Getting the most out of a diesel engine?

[LeadRogue]

If I may ask a few questions as I am learning all the time.

1. is it possible to get to insane horsepower levels in a diesel engined car like you can with a highly tunable petrol Skyline GTR for example?

2. How could this be acheived?

3. Which engine and/or car would be a good starting point for a project of this nature?

4. Is a turbo swap on a diesel a difficult task? Could a second turbo be added? if so could the engine cope and would it be poductive?

5. I have never heard of a diesel engine with a supercharger. Could it work?

6. What else can be done? Money no object.

Thanks in advance.

[Yugguy]

Howdo.


Range Rover have a 4.4 supercharged diesel.

Getting massive power is the same for any engines. Forced induction and strengthened internals.

[jarrus]

Thats an easy one, Get a Merc E Class E300 turbo diesel with the OM606 engine in it.

For this kind of tuning, modern common rail would be useless as the parts used on many cars are far too specialised to each car (mainly injectors and pumps, any turbo could be made to work). Unless you were prepared to get an american diesel truck (pick up truck, there are tonnes of mods for them, Cummins, Duramax and Powerstroke diesels) then the Merc is your only really option.

The reason for that is that the Merc uses a Bosch P inline injector pump which is by far the best of all the Mechanical injection pump offered on a diesel engine. It uses lobes to open each indiviual plunger for each injector therefore opening less times that a rotary pump plunger where one plunger has to deal with all the injectors so doesn't fill properly all the times it's being pushed hard. So inline pumps are great if you want to rev the nuts off the engine, which you will need to to make good power. Inline pumps were found on various tractors making silly amounts of power so the internals can be transplanted into the Merc variant to provide the fueling.

Also the OM606 will take the punishment. It will rev to 7000 rpms due to the fact it's an IDI which has longer injection duration. It will also take over 500 bhp before uprated internals are needed.

To make bower power on them you can use things like NOS, but the best ones are water/meths or Propane and Compound turbo/supercharing would be a thing to look into.

[HDi fun]

Ultimately you're going to see better performance from a turbo petrol engine than a turbo diesel one if they are of similar age and design approach.

500bhp from a 2.0 petrol is achieveable, from a 2.0 diesel you're not likely to see much more than 300bhp at best. The midband torque in the diesel will quite possibly be superior but you're never going to get the 8000rpm revability in a diesel car.

Personally this wouldn't worry me.

Jarrus is dedicated to doing some magical stuff with older diesels and he's good at it. Very good. it wouldn't be my starting point as it's not a project for the faint of heart like me .

[jarrus]

Thanks for the kind words paul

And yes he's right, ultimatly if you want more power from a diesel, eventually you will need to go for a bigger capacity engine and the reason I suggested the Merc OM606 is because you can rev the nuts off it(I've seen them being revved to over 7000 rpms and still making useable power) due to it's IDI design (and the Merc engien are mega strong) where there is a longer duration in the injection cycle and the turbulance created in the pre-chamber that there is always enough diesel anywhere in the power stoke so the flame front is always there. But IDI diesels do have there problems, they require much bigger compression ratios there not as smooth as DI engines, the cylinder head is much more prone to cracking because of the "big hole" aka prechamber is in the head.

Finding lots of power out of a small capacity petrol engine is easy, just up the revs and add a turbo but like said before with a diesel you have to start with a bigger capacity but this usually means as well that the diesel will produce the big amount of midrange torque they are known for. Also wacking a bigger turbo on any engine diesel or petrol will also shift the torque/power further up the rev range, thus the term bigger turbos need less boost pressure to produce the same/more power, this is true yes but you produce the higher power figure (only talking about HP/KW at the moment torque comes later...) at a higher RPM and power is a measure of work done ultimately, if you want to produce more power at the same RPM's then more boost will definately be needed also supporting the more boost=more power theory and it does (till the point of deminishing returns..)

Torque is another thing to consider, if you put a larger turbo on then you produce your peak torque later in the rpm band and you will often find (especially on a turbo diesel) that you will make a lower peak torque figure...why? Because then engine was originaly designed in such a way that the peak volumetric efficiencey was at that point in the rpm band (on most engines peak volumetric efficencey is at where peak torque is)

So really on a diesel you need a lot of work to make them produce big power, but ultimately though I find it worth it, just to wipe the smile off the "antidiesel's" face....

[LeadRogue]

Jarrus,

Your knowledge of diesels far surpasses mine. Have you got any projects on at the minute? How about starting one? I have some spare funds that I can put into something. Like you said diesels may be hard work but the reward would be just too good to pass by.

[jarrus]

I've got one on at the moment mate, my own motor my 306 check the link in my sig, I do have a 205 as well but I got to finish (when I say finish I mean to the point I can drive it then think about other stuff) I'm engine converting it at the moment with one of my "special" injector pumps.

I wouldn't mind doing a BMW 325 TDS E36 or a Merc C250 TD W202

[Grizbear]

Diesels can be supercharged, 2 stoke diesels MUST be supercharged or they will not run,

[jarrus]

Yes, as 2 stroke diesels don't have the scavenging effect.

[Grizbear]

Not entirely so, the intake ports on a 2 stroke are on the lowerportion of the cylinder wall, so as the piston travels down toward BDC the exaust valves open and then shortly after the intake port windows are opened by the piston, so in effect there has to be a positive pressure difference to preform the gas exchange, as there Isint a downward stroke to pull in fresh air as in a conventional 4 stroke, now if what I have described is scavenging , my apologies ... I dont mean to insult. But if anyone has an interest in 2 stroke diesels check out Www.deltahawkengines.com they have developed an aircraft diesel engine.... Cool stuff

[rhampton]

All mods are good till they go BANG

Chip it and keep it cheep

[HDi fun]

Originally Posted by rhampton

All mods are good till they go BANG

Chip it and keep it cheep

I'd always go for a proper remap over a chip tune. These, too, can be problematical if the tuners go too far or the owner is sloppy with maintenance or drives aggressively with a cold engine.

I agree though that a common rail diesel engine + quality remap is the cheapest source of performance out there.

For two stroke diesel units with superchargers check out the Napier Deltic used in British Railway's Class 55 monsters.

[jarrus]

Diesels can take much more before unrated internals are needed so things like big turbos and fuel pumps are completely above board.

[HDi fun]

Originally Posted by jarrus

Diesels can take much more before unrated internals are needed so things like big turbos and fuel pumps are completely above board.

Generally yes. Especially so if the engine has been designed from the ground up for derv operation. The DW12TED4 in my 406 2.2 HDi was unburstable but the 2.0 HDi units of that era were derived from the PSA petrol engines.

Cranks and rods OK for the application but a savage remap would overstress them I think.

[jarrus]

The hdi engine internals(even the 2.2 stuff) are interchangeable with the petrol stuff but I can asure you that the diesel stuff is far more robust, the diesel cranks are forged as standard (DW and XUD's) the con rods are slightly stronger on the DW's than the XUD and the barings are much larger, main barings big and little end, if you put XU10 rods in an XUD9 they would definately give out.

Yes they are derived from the petrol stuff but they are made out of much stronger stuff.

[Wanda]

Interesting thread. In theory would a twin turbo with smaller turbo work better than a larger upgrade?

[T9 man]

Originally Posted by Wanda

Interesting thread. In theory would a twin turbo with smaller turbo work better than a larger upgrade?

It works for the new Saab 9-3, they have a twin turbo diesel setup with one large one small which by all accounts works extremely well.

[pgarner]

as long as the air could still get passed the smaller one, otherwise it would become a restriction.

[jarrus]

Not really, you have tractors and big American pickups running 3 or 4 stages blowing into each other! But like i said in the other thread though, air flow isn't devided the big turbo has to flow all of the air...