Anyone put a weiand 8-71 blower on these engines? - Diesel Forum

shitface · 11-01-2006, 11:12 PM

I meen, the 8-71 blower started on a diesel (detroit to be exact), I'd need a manifold and pully.
Has it been done?
Results? [img]/ubbthreads/images/graemlins/smokin.gif[/img]

faz_fordfreak · 11-02-2006, 01:34 AM

I've seen it done. It takes a lot of intake work and a lot of mousing around with the injection lines. I couldn't say how much it increased performance because I only saw it at a truck show and never had a chance to ask how it ran.

Birken Vogt · 11-02-2006, 09:39 AM

It gets kicked around from time to time but since a turbo can make all the boost any engine can handle, and does so without robbing shaft horsepower (mostly), it would be a very expensive and inefficient way to do it. In semi trucks it was called an "iron lung" and went out back in the 50s or early 60s in favor of the turbocharger

Birken

kleenax · 11-02-2006, 10:43 AM

When I worked at a diesel truck garage that serviced a truck fleet, back in the late 70's-early 80's, we had a couple of trucks that were blown AND turbo-charged (on the same engine). Can't remember what they where; really big Cummins I think. That contraption stuck up about 2 feet off the intake runners!

faz_fordfreak · 11-02-2006, 11:31 AM

From what I understand, the blower/turbo combo was used to cover the spectrum of boost given rpms. Blowers were used for the low rev boost until the turbo could spool up in the high revs. It's basically the same thing as modern day twin turbos; a small turbo for low rev and quick sool up, and the bigger turbo for high revs and max boost. Blowers can be geared to compensate for the low revs of diesel engines, but the classic argument is that blowers rob power. Anything with a belt robs power because it it pulling off of the crank. So, yes, a turbo would be more efficient. However, a twin stack of 8-71 blowers hanging out of the hood would be pretty sweet.

CowKiller · 11-02-2006, 11:52 AM

the turbo blower mix was on 2stroke detroits. v series engine had them off the top like a racecar does, the inlines were hanging off the side.

perryg114 · 11-02-2006, 01:05 PM

Those engines I believe were a 2 stroke diesel that needed the blower and turbo for proper induction.

Perry

Jrod13 · 11-02-2006, 03:29 PM

all the 2 strokes needed them to run, but the turbo motors were just there for the extra kick. Mainly because a roots style compressor losses efficency fairly quick.

Now, I must say having one on a 7.3 would be pretty slick, though I'm not sure how it would compare to a turbo on one.

CowKiller · 11-02-2006, 09:45 PM

it would not add much power, since it isnt gona push that much "boost" and the power it takes from the crank to power it, on these engines i belive it wouldnt add much. there was a truck in petersons four wheel off road mag in the readers rides that had one. sharp lookin truck, but they put the intake hat back on WITH the butterflies still on it. i would remove the butterflies, get as much air in as possible. we dont need no stinkin' butterflies!

agnem · 11-03-2006, 08:20 AM

Somebody had stuck one on according to a recent ebay add I saw. It looked convincing enough, but as has been mentioned, a lot of work for not much more than bragging rights.

Birken Vogt · 11-03-2006, 09:25 AM

You could drive it at a speed such that it would give you the same boost, and hence the same power, as a turbocharger, but the economy would be terrible (since you would have that amount of boost at all times whether you needed it or not) and the power would still be down a little since the supercharging power would be taken from the crankshaft and not the exhaust stream. Plus there would be a weight penalty and a maintenance hassle.

Birken

faz_fordfreak · 11-03-2006, 01:46 PM

What about the concept of a variable gear drive for the bolwer? Kind of like a CVT on the drive pulley that was enhanced as the throttle was advanced. I know that they make certain blower kits that have varying spool gears, kind of like a little tranny in front of the compressor. That would allow for different flow rates for different throttle ranges. Also, I haven't had the time to figure it, but in retrospect, people mount belt driven air compressors to their motors and they don't totally fall on their face, so why is a power adding device such a big deal when it comes to arguing power loss? Shouldn't it make up for itself in a sense? Granted, not nearly as efficient as a turbo, but I just hate to count things out, especially when they would look pretty sweet and be totally unique, which, after all, is the essense of hot rodding!

Birken Vogt · 11-03-2006, 03:44 PM

The air compressors are much less air volume than a Detroit Diesel blower puts out. It certainly would be functioning as a power adding device but only when the power is actually needed which is rare, the rest of the time it would be a power wasting device in a big way. A variable drive certainly would help matters a lot but it would still be worse for several reasons

1. Expense
2. Exhaust energy is still wasted, unharnessed, out the exhaust
3. The Roots style Detroit blower is very inefficient compared to the centrifugal turbocharger style

The bottom line is that given the same base engine, slightly more power could be made with the turbocharger than the blower because the turbocharger gets its energy from otherwise wasted exhaust energy, and also the efficiency standpoint.

Birken

Dave Haven · 11-03-2006, 08:53 PM

[ QUOTE ]
The air compressors are much less air volume than a Detroit Diesel blower puts out.

[/ QUOTE ]Yup. And the air compressors also have a magnetic clutch that disengages them from the drive pully when they're not needed, as in most of the time.
Thanks for taking up the slack for me on these threads, Birken. [img]/ubbthreads/images/graemlins/wink.gif[/img]

ranchero50 · 11-03-2006, 08:59 PM

There's a lot of interesting theory in this thread. I think with a properly sized positive displacement blower these motors would run very well, much better under 2k vs the IDI turbo stuff I've run across. I would not run a 8-71 (inefficient junk), but a newer whipple style with an air - water after cooler ala the lightning or 2003 cobra. The real trick would be to size so it would boost correctly.

Jamie