Supercharging a Diesel?

[toyrota mota]

Ok im bored and thinking about small fun projects I can play round with. Got this turbo diesel pajero and want to get abit more power/torque out of it 4wding. I was thinking remove the turbo slap a sc14 on it and say a suby water to air i/c and see how we go.
After abit of a search it doesnt sound like that great of an idea. And that turbo is a much better idea specialy on a diesel. I know all the stuff about modern turbos spool up quickly and superchargers drain power.
But it sounds alot easier and maybe cheaper chucking a supercharger on it than trying to match turbos and compressor maps etc to have a turbo that will give boost right the way thru the rev range.
Just an idea whats your thoughts?

[touge rolla]

stick with the turbo far too much hassle and $$ switching to supercharged which may or may not be an improvement.
With all that mucking around you might as well go twin charge

[toyrota mota]

Looked into twincharging(which would be abit pointless i would think on a diesel) and thats just to complex!
Not really going to cost much money, might give it a try this is more im bored whats something different I can do with what i've got(i.e. not buy another project)
Anyone tried LPG injection on a diesel ?

[1I1]

Make a new exhaust manifold and put a T88 on it....

[Mr Revhead]

been a long time since i have driven a diesel pajero (thankfully!)

imo go supercharger
much more suited to a diesel engine.
common issues with turbos, they need to spool up.
common trait of diesel, making heaps of torque down low
common trait with s/c making grunt down low, lacking in top end (talking sc14, cheapest option around)

so, unless you can find a stock turbo off something that just happens to be perfectly suited to the pajero, then id be going sc14

things i would look into further, weak spots in the mitsi engine and max boost they can handle.

[toyrota mota]

Thanks Mr revhead that was exactly what i was thinking, just needed to make sure.
Hmmm now how to get a cheap water to air intercooler? If anyones read 21st Century Performance in there he says boat "oil heats" make great w to a i/c, anyone tried this? And I was thinking of using a pressure switch to turn the water pump on and off when its need? But then if its s/c it'll be boosting pretty much the whole time?

An any idea about how to set the s/c up? Done abit of reading about them. So if its a diesel engine with no throttle body do i need to worry about ABVs and clutchs? Just let the engine rpm control it all? Or will I end up boosting at idle and running the engine lean?
Cheers
Campbell

[method]

The engine controls RPM be leaning it out afik.

Try getting a water to air setup off a old subaru. Should be cheap as chips.

[rollaholic]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

[toyrota mota]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

Ahhhh turn the screw on the fuel pump to give me more diesel??????

[fivebob]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

Precisely. Diesels are fuel limited not air limited. So, unless you can change the characteristics of the pump to give you more fuel down low, then it's a waste of time fitting a device that gives you more air at that point.

IMO turbos are a better option for diesels because the drive losses in a supercharger make it too inefficient, given the low rpm that a diesel operates you'd have to gear the supercharger quite high and that makes the losses worse. Superchargers are usually only found of two-stroke diesels, don't know why that is.

[toyrota mota]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

Precisely. Diesels are fuel limited not air limited. So, unless you can change the characteristics of the pump to give you more fuel down low, then it's a waste of time fitting a device that gives you more air at that point.

IMO turbos are a better option for diesels because the drive losses in a supercharger make it too inefficient, given the low rpm that a diesel operates you'd have to gear the supercharger quite high and that makes the losses worse. Superchargers are usually only found of two-stroke diesels, don't know why that is.

I know their fuel limited, but i thought you could just turn the fueling up on the mechanical fuel pump? Meh i might just do it for some fun.

Oh two-stroke diesels are very interesting creatures, reason they have supercharges is they need scavenging and compression from start up. Some do use turbos put the turbo is belt drive at start up to get it spinning then a dog clutch disengages and exhaust gases take over, its called "turbocoupling", can you say that "tuurbocoupling" owwwwwwww. Got me think about an easier way of twincharging, instead of have a s/c and a t/c, just have a t/c. Which at low RPM run the turbo shaft off the crank then disengage that with a dog clutch at high rpm.
Hmmm screw the dog clutch what about a centrifugal clutch muahahahaaha ! That would be sweet! anyone heard of anything like this being done?

[Phothog]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

Ahhhh turn the screw on the fuel pump to give me more diesel??????

Ah..... which screw though.

there is 3 adjustment screws on the pajero pumps..
1 for non boost fuel
1 for mid boost fuel
1 for overall fuel ...

99.9% of jap turbocharged vehicles have a boost compensator on them,
it sensors boost & pushes something in the pump to give more fuel.

also one problem on the 4D56 is the pressure valve on the inlet manifold, they open at about 15psi (from memory)

Best thing for the Old pajeros..... apart from selling it & getting a Toyota.
Air to water i/c (if its not intercooled) and a 2 1/2" exhaust
and give one of those fuel screws a turn.

Chris.

[MAGN1T]

[Precisely. Diesels are fuel limited not air limited. So, unless you can change the characteristics of the pump to give you more fuel down low, .

Turbos on diesels will supply more air so reduce the ammount of black smoke, increasing power at the same time, stops them overfuelling.

Your best bet is probably to just turn up the boost a bit and maybe upgrade the intercooler.

There's info somewhere on Pajero UK forum.

Steve

[toyrota mota]

you'll need to find a way to convince the fuel pump to give you more diesel before you are going to see any benefit from more air

Ahhhh turn the screw on the fuel pump to give me more diesel??????

Ah..... which screw though.

there is 3 adjustment screws on the pajero pumps..
1 for non boost fuel
1 for mid boost fuel
1 for overall fuel ...

99.9% of jap turbocharged vehicles have a boost compensator on them,
it sensors boost & pushes something in the pump to give more fuel.

also one problem on the 4D56 is the pressure valve on the inlet manifold, they open at about 15psi (from memory)

Best thing for the Old pajeros..... apart from selling it & getting a Toyota.
Air to water i/c (if its not intercooled) and a 2 1/2" exhaust
and give one of those fuel screws a turn.

Chris.

Ah you seem wise, if using the s/c wouldnt I leave the non boost screw alone and turn the mid boost and overall fuel up(it'll be the same for increasing boost on the turbo).
15Psi that sounds like alot standard can't be more than 8Psi. The turbo is TINY, any idea what its good for? And how much boost the standard engine can take?

Hahaha just having an intercooler would be an upgrade.

[xsspeed]

Hahaha just having an intercooler would be an upgrade.

Apparently helps on N/A cars too

Sorry was irresistable, I have some hoons that live up the road, they have a cefiro that has no bumper, MASSIF IC in the front with pipe to air inlet and other end connects to podfilter. <----You're doing it wrong
[/rant]

Whats the deal with LPG injection into diesel? Obviously diesel ignites due to the compression, I imagine this then ignites the lpg in the fuel air mix?

But then wouldnt the lpg suppress compression ignition?

Or were you taking the piss? Curious cos I'd never heard of it

[toyrota mota]

BAHAHAHAHA sweet deal i must try that! What they do for a BOV? bahaha thats funny as F**k!

LPG injection into diesel is a real thing, but Im not to sure how it works. Just know a friend of our family tried it. Took the turbo of his pajero and used LPG injection and it all went BANG! Pressume since diesels use fuel to control them that your injecting more fuel so more power. And that yes the exploding diesel ignites the LPG. do a google search

[toyrota mota]

Go to http://www.mrsharkey.com/lpg.htm to find out more about lpg injection. Pretty much it makes sure that all the diesel is burnt, hmmm this might be a better project
crank the boost up 3PSI, add w to a i/c and add lpg injection, and hopefully don't blow myself up.

[sergei]

Superchargers are usually only found of two-stroke diesels, don't know why that is.

They are integral part of intake system and simply replace intake valve.
Two stroke diesel is very different to two stroke petrol, the biggest difference is that it does not suck out of crank case hence it is a lot more efficient and usually used on huge low rpm things.
The supercharger stop air reversing when piston going up and the intake port is not closed by it yet