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  #1  
Old 01-15-2009, 06:43 AM
Mein Schöne Stern
 
Join Date: Nov 2008
Location: Lion sur Mer, Normandy, France
Posts: 19
Porting M110

Hi folks

I have this cylinder head that I want to improve.

This is my analysis: exhaust ports are within 1 mm of the valve head side (approx 39mm) so as mild polish will do - no porting. The intake ports are substantially smaller than the valve head ( head: 45 mm, port approx 37 (avg).

What is the logic of this

IMHO, the ports look very restrictive and should be opened up by several mm. These small ports ensure good gas velocity but I was always under the impression that a port close to the valve size was ideal. This engine produces max. torque at 4000 rpm which certainly does not make it a big torquer despite the very mild camshafts.

Would 40 mm ports kill the torque ? I see not why...

For instance when I compare this head to a BMW 318 M10, the Benz looks strangely constricted and the BMW makes its max torque at the same rpm despite a more agressive camshaft, similarly sized valves and bigger ports (1-2 mm smaller than valve heads.

Any opinions ?

Denis
Lion sur Mer
France
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  #2  
Old 01-15-2009, 09:19 AM
Registered User
 
Join Date: Jan 2006
Location: Tucson, AZ
Posts: 4,585
Increasing the port size is going to alter the engine characteristics.

It would all depend on what you have planned for the engine.

You will gain mid-range and upper end performance but lose out on lower end torque.

Larger intake ports will require more rpms for the vaccum needed for the gas flow velocity. This makes for reduced "in-town" driveability.

If you're driving a W107 manual transmission then it's not a big deal but if you're driving a W114 automatic and you cruise through town then you'll actually be reducing the efficiency of the engine.

A fuel injected engine would be the best choice for this upgrade as you are not as dependent on the vacuum from the engine to "swirl" the fuel mixture.

Your best bet would be to "match" the ports between the intake manifold and the head and then a quick polish. This will keep the low end torque and improve the flow at the mid to upper range.
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  #3  
Old 01-16-2009, 05:12 AM
JayRash's Avatar
DON'T PANIC
 
Join Date: Jun 2005
Location: Beirut, Lebanon
Posts: 1,278
well if u want some top end power, try getting the cam shaft gear pins from ur local dealer, ask for the offset ones they have them in 2deg, 3deg, 4deg, and 5deg IIRC.
i used the 4 on both cames retarding them, ended with goood topend power all the way to 7200 rpm (w123 280 ce m110) but no low end at all
now running retard of 2 deg, good over all drive and good top end.
if u want lowdown pwr, advance but when i did advance 4degs, engine wont rev over 5800 and i did break three auto boxes, those of the w123 are of weak boxes, cant take much low down torque. try playin around and ull be stunned how much power u will find
__________________
Jay,
-----------------
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-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
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-1981 Gold W123 280CE.(Dareen)(Sold)
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  #4  
Old 01-19-2009, 05:00 AM
Mein Schöne Stern
 
Join Date: Nov 2008
Location: Lion sur Mer, Normandy, France
Posts: 19
M110 port and combustion chamber design (Euro)

Hi folks,

I can sort of provide an answer to my own question but also question some assumptions about this head.

Many people will point out that domed pistons and traditional hemi designs are not very good in terms of combustion and detonation resistance.

Well, MBZ did not do the usual "hemi" things in this engine. The Euro piston is domed but only under the exhaust valve. The combustion chamber is actually a pocket with the spark plug oriented towards its center. The combustion chamber area near the intake valve is lightly carved to improve flow. The intake ports are relatively small but very uniform and designed to maintain strong gas velocity at low engine speeds. All ports are actually divided by small humps before and after the valve guides - this is designed to maintain best velocity. American hot rodders would remove the humps but that would be a mistake with stock camshafts.

The exhaust could use a bit of porting. The intake side needs to have its area just above the valve seats make smoother - mass production machining artefacts do not make this as uniform as it could be. That is about all that needs to be done - small mods and cleanup.

This design with its very, very conservative camshafts seems to ensure that the relatively heavy cars it must propel will move swiftly at low road speeds. So "real" porting would only make sense if the cams were changed and the engine were fitted to a light car like say a W201.

Looking at the DOHC head one notices that it was designed to be as compact as possible and therefore has combustion chambers that are not heavily surrounded by water passages - hence the noisy character of this engine.

Voilà !

Denis

Lion sur mer
France
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