had my 561 heads redone and i have the flow numbers but not too sure how to read them...

.100 70.6 71.9
.200 113.0 132.7
.300 144.1 201.1
.400 187.7 248.3
.500 196.5 279.9
.600 206.0 280.3
.700 210.7 280.6

so can anyone tell me if these are good and how they compare to le2 heads which is what i wanted them to be like... thanks

 

Flow numbers wont really tell you that much. Run it and post the results, that will tell you something.

 

Don't flow numbers basicaly say how good air flows threw the heads? So how do flow numbers mean nothing?

 

Yes those are very respectable flow numbers. What is the intake cc?

 

If these are truly showing stock flow (I don't have any reason to doubt it)
Chevy High Performance
Malcams.com

Then yesireee those look as though they are gonna do well!!!

 

not too sure how to tell intake cc? is there a way?... wow this is a relief to me thought i had spent a decent amount of money for poor performing heads

 

Any competent engine builder can do it easily. It requires a glass buret, a Plexiglas plate and some grease.

The water bench and flow numbers dont tell the whole story. The quality of the work and attention to detail will greatly affect performance. The flow numbers are good to compare to where you came from and ensure uniformity from port to port. Many will say the flow bench is nearly meaningless.

There are plenty of experts here that can go into greater detail than this.

 

It's easy to measure intake volume...as mentioned above. For a ball park number, simply get a graduated cylinder, tilt the head so the intake port is up and level and fill the port with mineral oil or transmission fluid, noting the start and finish marks on the cylinder.

As mentioned, flow numbers don't mean much by themselves as they only speak to potential. If you have a cam that will allow those heads to flow thos numbers you'll make great power, a cam that doesn't take advantage of good breathing won't make more power using those heads that it would using heads that flow at it's max capability...

To make max power, talk to some cam guys...they can design a custom grind once armed with those flow numbers. I'll admit I'm not the guy to talk to about this as there are many much more knowledgeable people out there....

 

Here's a comparison.
https://www.camaroz28.com/forums/lt1-based-engine-tech-9/561-casting-flow-s-62301/

 

A bigger hole in a head will flow better but might not make a car faster. Quality of flow is not measured in a static flow test like that and an engine does not hold the valve steady open like that.

Run it then you will know how they are.

 

Complete nonsense!! The average Hot Rodder can't afford to buy hundereds of heads, have them ported, bench tested, and then dyno tested, just to get the perfect set. We have no choice but to rely on the flow numbers provided by the manufacture or porter. And over the years this has proven to be a perfectly valid method for comparison.
You are absolutely WRONG! Bench testing is a perfectly good way to compare heads.

 

I disagree. Flow numbers are not everything. They are CONSIDERED, but they are not the be-all end-all of cylinder head performance.

Flow numbers for the past 10 years for equivalent ported LT1 heads have stayed roughly the same, but the average ET of cars equipped with those heads has drastically improved, still using similarly equipped camshafts.

 

What are you disagreeing with? I never said they were the "be-all end-all" of anything. What I said is the average Hot Rodder doesn't have any other choice. Tell us, what's better???

 

Sure they have a choice.

The average Hot Rodder can't afford to buy hundereds of heads, have them ported, bench tested, and then dyno tested, just to get the perfect set. We have no choice but to rely on the flow numbers provided by the manufacture or porter.

What about the RESULTS of cars equipped with those heads? Those numbers are far more important than flow numbers. When I bought my AI heads, I didn't even look at a flow sheet, because I didn't care. What I did look at was all the records and success those heads have had. The flow numbers don't quantify overall performance by themselves.

 

If you think about the dynamics of the intake and exhaust activity on an engine, you can see where the numbers can be a guide but not much more. In every cycle, for small fractions of a second, the valves go through the entire range outlined by the tests 6 data points but under varying vacuum conditions throught the cycle and certainly not in a steady state at any single point, except closed. It would probably make more sense to try to correlate the area under the curve to horsepower than trying to get correlation with the flow at different valve openings.

The numbers are good for comparison purposes but really only speak to maximum capability. I guess the numbers are also good for bragging rights during bench racing sessions but that's rarely the point.

There is so much going on at the same time that the only way to really compare heads is by comparing the results people have generated. Complete data that way...not just port flow but cam lift and timing, port size, etc, etc, will make for a much more informed hot-rodder without buying dozens of heads to try out....