roots blower on a diesel?

I know older 2-stroke diesels used blowers to get the air going, but could a blower be used instead of a turbo? I know the answer is yes, but what I really want to know is... would it be a suitable match for a performance diesel? I am unsure about how screw-type blowers would affect intake temps and what their practical pressure limit is.

As you probably know turbos are used because they offer good power and also provide a near ideal amount of back-pressure for the diesel engine, although further up in the performance heirachy free-flowing exhausts are best.

they don't offer the same intake pressures as turbos do (look into two-stage turbocharging for serious intake pressures, my mate's running his 5.9 at 54psi) and i'd imagine with intercooling the intake temps wouldn't be too bad. even in non-intercooled form there isn't much of a problem, as many turbo diesels run without intercoolers.

if performance is what you're after, you'd be far better off with a turbo. (variable vane and/or two-stage turbocharging are the absolute ideals) there's far better efficiency and better power potential, but if you want to supercharge it, give it a try.

there's never been a vehicle built and developed without some trial and error involved in its development. :smooch:

you could have a supercharger feeding a turbo...
talk about forced induction.

i personally don't see the point of a roots blower on a diesel (well it would be unique and it might turn up some interesting results, this is just from what i know right now)

the roots blower creates heat and uses crank power to spin. a turbocharger creates heat and doesn't. a twin screw creates less heat than the other two but it uses crank power to spin. so i'd think it would be a better choice to go with a twin screw than a roots blower.

what was your idea concerning? turbo lag or eficiency? because with the variable vane turbochargers you can run rediculous ammounts of boost with alot less lag than before (which you alreay knew) so i don't really see any advantage to a belt driven supercharger.

da pimp factor...
:grinyes:



never mind
:shakehead

Toyota did some supercharged diesel passenger cars in the early 90's. But I've only seen a few and they were random japanese imports (kind of like the 4wd civics I occasionally see).

It would have had to be a positive displacement supercharger, otherwise the key attribute of a diesel (low end torque) would have been lost completely.

They probably used the samer supercharger they fitted to several of the 4AGZE's.

you could have a supercharger feeding a turbo...
talk about forced induction.

I hear the other way around gives the best results.
Turbo feeding the supercharger.

lol, well if you had alot of lag it would have been a possibility, but since turbochargers have come a long way and have reduced lag times, it's no longer necessary. not to mention that it would weigh alot more.

I hear the other way around gives the best results.
Turbo feeding the supercharger.

the best is actually a turbo feeding a turbo, or two-stage turbocharging as it's called.

http://www.turbos.bwauto.com/en/products/images/img_r2s_schema_g.jpg

The reason I'm doing this is for, well, pretty much, the pimp factor like Goose said.

I am a diesel freak and have converted a few cars/trucks. I'm putting a mechanical 6.5 in a 73 Impala Station wagon, I'm looking into the feasibility of putting a MWM brazilian diesel in a 65 Scout 800. Anyway, my goal with all of these is to make viable performance with simple diesels. Showing people that its a useful means of getting performance with efficiency is the goal. The 6.5 is a twin turbo that should make north of 400 hp on bio and still get me 25+ mpg. I would love to have a bumpersticker that says, "400 hp, 25 mpg, zero net emissions, $1.21 a gallon... ask me how."

Anyway, since I have an 8-71 sitting around I thought, what screams performance more than a huge huffer sticking out of the hood of classic sheet metal? Why not see if a blower could be mated with a diesel with good results.

sounds like a good beginning to a good story to tell.

if you dont like the performance, then you could always put a turbo in and leave the supercharger bolted on but not have it actually do anything.

i guess it all comes back to "da pimp factor"

Diesel engines have rather large displacements and expel hot gas which is full of unused energy. A turbo is the ideal device to capture that energy and reuse part of it. Turbos are by design more efficient that superchargers and even though diesels don't rev high, i would still opt for the turbo over the supercharger. It could be done, but i dont see the benefit of a supercharger over a turbo....even if you're just looking for more low end power, you can just properly size a turbo to fit the same need without being limited by the pulley on the supercharger, rather being limited by the compressor housing and efficiency range of the turbo.

Diesel engines have rather large displacements and expel hot gas which is full of unused energy. A turbo is the ideal device to capture that energy and reuse part of it. Turbos are by design more efficient that superchargers and even though diesels don't rev high, i would still opt for the turbo over the supercharger. It could be done, but i dont see the benefit of a supercharger over a turbo....even if you're just looking for more low end power, you can just properly size a turbo to fit the same need without being limited by the pulley on the supercharger, rather being limited by the compressor housing and efficiency range of the turbo.

You know as well as I do that Curtis knows all that. If he wants to supercharge a diesel then he either just wants to do something different or has some interesting parts that might fit together.

No point in preaching to the converted.

I'm kinda looking at it from a "can it be done" instead of what's best. I know a turbo is the best setup for a diesel, but if I can get similar or at least decent performance from a blower I might try it.

I would love nothing more than leaving the bar at 1 am with the smokers admiring my blown car and then starting it and letting them hear its a diesel.

I could always gut a blower and push two turbos through it, but that's a poser move. I only put real stuff on a car. I don't do wings, and I don't do fake speed parts :)

well if you're doing it for that then i'd say go for it. it'd look sweet, sound mean, and it would be pretty damn unique. and if a diesel can run NA, then it surely can run with a blower instead of a turbocharger. go for it and post pics and vids

Well, it will be a while. I'll have to custom-build an intake for it to fit the blower. But it might be worth trying. I figure if I can get 20 psi from the blower that should be good for 350 hp and close to 600 lb-ft from a 6500 economizer.

what engine are you thinking of using for the blower?

Well, it will be a while. I'll have to custom-build an intake for it to fit the blower. But it might be worth trying. I figure if I can get 20 psi from the blower that should be good for 350 hp and close to 600 lb-ft from a 6500 economizer.

What intake temps would you get on a blower at 20psi?

You might end up giving away a lot of potential power as the hot intake charge won't let you run as much fuel before hitting a safe EGT limit.

What intake temps would you get on a blower at 20psi?

You might end up giving away a lot of potential power as the hot intake charge won't let you run as much fuel before hitting a safe EGT limit.

good point....

Toyota did some supercharged diesel passenger cars in the early 90's. But I've only seen a few and they were random japanese imports (kind of like the 4wd civics I occasionally see).



Your thinking of Mazda. Toyota has always Turbo'd thier Diesels.
Mazda made a Diesel version of the vunerable B series 2.0 4cyl motor fitted to the 626/Telstar from about '88-'89.
It used what they called a "pressure wave" supercharger, that basicly replaced the inlet manifold.
Its unfortunalty regarded as one of the worst, and most forgettable diesel engines ever made.

what engine are you thinking of using for the blower?

Its a 6500 economizer. Its the marine/military version of the 6.5TD without the crappy injector pump and crack-prone decks. Basically what the 6.5 should have been if GM hadn't messed it up :)

This one is basically a marine twin turbo version (minus the turbos) that was rated at 400 hp. They take the marine 6.5 block and use a more reliable mechanical pump.

What intake temps would you get on a blower at 20psi?
You might end up giving away a lot of potential power as the hot intake charge won't let you run as much fuel before hitting a safe EGT limit

I thought of the same thing, but who cares? No turbo to fry, so as long as it doesn't top 1800 I should be fine. Its the marine engine, so it has inconel valves that should handle it. They handle WOT with two turbos for 20 hours at a time in boats, they should handle an occasional heavy foot.

Will you get 20 pounds of boost at idle also? If sized to flow more cfm than the engine it should be somewhat stable/equal boost at most rpm and loads.

I think this is not good. What do you think?

Your thinking of Mazda. Toyota has always Turbo'd thier Diesels.
Mazda made a Diesel version of the vunerable B series 2.0 4cyl motor fitted to the 626/Telstar from about '88-'89.
It used what they called a "pressure wave" supercharger, that basicly replaced the inlet manifold.
Its unfortunalty regarded as one of the worst, and most forgettable diesel engines ever made.

Right you are.
I thought it was a toyota carib which I saw, but it would have been a mazda wagon. My attention was fixed on the "supercharged diesel" stickers.

Curtis, do they have alumin(i)um pistons? Melting those would be your main EGT concern.

I figure if I can get 20 psi from the blower that should be good for 350 hp and close to 600 lb-ft from a 6500 economizer.
This one is basically a marine twin turbo version (minus the turbos) that was rated at 400 hp.
HUH???

so either you are decreasing the power by 50 horsepower, or you are nearly doubling it...
not sure which you meant, but i hope its the latter.


or did you mean that it was rated for 400 hp with twin turbos???

Will you get 20 pounds of boost at idle also? If sized to flow more cfm than the engine it should be somewhat stable/equal boost at most rpm and loads.

I think this is not good. What do you think?

I think that as long as there is a surplus of air, 20 psi will make very little difference at idle. Since diesels are throttled by fuel injection and that wouldn't change, it should be fine... unless there is some parameter of diesels that I'm missing.

HUH???

so either you are decreasing the power by 50 horsepower, or you are nearly doubling it...
not sure which you meant, but i hope its the latter.
or did you mean that it was rated for 400 hp with twin turbos???

Its rated at 400 with the turbos and about 25 psi. I would be replacing the turbos with a blower at 20-ish psi.

what kind of turbos were they and what were the flowratings??

It's a very interesting project. I hope you keep us informed.

well its not likely that a supercharger could ever put out 20 psi at idle anyway, so there isnt really a problem.

well its not likely that a supercharger could ever put out 20 psi at idle anyway, so there isnt really a problem.

If it's a true constant volume device (i.e. negligable leakage) then 20psi at idle will happen.

It will not cause any benefit at idle, but do you want it to be "working" at all engine speeds other than WOT?

In any case the excess air is great for the engine, my point was just about the power robbing and heat at all the engine loads/speeds other than WOT.

I think you'd be far happier with a turbo, but might be a bit more work/expense. Interesting project anyways.

It will not cause any benefit at idle, but do you want it to be "working" at all engine speeds other than WOT?

In any case the excess air is great for the engine, my point was just about the power robbing and heat at all the engine loads/speeds other than WOT.

I think you'd be far happier with a turbo, but might be a bit more work/expense. Interesting project anyways.

With a little work you could add a recirculating BOV, have it triggered either by rpm or pedal position.

Whether Curtis decides it's necessary or not will depend on the usage of the car.

That would go a long way in "unloading" the blower and may be benefitial.

hmmm, not sure why so many people are making this sound like this is somehow drastically different than a gas engine. There's some inherent differences of course, but the end results are pretty simular.

positive displacement forced induction has the advantage of offering boost at a larger range of RPM's, but they are less efficient and thereby create more intake heat.

The reason that diesels always use turbo's is more to do with fuel economy IMO.

I see no reason a SC wouldn't work on a diesel, but it'll have the usual disadvantages to SC. Nothing too shocking