Polish of in.manifold channels

[Sweeper]

Is there any improvements if I polish 5 inlet channels of inlet manifold ?

Or it's no no ?

P.S. I'm finally managed to complete dahlback intake manifold replica , just need to buy a new throttle cable.

[sorens2]

It might not give you 30 hp but I would do it anytime. Polish and grind off any edges or misalignment into the head.
My own have had that cure...

Søren S2

[Billman]

@Sweeper

Hey show us some fotos!!!

Greetings

[Sweeper]

Billman: here you go. Still need to be polished tho , will do today.

[Sweeper]

And just for to see the difference my new summer alloys vs my new manifold.

[robo]

blink

[Billman]

This is made oute of an AAN IM ?

I have heard we should not polish the canals at the IM because the inner surface of the IM must be row so that the air stream makes turbulance and mixed better with the fuel!

Greetings

[sorens2]

Hellooooo
On a carb. Yes.
But look at it. There is no fuel in these inlet runners. The injector is placed at the end of it. So go ahead. Polish all you wan´t.

Søren S2

[audiman]

Nice rug Vadim!!!

That manifold is one your bought right??? It looks just the same as the real thing, how did you make it you ******

[Sweeper]

Billman: No , it's all custom made. I had original Dahlback Manifold in my hands for one week(friend borrowed it to me) so i had a little play with it.

I have a friend that owns an aluminium factory , so in a month time i had an EXACT replicad made in factory enviroment with best engineer. Yesterday i finally made a throttle cable and polished everything.

The engineer told me that he will never make another one becouse he spent nights to make it.

The best thing is that I've paid 200$ for all together . Polished myself(first experience).

Still haven't tried to fit it(doh), hope it will fit.

P.S. Can't figure out how to polish internals (lines , canals) couse noone have a tools to do this :/.

[audiman]

You should have done it before it was welded togther!!! Doh.

Im sure loads of ppl would be happy to pay at least $500 for one of those, but with custom Logos on them??? Is this gonna happen then Vadim? I would like one if it fits past the AC and PAS

[Billman]

I take one for 300 $ ;-)

[Sweeper]

I will try to fit it in a few weeks and let everyone know.

[Billman]

Soern, on a carb you must polish the runners because you want that the most fuel go in the engine! In EFI tou must not polish the runners (you must make them rough with specific tool) so the air swirls and so it will be mixed better with the fuel when it will be sprayed!

That's what i know but i wait also for others opinions!

Greetings

Here http://www.billzilla.org/engineintro.htm i found this too:

There is some debate weather or not it is worth polishing the inlet tract and inlet ports. Most engines these days have a light sand cast finish to them, and I believe that this is close to the optimum for creating a good 'boundary layer', which makes for a more effective inlet system. The best finish seems to be the one left by a '400 grit' sandpaper. The other school says that there is not time for the boundary layer to form and so a highly polished manifold & head is the go. I believe that most dyno tests show that a slightly roughened surface gives more power in most cases, so in that case I don't think that it is worth the cost and effort to polish the inlet manifold and head at all. Simply clean up the casting 'dags' that are always present.

[sorens2]

A 400 grit sandpaper is what I call polished.
And on a carb. you should NOT polish the runners. The fuel condenses on the walls of the runners instead of mixing with the air because the atomisation of the carb is poor. Therefore, if the air swirls against the rough walls it will drag along fuel and mix with it.
On injection there is no fuel in the runners.

Søren S2