New Expansion Chamber Theory

[Fabian]

Try not to justify the cost. It gets in the way of good research.

 

[Deleted member 12676]

OK Fabian, since you're so pro-research, why don't you buy all the equipment for me to use to validate my theories?

I've been in contact with TFX and they say a back pressure sensor ($300) is also necessary. When asked why, this was their response:
"The back pressure sensor is needed to evaluate the stinger, it is also needed in conjunction with the exhaust port sensor data to generate meaningful data and data analysis in general. The amount of back pressure we normally see in a 2 stroke varies from about 2 psi to about 8 psi. There is of course a best value for a particular engine combination, but not really any sort of general target value to shoot for. "

 

[Fabian]

I am pro-research but i can't (at this point in time) bankroll your equipment purchases because i'm slowly bankrupting myself with all the unnecessary modifications to my motorized bicycle, and my bike is one heck of a research assignment in motion.

 

[BigBlue]

Hey,

I'll keep you guys in mind if I win the Powerball Lottery

Chris
AKA: BigBlue

 

[Fabian]

That's exactly what this project needs - a serious cash injection from a favourable lottery result.

Nothing like getting the ball rolling with a 5 axis CNC mill to turn out a complete engine from billet.

This is a great example of what a lottery win could mean for the technology we could invest in improving the mechanical side of things: engine options, transmission options and various other potential accessory options, directly from blocks of solid:

 

[geebt48cc]

I would be so dangerous if I had a great deal of unlimited funds!!!!!!!!!!!


Hey, what if you guys turn on CNN and see me being chased by many police cars? I have a very large bag of $$ thrown over my shoulder....................lol..................On a 66cc MB traveling all most the speed of traffic!!!!!!~

 

[mikejeffries]

I noticed in the blair link above, he mentioned using an internal convergent cone (in their stock exhaust setup), to get a broader torque curve and better accelleration?!

 

[Deleted member 12676]

Some street bikes like the Suzuki AX100 have a pipe with a diffuser cone and then a muffler instead of a baffle cone, in order to get the maximum grunt from the engine. That is because the return wave from the baffle only serves peak rpm power and detracts from lower rpm power. The return wave from the diffuser cone serves the both mid-range and top rpm power. (by mid range I mean starting when the return wave starts to come back to the cylinder after transfer port opening which is like around 2000 rpm and above)
In the same spirit of that, I have a new design of torque pipe that has lowered the baffle return wave strength as much as possible. I should be ready to test it Wednesday. It will have half the return wave strength of a motocross pipe (and all the pocketbike pipes sold for these engines) and 50% less strength than my posted design of torque pipe.

 

[geebt48cc]

Ok, so what I gather, is it's really boils down to the actual degrees rear baffle has/or doesn't have on expansion chamber regulating the sound waves back to cylinder? Right?

So, with that being the said, the whole world of all expansion chambers will or wont be decided by exclusively the angle of rear baffle?

 

[Deleted member 12676]

In a general sense that is a good summation, but technically wrong because what really matters is the percentage cross area change (from every 10mm baffle length in my calculator) which is determined by angle, but also by beginning diameter (of the belly). A skinny pipe with a 10 degree baffle will have a stronger return baffle wave than a fat pipe with a 10 degree baffle. No guesswork is needed though since any dork can use my Excel file to get exact calculations.