Larger valves.

[4.0l sahara]

Have a set of 6.4 heads that we stole the exhaust valves from for a 6.0. So since it's getting hardened valve seats and some porting done to them I would Like to at least put bigger exhaust valves in. So does anybody have any preference in what brand valves to get? What size? I was thinking 1mm bigger.

 

[Stroked777]

Subbing for info. How much difference would 1 mm make?

 

[getstroked27]

I dont have much experience with building diesel engines, but a lot with gassers, and seeing as far as heads go, its the same concept, oversized valves always help, but not a whole lot unless your tossing in a more agressive cam. higher lift, longer duration and overlap you will see huge gains. bigger holes mean more air. if you ever get a chance, look at a top fuel dragster head. you can fit a tennis ball in a valve opening (when theres no valve of course). thats my two cents

 

[jdgleason]

1mm makes a pretty big difference when you're talking about a large amount of CFM at 50+ psi...

 

[madman1234509]

I dont have much experience with building diesel engines, but a lot with gassers, and seeing as far as heads go, its the same concept, oversized valves always help, but not a whole lot unless your tossing in a more agressive cam. higher lift, longer duration and overlap you will see huge gains. bigger holes mean more air. if you ever get a chance, look at a top fuel dragster head. you can fit a tennis ball in a valve opening (when theres no valve of course). thats my two cents

Where you are wrong is that the valve opening isn't the restriction on these stock heads. Its the intake runners. You can make the valves the size of a tennis ball and it's only going to allow as much as the intake and exhaust ports will allow..... I'm speaking more so on the intake side of things because I know those runners are very restrictive. If you don't fix the bottle neck in the system it won't flow any more. As far as how restrictive the exhaust ports are, I'm not totally positive, next thing to look at is the restrictive 6.4 exhaust manifold.

And that really goes for any motor. If the valve hole isn't the bottle neck it doesn't matter how big it is.. It's just unfortunate that our heads suck. And even with the average port job they still don't flow near what Cummins or duramax ported heads flow

 

[outacntrl]

Interested in this as well. I just dropped a set of heads off and he mentioned if he had to do any seat work it wouldn't be much more to install bigger valves. Any vendors here sell oversized valves?

 

[Pizza pig]

Should have an answer tomorrow for you guys !


Hellen Keller sent this?

 

[Morgan@Midwest Diesel & Auto]

We can get any sized valves in any length built from several different materials.

I think people discredit the heads. I mean, I'm making big power with a single in the biggest scale of engine performance battle there is. I run against Hamilton aftermarket cummins heads and factory and aftermarket duramax heads both cnc'd and hand finished making big numbers. We did a 12v setup for a 2.6 puller making big numbers out of a very extensively machined Hamilton raised port head. I know exactly what that head flowed..... I am not worried in the least bit about it.....

A lot of people have overlooked (or underlooked) what is really going one here. These heads are not the greatest. But if your willing to go the extra step to make real flow and make real parts work together it's not that bad. Not reasonable for the average guy wanting small gains. But even a small port job can make a nice gain in flow.

Better flowing heads have less restriction to flow and will net larger hp numbers with less boost and back pressure.

But it also takes a cam matched to what your goals are to really make the combo work.

It's amazing what we did in the gas world to heads in order to make flow better. Yet no one in the diesel world thinks that cams, heads or manifolds make any difference or are worth the money.

There is a reason that duramax and cummins have advantages. It's because they are adding airflow via all these options. While 90% of powerstroke owners think that their heads are junk so they just pass it off as unnecessary in a build.

There is a duramax head out there that flows 400cfm on the intake side, per cylinder. 10 lbs of boost at that intake cfm would be over a 1000 hp. How's that sound?