Thinking about doing the whole shabam this weekend if I hear anything from someone that has the 351 kit that has ported and polished there heads.

 

nah..

 

your not going to make less power doing it, i would imagine the castings on these could use some help.

 

Didn't Finger Mullet or someone clean up their ports a bit? I don't recall it being a heavy port-and-polish, but a good cleanup from the pics posted, if I remember correctly.

 

I chose NOT to polish the ports because I would end up with an even more cold blooded engine. We need the turbulence from the casting to mix the fuel and air. The gain is small. Textured is better than smooth for a daily driver.

If you want a 650.....

Just a side note. The fuel is NOT VAPORIZED, Its ATOMIZED.

David

 

I don't know, David...may not be as simple as that...and I claim no engineering/physics degree in any of this. I do know there are two kinds of turbulence in an intake system...beneficial and non-benficial. And even in that, they are not always the same depending on what the tuner is trying to accomplish.

You're right on some turbulence usually being beneficial to a street engine that has to operate at some acceptable level of performance over such a wide variety of speeds and uses. But if the "roughness" in a given intake tract is of a kind that doesn't cause the turbulence in such a way that helps atomization, it is non-benficial. Some intake tracts even have some bumps and ridges of a kind to improve atomization...usually at low rpm. Most other rough spots are not beneficial and would improve atomization and overall flow if they were removed. Velocity also helps atomization, and at some point smoother flow will increase velocity and aid atomization. The point at which this occurs is the tipping point where you can lose low rpm power to gain higher rpm power. Everything's a compromise. And of course, really hogged out ports with mirror finishes are usually reserved for higher rpm benefits...but...then you can throw a bit of a monkey wrench in the mix when you consider fuel injection. The injector itself goes a long way in creating a spray that pretty well achieves instant atomization.

But we were talking about the carbed KLX here for the most part, so I go back to the initial comments I made. The fly-in-the-ointment here would be that you'd pretty well have to have a flow bench to really know what you were accomplishing, and even with it that would take some time and a knowledgeable person running things. The term porting "usually" involves opening things up in the head. This is the harder thing to accomplish and really requires some knowledge to achieve what kind and where some power would be found. Polishing and/or just cleaning up casting imperfections and such would probably be beneficial...as long as one didn't go crazy with the Dremel or whatever tool is being used. Smoother intakes and exhausts also pickup and retain deposits less which also usually results in better performance.

 

Hi there,

I did some polishing on the exhaust side and gasket match the exhaust port did also cleaned the intake roughly. 33hp 351cc webcam 101... good luck