]

Hi all,

As some know, I have a LAF1113B from 1978.

It has the top-of-the-line OM352A with 168hp and 461nm/340lb/ft.
While it actually drives ok, there's a few things that bothers me. For one, I'd like to update the turbo, there's considerable turbo lag, there seems to have been made some progress in this particular area since 1978...
Another thing is I'd like to lower the revs while cruising.
Last thing is these old lumps do smoke quite a bit when cold, and 1,000lb's of cast iron seems to take a while to warm up...

So I found few turbo options, and without going in to detail, I started looking at standalone VGT controllers. Add an intercooler to that too - and maybe pump work... Yeah, I know, so do you...
I found a suitable gearbox, the G56-6 from Atego/Vario with a final drive of 0.79:1 in sixth, but that takes a SAE II/III bellhousing, which can be found for the OM352, but not easily. I'd have to incorporate another hydraulic clutch and custom clutch assembly.
So all in all, as one thing lead to another, I ended up planning to make a hodgepodge of parts and have them all play nice together...

That actually goes against my own design philosophies and IMOP is a recipe for trouble.
So I started to look at options to get a complete driveline. And after a bit of deliberating settled on the OM904/G56-6 combo. The OM904/6 series is used in a lot of trucks here, in the US you'd know them as MBE900 from Detroit Diesel.
The OM904/6 revs to 2,600, the OM352 to 2,900, but in 6th I'd lower my rpm at 100km/h/62mph from 2,900rpm to 2,100rpm.

Except I'd want the 180hp OM904, which doesn't come with the G56-6, as Mercedes only rates that at..... YES! 560nm, the 180hp OM904 has 675nm/498lb/ft. The advantage would be an engine that is 60/120lbs lighter than the OM352 though.

But I got a Mercedes Atego 1223 on my hands now, that's an OM906LA with 230hp and paired to the G85-6, which is 0.73:1 final drive, stronger, but heavier than the G56-6.
The OM906LA is the same size as the OM352A within an inch, but 40kg/80lbs heavier, so I won't save any weight.

And before you start talking about wiring, i have found the schematic (albeit for the Detroit MBE900, which should be the same) and it doesn't look too complicated, as long as you get all the part from the same truck. There's drive-by-wire, ECU, VCU, most sensors are on the engine, I might need a VSS and help with eliminating the max. speed block, but it all looks doable, a lot of things are just switches, like the cruise control...
And I'd get rid of that ½ hour of smoke, which seems to be frowned upon heavily here...

But am I mad? What do you guys think?

 

[Iain_U1250]

I think it's good idea, provided there is enough space for everything to fit. The 1970's OM352 motors are quite reliable, but there are limits to what can be done especially as far as emissions are concerned. Doing the complete swap would be easier than a Frankenstein motor / gearbox combination. It would bring a classic truck back to life for another 20 years at least.

I've done a number of car engine/transmission swaps, and space is normally the problem, every seemed to fit,until it came time to fit all the ancillaries like alternators and radiators etc, and then I ended up making custom brackets or custom parts. The extra HP also means a bigger radiator - your need one at least as big as the one out of the Atego 1223, possibly bigger given aerodynamics under the bonnet and around the engine in the LAF might not be as good at the Atego.

I recently fitted a UG100/8 transmission into my U1250 Unimog, and it was a very tight squeeze to get it in, and there were a few things the old UG3/40 had on it that no longer fit - the rear "safety post" behind the cab being the main one, which also held a cover over the propshaft. It also needed a custom "manual shift" adapter plate to make it work, and solenoid valves for the pneumatic gear changes in High/Low and Forward / Reverse. I've just finished re-fitting everything back, so will test drive tomorrow to see if everything works. It is never as easy as it seems at first, but everything is possible, given enough time and money.

 

[Sitec]

I too am a fan of transplanting both engine and trans if needed. I haven't done it with our truck but did with our last Land Rover... I removed a 3.5 V8 and 4 speed, and replaced it ith a 5.9 Cummins and a ZF 5 speed. It transformed the vehicle. However, as Ian rightly says, there can be a lot of work involved to get it all to work, and some $$$. Lastly though, it would probably be worth having a chat with the relivant authorities re the rules around engine swaps in your area... Good luck!

 

[Christian]

I think it's good idea, provided there is enough space for everything to fit. The 1970's OM352 motors are quite reliable, but there are limits to what can be done especially as far as emissions are concerned. Doing the complete swap would be easier than a Frankenstein motor / gearbox combination. It would bring a classic truck back to life for another 20 years at least.

I've done a number of car engine/transmission swaps, and space is normally the problem, every seemed to fit,until it came time to fit all the ancillaries like alternators and radiators etc, and then I ended up making custom brackets or custom parts. The extra HP also means a bigger radiator - your need one at least as big as the one out of the Atego 1223, possibly bigger given aerodynamics under the bonnet and around the engine in the LAF might not be as good at the Atego.

I recently fitted a UG100/8 transmission into my U1250 Unimog, and it was a very tight squeeze to get it in, and there were a few things the old UG3/40 had on it that no longer fit - the rear "safety post" behind the cab being the main one, which also held a cover over the propshaft. It also needed a custom "manual shift" adapter plate to make it work, and solenoid valves for the pneumatic gear changes in High/Low and Forward / Reverse. I've just finished re-fitting everything back, so will test drive tomorrow to see if everything works. It is never as easy as it seems at first, but everything is possible, given enough time and money.

Thanks for the detailed reply Iain.
And you are right, there will always turn things up, you haven't taken in to consideration. And - as you wrote - bring it back to life. And when I'm done soundproofing the cab and bringing the comfort parts up to date, the engine/gearbox is what dates it the most.
There's plenty of space, that's a big benefit one these bullnose trucks, only issue might be length-wise, the OM352 and the OM806 are just about the same, but I need room for a more effective radiator, intercooler and I'll make room for an A/C condenser too.
The 1113 has a divorced gearbox and X-fer, so I hope not running in to issues like your refit, and the G85-6 has a hydraulic shifter system, so I have some flexibility there.

I too am a fan of transplanting both engine and trans if needed. I haven't done it with our truck but did with our last Land Rover... I removed a 3.5 V8 and 4 speed, and replaced it ith a 5.9 Cummins and a ZF 5 speed. It transformed the vehicle. However, as Ian rightly says, there can be a lot of work involved to get it all to work, and some $$$. Lastly though, it would probably be worth having a chat with the relivant authorities re the rules around engine swaps in your area... Good luck!

Thanks Sitec, did you put that conversion up somewhere? I haven't seen it? I'm sure it must have transformed the LR, I was never a fan of gasoline powered 4X4's. I have looked in to the 5.9 Cummins, but they are non-existent here.
I did do a swap on a Volvo TGB1314, the small portal axle 6X6, I removed the Volvo B30 and gearbox, and replaced it with a Toyota 1KZ-t with gearbox and X-fer, same philosophy, no mixed parts, except the driveshaft, Toyota at one end, Volvo/LR at the other.
Regarding authorities, it's kind of funny, there are no rules when dealing with trucks, cars, sure! but not trucks. I believe it's either because they almost always are governed at a max speed, or because no one thought anyone would...

 

[Sitec]

Thanks Sitec, did you put that conversion up somewhere? I haven't seen it? I'm sure it must have transformed the LR, I was never a fan of gasoline powered 4X4's. I have looked in to the 5.9 Cummins, but they are non-existent here.

Hi fella. Yeah, I had a thread running on an Australian Land Rover forum that I used to frequent a lot before getting back into the world of trucks. I'd post a link to it, but I think takling about one platform on another is frowned upon... PM me if you want any more details. As for transforming it, yup, it was awesome.

 

[charlieaarons]

Hi all,

As some know, I have a LAF1113B from 1978.

It has the top-of-the-line OM352A with 168hp and 461nm/340lb/ft.
While it actually drives ok, there's a few things that bothers me. For one, I'd like to update the turbo, there's considerable turbo lag, there seems to have been made some progress in this particular area since 1978...
Another thing is I'd like to lower the revs while cruising.
Last thing is these old lumps do smoke quite a bit when cold, and 1,000lb's of cast iron seems to take a while to warm up...

So I found few turbo options, and without going in to detail, I started looking at standalone VGT controllers. Add an intercooler to that too - and maybe pump work... Yeah, I know, so do you...
I found a suitable gearbox, the G56-6 from Atego/Vario with a final drive of 0.79:1 in sixth, but that takes a SAE II/III bellhousing, which can be found for the OM352, but not easily. I'd have to incorporate another hydraulic clutch and custom clutch assembly.
So all in all, as one thing lead to another, I ended up planning to make a hodgepodge of parts and have them all play nice together...

That actually goes against my own design philosophies and IMOP is a recipe for trouble.
So I started to look at options to get a complete driveline. And after a bit of deliberating settled on the OM904/G56-6 combo. The OM904/6 series is used in a lot of trucks here, in the US you'd know them as MBE900 from Detroit Diesel.
The OM904/6 revs to 2,600, the OM352 to 2,900, but in 6th I'd lower my rpm at 100km/h/62mph from 2,900rpm to 2,100rpm.But am I mad? What do you guys think?

The 900 series develop peak hp at 2200 but they are happiest cruising at 17-1900 rpm. Over 2100 is ridiculous. 2600 or 2900 is even worse.
I’ve owned one for 15 years.

 

[nick disjunkt]

The 900 series develop peak hp at 2200 but they are happiest cruising at 17-1900 rpm. Over 2100 is ridiculous. 2600 or 2900 is even worse.
I’ve owned one for 15 years.

Having spent a lot of time driving a truck with the om906 and G85-6, I'd agree. It's a nice refined package, but at 2,100 rpm you can tell it's working hard. I had no qualms about pegging it at 2,100 on steep grades, but fuel consumptions goes skyward and it makes a lot of noise. 1,700 rpm is perfect cruising speed, but it's certainly down on power there, and you won't be able to hold grades in an 11 tonne truck at that engine speed.

 

[joeblack5]

We have a 906la with an allison b300r in our bus.
5th gear 2100 rpm at 55mph.. have not driven with the 6th gear unlocked.
Very nice engine..420000 miles, no smoke , no leak ..gave us 9 mpg on a 9000 miles trip with 22000 lbs and a toad.

That all being said.. just swapped an TDI in a 404 unimog and it takes a long time. Life is fast and short.
Better to first finish the conversion , take it on the road, have some fun and then start hacking if you still feel like it.

Good luck,
Johan

 

[charlieaarons]

8.7 mpg @ 57mph, GVM ~12.5 metric tons. Since then removed unmounted tires from roof but built box on moose catcher to hold heavy recovery gear. Estimate net effect = 0.
I have spare ECU with timing advanced from 14 deg BTDC (EPA 2004) to 18 deg BTDC (Euro 3). Effect remains to be seen.
Anyone have specific experience with timing change on 900 series in this range?

 

[joeblack5]

Sorry, no...but if that spare is from another 906 series truck likely the injector calibration for the unit injectors will not be the same.

Johan

 

[charlieaarons]

Sorry, no: “Spare” ECU is brand new for my VIN, but remapped a bit.

 

[nick disjunkt]

There are quite a few companies in the UK that produced a remap for this engine. I had presumed that they mostly played with injector pulse duration, but it might be worth speaking to them and see if the map adjusts timing too. When I had my truck I spent some time scouring through the Mercedes EPC to see which components were different between the 230hp and 280hp versions that my truck was sold as. All I could find were the ECU and turbo.

 

[Neil]

Hi Nick

There are quite a few companies in the UK that produced a remap for this engine

I don't think the OM352a engine can be remapped. It's far too old for all that electric Trickery

Mechanical adjustments such as the pump is about as good as it gets.

Neil

 

[nick disjunkt]

Hi Nick



I don't think the OM352a engine can be remapped. It's far too old for all that electric Trickery

Mechanical adjustments such as the pump is about as good as it gets.

Neil

Hi Neil,

Sorry if I wasn't clear, I was referring to the OM906LA engine

 

[joeblack5]

Charlie, maybe this is helpfull?