Introduction, Tuning/Uprating Story And How I Got here

[Tonka_Truck]

Hello everybody,

I'm Daan, from the Netherlands.
I originally registered here to ask if anybody here knew if a LDA (the turbo membrane thingy on the back) off a Bosch PES6A injection pump would fit on a Bosch PES6MW injection pump. Because I didn't have the patience to wait for the registration on this forum to pass, I just bought the "MW" pump because by looking at the pictures it looked like it would fit.
Well, it does fit, but it won't work..... Impossible to tune.... So now we know....

I'm in the process (already for 14 years) of uprating/tuning my truck (Ex bundeswehr 1017A, OM352A) because you can never have enough power, especially in sand or mud....
It already has an upgraded "A" pump (Atkinson Voss), better injectors and a intercooler. This setup has been working well for the last 8 years with slight improvements on the piping. I think this is version 3 of the inlet piping and I'm thinking of another improvement. Last year I also upgraded the turbo from 1 bar (14.5 psi) to 1.4 bar (20.3 psi) boost (from stock, no wastegate to a wastegated turbo) which means I'm faster at traffic lights but no apparent improvement on highways. I hope the new pump will help in that regard (the guy who overhauled the pump sourced another "MW" pump with the right LDA).
I go up most mountain highways with 97km/h (60mi/h) (big tires, 395 - 85 R20) , but I felt like I could do better.... So I bought a "MW" pump, same as a 366.
If people are interested or curious I can document the process, with the final goal being 115km/h (71mi/h) by upgrading the pump, gearbox and axles (already got the pump and gearbox, just need to switch it (he spoke optimistically) ).

*** Disclaimer: I'm not very good at this internet forum business, so please forgive any protocol or other mistakes***

 

[MogsAndDogs]

Hi Daan, welcome to the forum! Nice truck.

Have you heard of Brown Bear Components, from Australia? They seem to focus on getting the most performance out of these engines.

 

[Tonka_Truck]

Hello MogsNDogs,

Thank you.

And yes, I know Brown Bear Components, I saw their work, really cool and they seem to go quite far with customization.
But, as I'm from the Netherlands fortunately I don't need to get tuning parts or knowledge from the (literally) other side of the world. There is quite a big and long Dutch heritage in truck rallying and tractor pulling. And here we try to keep it simple and stupid. More Air + More Diesel = MORE POWER. That's why I went for the "MW" pump upgrade. They have 10mm plunger's instead of the 9 of the "A" pump. You can also go for a "P" pump (on which, legend has it, the "MW" was based), if you really want to make stupid horsepower (400+ hp) but I have a camper, not a rally truck.

Wanna See A Dutch Truck Go Stupid Fast? Click Here

 

[Iain_U1250]

Hi, welcome to the forum, I've been down the "more power and speed" road, and settled down to around 200hp, up a bit from the original 125hp in our 8 ton Unimog U1250. I could make a bit more by turning up the fuel screw on the pump, but my goal has always been reliability reducing fuel consumption. Over here in Australia, we are not allowed to drive faster than 100kph, and our does that easy enough, when there are hills, there are usually bends and the bends are what slows us down more than the gradient. We can go up the hills faster than the trucks here which is good enough for over here. My camper and travel thread documents most of it, and I have radically different turbo - a GT2860RS with a water/air intercooler. I make almost 1psi boost at idle, 14psi boost at around 1500rpm and up to 23psi at 2500rpm. MY EGTs are around 600-620 Deg C ( pre turbo) at full boost so I am not near the limit on the pump yet. I'm in the process of changing the turbo dump pipe, the one I made 10 year ago has cracked, and this time I have decided to go with 4" pipe for the first 2m of the exhaust, then taper it down fit to the 3" I have at the moment, as a bigger pipe won't fit through the space I have.

The LDA just retards the fuel rack when there is no boost, to prevent overfuelling, more of a black smoke/emissions thing than a power thing. It doesn't push the rack any further forward with more boost.

One thing to check is do you have the oil squirters on the underside of the pistons, as not all OM352A have them, and there is no way to tell without looking. A bore scope through the turbo oil return on the sump would be easiest. Without the oil squirters, going over 200hp would melt the pistons.

 

[Tonka_Truck]

Hi, welcome to the forum, I've been down the "more power and speed" road, and settled down to around 200hp, up a bit from the original 125hp in our 8 ton Unimog U1250. I could make a bit more by turning up the fuel screw on the pump, but my goal has always been reliability reducing fuel consumption. Over here in Australia, we are not allowed to drive faster than 100kph, and our does that easy enough, when there are hills, there are usually bends and the bends are what slows us down more than the gradient. We can go up the hills faster than the trucks here which is good enough for over here. My camper and travel thread documents most of it, and I have radically different turbo - a GT2860RS with a water/air intercooler. I make almost 1psi boost at idle, 14psi boost at around 1500rpm and up to 23psi at 2500rpm. MY EGTs are around 600-620 Deg C ( pre turbo) at full boost so I am not near the limit on the pump yet. I'm in the process of changing the turbo dump pipe, the one I made 10 year ago has cracked, and this time I have decided to go with 4" pipe for the first 2m of the exhaust, then taper it down fit to the 3" I have at the moment, as a bigger pipe won't fit through the space I have.

The LDA just retards the fuel rack when there is no boost, to prevent overfuelling, more of a black smoke/emissions thing than a power thing. It doesn't push the rack any further forward with more boost.

One thing to check is do you have the oil squirters on the underside of the pistons, as not all OM352A have them, and there is no way to tell without looking. A bore scope through the turbo oil return on the sump would be easiest. Without the oil squirters, going over 200hp would melt the pistons.

Hi Iain,

Thanks for the welcome, and your insights and experiences. I would like to make a few remarks on your post:
I'm 100% sure the LDA opens the fuel rack under boost conditions and will add more horsepower. I know this from the guy who rebuilt my pump (a Bosch specialist) and the fact that there are 2 OM366LA versions, one without LDA which produces 200HP and a version with LDA which has 240HP. Maybe the confusion stems from this, as I can imagine a situation with low boost and relatively high revs producing quite some smoke from unburned diesel in a truck without LDA.

Also, I find it interesting you say reliability but choose a water/air intercooler. I might be wrong but I thought that would mean a separate cooling system for the intercooler (Water piping, pump, extra radiator) to do this properly. Is this correct? And what were the reasons behind the decision to go down this route? I would say an air/air intercooler is simpler and therefor more reliable.

About the exhaust, you say you want to make the first 2 mtrs wider, aren't you afraid of back pressure or weird counterwaves? Because it sounds like you're building a resonance chamber, like a two stroke exhaust. A widening introduces Bernouille's principle with a slowing of the air meaning a higher pressure. But maybe I'm overthinking things.

I hope you're not offended by my remarks and questions. I'm a very curious person.

 

[Iain_U1250]

Hi, not offense taken, all good discussions are great.

I have official Bosch technical manual for the inline fuel pumps, it covers everything on these pumps in detail. One section here below:

The LDA doesn't increase the fuel beyond the full load - I've highlighted the section. I also didn't know this, but when I had my fuel pump set up to a proper Bosch test plan for 200hp, the guys at the shop explained all the part of the pump to me. We even tested a whole load of new injector nozzles to find some that work properly.


Mine makes boost quite low, and the initial target was only 15 psi, which I set the wastegate to, and they set the LDA accordingly. Now I have disconnected the wastegate, so it runs up to around 22-23psi boost once we rev over 2300rpm, and EGTs drop, which means I could increase the full load screw, but would need to adjust the LDA to compensate for overfueling at 15psi. That is all to complicated so I'll just leave it as is. The test plan machine they set the fuel pump up on was quite complicated, with Bosch supplying the proper values for the motor etc etc, not something your average diesel mechanic has.

The reason the one without the LDA makes less power, is because they can't turn up the fuel as much without blowing black smoke and melting the pistons at low rpm and low boost. Adding the LDA means they can turn up the full load screw without risk but it was officially done for emissions. I think we are talking more or less about the same thing, these old mechanical pumps have a lot of limitations to try and match the output of the engine.


The reason I went with Water/air is that if something fails, then basically we just loose some performance, and can carry on driving. We did have a failure of the intercooler radiator after I tighten the fan too much and it hit the core, and all I noticed was the EGTs were around 70C higher than normal going up steep hills. We were away on a trip, and after 10 years my cheap Chinese intercooler started to leak, the boost blew the water out of the intercooler pressure cap. I could be because I just user water, not coolant and it started to corrode, but could have been just vibration and the aluminium fatiguing. Again, nothing stopped us from driving the 500km or so back home, just had to watch the EGTs up the hills. If an air/air intercooler leaks, then you loose boost, and it once it starts to leak, it kind of self destructs and then you have a serious problem, even with the LDA . Having the intercooler right up close to the grill means it is in the direct line of fire.

Water/Air offer a lot of advantages.

1. My air intake temp seldom goes over 70C, even at full boost up a long hill, and from reports from others with air/air, they don't get anywhere near that performance.
2. No loss of boost.
3. No heat load on the radiator, we have just come back from a 5 month trip, and experienced a few 48C day, truck stayed cool, a/c worked. The intercooler radiator take some of the heat load that on an air-air goes into the engine radiator.
4. We have air conditioning, with the condenser in front of the radiator, and an electric fan in front of that, and there is no space left behind the grill to fit anything.
5. It was also considerable cheaper - less than $1000 for the whole set-up compared to the $3-4K for the air to air from the aftermarket people, and more for an OEM one. Mine is all off the shelf component available on ebay, Aliexpress or my local speed shop. I've heard of people waiting 3-4 months for an air to air intercooler.


I started making the exhaust today, and have done the first half. I think I may be able to squeeze in the 4" pipe all the way, if I move a couple of things out the way. It will be a tight squeeze, but when I did the first one I was a conservative in regards chassis flex, and now I have a better idea of how and where the chassis flexes, so I will be using two flex joints at the key points, and this should allow me to bring the pipe closer to various parts which I will control with a couple more hangers. I will know tomorrow whether 4" all the way is possible. I was going to do a 15" long taper, which according to my very crude and rusty knowledge from my fluid dynamics course 4o years ago, I did some flow calculations, and assuming the 600C exhaust gas cools at roughly 100C by the time it gets to the smaller part it should not make a difference but it all goes as planned, I will never find out now. The hardest part is the transition from the 3" exhaust brake flange to the 4" dump pipe, I don't have that much space but what I have come up with should work OK, but there is not much of a taper going on, but then the exhaust brake valve is right there, and it goes through 90 deg at the same time, so hardly the smoothest flow and no doubt pretty restrictive compared to the 4" pipe.

I tend to overthink everything, but I enjoy making modifcations to my truck, and try to do is sort of scientifically, trying to measure the things before and after each change. As W. Edwards Deming famously said, "Without data, you're just another person with an opinion."