supercharger

[Thepartsguy]

Do you know the displacement of the pump?
How many CC per revolution?
And the pulley sizes?
And the displacement of the engine?

Did you try to calculate the amount of boost to expect? I have an idea of how to do the math, but not 100% sure it is correct.

I know nothing of the pump unfortunately. I do know the pump got a full service along with 5 case holes and the pumps “pressure diverter“ valve plugged solid with jb weld.

On YouTube a non touched out of the box 1970’s pump put out 3psi on the persons gauge. I figured if it pushes 3psi before the diverter opens along with 5 open case holes I would get 5-7psi with all that plugged and a back case gasket. I got way more.

5 3/4 driven 4 1/2 driver.. My plans are to have fun and really push it. I have a super high compression head. I thought kick the timing back and I have a 4 3/4 pulley for the pump to make it 1to1 ratio. It keeps wrecking headgaskets.

It’s a 163cc briggs 4hp with a flywheel. No other work done. Billet rods do not fit 4hp model 10’s

 

[Denny]

With those kind of pressures you’re into top fuel engine territory. You need a smaller drive pulley for the super charger.

 

[Thepartsguy]

With those kind of pressures you’re into top fuel engine territory. You need a smaller drive pulley for the super charger.

Yes I have a 5 3/4 pulley on my driven (the pump) and I plan to go to 4 1/2 as picture with the smaller pulley above. I can still back the timing off a good bit with the bracket I’m using i’m not already adjusted as far back as it can get yet. MORE BOOST and less timing. ahahahahahahahaha I plan to mix the nitro heavy but ya know not to to heavy.

 

[bob58o]

My blower puts out 300 cc per revolution on a 212cc engine that “uses” 106cc per revolution.

If I slow down the blower so it only spins once per two crankshaft revolutions then I’m putting 150cc into the engine per crank revolution or 300cc per full cycle.

300cc / 212cc = 1.41
1.41 * 14.7psi = 20.8 psi
20.8-14.7 = 6.1 psi boot

To achieve this I need the pulley on the blower to be twice as big as the pulley on the crankshaft.

For my blower and engine, if I use 1:1 ratio pulleys… I would be putting 600cc into a 212cc engine… I would expect 27 psi of boost.

 

[Denny]

It has to be mixed with alcohol. 80% nitro 20% alcohol seems to be the sweet starting spot. It will not mix with gasoline! 50*-60* of advance for the spark.

 

[Thepartsguy]

My blower puts out 300 cc per revolution on a 212cc engine that “uses” 106cc per revolution.

If I slow down the blower so it only spins once per two crankshaft revolutions then I’m putting 150cc into the engine per crank revolution or 300cc per full cycle.

300cc / 212cc = 1.41
1.41 * 14.7psi = 20.8 psi
20.8-14.7 = 6.1 psi boot

To achieve this I need the pulley on the blower to be twice as big as the pulley on the crankshaft.

For my blower and engine, if I use 1:1 ratio pulleys… I would be putting 600cc into a 212cc engine… I would expect 27 psi of boost.

I forgot to add this is a stock 163cc model 10 4hp briggs engine. I did add a 5hp cylinder head to lower compression slightly. I added an arc 3hp diameter billet flywheel and drop bracket. Also an exhaust. That is it besides the smog pump deal.

Expecting 27psi with a 1to1 ratio? I’m NEARLY at a 1to1 now and the gauge slightly taps 24psi.. I also want to go to a 1to1 ratio.. My 4hp eats headgaskets like candy.. Very quickly. I was told to go to copper gaskets and open the ring gap slightly. With the pulleys you got how much boost do you intend to actually run?

 

[bob58o]

I forgot to add this is a stock 163cc model 10 4hp briggs engine. I did add a 5hp cylinder head to lower compression slightly. I added an arc 3hp diameter billet flywheel and drop bracket. Also an exhaust. That is it besides the smog pump deal.

Expecting 27psi with a 1to1 ratio? I’m NEARLY at a 1to1 now and the gauge slightly taps 24psi.. I also want to go to a 1to1 ratio.. My 4hp eats headgaskets like candy.. Very quickly. I was told to go to copper gaskets and open the ring gap slightly. With the pulleys you got how much boost do you intend to actually run?

6 PSI is my plan, I don’t want more than 10 or so.

My engine is 10.5 :1 Static Compression Ratio, and I plan on running E-85 with the blower.

I looked but wasn’t able to find displacement for smog pumps. They are same as a roots style blower, but I can’t find displacement per revolution for the smog pumps.

I imagine you gunna want to run less boost on this engine. Maybe open up the piston rings a bit.

I’d put a smaller pulley on the crank. Half as big as you got. 2.5” or so.

 

[Thepartsguy]

6 PSI is my plan, I don’t want more than 10 or so.

My engine is 10.5 :1 Static Compression Ratio, and I plan on running E-85 with the blower.

I looked but wasn’t able to find displacement for smog pumps. They are same as a roots style blower, but I can’t find displacement per revolution for the smog pumps.

I imagine you gunna want to run less boost on this engine. Maybe open up the piston rings a bit.

I’d put a smaller pulley on the crank. Half as big as you got. 2.5” or so.

I’m was wondering how different the displacement outputs of a smog pump and AMR supercharger are also. When you get your engine actually supercharged and up and running let us now how off the line torque is.

Even the hansen was a dog off the line because both valves acting as one way open/closed doors for boost. My little 4hp was gutless off the line but once the valves started opening/closing quick enough it would really come alive.

The pumps do take a lot to spin up. So I went for the smallest lightest billet flywheel possible. I’m very curious to how your engines gonna react to boost. I was EXTREMELY shocked on a single cylinder it doesn’t add low end torque like it does on v8’s..

Thinking about both valves being doors makes me wonder if lower boost would even show gains because of what it takes to drive the boost system in the first place. Makes me think on a single cylinder it‘s an ”as much as you can possibly get” system.

 

[bob58o]

I went with a cam already designed for low end torque. Short duration with wide LSA should help keep it in the cylinder.

104 ICL
111 LSA
220 Duration
280 Lift

 

[Denny]

Smog pumps are not Roots design. They are rotary vane pumps.

 

[bob58o]

Smog pumps are not Roots design. They are rotary vane pumps.

I meant they are a positive displacement style pump.

 

[Thepartsguy]

I went with a cam already designed for low end torque. Short duration with wide LSA should help keep it in the cylinder.

104 ICL
111 LSA
220 Duration
280 Lift

I’ve spoken with the owner at s-Charger and the first questions that were asked is about a ”BST” boost storage tank or “accumulator”.

I do not have one and he explained that is why my boost gauge is jumpy. Here is the hansen BST I have zero idea how I could make one for my engine. Any plan for one on yours? I’ll pull up the convo again but I believe he said 40% cylinder volume. I was told many times “I really need an accumulator“

 

[bob58o]

I’ve spoken with the owner at s-Charger and the first questions that were asked is about a ”BST” boost storage tank or “accumulator”.

I do not have one and he explained that is why my boost gauge is jumpy. Here is the hansen BST I have zero idea how I could make one for my engine. Any plan for one on yours? I’ll pull up the convo again but I believe he said 40% cylinder volume. I was told many times “I really need an accumulator“
View attachment 150271

6” intake runner 1” ID should cover 40% of your engine displacement.

0.5” * 0.5” * 3.1416 * 6” = 4.7 cubic inches

4.7 ci = 77cc

77cc is 47% of your engine displacement.

 

[Thepartsguy]

6” intake runner 1” ID should cover 40% of your engine displacement.

0.5” * 0.5” * 3.1416 * 6” = 4.7 cubic inches

4.7 ci = 77cc

77cc is 47% of your engine displacement.

The convo was back in may. Not %40 actually has to be bigger then the engines displacement. I wondered why Hansen’s tank was so big.

 

[bob58o]

The convo was back in may. Not %40 actually has to be bigger then the engines displacement. I wondered why Hansen’s tank was so big.


View attachment 150272View attachment 150273View attachment 150274

Ah, so 60 -100 cubic inches.
So like 3-5” of 5” schedule 40 PVC

 

[Denny]

The boost tank makes a lot of sense to help cushion the pulses from the intake valve opening and closing on a single cylinder engine. Only problem I can see is fuel falling out of suspension with a poorly designed tank. It should be shaped like a funnel, as above.

 

[Thepartsguy]

I spent the day contemplating how I could make my own tank. Then it hit me I should just unbolt my intake tube and find a Hansen accumulator.. I guess it’s not entirely impossible to find good deals on the Hansen units.. Two for $50 seems like a before I scrap them price... I wonder if this guy paid to ship these and lost money?

 

[Thepartsguy]

5hp shroud swapped on.. A timing adjustment.. Add more compression! And then a 280 lift Horstman camshaft. I will 1to1 ratio the pump eventually. It’s fun these little Briggs are disposable. When I’m done having my fun it’s gonna be in pieces..

 

[Thepartsguy]

Supercharged Briggs 4hp

163cc model 10 4hp engine with a gm smog pump. Gauge broke right before I started filming

www.youtube.com

Added a standard head less timing and the gauge broke. Crankcase pressure blew the seal out. Next add a cam and 1to1 the pump. Volume/language warning ahead. Made a foghorn exhaust and was in a bit of shock.

 

[Whitetrashrocker]

I'm at a loss. Lmao. Wtf.
Awesome.