Smog pump supercharger

[Thepaetsguy]

I have searched the forums and got interested.. This smog pump on eBay is 40$-75$ I thought I could make a very short intake out of some washers and a pipe for a 22-28mm carburetor for the smog pump inlet port. Then on the pumps outlet port just a washer and a pipe. same on the intake port on the engine itself just a washer and pipe. Hang this all close to the engine intake port off the frame under the seat and connect the outlet of the pump and intake port of the engine with a piece of hose. I have plenty of room behind the clutch for a driver pulley. And plenty of room under the seat to place it all out of the way.

 

[sparkwizard]

I played around with one a while ago. The only way I could get it to work was to leave the carb on the engine, build a box around the carb, blow pressure into the box and run the pump off the back wheel. I rigged a PCV valve on the side of the box for idle air when the pump wasn't spinning. Have fun and let us know how it works out.

Oh, I also had to run a piece of hose from the box to the gas cap vent to keep it from leaning out.
Have fun.

 

[sparkwizard]

When you were searching, did you find this one?
https://www.oldminibikes.com/forum/index.php?threads/briggs-5hp-supercharger-ideas.56314/

 

[Augiedoggie]

I was always interested in a blower for small engine. There are kits for them now. I also heard of some builders using the smog pump from the mid 80s Porshe. I rescued several industrial vane type rotary vacuum pumps a few years back in hopes of building a killer blower motor but abandoned the idea. I seldom have enough time to keep my current machinery running and was afraid I would never have time to engineer and build and finish the project. Probably one of my rare good decisions I think the pressurized carburetor enclosure is the simplest and best method. Hope to watch and learn by watching.....keep us posted

 

[Thepaetsguy]

When you were searching, did you find this one?
https://www.oldminibikes.com/forum/index.php?threads/briggs-5hp-supercharger-ideas.56314/

yupp did a ton of researching! My duel engine kart has one 5hp and one 8hp engine mount. I’m not cutting the other mount to fit the 8hp. The thin sears rotospader plate has bolts down through for any 5hp gokart slide mount. Then has bolts up through for the big 8hp pattern. Direct bolt on 5hp to 8hp conversion for any yardkart. So now I can just bolt up two 8hp’s on my twin engine kart. My thinking is 8hp at 3600rpm so all the backyard mods for both 8hp’s and even 4-5 pounds of boost each engine? If I could get each 8hp to make 3hp more then stock ungoverned/boosted it would be 22hp on the back of a yard kart.

 

[Augiedoggie]

There are electric "superchargers" on ebay and Amazon for sale. Interesting idea and probably workable, but still not as simple as they would appear. Most of our small engines don't have charging coil(except some snowthrowers and eStart motors) and blower requires wiring challenges. Total loss battery system is also possible, but I can just imagine the poor motor falling on its face when battery was weak. I would lean towards a belt driven blower(or two) for simplicity and reliability. Perhaps a repurposed leaf blower fan overdriven from crank with a simple pop off valve? Just a thought

 

[sparkwizard]

Radiator cap is a ready=made pressure relief device.

 

[Augiedoggie]

Radiator cap is a ready=made pressure relief device.

Brilliant!! Older cars used 4-5 psi caps

 

[sparkwizard]

Some old tractors had 2 PSI systems.
These would seem ideal for a BLOW THROUGH system but I would be hesitant to use a radiator cap on a DRAW THROUGH system because that would release a flammable mix of fuel and air.
Also, newer cars use electric powered "air injection pumps" which are essentially high speed centrifugal superchargers.

 

[Augiedoggie]

Some old tractors had 2 PSI systems.
These would seem ideal for a BLOW THROUGH system but I would be hesitant to use a radiator cap on a DRAW THROUGH system because that would release a flammable mix of fuel and air.
Also, newer cars use electric powered "air injection pumps" which are essentially high speed centrifugal superchargers.

Reckon those would be worth a look. A power tool rechargeable battery would likely power them. A spark wizard should be able to devise a dual battery device which allows full voltage and switches over when primary battery drops below required voltage

 

[sparkwizard]

Yes, Sir. Dual batteries for starting, switching to one for running, back to dual when voltage drops.
Should be pretty simple.
I don't know what the current draw is on those blowers, but they do move a LOT of air.

 

[Thepaetsguy]

There are electric "superchargers" on ebay and Amazon for sale. Interesting idea and probably workable,

I saw those and figured if it ran out of battery it would become a problem/restriction. I’m pretty set on a roots style system. I just hope I can find a pump in the yard with flanges.

 

[Augiedoggie]

My inner "Mad scientist" wondered how cool it would be to plumb the blow off pressure into exhaust stream....
Reckon it would give it a flame thrower effect if fueled rich enough

 

[sparkwizard]

I saw those and figured if it ran out of battery it would become a problem/restriction. I’m pretty set on a roots style system. I just hope I can find a pump in the yard with flanges.

Mechanical is the way to go, in my opinion.
Are you talking about one carb, one blower into two engines? If that is the case, I'm REALLY paying attention!
Are you looking in scrap yards for a blower?
What is the cubic inch displacement of your 8 horse engines?
I can figure your CFM requirements, if that helps your research.

 

[Augiedoggie]

Sourcing an eStart clone motor with charging coil solves a lot of problems when using electric blower...but...
Heavy stock flywheel required for charging coil/alternator could grenade itself at higher speeds developed by our theoretical blower motor. Reckon belt drive alternator is safer, but why not simply belt drive our blower? Probably the most practical method

 

[sparkwizard]

In that case, Sir, we would need to pretty closely match our flow rates between the blower and the engine.
While a blow through system might be fine with a blow off valve at idle, the power loss at idle would be considerable.
In a draw through system it could be hazardous.
To make boost, our blower would need to push more air than the engine move without the blower.
The last one I messed with, the blower moved the same amount as the engine displacement. Normally aspirated engines rarely produce better that 60% volumetric efficiency. By forcing the engine to achieve 100% VE, I did not make and measurable pressure, but by making manifold vacuum=atmospheric pressure, I doubled torque output.
Think on that one.

 

[Mr. Pink]

how cool it would be to plumb the blow off pressure into exhaust stream....
Reckon it would give it a flame thrower effect if fueled rich enough

Just like an afterburner.

 

[Thepaetsguy]

Mechanical is the way to go, in my opinion.
Are you talking about one carb, one blower into two engines? If that is the case, I'm REALLY paying attention!
Are you looking in scrap yards for a blower?
What is the cubic inch displacement of your 8 horse engines?
I can figure your CFM requirements, if that helps your research.

Yes I was thinking one pump for both engines. that would be so I don’t have two of everything. 305cc briggs 8hp engine. I also was kicking around the idea of an amr300 as there for I think 400-1000cc engines and I would be right at the middle with 610cc Edit: any pump I can find will likly come from the scrap yards or a direct pull off from a car in the yard. I’m hoping to find a few junker vans as from my ebay search they seem to be flange mounted inlet/outlet Edit: another thing about one pump for both engines would be a 28-32mm I’m guessing..

 

[Thepaetsguy]

It can go on anything if it’s flange mounted cause I can make the Flanges out of washers. two 5hp’s or two 8hp’s I can easily make the mounts and flanges.

 

[Thepaetsguy]

Sourcing an eStart clone motor with charging coil solves a lot of problems when using electric blower...but...
Heavy stock flywheel required for charging coil/alternator could grenade itself at higher speeds developed by our theoretical blower motor. Reckon belt drive alternator is safer, but why not simply belt drive our blower? Probably the most practical method

This is all just my wild idea. I can skip the 8hp’s all together and boost the 5hp’s both have a rod and flywheel. I have plenty of room behind each clutch on the 5hp’s for a pulley.