Inlet/Exhaust Valve Info

[cobra kid]

As part of one of my university modules, we are looking at the relationships between the dimensions of valves and the cylinder head.

Does anyone have the dimensions or a dimensioned drawing of any valve with details of which vehicle it came out of?

Any help would be greatly appreciated.


Cheers.

[thong]

engine machine shops may be a good help to you.

[stevieturbo]

More important than valve sizes....would the airflow comparisons between the entire head/port/valve ( and perhaps cam choice ) combination.

Valve size alone is only one aspet. At the end of the day, its how much airflow each entire system can cope with that is important.

[tvrgit]

Agreed. Critical factors are the circumference of the valve (hence why four small valves give better breathinbg than two big valves), the amount of cam lift, and the profile of the cam - ie the speed that the lift is gained over. These can affect how flexible (or, conversely, how "cammy" ) the engine is in use.

Edited by tvrgit on Sunday 22 October 08:58

[rich 36]

any good pictures/drawings,

of valves-heads-guides & seals anywhere to be had

[boosted Ls1]

I'd have thought valve area to cylinder volume would also be important.

Boosted.

[tvrgit]

boosted Ls1 said:

I'd have thought valve area to cylinder volume would also be important.

Boosted.

Well yes exactly - what I meant was "for a given cylinder volume... blah blah blah..." Sorry if that wasn't clear

[knightly]

get yourself a copy of four stroke performance tuning by A.Graham Bell, there is a very good (and large) section on valves - a practical guide with plenty of theory too - you will learn a great deal from this book.

as stated above - valve size is pretty much dictated by flow requirements from the RPM limit and cam spec - going too big can not be the ideal solution - the magic dimension is the ID of the port just prior to the valve head - you can quite often notice significant gains in flow when using the same size valve but with a smaller ID seat and bigger port ID - but the seating loads will go up - hence an upgraded seat material be required - most people use copper-beryillium now days.

I would also strongly advise you start looking into the effects of swirl and tumble and how they are created in the cylinder.....swirl is created via a helical port......tumble is via horizontal flaps in the ports or port shape near the valve......swirl is more important on a 2v engine.......tumble more important on a 4 valve engine......its all in attempt to get better fuel air-mixing better combustion - therefore greater cylinder pressure and and increase in torque - therefore more power........in short the port construction is just as important as valve size

what drawings are you looking for?....... race valves or road valves?......what are you looking to learn from these drawings?...... as I might be able to help you if you let me know