Re: Interesring article on fluid dynamics and airflow
Subject: Re: Interesring article on fluid dynamics and airflow by jsup on 2008/11/22 15:52:41
Quote:
cuisinartvette wrote: THe biggest cfm, biggest port possible as mentioned above usually nets a disappointment, wev'e seen that for yrs; proven over and over with the newer head tech that has been out, old hat. True. You see overported heads all the time, people fall for it over and over. Question is what size/shape is the port for the given application and was it a good choice.
I had to chuckle when I read this. You can get all the fuel in the world through a head but if you cant get the air through to burn it what good is it. While there certainly is somethign to fuel flow you need air, too or its no good. http://www.dartheads.com/dartboard/showthread.php?t=323
Btw your flow numbers are on there and verified if youre curious.
I know, you've been around thought some of the people who haven't may find it interesting. I agree to your point it's more about design than flow numbers. I've been saying that forever, thanks for joining the bandwagon.
You chuckle when you read what? That thread?
Interesting thread. I never knew flow benches could be off by as much as 15CFM and are effected by environmental conditions such as altitude and barometric pressure. Kinda makes it more worthless. Question, with all these factors and inaccuracies seems the only role of a flow bench is to take a set of heads and see how much was changed. Same heads, same bench. Doesn't seem accurate enough to prove anything else from bench to bench...
The last thing I note is that from old heads to new heads the flow numbers stayed the same, but the performance improved. Really is a science isn't it?
Thanks, I had my heads ported before leaving the factory, quick CNC clean up, not a full port. My numbers may be different or not IDK, nor do I care. I can't change it. This is consistent with the response I got when I called and spoke to them:Quote:
To be honest we almost never use flow numbers these days. Our newer heads are all developed on a wet-flow bench, which has completely different flow figures and reference points than a typical flow bench.
Yes, we do still make airflow numbers available, I'm not sure if we used conservative ones, we do like any figures we release to be accurate and not over-inflated, but it's also entirely possible that those flow numbers are spot on. In wet flow testing we have found that heads with approximately the same (Or sometimes, even lower) airflow numbers can have significantly better performance based on fuel behavior in the fuel/air mixture. Because of that we have started focusing less on airflow and more on the more realistic testing conditions that wet-flow provides.
But in any event, if you do want some idea exactly how conservative our stated airflow numbers are let me know and I'll talk to one of the techs about it.
