Max Honda gx200 head flow?

[bruce bruce]

What's the most flow you can get out of a Honda gx200 head? Welding, big valves and whatever else on a max effort race engine. Seems like the billet head would be better. Opinions?

 

[Atsownz]

Charles is the man when it comes to heads for sure!
Check out these links over on 4cycle., He has done alot of R&D on heads, he should chime in and be able to tell you exactly what you need.
But in most cases Billet heads will win!:thumbsup:
4 Cycle Karting Forums - Welded Tunnel Ported GX200 Head Flow
4 Cycle Karting Forums - Belmit Billet gx200/Clone head Flow Test
4 Cycle Karting Forums - Matts Billet Head Flow Test

 

[minidragbike]

The most I have ever gotten is 113cfm only 1cfm less than a billet head. This was a welded tunnel ported cast head, and out flowed the billet head at all lower lifts than .450".

The regular un-welded cast super big valve heads I do flow from 98-102cfm.

Remember many people are happy with a simple off the shelf big valve head flowing only 75cfm. Because 75cfm is good for up to 22hp, and that is what most people are satisfied with.

 

[Wax]

I know this is an old post but are you sure on the flow figures. If I do a calculation from all the web calculators it shows up different. Maybe I am reading it wrong

 

[trinik7597]

if i had to guess his numbers are on point :thumbsup:

 

[ole4]

What kind of web calculator? You can figure what the most a particular ports minimum CSA will flow but then you have the valve, valve seat, SSR ECT which can drastically reduce flow.

 

[Wax]

You need a certain cfm to make a certain power. Regardless of head, if you don't flow that much it's impossible to make the power. The question I am asking is he sure his math is correct

 

[ole4]

his numbers are pretty close. however just because a head may flow 75CFM with the addition of the rest of the intake system it may be a lot less. If you like I have a spreadsheet I use when flowing heads and if you input cubic inches, VE, and desired rpm it will tell you the required CFM@28" of the inlet tract. Example:
Most Desired Airflow To Produce Up Too The Desired Volumetric Efeciency
# of Cyls CID Desired rpm Desired Ve% Req'd Airflow @28"
1 12 8500 100.00 78