I've wondered about putting a blower on my diesel. If I had a huge amount of time and money... I'd make one that started to spin at 800 RPM (just off idle) and be geared like crazy, so it was blowing 5 psi by the time I hit 1500 rpm. By the time I get there, I have plenty of turbo boost. At that point, I'd like a clutch in the blower to engage, so it no longer robs power.

Seems like the best of both worlds - no lag, instant power, huge boost pressure and the mostly free boost of a turbo.

I think I need to win the lottery.

 

Sounds exactly like the Deltahawk engine. Check out www.deltahawkengines.com/
Tony

 

i am in deisel mech. school and we just built two 71 series detroit 2 stroke v8 engines. they both have superchargers on them with a big turbo on top of that. the superchargers were gear driven and were needed to forrce the air in the engine since they are 2 strokes and pretty much obsolete. the detroit 71 series is anyways.

 

Yeah the 53, 71 and 92 series are all pretty archaic, but you can't kill 'em. We've been running them in our fishboats for many years and though they're loud, leak oil and are thirsty, they won't leave you stranded. Personally, give me a nice turbo cummins, like an 855 or an 1150. They're alot better on fuel and they sound so much nicer.

 

what about the cummins M11

 

i'm exposing my ignorance here, but I'm not familiar with that model. All I am familiar with is the 855 and 1150, and I think those are older model designations. The guy that bought one of my dad's boats replaced the 12-71's with KTA 855's. I was actually the first person to run the boat (he wanted to be in the engine room) and let me tell you, after running the boat with either pair of engines, the cummins were GREAT. And I love that sound.

 

they're all to loud for me. my hearing is bad enough as it is and i am only 19 and i do not listen to ground pounding music.lol i was born with bad hearing, and no it is not selective hearing either.lol

 

And you're a mechanic? Man I love engines, especially diesels. I'm no engineer but I know my way around an engine room.

 

well don't like the no exhaust straight exhaust manifold diesel engine sound that we have in our little shop, that just echos all over and when you are standing right next to the exhaust manifold it really sucks. don't get me wrong, i have a fox body mustang with open long tube headers. i love it

 

Bless you, now go forth and rev thy engine.

 

it's an 89 coupe with a 5 spd.i built the motor myself and let me say, it really flys. i even brought a turbo home from my class to put on it but i think i am going to sell or trade it.

 

Turbo power isn't free because it provides an obstruction in the exhaust system. If you can't get the spent gas out you can't get the fresh in. That's the whole premise behind headers. Turbo's may be more efficient up to a certain point, but there is a law of dimishing returns.

Blowers as used on the Detroit Diesels aren't superchargers per se, they are only made to fill the cylinders at more or less atmospheric pressures. The turbos are used on these engines to increase cylinder filling above atmospheric.

I have often considered the possibilities of a roots type blower for a diesel. With a positive displacemant and choosing the correct size there shouldn't be a need to spin one really fast. Plus you have the added benefit of no exhaust restrictions. You probably wouldn't have to run that much boost to see a big performance increase. I wish I had the funds to experiment.
DannyP

 

AHHH, finally a like minded response. :-) I think I read what the new whipple blower being modded onto the v10 uses 1 HP at cruising speed. Wow. Put some open flowing hedders on a diesel and supercharge it... and gear it really high with stout gears and it might get 30 + mpg??? Maybe not too. I think a turbo lengthens the usefull rpm range over a NA diesel. I wonder if a super would have the same effect.

Tony

 

71 series obsolete? Maybe, but the most reliable engines I have ever encountered. All mechanical, leaky, smoky, noisy, thirsty, but reliable. I had a pair of 8v71N's in my last boat. The silly things had close to 9000 hours on them and I kept hoping they would die to give me an excuse to major them, but they just wouldn't....

As far as the blower on these, they are mostly to ensure a clean air charge in the cylinders for the compression stroke. They are 2 cycle engines, and therefore the pistons don't force the exhaust out. A supercharged Detroit (I am not aware of any 2-stroke Detroits that weren't) is still called a naturally aspirated engine.

Something else to add on the blower/turbo comparison is that Roots type blowers are positive displacement, making the output directly proportional to the rpm, i.e. if you double the rpm of the blower, you double the output. A turbo is not positive displacement, making the output closer to exponentially proportional. Double the rpm and the output is squared, notwithstanding manifold backpressure.

 

This I can believe except at low RPMs. I can't quite believe that a turbo's output is squared between 8 and 1600 rpms as it would have almost nothing at 800 rpms. But this does help explain why the deltahawk engine would encorporate both superchargers and turbocharging on the same engine.

Tony