Wiki... nice
So why will it not work? Assume the valve timing is OK. Will there be an exhaust pulse? So why cant that pulse be timed to scavenge? i know the pulse timing will vary w/ RPM (it does on a 2 stroke too), but that should be tuneable enough to work still... The V-8 guys are starting to play w/ stepped primaries, i envision it wont take long for them to get more expasion chamber-ish.
BJH
Full Version: Dual exhaust vs. collector
The thunder header was really built for reversion purposes. Not so much extraction like a tuned 2 stroke chamber.
So Says Bruce at Accutrue Engineering. He is occasionally the dyno guy and product tester for Harley Davidson Inc. and Hot Bike magazine. He is a good friend and knows more about Harleys that anyone else I happen to know.
So Says Bruce at Accutrue Engineering. He is occasionally the dyno guy and product tester for Harley Davidson Inc. and Hot Bike magazine. He is a good friend and knows more about Harleys that anyone else I happen to know.
Wiki is cool, lots of good info as long as you have an idea of what the answer is.
Anyone can post there so you can also get a load of crap.
2 cycle and 4 cycle is apples and oranges, you can eat both but they are no where
near the same. You may get a pulse back but as you mentioned utilizing it with
valves in the way especially on the compression stroke when the exaust valve is
closed. When the exhaust valve is open the piston is on it's way up to expel
burnt gasses and then the e valve then closes as the piston heads back down
to draw fuel and then back up on it's compression stroke. The pipe from FMF has
no real restriction on the gases as you need on a two stroke. Better minds then
mine have pondered this and I still have not seen a 4 stroke that has made it work
like you can on a two stroke, IMHO I think you would be better off useing that
exhaust to drive a turbo on a 4 cycle.
But there is nothing like the feeling of a built 2 stroke when it comes up on the pipe.
Hope this makes sence to you.
Anyone can post there so you can also get a load of crap.
2 cycle and 4 cycle is apples and oranges, you can eat both but they are no where
near the same. You may get a pulse back but as you mentioned utilizing it with
valves in the way especially on the compression stroke when the exaust valve is
closed. When the exhaust valve is open the piston is on it's way up to expel
burnt gasses and then the e valve then closes as the piston heads back down
to draw fuel and then back up on it's compression stroke. The pipe from FMF has
no real restriction on the gases as you need on a two stroke. Better minds then
mine have pondered this and I still have not seen a 4 stroke that has made it work
like you can on a two stroke, IMHO I think you would be better off useing that
exhaust to drive a turbo on a 4 cycle.
But there is nothing like the feeling of a built 2 stroke when it comes up on the pipe.
Hope this makes sence to you.
QUOTE(So.Cal.914 @ Apr 14 2007, 01:02 AM) 
IMHO I think you would be better off useing that
exhaust to drive a turbo on a 4 cycle.
But there is nothing like the feeling of a built 2 stroke when it comes up on the pipe.
Hope this makes sence to you.
Boat, quads, dirtbikes (even a ride on a 2stroke street bike), go-peds, carts, pocketbikes and a vespa or 2... I've played w/ a few oilchange-less motors.
Why cant the pipe be tuned so there is a vacume (negative pulse if you will) on the valve as it opens? By no means rocket science. It will help w/ scavaging the cyl. (like a tuned header will do) and really has no downside that i can see.Wonder if the header scavaging is stronger
Might only be practical on single cyl motors (like the bike motor the FMF pregnant pipe was designed for).Best sound and smell in the world, either a Built Banshee @ full wail, or a Tuned outboard @ 10K rpms...
BJH
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.