port and polish

[Ziggy]

Has anyone ported and/or polished their cylinder heads and manifolds? I want to try this on a m130. It seems the head is already pretty flowing. How do you hone the exhaust manifold?

[norton]

Extrude  Hone is one way to do the intake and exhaust manifolds
http://www.extrudehone.com/auto/auto-performance.php

[graphic66]

I don't think you will gain anything in performance. These engines are very well designed stock. They develop about one horsepower per cubic inch already. I would bet these heads flow very good right out of the factory.

[ja17]

Hello Ziggy,

I ported and polished the cylinder head of a M130 years ago.  It made a noticable difference at higher rpms.

[pagode.info]

Rough surfaces inside intake manifolds are intended.

They are to ensure good mixture of gasoline and air.

TOM

[Markus]

Ported and polished mine when I rebuilt the engine, used  both a cylindrical and rounded steel bit attached to an air die grinder, to remove metal.  Found that the most improvement to be made really was matching the manifolds, gasket and cylinder head. There was so much overlap at the manifold gasket (before tighten and crushing the sealing rings) that I custom made one from gasket stock used in NHRA dragsters, (so far no problems, also considered using copper)   The intake runners on the manifold can be opened up or rough polished using a round steel wire brush attached to a 14" mandrel.  Exhaust manifold was matched perfectly with the gasket then polished with tapered sanding drums attached to the die grinder, and the same goes for polishing the intake manifold and head. (it does not need to be "mirror bright") You can also have your exhaust manifold high temp coated. The point is, anytime an engine can exchange its gases more readily, it becomes more efficient, and "yes" there is room for a little improvement even on these engines.

[waqas]

There was so much overlap at the manifold gasket (before tighten and crushing the sealing rings) that I custom made one from gasket stock used in NHRA dragsters, (so far no problems, also considered using copper)

Hello, what exactly do you mean by "overlap"? Is this the incorrectly matched sizes of the openings on the manifold and the gasket?

[Ziggy]

It took a while for this thread to be noticed, I am almost finished now.
I compared a couple of heads and manifolds and while on first sight they may look identical, but if you inspect them closely, there can still be huge differences due to casting artifacts and such.
I had to trash my manifold because the intake ports were smaller then on other manifolds (with the same number), the casting was also very sloppy. Must be a bad day at the factory.
The manifold gasket is terrible indeed. As Markus stated, there is a lot of overlap on the exhaust ports of the manifold, and some overlap of the intake ports of the head. This is due to a bad design by Elring. The old type gasket with straight sides on the intake ports did not have this problem, that matches up pretty good.
It took a while to match the gasket, so I am going to try it. I figure the parts of the sealing rings I had to cut don't do much either when they are used from stock (since they do not touch metal..). Just get to clean and polish the exhaust manifold, it is difficult to reach all the way inside.

[JimVillers]

Wagas ..... "Porting" is matching (or making it match) the passage in the intake manifold to the head passage so that the air flows cleanly.  The overlap that was referred to was the the gasket sticking out into the port.     

[waqas]

Got it, thanks Jim!

[bigmellon]

Well, porting to me would indicate using a flow bench to see if you can increase the airflow by changing the runner geometry.  This really is an art form and should be done by a professional. 

I agree that port matching would be a good idea.  I recently matched the ports on my head.  The raw casting had many imperfections that needed some attention.  The intake/exhaust manifolds matched the gaskets quite well.  So, I did some grinding on the head so that it would match the gasket.  This may not be for the faint of heart.  The head should be off the engine, and you should be sure to clean the head well when all is done.  You certainly don't want aluminum filings in the engine. 

Here are some pics to demonstrate what I am talking about...  Hope this helps.

[Benz Dr.]

I had a 250SL head done on a flow bench and yes, they do flow very well right out of the box. So well in fact that they guy who did it for me was very impressed. He's rarely impressed with stock engines being a long time drag racer.
He figured that the 250SL head, which was very dirty and not cleaned in any way, flowed as well as a typical small block chev.

There are different ranges on a flow bench which I don't understand about but this is the info I saved from 5 years ago. On range 3 he found:

intake at 300 lift  was 96.5% flow and 142 CFM

exhaust at 275 lift was 69.5% flow and 110 CFM

When pushed to maximum range 6 the intake was 596 and the intake was 812.

[Khurram Darugar]

Rough surfaces inside intake manifolds are intended.

They are to ensure good mixture of gasoline and air.

TOM

Tom,

Ideally would the exhaust manifold inside surface be smooth? 
Kay

[norton]

Yes smooth surfaces on the exhaust are best for flow, but mostly best to minimize build up of deposits that could hinder flow.
Smooth is also best on the intake side of a fuel injected engine, because there is no fuel in the intake manifold.