i was just giving an example of "altered" flow numbers.

and actually it was an LS1 head.

Now that we know your test mothod we can start to compare.

only problem being that the only way to do a fair comparison would be to flow them on the same bench.

 

I am not looking for exact Compare numbers I am just wanting to confirm that the exhaust out flows the intake this is not common..I am just wondering if I was the only one who got these results. It just had me curious especially when I browse the boards and read how most say the stock heads are Good enough from the factory .. I.M.O I like a like ratio of 75-85 % Depeding on the type of engine .. this heads shows that it is over 100 % percent I/E .. I know there has to be someone who as flowed a stock head that can confirm this it should be a fairly easy question..

 

ok, When i got head flowed on a superflow 1200 flow bwnch the intake and the exhasut flowed within 10cfm of each other i don't rememeber wich was higher though.

 

Delete please

 

Please clarify why you want this deleted. This is usefull information for all of us to look at. Nothing like hard data.

 

VTECH8TR, relax. I wanted my own post deleted because I couldn't do it myself and didn't want to take up space.

 

Ok here is the lowdown I did some clean up on the exhaust ports I wanted to pick up the velocity with I did in some place's over 100 fps Iwas extremely happy with the veocity.. Flow picked up on the top end losing some down low I did a full cleanup on the exhaust using stock valves in both test. I also did the intake it was choked up quite a bit velocits also picked up some but the port was screaming I still need to make a few more changes I was not to happy with the intake flow It needs to be a touch bigger to try and make the I/E ratio more to my liking.. The velocity is still high and even more then stock so I'd say enlarging this would do it some good...

 

Also as you can see we lifted it to .500 before it seemed to fall off @ .350 this engine will be uing .470+ lift cams.. If we were to make custom cams to help keep the exhaust valve closed longer I thing in this state the head would rip..

 

.470 is not high lift? Why run that much lift if you say it does nothing?
For everyone else .470 is 12mm of lift which is currently higher then any cam on the market.

 

This is an interesting thread. Although I think the stock flow-numbers are a little off from what others have indicated ... but I'm not really sure.

It's particularly interesting that the stock flow peaks near 1/4 the valve diameter. In my somewhat-limited experience, this seems to be the case with most factory stock heads. But the most interesting thing, for me anyway, is that most port-jobs so dramatically change the lift for peak flow. Although I have some ideas for what might be the cause of the change, I've never found an explanation which seemed logical to me; it doesn't seem like the port-geometry needs to be dramatically changed for the peak flow lift to be dramatically changed.

Something else that I find interesting is the reduction in flow through the low-lift regions in the exhaust graph. (which was accidentally marked "intake flow") With appropriately detailed cam-specs, I could probably get a rough idea of whether this would negatively affect overall flow by regressing the data and using a tripple integral. (though that's a long way from actual testing )

$5 says the new exhaust port-job will be much more sensitive to ramp-rates on the exhaust cams.

edit: Hey, Shaun, didn't you have some flow-data from the Evo head, or was it just the older 4g63 heads?

-Adrian

 

Oops bottom graph is the exhaust .. .470 would be tiny for a bbc 2v engine and that is what I was comparing it too. I agree .470 is quite a decent size cam for a 4v 4.6 we use .482 in our 4.6 4v engines some have seen well over 1200 hp on .385 lift

 

Also as you can clearly see on a stock heads it falls off at .350 on the ported it stays up until .500.. As I said I am not a evo guy reason why I came here for input thanks again..

Dave

 

It's almost 3 am, I'm at home and can't sleep as usual.

Anyway, I haven't looked at our flow numbers for awhile and every flow bench measures different. The flow bench we use reads very low compared to a Super Flow bench. The numbers you put up there look like what I can remember off the top of my head.

The only thing that concerns me is the fall off after .350, I have NEVER seen that on any head we have flowed (4g63) that is very odd, very odd.

I notice stock the heads don't pick up very much by opening the valve further and further but I have never seen one drop.

We built a fixture just for the 4g63 heads on the flow bench. The tube we use is standard bore size for a 4g63. We do not flow the heads with a pipe but do check them when we are done with a pipe out of curiousity. We also are very prone to bolting whatever actually is going to go on the head onto it. In other words, rather than sticking some worthless piece of pipe up to the intake or exhaust runner we will flow them with the exhaust manifold or intake manifold on them that go on them. I never really saw the point of sticking a piece of pipe up to the port. It has no relavency on what the head is going to see once it is in the car.

Bottom line is the head is damn good out of the box. On a 400 whp car if you port the cylinder head with absolutely no other changes you will be lucky to see a 15 whp gain from it. That stock head is really good. One reason I don't force heads and shortblocks on EVO customers is the stock parts work and work well. I am not implying you are trying to sell anything, just making a statement

Nice information and nice gains from the port work.

David Buschur
www.buschurracing.com

 

Thanks Dave as this was only a quick project for me I did not make a enrty plate as I ussually do on other heads. We are just using clay for a entry. As for the exhaust port we are just using a the port so we can get some velocity test I did some pretty cool graphs with the velocity mapping hoping to send it to Audie tech and maybe have this be included in the new software it actually is alot easier to look at then just the plain old lines of numbers.. You guys do any mapping at all I'd love to show you what have come up with if you are interested. Our tube is slightly bigger then stock maybe why we are getting a tad bit higher numbers..

Thanks for your input... B.T.W I have the same problem with staying up late maybe its th profession and the fact that I am 22 and trying to soak it all up at a young age. It also help that I am In Cali. so its 12 here..


David

 

+1 ... but I don't get to play with a Flow Bench during the daytime.