Polishing cylinder head ports

[Anders Dinsen]

Hi all,

My father in law and I had a chat the other day about cylinder head ports - in his young days (must have been in the early 50's), he worked a lot with his motorcycle, which was on a few occasions dismantled totally on the family's dining table. I wonder where they had dinner then? On one occasion he and his brother spent a few days polishing the ports in the cylinder head, and gained some 15 km/h on the top speed!

That made me think, and I found one of the spare cylinder heads I have and took a look down the inlet port. This is what I found:



Notice the two sharp edges on the lower side of the port. Apparantly the head was cast with an insert on the inlet, and then the valve seat and opening was machined afterwards in at least two steps. This has left the sharp edges, as well as some grooves in the surface on the port. Exhaust ports look similar.

Krede and I have discussed it, and while he is apparantly a chicken that would only let a professional do the job, I am a lot more adventurous and plans to do the polishing and edge-rounding myself. I have a plan to upgrade to sidedraughts on my car, and the manifold will then be mated and polished in the same way so the air path is clean all the way (this is a future project...)

Now....... anyone has any opinions on this?

I have no idea what to expect, but as my engine is already on a permanent dose of adrenalin with the Holbay cam, I think it can have a significant influence on the top end.

Cheers to all,

Anders

[macaroni]

I'm with Krede on this one. Engine builders use porting as their USP (unique selling point) and keep their techniques a closely guarded secret. Now, the cynic amongst us may say this is just to mystify their profession, but apparently its a tricky business.

A badly ported head can, at best, give you no gains at all. As far as I know, the Murena 2.2 head has a water jacket very close to the port, so beware.

I, personally, would fork out for a professional job, with 3 angle valve seats aswell.

Just my 2p'orth...

[darrenheli]

Hi guys ive got polished valves and phosphorus bronze guides and re shaped inlet and exhaust ports

[Anders Dinsen]

Hi guys ive got polished valves and phosphorus bronze guides and re shaped inlet and exhaust ports

Those valves really look good. If you don't use them in the car, you can always put them on the mantlepiece I can't see what has been done to the ports, can you tell us? And.... are you running with these parts?

[darrenheli]

sorry the other pictures are rubbish and its back together now ready for a drive down to spain sunday , every thing is lightened and balanced , running side drafts, reworked/ matched inlet manifold to head, skimed head and lapped flat, new valve seats with 3 angles. ported inlet/exhaust not polished as its a wast of time and wont help with the fuel/air  mixing and an extracting exhaust silencer which works at 4000rpm and above. i dont know whot the bhp is but is does go VERY well now

[krede]

Great work darren... thoug I must warn you that posting pictures of pornographic nature does not go down well with the moderator... and those engine shots come very close!! 

Now... what you need to do, is tell Andres where you got the work done.. and how much he has to save up for it.... before he goes in the tool shed on and spoils his cylinderhead

ps: It looks like you are using the straight politechnic weber/solex manifold and not the original "bend" one that lifts the carbs up above the fueltank?....
I ran my car with a similar setup, but came yo hate the fact that there is no room at all for a proper airbox.. or even bolt on filters...
Simons have a "cheap" reproduction of the original for sale now... and if I hadnt allready planned for a turbo convertion, I would surely have bought one of those by as it not only allows a better airbox or filters.. but also gives you room to fit som longer inlet trumphets.

[RazorbackNOR]

Krede, would that be worst to have it bent upwards regarding hot air above the engine....?

and what advantige would longer trumpets give....?

[krede]

Krede, would that be worst to have it bent upwards regarding hot air above the engine....?

and what advantige would longer trumpets give....?

The best would be to have an airbox with a cold air intake like on a true "s".
This will kill off some of the inlet roar, but after a years driving with bolt on filters I , at least, have fond the trade off to be acceptable.

Longer trumpets will increase the speed of the air in the inlet, and give more low and midrange power..

[Anders Dinsen]

Longer trumpets will increase the speed of the air in the inlet, and give more low and midrange power..

... and if you're a dedicated engine tuner, you will tune your trumpet lengths to match the torque peak of the engine!

A ram inlet fitted in the front bumper and a fat and smooth pipe under the car to would be the perfect cold air inlet. Lancia Montecarlos used to have this AFAIR.

[krede]

Lancia Montecarlos

Are inferior to Murena 2.2's in every way that matters!! 

[RazorbackNOR]

Krede, would that be worst to have it bent upwards regarding hot air above the engine....?

and what advantige would longer trumpets give....?

The best would be to have an airbox with a cold air intake like on a true "s".
This will kill off some of the inlet roar, but after a years driving with bolt on filters I , at least, have fond the trade off to be acceptable.

Longer trumpets will increase the speed of the air in the inlet, and give more low and midrange power..

Wouldn't an angeled inlet manifold pointing downwards be the best then....? longer trumpets, colder air, and if one needs, and plate underneath to stop dirt and water spalshing up....?


Wouldn't be hard to make those inlets with the angle grinder and some Bondo....
Just kidding of course.

[Anders Dinsen]

Wouldn't an angeled inlet manifold pointing downwards be the best then....? longer trumpets, colder air, and if one needs, and plate underneath to stop dirt and water spalshing up....?

The original Murena S actually has what's probably the best possible design if you don't want to go to extremes: A manifold that lifts the carbs up so there's space for a nice airbox, and an inlet (identical to the original) right above the gearbox, where there's plenty of cold air.

We are OT now!

Darren, what cam do y ou have in your engine there?

[RazorbackNOR]

Anders, here are some that you can work on:
http://cgi.ebay.com/Culasse-peugeot-505-turbo-talbot-matra-murena-2l2-simca_W0QQitemZ300222963790QQihZ020QQcategoryZ79069QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[Anders Dinsen]

Anders, here are some that you can work on:
http://cgi.ebay.com/Culasse-peugeot-505-turbo-talbot-matra-murena-2l2-simca_W0QQitemZ300222963790QQihZ020QQcategoryZ79069QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


 

I have seen it, thanks. I have two heads in my basement (cylinder heads! ) of which one is failed, so I have a bit to work on.

Since this is a 505 turbo head (and has the studs nececssary for compatibility with the Murena engine installation), this is actually a good offer if anyone needs a spare.