port and polish

[85Ecoupe]

hey nube question here:o

what must i do/have to port and/or polish my intake manifold??

i have a 1985 325e that i am rebuilding

[NC325iC]

sell the car, no i wont be the only one to suggest it

its not worth it

[JasonC]

As much time as it takes to P&P. I wouldn't waste my time on doing it to a "e". And this is coming from a guy that has 2 e's. But if you want to, i used a die grinder with differnt tips and then had one tip that held a piece of sand paper to smooth out the port. Then i polished it with a mag wheel polish. This is what i done on a head and intake on a 2.2 turbo dodge that i had. And on the exhaust manifold i used the die grinder to smooth it out, buy never polished it.

[E30Idea]

I think keep your E car. They are a ton of fun. If you are going to do a P&P and build the e motor at all than you need to do the entire system. You will need to P&P the intake runners and get as far up in the intake plenum as you can. Also, you need to do the head on both intake and exhaust side or the P&P on the other pieces wont be as ( if any more ) effective. Just my

[nando]

generally it's a bad idea to polish the intake side...

[asubimmer]

you from WNC?

[85Ecoupe]

yeah Charlie, its jimmy

[asubimmer]

cool deal. We really should have a Boone e30 meet soon. There are a lot up here now it seems.

[85Ecoupe]

that would be awesome, mine is down right now i took the head off And im gonna ask cheshier to port/polish it or get some one else to :)
and it was hella dirty (the motor)so im cleaning it up

[E30Idea]

generally it's a bad idea to polish the intake side...

Why? I honestly dont know... But I would figure that a smother more free flowing anything on a motor would be a bonus. I dont know, I am willing to be wrong.

[PiercedE30]

Why? I honestly dont know... But I would figure that a smother more free flowing anything on a motor would be a bonus. I dont know, I am willing to be wrong.

Best description that I have ever found to explain it:

Surface Air Flow
As air moves over a smooth surface, the thin layer of air having direct contact with the surface is nearly dormant (barely moving). Why? This layer is clinging because of surface tension. The clinging is disrupted by any increase of movement created in that first layer. Movement in the successive layers is enhanced since they are then "riding" on an already rolling foundation.

Smooth Surface
Air flowing over a rough surface is greatest simply because the air contacts “touch" the entire surface and this causes maximum resistance.

Rough Surface
Air flowing over a rough surface "touches" mainly the high points. This sets up a stumbling action at the surface disrupting the dormant layer and generating a slight flow increase.

Sculpted Surface
A sculpted surface is one with a repetitive pattern specifically designed to generate rhythmic air turbulence at its surface for maximum air flow. It's the basis for the Surface Turbulence in our Engines and Heads.

[nando]

Why? I honestly dont know... But I would figure that a smother more free flowing anything on a motor would be a bonus. I dont know, I am willing to be wrong.

because fuel will end up sticking to the walls of the port rather than mixing with the air. you want a smooth surface with no sharp points but the surface itself needs to be able to create turbulence in the airflow so the air and fuel can mix properly.

[Sean]

because fuel will end up sticking to the walls of the port rather than mixing with the air. you want a smooth surface with no sharp points but the surface itself needs to be able to create turbulence in the airflow so the air and fuel can mix properly.

Yea if it's smooth, the fuel will not mix correctly.

[E30Idea]

Well played, Now this is a good r3v thread. I am learning with constructive feedback. Really, Thanks you guys. I was about a week or so from going nuts with a dremmel on anything that I could port or polish on the intake. Thanks again.

[nando]

you want to polish the exhaust, because the only thing that matters there is airflow. on the intake a rough but smooth surface will do. also, polishing the combustion chambers is a good idea, but be careful not to remove a lot of material as you will change the compression ratio and each cylinder might be different..