flowtech triple exhuaust port job with a 3mil crank
- Thread starter BlasterCrazy
- Start date
I can explain the theory behind them as I understand and then my personal experience with the setup.
The problem is as follows: The time between the exhaust port opening and the transfer ports opening is called blow-down. On a high rpm engine, there's very little actual time for this to happen (while the cylinder pressure is still high and before the new charge has had time to mix).
A single oval exhaust port begins as a tiny little slice and grows gradually (due to the shape needed to keep the rings in one piece) but during the entire time of blow-down it never reaches full width. There have been as many different types of attempts as there are different types of quads to cheat this fact. The most evolved layout involves having a path outside of the normal oval port that is only REALLY effective during blowdown (it's situated above the front most transfer port). The advantage is that you need a less wide main exhaust port to get the same amount of blowdown area.
The difference between a standard port job (raising and widening the exhaust port) versus a triple exhaust port isn't like the difference between stock and ported.... The differences are more subtle but those who like to keep their engines in one piece will appreciate it.
In order to maximize top end hp, you need a LOT of port time area in order to get the old fuel out and the new fuel in. With this comes a general trend towards less reliability. Part of the reason is stresses on internal parts.... There are a few that smaller ports actually help. One, the exhaust side piston thrust face. When the rod pushes the piston back up, it also shoves it forward and against the front of the cylinder. A smaller (narrower) main exhaust port increases the amount of cylinder there to support the piston. The rings tend to "poke out" into large (really wide) exhaust ports. This causes ring wear only in one spot as the rings are pinned. Setting up a cylinder that puts out the same horsepower with triple exhaust ports increases engine life. Setting up an engine with the same engine life expectancy will put out more power with triple exhaust ports.
As Awk pointed out, this affect is the strongest at mid to top rpm with an extremely strong pulse wave pipe and a carburetor big enough to feed the need.
My personal experiences with triple exhaust ports? Ported Vito's BBK on a stroker crank hung with a stock 2007 polaris outlaw 500 this past weekend. No the outlaw rider didn't skip any gears and no I wasn't the pilot I:I
Not enough information, what fuel, what mods, what gear/sprocket ratios, what tyres?.
Should just start your own thread. This has nothing to do with tripple ex X(
Why are you boreing .080 :-/? No extra power to be had
Should just start your own thread. This has nothing to do with tripple ex X(
Why are you boreing .080 :-/? No extra power to be had
i just got my cylinder back from Denny couple months ago ima start a thread on how it rides i been wanting him to port my motor for a while. plus he matched it for a 3mm stroker. and ima use a 34PJ with a 155 main. 45 pilot idk the size needle i thnk its a DGH tho. +4 swinger wit aluminum airbox. and ima try to get a power pros pipe. thats what i had it ported for.
