What is Porting...Tuners...custom exhasuts ???

[Ilovespeed]

I am being confused with all these different terms...what is porting what is a tuner and what is what talon2.5 did on a custom exhaust??? is drilling teh mid the same as porting?????
Thanks
Tyler

[Raceman]

The term porting usually refers to changing the port timing in the block. The tuner is an extension on the bottom of the powerhead going down into the mid section. Unfortunately, many people who buy tuners confuse the function with that of the stinger on an expansion chamber and it's not the same. Tuners make very small differences in powerband and almost never result in top end increases. In my opinion they're the single most over rated modification ever done to an outboard. As far as exhaust relief, it's the drilling or cutting of holes in the mid section, allowing some or all of the exhaust pressure to escape before it goes through the gearcase. Usually it is responsible for better sound, if you don't like a quiet motor and better acceleration right off idle on some boats. It usually doesn't contribute to top end increases either.

[JW]

blown motor every month or so. Keep it stock unless you've got lots of cash to burn!

[Boz]

On my 200 Pro-V Yamaha (93), I put a tuner on it, cut the canister and liner out and drilled 4 - 3/8 inch holes on either side of the cavitation plate (just above). Should I have done something different or can I change something at all?

[Raceman]

Boz, I have no experience with Yamaha's whatsoever. Maybe JeffYammamomma will see this and give you a thought or two.

[Rocket]

SEE JSRE for Tunner work, Relived Exhaust, and you will see improved acceleration! You have to be concerned with Mid section splitting when you go drilling on them! Jay will fix you up!


My two cents!

[Boz]

I've spoken to Yammer a couple of times and he is nothing but helpful; we are actually in the midst of exchanging a few parts etc. Thanks for your input!

[MTCM]

Porting is like Open-Heart Surgery......one slip of the knife and you're screwed. Best left to a skilled surgeon.

Tuners (exhaust extensions).....Changing them on stock unmodified engines, on some I have seen them hurt performance, never improve it.

[Techno]

Porting is changing the timing of the engine, like changing a cam. Since these are holes in the side of the cylinders the piston uncovers/covers them at different times on the crank rotation.

I believe fishin motors have them further down in the cylinder and HiPos have them higher. The size and "overlap" of them could be changed too.