Shade-tree engineering idea: poor man's smoke turbo?

[Buffalo SpaceShip]

As I've bemoaned here numerous times before, I'm having smoke issues at altitude with my 8V71 w/ C65 injectors and normal timing. While I appreciate the extra power at lower elevations, anytime I'm above 3,000MSL or so, I'm blowing black smoke on acceleration and esp. on climbs. Once I'm above 8,000', it becomes a real problem with heavy smoke and running hot on any kind of climb. I'd like to take our coach up into the high-country more often, but keeping it cool is a real problem.

The obvious solution is to put in stock C60 injectors to limit the over-fueling. Other than the cost of the injectors, though, I'd have to find someone to re-run the rack... and do it right, which is becoming harder and harder to find qualified two-stoke mechanics.

Also, a smoke turbo would be another solution, but I'm reticent to put several thousand more $ into this coach. I'd rather buy a conversion with a 6v92 (and maybe a 40'er while I was at it).

Last week I had to change out my air filter and air box system, since the old paper element was "unobtainium". I went with a Farr Ecolite-style all-in-one housing/filter unit I bought from NAPA that has 6" inlet/outlets and initial restriction rated for 1000cfm @ 5" H2O. FYI: They also make one with 7" inlet/outlets rated 1500cfm @ 5" H2O. I did a quick hack job on the air box to make it work, thinking I'd come back in later and add a new air inlet at the top of my rear cap and keep the inlet air far away from the heat of the engine compt. (see pic)

As I was hacking away, I had this shade-tree engineering "light-bulb" idea: what about putting in an inline utility blower before the air filter to try to "suck in more air" during those black smoke moments? A quick eBay search netted a 10" blower that puts out 1800cfm, turns 3400rpm, static pressure rated at 441 Pa (Greek to me), and uses 320w. Here's a link to one of 'em. They also make a 12" model of 2472cfm, 490 Pa static pressure, and 520w OR an 8" model (1236cfm,410 Pa, 150w).

I'm attaching a quick-and-dirty sketch of my hare-brained idea. There's a lot of folks here on MAK a lot smarter than I am when it comes to these things, so I'd appreciate any technical discussions about whether on not this idea is worth pursuing further.

Thanks! And sorry for the long-winded explanation. Maybe the sketch was enough!

Brian B.

[Jeremy]

What you're describing is an electric supercharger; they do exist but are not common, because (I assume) they are horribily inefficient (electric power input greater than increased engine power output). Having said that, for a 'temporary' power increase (ie, overtaking, or perhaps climbing a short hill) I dare say the numbers would work.

The problem with any sort of on/off forced induction on a petrol engine is setting the mixture up so that is correct in both scenarios. I have no idea at all on what fueling adjustments need to be made when turboing / supercharging a diesel, but presumably the same situation exists - although I realise that the point about 'smoking at altitude' is that the fueling / mixture is already completely screwed up anyway.

It's an interesting idea, but probably falls into the category of 'if it worked then they would already do it'

Jeremy

[prevost82]

Hi Brian ... while it may look good in theory, I doubt that it would work. It can move enough air but can't create the 5 to 10 lbs pressure and that what you need for a smoke turbo. Also you may want to look for a 8V92TA in a coach as you live in the mountains like me, not a road out of this town without a 6% grade. The fuel milage isn't that much differant but it sure nice to have all that HP and torque on the long steep grades compared to a 6v92ta.

Good luck
Ron

[Buffalo SpaceShip]

It's an interesting idea, but probably falls into the category of 'if it worked then they would already do it'

Jeremy, I'm sure that once the turbocharging technology "caught on" with 2-stroke diesels, there was no need for power-hog "solutions" such as mine.

Looks like I forgot the link for the blower. Here it is.  My guess is that I would only turn on the blower on black smoke conditions. The big question is whether it would make any real difference. If I'm reading the conversion tables right, 441 Pa doesn't even approach 1psi ... but I didn't know if the reduction from 10" to 6" would add any "venturi-effect" pressure. 

I do like getting up to 8.5mpg on the flats with this coach. I've never gotten worse than 7.0 mpg, even on a short trip across the Divide and back. But a lot of it was blown out the tailpipe!

Maybe I just live with the smoke and add misters to the rad to help the cooling a bit.

Cheers,
Brian

[coolbus]

Hi Brian

"Pascals" is a measurement of pressure, just a much lower scale, much more accurate.


441 Pa equals only .0639 inches of water; 1Pa equals .000145 inches of water column.

HTH, (you'll have to do your own math!)

Mark

[prevost82]

Hi Brian ... to create pressure you need a compressor (turbo, super charger), these have very tight tolerances so the air doesn't bleed back pass the compressor or stagnate, the fan you have the link to is just that ... a fan.

[lostagain]

Brian,last year, I fabricated a ram air scoop (riveted tin) for my air intake, which is on the roof of my Courier 96. It worked very well at eliminating all the smoke during acceleration, and climbs at altitude. It is effective at surprisingly low road speeds: 20, 30 mph is enough. I don't think it gave me any extra power, but it  took care of the smoke. And it didn't cost anything other than a couple hours of my time. Worth a try for you. I took it off since I installed a real turbo.

[DavidInWilmNC]

I bet that dual squirrel cage blower from the OTR system in a MCI could supply enough air.  Of course, it's heavy as hell and would require a bit of fabrications, but it sure blows a lot of air through very a restrictive distribution system.   Would a 'real' smoke turbo require a lot of work on your engine?  I wonder if the moderate boost provided by one would be too much for the stock build.

David

[luvrbus]

Brain i thought i would pass this on to you i have a friend that retired from S&S and he said back in the late 80s and early 90s that they were installing what he called a turbopac on 6v92s in transit buses that were electric, made by Turbodyne Systems he's sure that about 50 of these units went to Denver he told me if you can find one in a bone yard be sure and get the valve and the control box and it may work for you

[Stan]

I agree with lostagain and his ram air. I did this on my first bus (by coincidence the same as his) and it made a big difference. I ran 70 injectors and with the scoop I couldn't make it smoke, even in the mountains, as long as I kept the RPM up. Many buses in the fifties used a scoop on the roof for both rad air and combustion air. They were probably removed in later designs to gain the one extra seat on the back bench.

It is hard to pull air in through the side of a bus. If you open your toll window at speed, air moves out, not in. A simple sheet metal box will catch a lot of air and feed it into the air cleaner. Very little material or labor involved and I suggest you try it.

[Len Silva]

From
http://www.onlineconversion.com/

440 pascals = 0.063816605 psi

I also wonder what restriction the blower is putting in the line when it's not running.

FWIW,

Len

[pipes]

http://www.turbodyne.com/

[TomC]

Just talked to an engineer from Vortron which is the industrial blower division of Paxton superchargers-belt drive superchargers that have been on cars for over 50 years.  Basically- to get 5psi from 1200 cfm would require 30hp!  That's why we turbocharge. 
I turboe'd my engine for all your reasons.  But I also bumped up the horsepower by going from the 65 to 75 injectors and added an air to air intercooler.  If you stay with the 65's and only use 5psi for a smoke turbo, you could just add the turbo without all the extra cooling. Then you'd have the same performance at altitude as at sealevel.  It would probably cost $2-3000 to do.  Good Luck, TomC

[prevost82]

I will repeat ... blowing air and making pressure are too differant animals. You could put 10 squirrel fans end to end and still not develop 5 psi ...
Ron

[Buffalo SpaceShip]

0.06 psi, eh? Well, I guess that answers that "light bulb" moment of mine. Har! And I (now) get the fan vs. blower concepts, Ron. Makes perfect sense. I'm sure glad I have you guys to run my hare-brained ideas by before I invest in these shade-tree "solutions" of mine!

$2k-3k for a smoke turbo is not as bad as I had thought, Tom. Probably cheaper than going back to C60's by the time I pay someone else to do the work and rack run. And I really don't care to go anywhere any faster... just cooler, and not offending my fellow motorists and fouling the environment with noxious smoke.

And I do like the ram-air ideas for the interim. If I rotate my filter intake around and run 6" ducting to the roof and scoop it off... quick and simple. My only concern would be removing any water that gets into the intake. Maybe an airbox with a drain somewhere near the top???

Thanks guys!
Brian