rotorhead

can you port the exhaust, even mildly, without tearing down the engine? i'd like to just unbolt the headers, zip some material away, bolt on and go, but i sure don't want to get a chunk o' leftover wedged in the rotor seals.

Blake

Absolutely not! Don't do it.

REVHED

Blake's right. There's no way you could do this without getting some crap inside the engine and destroying it.

rotorhead

thanks for the info... glad i haven't unbolted the headers yet

peejay

Plus, you'll want to put a slight radius on the port edges so the apex seal doesn't "catch" on them... have to do that from the inside.

MIKE-P-28

iTrader: (1)

That would be kinda like , boaring out a piston engine, by putting sand in the intake.. You definately dont wanna do it whilst together, much less apart. Theres a small science to this. Too bad no one doesnt have some really good pictures of a ported motor that I could study

Pele

iTrader: (28)

See the post in the lounge a few days ago? Pics from the Miata forum... A guy got B-B's in his engine.

MIKE-P-28

iTrader: (1)

B. B's ? How do you do that LOL?

Pele

iTrader: (28)

He was rebuilding it, and a bunch fell into the intake as it was sitting on his workbench. Search the lounge.. the pics are horrific.

rotorhead

lol.... bb's! car was killed by 'daisy'! really, what i was trying to see was if i could smooth the exhaust going into the headers, y'know, squeezing out the free ponies if i could. maybe if i said matching the exhaust holes to the header pipes.... but i was worried 'bout something falling back in. then i started thinking, if i dremel while holding the old shopvac nozzle right there... just maybe... but the last thing i want to do is grenade the engine.

peejay

You'll actually gain more power if you make a port plate, which is kinda like a tongue that sticks into the port so that it keeps the port about the same size all the way through. You want some port mismatch (port smaller than header) because that helps keep exhaust from backflowing back into the engine. Same on the intake side BTW... you want the manifold ports to be smaller than the engine's, it acts like a one-way check valve.