thats great info, i just dont understand what im reading lol,

 

I suggested the stock diameter. I have talked to him numerous times on heads for these trucks. He basically said that the trucks dont gain really from going all out on the porting. He is working on them right now, so hopefully I will have them within the next couple of weeks.

 

Take a look at this picture and look at how the air has to travel around the outside of the valve between the valve and the cylinder wall. If It cant flow between the outside of the valve and the cylinder wall, you create turbulance, which hurts flow. Think about trying to blow through a straw with your mouth wide open. It doesn't work too good does it. It works a whole lot better if your lips are the same diameter of the straw. That is velocity.

http://www.mitsubishi-motors.co.jp/i...derAirflow.gif

 

2.02-1.65

 

Damn, nice diagram. Hink, pay attention to the right video, more accurate of an ls1 except for the spark plug.

Valve size does play a part in velocity, correct? And shrouding would be slowing down the flow as the air/fuel try to go around the valve. Would that be wrong?

Texas, what are the valve specs, what you would recommend?

 

Texas, what are the valve specs, what you would recommend?[/QUOTE]
what else do you want to know? they are 2.02 intake and 1.65 exhaust stainless ferrea valves in modified (obviously) 6.0L heads. i also had them polydyne coated. as far as a recommendation, you need to figure out what kind of setup you are going to end up with. will it be forced induction? spray? N/A? what kind of cam profile? what C/R? what kind of flow numbers are you looking for? what kind of porting will be done to the heads? there are several factors.

 

My mistake. I didn't realize you were responding to original topic when I read your first post.

Thanks for including the factors that deal with how to decide upon the correct valve sizes. Would you mind sharing details on how compression ratio/flow numbers/cam profile tie into valve size?

 

so basically any valves over 1.90 let's say are overkill on intake and anything over 1.55 on exhaust is the same.

 

What is it, a 75% exhaust to intake ratio that seems to make the best results? How do you come up with this ratio? Can you just compare valve sizes to find this ratio?



Any guidance would be appreciated

edited: exhaust to intake , not intake to exhaust.

 

On the 3.78" bore. Yes

Here is someone else who also thinks so.

http://forum.ls1truck.com/index.php?showtopic=2524