I don't have the equipment to measure the port velocity and neither does Super Flow. I don't know if anybody does.Super flow told me to put a velocity probe in the intake but had not done it before on a dyno.
The EAP and my old Pro Stock program figure it out and display it for every RPM that ya got it set up for.
Ya should get a program. It ain't gospel but it is close to real life.

 

Great info here, love the thread. Make it a sticky ;]

 

LR,

EAP talks in average MACH based on a average equivalent diameter. Problem is most head ports especially STD 23° stuff has tons of variation in the cross section going down the port. While computations are based on a centerline length to port volume the real world ain't.... well for most of us, some lucky cylinder heads are pretty close.

A bench that moves 400cfm @ 100" of H2O and a velocity probe can tell you some amazing things, one day I will have a bench that can do that. If you want to learn more about this search out what Larry Meaux and Darrin Morgan have said about this on the net.

Bret

 

Thats fine and dandy,but that's on a bench not on a running engine on a dyno. The way EAP figures it is actually more than what is in the head that is entered. So if it says .42 MACH, on the engine it is less.
Have seen the probes used on the bench and understand what they do. They are mostly used to find the dead spots where air isn't moving correctly so it can try to be cured.All in the hopes of making a more efficient port.
Is there any way to say that 100" is correct without first having measured a running engine at a given RPM? How do they measure or is the figure a theory as to what the pressure really is. That figure will change with CID and RPM's and port cross section and design so what is the MAGIC number.
As I stated in an earlier post the only way to make .6MACH work IMO is to have a port high enough and with no valve installed ya can see the piston when it's down, from the intake side. That would be to try to prevent any more turbulence from the fast air hitting the cyl wall and having to turn.Ya got enough with it flowing .6 MACH.
I will go hunt up the info and see if it makes sence to me.Sounds to me like a bunch of trial and error and a lot of money spent for dyno time to get it right with "ONE" combo. Then when a different combo bore/stroke/head comes along ya start all over again.
The theory makes sence but how to get it done correctly in an engine doesn't. It's not just put a small port 185 CC with a 2.200 valve on a 406 or a 732 and turn it 9000 and say you are flowing .6 MACH,it don't work that way.

 

What is the maximum amount an LT1 head deck can be milled? What size are the combustion chambers at max mill specs? If the head was milled down as much as it could be and the combustion chambers were at their smallest, approximately how much valve lift area would be left to work with if the pistons were NOT fly cut? I'm trying to determine if a stock LT1 head can be modified sufficiently to accomodate the setup I'm working on.

 

They can go to 50CC's stock is 54CC. After that the deck gets to thin.
If your piston is way in the hole ya can do it but that doesn't do quinch any good.Ya pretty much have to run a 4CC set of valve reliefs -2 eyebrow. If the compression isn't there ya need a set of dome pistons the height ya need to get the compression ya want. More info on the set up would tell me a lot more.

 

Like someone said above, I just want to thank all the "big guys" that have posted in this thread, and basically anyone else out there that posts on here, and isn't just an internet racer...

2nd... this is also prob the strangest threads ive ever read here(but in a good way) people that can actually talk to each other, and not end up freaking out (GJ)

3rd... not even going to try to hide it, i dont know much heh, i read more than i post here. but there is ALOT of info ive learned from reading this thread, and i still know its not even scrapping the surface on what i could know...

thanks,
cory

 

Thanks for the response 1racerdude. I think I'm gonna be better off going with an aftermarket casting. For fear of being bombarded with a bunch've "why the hell would you wanna do THAT?" type of questions, I'd rather not post my setup.

 

When Taylor wrote his book way back in the late 30's he did what I'm sure amounts to a ton of research. He put formulas to his findings to prove out the theories. Interestingly enough, everyone's work since then seems to reference Taylor's findings. Even the stuff I've read where people had went back and performed the same tests came to the same conclusions.

Taylor was shooting pretty straight way back then when he said that maximum port velocity was controllable in the .5-.6 Mach range. In other words, with a properly shaped port and turn radius (short side) the air/fuel mixture would follow the port.

He also stated that .6 mach equated to roughly 127% volumetric efficiency. Funny thing about that is.... Pro Stock, the most developed of NA motorsports racing engines, are right in that range!

VE and Mach are directly related. Not my words either.

At 28" H2O... you're flowing less than half of what a live engine will see. That's why so many people are interested in flowing heads at 100+ H2O now. Some very refined shops are already doing just that for the reasons mentioned.

-Mindgame

 

Interesting reading. I'm not used to seeing this kind of drama at Cz28.com.

I don't know anyone at AI and have never purchased anything from them, so I can't speak to them.

I can, however speak to Lloyd. I have a set of heads he did for me in Spring 2003, before he had a website and before he had the "LE" packages. He did great work, at a very very reasonable price, with good parts, and excellent turn around time. He was polite and informative on the phone and always easy to reach by phone or email.

I've been pleased with the heads and their performance. Could I get more somewhere else? Maybe, maybe not, but I have nothing to complain about with regard to Lloyd's work.

Good info in this thread BTW. I've always loved how people (not porters per se, but customers) quote .600" lift flow numbers when talking about their heads even though most of us aren't running that much lift.

 

The thing with Pro Stock is they are dealing with ONE engine combo and have BIG dollars to spend on heads. Most MAKE their own. Us small timers can't do that and most heads are not capable of flowing those MACH numbers.
I did call Richard and he said he doesn't have a bench to do the 100" of water so he concentrates on just getting the head to flow right at 28".
He was also unaware of any of his heads that had been measured for MACH.
Some of the heads that I run may already be flowing those MACH numbers and everybody is un aware that they are doing it
It is like I posted earlier the obstructions in a port determine the flow and speed and without a purpose built head those numbers will be hard to come by. It's good conversion but in reality I will stick with what has worked for me in the past and is proven. .4-.45 MACH as shown on my programs has made plenty of winning HP in the past and I haven't found the need to go into a big R&D mode to get more. If these guys could just put it to the ground they would be faster yet.

 

Why did we get off into Pro Stock?

I only mentioned it because it seems a very strange coincidence that Taylor would draw parallels between maximum "controllable" mach speeds of .6 and a VE of 127%, then we see actual VE for Pro Stock engines as of a few years ago and guess what... they're right in that range! I find that amazing myself but I guess I'm the only one getting it.

You seem to like EAP and myself being a programmer I'm always interested in programs no matter what they do. Got to doing a little research to see if I could find out HOW EAP is calculating Mach and guess what... they are using a formula developed by Itaru ***utani and Eiichi Watanabe from a paper titled An Analysis of the Volumetric Efficiency Characteristics of 4-Stroke Cycle Engines Using the Mean Inlet Mach Number Mim.

There is a key word in that title. Anyone have a clue what it is?

I'll give ya a hint.

http://math.about.com/library/weekly/aa020502a.htm

It would be nice if people really knew what they were looking at and basing their arguements from sometimes. A little bit of research goes a long ways but you have to want to dig a little deeper....

BTW: I have the Fùkatani/Watanabe paper. If anyone's interested in reading it.... send me a PM

-Mindgame

 

If ya had these programs ya wouldn't have to do the reading on theory to get the answer.

 

Na, I like knowing how things work. That includes programs.

So what say ya Larry... you know what "mean" means?

Oh.... tell us again how EAP is figurin' it.

-Mindgame

 

You did all the research you tell me!!!!! I don't much care about how they work the formulas, just that I GOT the answer.