9 replies to this topic

[CraigyBoy]

I have a 12G940 cylinder head that has 33.5mm inlet and 29mm exhaust valves with double valve springs and some porting work.

The valves are nearly touching, so couldnt gon any bigger and want to know hat state of tune this is.

The engine it's going onto is a 1275 A+ that had a 12G940 head with 29mm exhaust and 31mm inlet valves as standard.


If anyone anyone can help that would be appreciated.

Edited by CraigyBoy, 23 April 2008 - 10:41 PM.

[Big_Adam]

Wait, so what is it you want to know?

You know everything about the head already.

[wolfys_mini]

stages are just a way of putting a head into a catagory so it can be sold to people

it has big valves, sorted...

any smothing of the ports...this is the important bit. you can have valves like dustbin lids, but if the air hasnt got a nice flow through the port, they are absolutly useless!

[Jammy]

To some companies that rank their heads on a scale of Stage 1-6 that may well be a Stage 3 or 4, other companies only have 4 stages of tuning on heads, so that would probably be a Stage 2. Ultimately stages don't mean much.

[bpirie1000]

Smooth ports is certainly not the best all and end all smooth is good for higher RPM.. rough is better for some cars with lower RPM AS IS MIXES THE FUEL AND AIR BETTER.

SMOOTH PORTS CAN OVER FLOW THE CYLINDER AND GIVE INCONSISTENT FUEL FLOW. Smooth more for atomised fuel through injection like mpi or spi.

more important to get the shape of the port correct for what you are using the car for to allow flow..

Very technical section of a mini this plenty to read and play with but as always loads of trains of though on this just find something you are happy and able to fiddle with..

Just enjoy the mini

[Shooter63]

SMOOTH PORTS CAN OVER FLOW THE CYLINDER AND GIVE INCONSISTENT FUEL FLOW.

Start early this morning did we?

Shooter

[bpirie1000]

Two pages worth a read shooter63


https://www.reddit.c...pling_vs_rough/


https://www.google.c...mobile&ie=UTF-8


Always up earlier than you it appears....

[IronmanG]

Not sure the OP will see this seeing as it's a 17 year old post....

[Shooter63]

Two pages worth a read shooter63


https://www.reddit.c...pling_vs_rough/


https://www.google.c...mobile&ie=UTF-8


Always up earlier than you it appears....

May I strongly suggest you toddle off over to the SAE website, pay your money and read real quantified info rather than relying on AI etc. Believe it or not, not everything that's posted on line is correct.

Shooter

[gazza82]

AI works by scanning websites for content and merging it ... so if the source is wrong, the AI advice is too ... it even contradicts itself!

I once asked ChatGPT for the replacement mileage of an Alfa MiTo cam belt. It's reply was along the lines of 'there isn't one as it's a timing chain' ... which is partially correct. Diesel engines are chain driven but all the petrol engines are belts ... so fir me AI is as useful as a chocolate teapot.