supercharged Tecumseh suggestions

[mattber]

I know this has probably been discussed before, but i am going to try to supercharge my tecumseh hs50. I'm going to use a smog pump. I did some testing on the smog pump (made a adapter to hook a impact to the end, and a presure gauge to the other side) i found that at 1:1 at about 8000rpm it made 15-20 pounds of pressure. I think that is more than enough for my hs50.

I'm going to run my carburetor in between the engine and the supercharger and drive the super charger off the axle. I want to install a pcv style valve on the carb so it can still get air at idle. once i start moving the supercharger will kick in, this is basicly giving the supercharger a push start, as i do not think the engine can turn the smog pump over at idle. I am also going to figure what size pulleys i need to run so i can overdriver the supercharge.

I am going to get a better carburator and billit rod and stiffer springs and better cam, along with head studs.
What do you guys think? Any suggestions? Where can i get stiffer springs? Do they magnetos for tecumsehs?

 

[Briggster]

Heres a link to the briggs I did, and ill be the first to admit that it wasnt worth the effort.
https://www.youtube.com/watch?v=FaQe5Iub-EY&feature=youtube_gdata_player

 

[The Restore Kid]

The briggs is vapor locking because the PCV isn't working rite..

 

[Txpowdercoater]

I did a smog pump on a clone and it hauled major balls, Mine was chain driven and we called it "the mangler", it was plenty dangerous fun. feed it a lot of fuel and have fun.

 

[65ShelbyClone]

I'm going to run my carburetor in between the engine and the supercharger and drive the super charger off the axle. I want to install a pcv style valve on the carb so it can still get air at idle. once i start moving the supercharger will kick in, this is basicly giving the supercharger a push start, as i do not think the engine can turn the smog pump over at idle.

What you're describing is a blow-through setup. The problem with your layout is that the smog pump is going to dead-head when you close the throttle. It is going to need a blowoff valve to vent that pressure otherwise it could break the vanes inside which are likely phenolic resin, not metal.

Another consideration is that you are going to need a fuel pump and boost-referenced pressure regulator. Without them, boost will simply push fuel out of the carb circuits and the engine won't run.

Running a positive displacement supercharger like this in a blow-through configuration is not that convenient with carburetion. EFI makes it a lot easier because the throttle can be put ahead of the blower and fuel can be injected after it although EFI is probably not practical in this case. Running fuel through a smog pump would probably wash out the bearings inside since they are designed to pump clean air.

 

[mattber]

What you're describing is a blow-through setup. The problem with your layout is that the smog pump is going to dead-head when you close the throttle. It is going to need a blowoff valve to vent that pressure otherwise it could break the vanes inside which are likely phenolic resin, not metal.

Another consideration is that you are going to need a fuel pump and boost-referenced pressure regulator. Without them, boost will simply push fuel out of the carb circuits and the engine won't run.

Running a positive displacement supercharger like this in a blow-through configuration is not that convenient with carburetion. EFI makes it a lot easier because the throttle can be put ahead of the blower and fuel can be injected after it although EFI is probably not practical in this case. Running fuel through a smog pump would probably wash out the bearings inside since they are designed to pump clean air.

Ive been thinking about the supercharger set up with a smog pump abd am thinking about making a procharger style set up using parts of a old turbo that i have. It migh be a little more efficent

 

[65ShelbyClone]

There again, you will need to find a turbo compressor that you can spin fast enough to do anything and have a useful output. The turbo compressors suitable for engines this small typically have an operating speed range of 150,000-200,00RPM.

 

[mattber]

There again, you will need to find a turbo compressor that you can spin fast enough to do anything and have a useful output. The turbo compressors suitable for engines this small typically have an operating speed range of 150,000-200,00RPM.

If I put a smaller pully on it and overdrive it, it should be to much of a problem.

 

[65ShelbyClone]

That equates to a 15-20x overdrive when the engine is at 10,000rpm.

To put that in perspective, it would mean using a 2" diameter pulley on the blower and a 35" pulley on the engine.

 

[Newoldstock]

I am trying hard to think of any turbo bolted on a 6 hp engine I have ever seen that worked well.

Only one comes to mind.
I seen a few CS 6/1 with a automotive turbo added.
Most of the time they only manage a couple of pounds boost.
Help to have the electric flywheels and 8/1 injector.
But they will run like that reliably off the cs oil pump.

1Lb. Boost!!! - YouTube

 

[Newoldstock]

Jut sitting here thinking about it.....

I have a DM-10 petteroid with more oil volume than i know what to do with ( as built you bypass to sump through a filter )

You know that would be a cool mod I should try.
Weighs 400 pounds, won't go very fast on a mini.....

 

[mattber]

This is like what I had in mind.

http://m.youtube.com/user/speedandfabrication3

 

[cdoublejj]

i'd say a a head that is not milled maybe even a fire slot along with possibly a fly cut on the block maybe even a dished piston and EFI. small single cly engine projects tend to not go well with carbs.

 

[mattber]

i'd say a a head that is not milled maybe even a fire slot along with possibly a fly cut on the block maybe even a dished piston and EFI. small single cly engine projects tend to not go well with carbs.

What is a fire slot?

 

[cdoublejj]

http://www.ihcubcadet.com/forum/messages/106/46148.jpg

http://www.hotrodders.com/forum/attachment.php?attachmentid=48246&stc=1

head.jpg Photo by kornpoke | Photobucket

http://www.hotrodders.com/forum/singh-grooves-184745.html

these how seem different form i've seen in the past. i've seen bigger deeper more round slots, it's said to help air/gas travel a little better in the head/piston are and help the combustion in the flat head engine.

 

[Carlos]

Here's my blown Honda ST70, with a home made supercharger conversion from an old Air Ministry rotary vane pump ... not easy to supercharge a single cylinder engine and get the balance right between throttle lag and pulsing in the intake manifold/plenum chamber.

 

[Inventorpardue]

Welcome! Looks like a CV (Constant Velocity) carburetor, and some nice machine work. That's a well-executed build.

 

[Carlos]

Thanks. It is an old CV carb, a 26mm Klein I believe from one of the larger Honda scooters circa 1990's.

I wanted a large carb with a throttle butterfly because the carbs can ice over and the extra suction and/or icing can lock throttle slides.

Not an easy build and possibly my most dangerous creation to date.

 

[65ShelbyClone]

What is a fire slot?

As shown in the pictures, an old gimmick used to sell cylinder heads.

 

[cdoublejj]

As shown in the pictures, an old gimmick used to sell cylinder heads.

just came across this reply doing some googling. any context behind your comment? there is little information on fire slots on the internet. or at least not super easily available so any input is appreciated.