Box Stock

Supercharged Predator 212

95 shaw said:
If you do not understand that driving the blower faster requires more power from the crankshaft , I fear the rest of the build is way above your pay grade.
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Let's use idling rpm for this example. The crank is turning at a certain rpm at idle, if I put a bigger pulley there, and a smaller pulley on the blower, the crank is still gonna be turning at idle speed but turning the blower faster because of pulley sizing. As the crank spins faster it drives the blower faster. I don't know where you're getting this "more power consumption" from when I'm swapping the pulleys so that less rotation of the crank is required to turn the blower one revolution.
 
Ok, so just a few rough estimates. A 212 is roughly 6.5Hp.. A super charger can take roughly 30-50% of the engine's power to run. Now the build you're planning doesn't mention a cam but basically you're putting together at best a low end small block open type engine in the kart racing world. Maybe 12-16hp if I cautioned a guess?



So, efficiency is key. Unless you get this to flow very well, run it on Nitro methane, and some how keep it together. You'll probably gain 2-5 Hp I'm guessing at 10lbs of boost over driving the compressor. So when you turn the crank once to the compressor twice you're effectively doubling the power needed to provide boost because of lost efficiency. Energy isn't free, it cost to do double the work. 1:1 would probably produce maybe 3-4 lbs of boost if it even got that high. And you'd lose hp after driving the compressor at that rate for so little boost.

Now, where the efficiency would pick up is mass flow, because it's not exactly about the boost number. It's about mass flow at boost pressure. So, if you can provide double or triple mass flow, at a maintained 10lbs of boost that is where power comes back. But, again heat robs efficiency, and this style of blower has no intercooler and inefficiency will drop you by 30% or better on mass charge density because the air will be hotter.


So ultimately if you see gains don't expect to set the internet on fire. A properly tuned, well-built small block can put out better numbers N/A. You really need properly sized equipment or engine (preferably 2 or more cylinders) and very well designed systems to achieve good results that are worth the time and money.


(Edit) I'm not trying to dissuade you from building it. I suggest building the engine, have it dyno tuned as an N/A. Get numbers for it as an N/a, then do the super charger. The pitfalls of making a super charger just work aren't as easy as a lot of people think. Especially with a carb and not EFI. Prove me wrong, I'd love to see it actually work.
 
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I can't say your wrong, but then how did big boys boosted make such a noticeable difference? Once again he never dinos it, but claims its a lot more power. He did use a smaller blower that is more proportional for the engine, maybe that's it. But then all tge things your claiming, he somehow overcame, so how was he able to do do.
 
I can brag all i want . Long as what i say you can't prove wrong . I must be right . All the problems can be over come , except it takes power to drive the blower ; no matter over driven or under driven .
 
Gappin Foos said:
I can't say your wrong, but then how did big boys boosted make such a noticeable difference? Once again he never dinos it, but claims its a lot more power. He did use a smaller blower that is more proportional for the engine, maybe that's it. But then all tge things your claiming, he somehow overcame, so how was he able to do do.
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Like Flattop said, I checked his page and he had nothing else about it and not even seeing a video period on his page anymore.


Again, I'd like to see it built as N/A and dynoed then put the super charger on and get it to work. I honestly think you'll learn more doing it than taking our word that it won't work. But, be ready to invest time and some more money into it. I don't suspect it will be easy. The only way to verify anything is Dyno numbers N/A and Supercharged. Video never hurts.
 
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BigMoneyGrip said:
Years ago, I machined the silver one and had it on a ATC70 that had many custom one off parts. After the proof of concept, I CNC'd the black/purple one to put on a Briggs but never got to it. The 70 had 12:1 compression and I used a Tillotson carb on methanol and made 14lbs of boostView attachment 25427. It was a mean machine!
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Dude that is seriously awesome stuff you got mad machining skills. Do you have more pics of what the inside looks like? Plus you had on a honda atc those motors are insane have a ton expertise in that area the go kart thing I just jumped on my buddy built a dirt oval behind his house, and just scooped a tri set legend with a ghost on it. Have a 212r tilly too that I was going to put on something else. I like the ghost but the tilly just seems better build quality. Dunno which one makes more power either lol.
 
ephenj93 said:
Dude that is seriously awesome stuff you got mad machining skills. Do you have more pics of what the inside looks like? Plus you had on a honda atc those motors are insane have a ton expertise in that area the go kart thing I just jumped on my buddy built a dirt oval behind his house, and just scooped a tri set legend with a ghost on it. Have a 212r tilly too that I was going to put on something else. I like the ghost but the tilly just seems better build quality. Dunno which one makes more power either lol.
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I have more pics somewhere. I built the first one about 25 years ago. Aftermarket support for the horizontal singles was almost non existant. The valves and seats were OEM Honda, but from a different motor. The cam was from Web that had a lot of overlap to bleed off some of the cylinder pressure. I made my own ignition. It was a "total loss" design and didn't use a flywheel. The spark was provided by a battery that required charging after about four hours of use.
I still have all the parts except the carb. I should see if I can get it back together.
 
Gappin Foos said:
Yeah so I would be running a blow-off valve, so when it builds up it'll just open up and dump at the desired psi. It would be awesome if I could retard the timing. I guess I could mark TDC with a sharpie then go to BDC and mark there on the flywheel then make marks from there to figure out the timing. I saw a picture with three blowers, a 68-69 VW smog pump for 33cc-300cc motors, then the AMR300 for 250cc-1000cc motors, and the AMR500 for 1000cc-2000cc motors. So furthermore the AMR300 is a little big but if I overdrive the supercharger so that when the crank rotates once, it rotates the supercharger twice, I can make up for the consumption of power used by the supercharger from the crank. Boom problem solved. So the only thing It needs is to retard the timing, keep the engine and supercharger cool, and get the air-fuel mix right. Now maybe, just maybe, the stock timing will be good enough for 10psi. Cause, correct me if I'm wrong, but the more boost the more retarding of the timing. So I'll probably try and leave stock timing for now, and run it on 91 with some octane booster. Any other thoughts or suggestions.

Heres the guy I was talking about
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Something looks really wrong with the boost gauge while he's blipping the throttle right at the end of the video.
It looks like it's reading vacuum, and acting like I would expect a vacuum gauge to act when the throttle blades are opened.
Even if it was reading boost, it looks like it drops to 0 when the throttle is cracked.

Edit: It looks like the video was removed just a few minutes after I posted this. Probably coincidence.
 
ABR #69 said:
Like Flattop said, I checked his page and he had nothing else about it and not even seeing a video period on his page anymore.


Again, I'd like to see it built as N/A and dynoed then put the super charger on and get it to work. I honestly think you'll learn more doing it than taking our word that it won't work. But, be ready to invest time and some more money into it. I don't suspect it will be easy. The only way to verify anything is Dyno numbers N/A and Supercharged. Video never hurts.
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BigMoneyGrip said:
I have more pics somewhere. I built the first one about 25 years ago. Aftermarket support for the horizontal singles was almost non existant. The valves and seats were OEM Honda, but from a different motor. The cam was from Web that had a lot of overlap to bleed off some of the cylinder pressure. I made my own ignition. It was a "total loss" design and didn't use a flywheel. The spark was provided by a battery that required charging after about four hours of use.
I still have all the parts except the carb. I should see if I can get it back together.
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That's unreal, would love to see the pics if you find them. The aftermarket scene back then I can only imagine, I got into the pitbike raceing the first time around back in the mid 2000s. Still have my full mod 50, back then aftermarket scene blew up like crazy then crashed which was a bummer granted everyone wants the old stuff now. What style did you go with for the internals of the blower? There's a guy elsburgtuning.dk he did one with a amr300 makes insane power. I feel Like these Tilly, Pred, Clone motor's after a good billet rod and flywheel a ton of power can be made in the head.
 
Most of the power is made in the head on an OHV, flow is king. But, I'd like to see an actual dyno run of a blown single cylinder.

My comparison for him specifically wasn't really a good example and probably a bad idea in actuality. Because when the engine is tuned for N/A and blower, the head, cam, valve train and all will be quite different. So really and truthfully we could just take normal SBO dyno runs and compare them to a blower engine. But, then you have the all so common correction factor that people like to play with. So then it would need to be run on a reliable dyno. But, I'd still like to see what someone can actually produce out of one.

This should give you an idea of what a N/A engine will do. These are Animal/Clone/Honda style engines, pretty similar in design. So I'd be really interested to see if someone could get more with a blower.
 
I'm curious how long a Chinese block would last with a noticeable amount of supercharging, if it was actually attainable.
 
mike97760 said:
I'm curious how long a Chinese block would last with a noticeable amount of supercharging, if it was actually attainable.
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There are twin cylinder Predators that have survived decent amounts of boost, but they're quite different designs. I'd be tempted to say not long.
 
ephenj93 said:
That's unreal, would love to see the pics if you find them. The aftermarket scene back then I can only imagine, I got into the pitbike raceing the first time around back in the mid 2000s. Still have my full mod 50, back then aftermarket scene blew up like crazy then crashed which was a bummer granted everyone wants the old stuff now. What style did you go with for the internals of the blower? There's a guy elsburgtuning.dk he did one with a amr300 makes insane power. I feel Like these Tilly, Pred, Clone motor's after a good billet rod and flywheel a ton of power can be made in the head.
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The first one I machined was a two lobe Roots style with no helix. The second one was a three lobe Roots with no helix.
At the time, I didn't have a way to machine a helix. A few years ago, I 3D printed a screw blower rotor, both male and female. I have a 4 axis CNC now and could machine it but I've lost interest. Maybe some day...
 
Gappin Foos said:
Does anyone know the intake size of an amr300?
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What are you trying to get a size of?

It's designed for about 1.3L down to .5L. Besides that specifics are going to be quite difficult to track down. I'm sure a good internet search will net what you'd like to know.
 
AMR300 runs like a champ on a built predator 212 non-hemi with a nibbi racing pwk carburetor 32/27 hi-comp head .315cam and #46 springs
 

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