exhaust manifold trick

[jetski9010]

Ok not some thing i have done
But when you consider that that the exhaust gases and fresh air goes out of the engine and into the exhaust
not only will you be blocking new air in but also new air out

He was telling me you have to set the lip up for your motor. He use to run 4-6mm lip and then with RAVE valves came out he still had the lip but it was a lot smaller.

 

[masterblaster]

Ok not some thing i have done
But when you consider that that the exhaust gases and fresh air goes out of the engine and into the exhaust
not only will you be blocking new air in but also new air out

not really,Ive seen this done before,the lip or "ramp"rather is starting at the same level as the bottom of the exh port and just drops lower with bottom edge of the mani,in essence the mani is lowered a tad the bottom edge of the cylinder is ramped and the top of the mani is then port matched to the cylinder. Kinda the same thing as when transfer roof ports are grinded at a 45 deg angle down.

 

[waxhead]

Ok i didn't understand what you just said
Maybe it over my head, i will not be trying this anytime soon but good luck to the people that try it, keep us updated

 

[egbrig]

Hey Wax, I think this is one of those old tricks that was never verified but people did it because they "heard it from some guy". Two stroke engines have come aways since the 80's and pipes have progressed as well. Also, the charge flow/exhaust and the sonic wave don't react the same to obstructions.

 

[masterblaster]

who knows how well it really works. basically the exh out sees no lip on ly the pipe waves coming back in are effected by the ramp to send them upwards

 

[2XLR8]

If it worked everyone would know about it, and everyone would be doing it.

 

[waxhead]

Im making some exhaust divirters
180 each
put them in your exhaust and add the step

 

[Flash-FX]

Anti-reversion cones for 4 stroke motors were supposed to untap some "magic horsepower and torque" years ago. Check out the "DYNO" run sheet. Slight gains if anything. I think a properly designed pipe would do better on a 2 stroke, correct me if I'm wrong here.

http://badweatherbikers.com/buell/messages/3842/16474.html?1125948543

 

[Matt_E]

again, real good motors from top level porters. Different than 99% of what hangs out on forums. It's more than just a lip but in principle its what was described.

Care to drop some names?

 

[Matt_E]

Define top level - give us some names, please.

 

[Matt_E]

I take it you re not willing to share some names of top level porters? :dunno:

 

[egbrig]

I shouldn't be saying this but I have had my head in those few motors and there is no lip. What there is, is a well developed package of parts, work and tunning. I have seen some cool team Kawi, Riva, insides and even those tiny little "thats different" things disapeared and morphed into a common looking but developed engine.

 

[Justanotherusername]

egbrig you party pooper!

 

[SUPERJET-113]

Do you have a "macro" setting on your camera. That is what you'll need for a good close up pic.
Hard to tell in those pics. Very interested in this subject though!
Thanks

 

[2XLR8]

If it worked good enough to be worth the time to do the mod there would be more people doing this mod. In theory it sounds good but in reality it more than likely does nothing at all. Because someone's sled or ski is running very good that is using this doesn't mean it is this mod that contributed to any increase in power.
Anti reverse theory is more of an issue during the exhaust stroke due to the much higher gas pressure and air speeds. In this case we are talking about the reflected wave pushing the pulled intake charge back into the cylinder. The gas volume,speed and chamber pressure is too low to create such a big movement of air through a port large enough to flow during the exhaust stroke. The theory of improvement on this is that the fresh charge is guided toward the top and has less tendency to short circuit out the exhaust. If the port was designed with a decent flaw in this respect then this mod might give a small improvement.
You know how it is, There is always some top pro that ends up selling their stuff because they get out of the sport, needs money or is switching manufacturer brands or even switching engine builders. I think this secret would have been out a long time ago if it really worked. :shhh:

 

[waxhead]

Ok The 125gp bike do not have that
I have built and raced enough rs125 engines to know that

 

[GIL]

You haven't seen the cylinder side of the connection between the exhaust manifold on a kawasaki twin under the tent then, or a CR250, YZ250, KX250 in SX, or a 125cc gp bike, they have quite a large step between exhaust port and header.

I'm sure you've seen a lamey from lamey but that's not a Lamey in a boat under the tent in the day.

Here are two pics to show the concept. Kaw cylinder and a YZ250

So u are saying what Dan told me is not a bunch of BS trying to get me to leave him alone about the 'curtains' on my ex ports? (That appears to be mis alignment on the casting process)

 

[egbrig]

2XLR8 nailed it.

 

[MTRHEAD]

I obviously didn't add any value in my postings trying to support the original post.
I deleted my info so not confuse or distort what others think....

 

[Watcon]

Knowledge.....

I have a friend that has the following tag line on his avator..
"I'm so clueless that I don't even know I'm clueless"

Don't worry Mtrhead, you can lead them to the water, but you can't force them to drink..