Rember the intake port texture debates?

[pamotorman]

Every time you post pictures I cringe.

Been trying to duplicate that finish and I just can't get it. Don't know what the trick is, but I'm jealous.

Maybe the key is the double cut burr need to be bent!

why does the gasket surface have the same finish as the port ???

[cjperformance]

Try putting a small hose clamp around the neck behind the collar of the grinder chuck, this puts it out of balance and makes the burr bounce, the longer the burr's shaft the more it will bounce, the higher the rpm the more it will bounce, different burr cuts will get a different finish as will different diameter burrs.

[maxracesoftware]

Larry, if I can control my speed can I use air?

And BTW, I wasn't smart enough to ask Chad how much he bent the carbide. I suspect I whacked it and gave it .040-.060 runout.

.003-.005 should be doable. Maybe then I can hang on to it.

If I have to use electric I'll have to buy something to slow my grinder down, or buy one of those expensive things that I can't think of the name of right now.

Thanks Larry.

yes i'd use Air Grinder , much easier to control ,
in fact , i use Air Grinder in Ports + Intake Manifolds and Electric Grinder in Chambers + Bowl areas

However , an Electric Grinder creates the best effect !

[Carnut1]

Super interesting! Now a question, a super rough aggressive surface like that chamber if used on a port what amount of port thickness do you need behind it to resist the cracking? I am wondering if the rough surface treatment would be worth power over a mcsa limited application that might be better off with a larger port and a surface treatment that was less aggressive? I am thinking the port needs to be ground thick enough and smooth enough to get a clean sonic measurement and then surface treated afterward. Thanks, Charlie

[Bob Hollinshead]

I've found if you put a little piece of tape or something to shim the shank of the bit where it goes into the collet making it off center it will make a nice wobble without resorting to a bent bit. Low speed keeps it to a controllable bounce on the surface.

[n2xlr8n]

Larry, if I can control my speed can I use air?

And BTW, I wasn't smart enough to ask Chad how much he bent the carbide. I suspect I whacked it and gave it .040-.060 runout.

.003-.005 should be doable. Maybe then I can hang on to it.

If I have to use electric I'll have to buy something to slow my grinder down, or buy one of those expensive things that I can't think of the name of right now.

Thanks Larry.

If it were me (I have zero experience in this area)-

I'd buy a variac off ebay and use the cheapest electric grinder I could find to get my burr finish chops.

(Sorry- Larry talking about the way one's hand holds the grinder made me think of the proper way to hold a drumstick)

[David Vizard]

Textured turns don't work, I played with that quite a bit & now go the other way - polished turns & rough everywhere else.

My experience indicates that there appears toy be some truth to this.

DV

[Boz-Race Engines]

i have found smooth ssr and textured runner seems to work best also

[Carnut1]

Work I have done recently on the bench point this way as well. Thanks, Charlie

[Bob Hollinshead]

Has anyone played with a sharp edge just upstream from the short side turn to get the air to turn when the velocity is high?

[statsystems]

i have found smooth ssr and textured runner seems to work best also

How far around the short turn do you polish? How far down into the bowl do you polish?

[KnightEngines]

I polish right to the seat contact & just past the apex of the turn in the runner.

80 grit sanding roll followed by 120 grit linishing tape fed through the port & pulled back & forth over the turn to smooth it out, I don't get carried away with mirror finish or anything.

This is mostly for low turns, turns with a lot of height like raised runner castings designed for racing etc don't seem to benefit as much, the quicker you need to turn the air the more a polished turn helps.

[treyrags]

i have found smooth ssr and textured runner seems to work best also

Best for flow or power?

[cjperformance]

I polish right to the seat contact & just past the apex of the turn in the runner.

80 grit sanding roll followed by 120 grit linishing tape fed through the port & pulled back & forth over the turn to smooth it out, I don't get carried away with mirror finish or anything.

This is mostly for low turns, turns with a lot of height like raised runner castings designed for racing etc don't seem to benefit as much, the quicker you need to turn the air the more a polished turn helps.

Yes, the reduced activity/turbulence of the boundry layer over the short turn will help to keep the air attached

[John Wallace]

Along same line as treyrags, any dyno numbers or track numbers showing the differences between the polished and the textured, before and after?

Larry M seems to have a ton of data on HP increases along with track data on his textures being better than the polished?

No one else actually tries to run them? Just don't think it works?
Just, "it can't work"?