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why no supercharged diesels??

shady

shady

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I've been pondering this question for ever. now with all the brains on this site I figure I may get an answer. Why are diesels always turbo'd and never supercharged. I've never seen or heard of it done. It seems that it would work better due to all the torque they make, it wouldnt rob as much power to operate as they due on gas motors. I'm sure some lab or techs have tried it and come up with good reasons. I just cant figure them reasons out.
 
over 1/2 the Detroits out there are supercharged... some in conjunction with turbo/s.....
 
Huh, shows how uninformed I am,:whistle: Some how I knew it was a stupid question:rolleyes::haha: I was just thinking about small trucks. I've been around semis my whole life. but in them, not under the hood. I have never been a tubo fan and have always been a diesel fan. I've just never really tried to hop one up.
 
raping old school bus's for the blower used to be the hot ticket...


here's a supercharged, twin turbo Detroit in a boat...


Lafco-44-painted-051.jpg
 
ya man were you think thay got blowers from ?

and good rule of thumb i heard is 1/2 the power thay make is used to spin one up.

turbo's use wasted exaust gas for free power.
 
Detroit diesels are 2-strokers. Without the benefit of an intake stroke the engine needs something to force clean air into the combustion chamber and scavenge any residual exhaust. In comes the “Blower” (not supercharger) to blow air into the cylinder. Little to no boost is created by the blower.
Some years before my time some guys wondered what would happen if you set a blower up on a gas engine with an overdrive to create boost. That was the day a blower became a supercharger. Essentially, a Detroit with a blower and no turbo is what is frequently called naturally aspirated.

The major problem you have using a belt driven supercharger (as opposed to an exhaust driven supercharger like a turbo) is that diesels have nothing to regulate the incoming air flow like the throttle plates on a gasoline engine. A belt driven supercharger would be creating boost (pressure above atmospheric) at all times, even when there was no need for it. A diesel takes in much more air than is needed at idle and cruise but can’t get enough under load.

A turbocharger, being exhaust driven is a perfect fit in that more fuel = more exhaust = more boost. Take away the fuel and you take away the boost.
 
Theres a Supercharger Kit for the 6.2/6.5's Pretty rare I'd like to have one.



Also Cummins Had a few Engines way back in the 50's and 60's that Used a supercharger, But they were a 4-stroke unlike the 2-stroke Detoits
 
yup all 2 stroke diesels have a blower. they will not start without one. no intake valves in the head, only intake ports in the liner. the piston creates little to no vaccumme in the common air box so no air flow no running. the blower allows the engine to actually start and run. which also the reason 2 strokes with a blower and no turbo are considered naturally aspirated. and it scavanges the cylinder like was mentioned before.
 
SOME Detroit diesels are 2-strokers.
There fixed it for you:thumb:

On your pickup sized Diesels you wouldn't want to give up so much hp to run the supercharger because the only advantage is no turbo lag, but you wouldn't notice it in a diesel anyway. (much):whistle:
 
TexasSilhouette said:
Detroit diesels are 2-strokers. Without the benefit of an intake stroke the engine needs something to force clean air into the combustion chamber and scavenge any residual exhaust. In comes the “Blower” (not supercharger) to blow air into the cylinder. Little to no boost is created by the blower.
Some years before my time some guys wondered what would happen if you set a blower up on a gas engine with an overdrive to create boost. That was the day a blower became a supercharger. Essentially, a Detroit with a blower and no turbo is what is frequently called naturally aspirated.

The major problem you have using a belt driven supercharger (as opposed to an exhaust driven supercharger like a turbo) is that diesels have nothing to regulate the incoming air flow like the throttle plates on a gasoline engine. A belt driven supercharger would be creating boost (pressure above atmospheric) at all times, even when there was no need for it. A diesel takes in much more air than is needed at idle and cruise but can’t get enough under load.

A turbocharger, being exhaust driven is a perfect fit in that more fuel = more exhaust = more boost. Take away the fuel and you take away the boost.
Click to expand...

thats a really good explanation.

i love detroits. we never had one, but some of my dad's friends did. all the local concrete companys had 6v92s in the rear. and the mixer dumped out the front of the truck. very cool trucks if you are into 6v's.
 
there is actually a number of guys now using a blower compounded with a big turbo in a set of "twins" on 4 strokes. I've seen a couple 5.9 cummins and 1 duramax. basically they use the supercharger as the primary, instead of a small turbo. then use a bypass when the secondary is spooled up. its a pretty deadly setup. immediate instant boost off the line and a big boy turbo for the top end. best of both worlds. I'll look for links they;re pretty sweet actually.
 
this a 7.1L stroked 2008 Duramax engine. 2 turbos feeding that massive blower.


[YOUTUBE]6bG-KSYkR0A&[/YOUTUBE]
 
It's been talked about a little already but turbos are considerably more efficient than superchargers. The downfall is that turbochargers typically have a limited RPM range that they work in (i.e. they only produce substantial pressure for a limited range) but on a diesel that only sees ~2000 RPM of usable RPM (say, 1000-3000 RPM) a turbo is a great fit.

This is why you see twin turbos in some vehicles (many have one that creates boost at low RPM and one at high RPM) and why turbos in new vehicles often use variable vane turbos, to make boost at low and high RPM's.

Honestly, turbo technology has become good enough that superchargers are somewhat becoming a thing of the past for most non drag race applications.
 
you tube it!

Pretty sure this one is a super/turbo. Where the turbo shoves air down the throat of the super charger!

 
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Honestly, turbo technology has become good enough that superchargers are somewhat becoming a thing of the past for most non drag race applications.
Click to expand...


they die hard for oldschoolers.... blower whine is a sound of joy....

heard the other day it takes 400hp (a healthy sb) for the 8000 hp top fuelers to spin the blower...
 
thats exactly whats being done. replacing the "little" turbo in a compound twins configuration, with a supercharger. you cannot beat a SC downlow for boost. then the big turbos take over.

I'[ve had a couple variations of twin turbos on my cummins before. and there is still lag on the bottom end. with a turbo, you just can;t get away from it. With a SC in its place it really is the best of everything.




38377k5 said:
It's been talked about a little already but turbos are considerably more efficient than superchargers. The downfall is that turbochargers typically have a limited RPM range that they work in (i.e. they only produce substantial pressure for a limited range) but on a diesel that only sees ~2000 RPM of usable RPM (say, 1000-3000 RPM) a turbo is a great fit.

This is why you see twin turbos in some vehicles (many have one that creates boost at low RPM and one at high RPM) and why turbos in new vehicles often use variable vane turbos, to make boost at low and high RPM's.

Honestly, turbo technology has become good enough that superchargers are somewhat becoming a thing of the past for most non drag race applications.
Click to expand...
 
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