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powder_rider
New member
hey i have an m7 and i was wanting to do either a turbo or supercharger and wanted to know what works the best
turbo vs. supercharger
- Thread starter powder_rider
- Start date
If you SC a 2s, your only pressurizing the intake not the exhaust, with a turbo you will have drivepressure/backpressure in the pipe which in a 2s needs to be somewhat balanced for them to make power.
There was a guy a while back that had SC a TCat or big cat tripple but it had all kinds of vavles and extras in the pipe to create backpressure. Ended up working but not very economical or user friendly!
A supercharger is just an air compressor that runs off of a pully off of the crankshaft of the motor. It forces more air into the intake which allows you to add more fuel and thus more power. That same air going into the motor comes back out in the exhaust thru the expansion chamber of the pipe, creating the exhaust back pressure, only with more volume because there is more air going thru the motor. I'm no expert but I would think it would work just fine without having to modify the pipe or changing exhaust back pressure. If you have more air going in the motor (more pressure) you will have more air going out of the motor (more pressure). I would say they would be proportionately equal.
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BB454
Well-known member
Supercharger
Benson down at ATS turbos was working on this a while back, don't know if he had much success. I know one issue was getting a belt drive tucked in behind the clutch to run the supercharger. Another was making a supercharger small enough to fit in the chassis. Oiling is another issue, I beleive they tap into the oil system on a 4 stroke to overcome that. The new 4 stroke charger may be a fit now. It kind over appeals over the turbo if when doing the instal you don't need to mess with the exhaust. In an automotive application, they say there is no lag on a supercharger.
Benson down at ATS turbos was working on this a while back, don't know if he had much success. I know one issue was getting a belt drive tucked in behind the clutch to run the supercharger. Another was making a supercharger small enough to fit in the chassis. Oiling is another issue, I beleive they tap into the oil system on a 4 stroke to overcome that. The new 4 stroke charger may be a fit now. It kind over appeals over the turbo if when doing the instal you don't need to mess with the exhaust. In an automotive application, they say there is no lag on a supercharger.
Im pretty sure I know how a SC works!
Heres what your missing, a turbo and a SC both create air flow, the reason we make "boost" is backpressure or restriction. A 2stroke uses an expansion chamber to help make power (ever riden a 2stroke with no pipe on it??? Pretty flat powerband) Its all based on volume, length and timing to determine what RPM the "powerband" comes on. A 4stroke doesnt work like this. If you take a turbo 2s and measure pipe pressure compared to intake boost pressure you will see a linear (not equal pressures, maybe a couple lbs diffrence but still linear after boost starts to climb) rise in pressures. With a supercharger you dont have the "restriction" on the exhaust and your exaust pressure/intake pressure isnt even close to equal anymore and the expansion chamber theory goes right out the window! Your "sonic wave" in the pipe doesnt work in harmony with RPM anymore, your power is totally flat once agin!!!!
Have you ever seen the "backpressure bolts" that some of the better tuners run on their pipes when they change elevation? They are loosing air volume in the pipe from alt. which changes how the exp. chamber works in relation to the motor it was designed for (thats why theres low atl pipes and high alt pipes, diffrent stinger plugs for diffrent backpressure/airflow requirements) A nut welded just past the outlet stinger of the pipes cone (just before the ''U" bend with a bolt and a jam nut to create a restriction in air flow to bring pipe volume up with the thinner air one would see with climbing in altitude)
If you take your SC and dont do EXTENSIVE mods to the exhaust you wont build the power you think you will, trust me its been done!!!!!!!!! And if it were so easy someone would have already done it!
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Thanks, that does make more sense to me now. I did understand the need for back pressure in the 2 stroke, but obviously there is a lot I didn't understand. It's too bad it is that complicated, because I think the supercharger would be the way to go. Absolutely no lag, and if you're climbing a hill and have to let off for an instant and get right back on it, you wouldn't lose the boost.
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triple7
Well-known member
I personally feel that a supercharger will work awesome on a twostroke because I feel that the only reason boost works at all on a twostroke is because you are actually pressurizing the crankcase rather than the cylinder itself. With pressure in the case, more mixture is forced into the cylinder when the transfers open. I feel that a turbo works this way and that a supercharger will work the same. I have a supercharger ordered and plan to verify my theory.
I think that the supercharger is far superior to a turbo on a two stroke because of the greatly reduced charge temperature and the anti lag affect.
I think that the supercharger is far superior to a turbo on a two stroke because of the greatly reduced charge temperature and the anti lag affect.
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I've owned three boost 2S's and even though I read and hear about lag all the time, especially on the 4m, LAG has never been a word I would use to describe the power experienced on those sleds. Two M8's: one aero and one 2860, and now the 12hundy with a 3071. No lag here! I think on the EFI's especially, lag can pretty much be clutched out. I also have quite a bit of seat time on boosted Apexes and Nytros with the Impulse system and I'm hear to tell you, the power is instant and lag is gone!
boost
more over with a sc as you gain alt it is still trying to push the same volume which isnt there anymore and power will fall off unless you can shift it to spin a higher speed with some kind of transmission. where a turbo will compensate being it can only use what is available. so turbo
more over with a sc as you gain alt it is still trying to push the same volume which isnt there anymore and power will fall off unless you can shift it to spin a higher speed with some kind of transmission. where a turbo will compensate being it can only use what is available. so turbo
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Boyko
Well-known member
I hope you ordered a massivly huge supercharger, you will need it because your going to be blowing most of your boost and fuel out the exhaust. Look at Mats gif and you should be able to see the problem
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HANDSOME
Well-known member
Bear Mountain Boy and his brother played with centri***al blowers back in 94 and they didn't have much luck .... I believe that because a 2 stroke runs in pulses was a lot of the problem. Because the blower is direct drive where the turbo is exhaust driven ( exhaust pulses ) so the turbo works in harmony with the pulse where the blower does not hence the exhaust valving that mattymac is talking about to mimmic the pulses. OOhh, that just gave me a head ache.
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kennyblatz
New member
-a turbo uses a wasted energy, the exhaust air
-a SC uses motor hp. bad
2 strokes don't have good low end power, bad when trying to turn a SC all the time.
and im no expert but i kinda think you would loose alot of boost out the exhaust port befor it got compressed
i would go turbo on a 2 stroke.
-a SC uses motor hp. bad
2 strokes don't have good low end power, bad when trying to turn a SC all the time.
and im no expert but i kinda think you would loose alot of boost out the exhaust port befor it got compressed
i would go turbo on a 2 stroke.
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Barrett
ACCOUNT CLOSED
My opinion is that Turbos are superior.
BUT......... Superchargers most certainly will work on 2-strokes, and can work very well. Detroit deisel built many thousands of 2 cycle supercharged deisel engines. some even had turbos feeding into the supercharger!
The drawback, as mensioned above, is that a SC 2 stroke will suffer from alot of lost charge blowing out the pipe when transfer ports and exhaust ports are open at the same time. the key to making it work is to completely modify the port timing to work with the new boosted configuration. this really makes it next to imposisble for joe average to fit a SC to a sled in any cost effective manor , so in the end a turbo is a more practical AND efficient setup.
Barrett
BUT......... Superchargers most certainly will work on 2-strokes, and can work very well. Detroit deisel built many thousands of 2 cycle supercharged deisel engines. some even had turbos feeding into the supercharger!
The drawback, as mensioned above, is that a SC 2 stroke will suffer from alot of lost charge blowing out the pipe when transfer ports and exhaust ports are open at the same time. the key to making it work is to completely modify the port timing to work with the new boosted configuration. this really makes it next to imposisble for joe average to fit a SC to a sled in any cost effective manor , so in the end a turbo is a more practical AND efficient setup.
Barrett
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