Advanced Engineering Tech - 241 243 castings. CFM?

What is the most you have seen a stock valve size 241 and 243 casting flow? Stock port as well as ported.

What is the most you have seen a stock valve size 241 and 243 casting flow? Stock port as well as ported.

With your screen name Porting4Power, why do you ask? Haven't you measured them?

Do you think max flow is a good criteria for judging a head's ability to make power?

Perhaps I don't understand why you asked.


Jon

Are you looking for complete numbers or just peak numbers? I would be more concerned with the low and mid-lift flow numbers than peak numbers. Your valves don't spend too much time at max lift so the peak numbers really don't say too much for a head's potential to make power.

Are you looking for complete numbers or just peak numbers? I would be more concerned with the low and mid-lift flow numbers than peak numbers. Your valves don't spend too much time at max lift so the peak numbers really don't say too much for a head's potential to make power.

Oops! Not necessarily, Pilgrim.

Jon

Oops! Not necessarily, Pilgrim.

Jon

I'm not sure I understand the "oops". Mid lift flow numbers are EXTREMELY important. The only argument I see is what may be considered "low", "mid", and "high" flow. This would all be cam dependant. Of course this would be much better explained/understood in graph form as opposed to text arguments.

mid and low lift numbers are good, and so is peak... and so is port volume/velocity. It's a combination of everything.

I'm not sure I understand the "oops". Mid lift flow numbers are EXTREMELY important. The only argument I see is what may be considered "low", "mid", and "high" flow. This would all be cam dependant. Of course this would be much better explained/understood in graph form as opposed to text arguments.

The "oops" meant that not everyone agrees with your statement. Some who do not agree make lots of power. I thought this might generate some discussion.

I suppose you could split the valve lift into thirds for discussion of "low", "mid" and "high" lift flow.

What happens in a operating engine is quite far removed from what happens on a steady-state flowbench test.

Jon

Are you looking for complete numbers or just peak numbers? I would be more concerned with the low and mid-lift flow numbers than peak numbers. Your valves don't spend too much time at max lift so the peak numbers really don't say too much for a head's potential to make power.

I would say that they spend more time in the top 10% of lift than any other 10% area.(Other than closed:nod:):engarde:

Look at the lobe on a cam:secret2:

I guess I should rephrase. It's really not safe to say flow in any one area is more important than another, and I feel that people often ignore the low and mid lift numbers in favor of peak numbers. I see people that buy which ever head has the best peak numbers, and end up with an engine that doesn't make the power it's expected because the intake ports are lazy in the low and mid-lift ranges.

I guess I should rephrase. It's really not safe to say flow in any one area is more important than another, and I feel that people often ignore the low and mid lift numbers in favor of peak numbers. I see people that buy which ever head has the best peak numbers, and end up with an engine that doesn't make the power it's expected because the intake ports are lazy in the low and mid-lift ranges.


No offense, but you might want to rethink how an engine moves air during the entire valve event. Things change a lot during the valves' lifts.

I agree that folks buy the peak numbers, especially if they are not too knowledgeable. I disagree with your analysis of what constitutes good port flow and why some heads don't perform, especially in higher power engines.

It is fairly easy to detrmine if a head makes torque and power by running the engine, but it is much more difficult to explain why the port "worked"...or did not work. If we pick the wrong explanation, and try to correct the port to jibe with our analysis, we may not get the improvements we expect. Tom Ankeny was correct.

Jon

No offense taken. We're all here to learn.

Can you give us a better explanation of how you determine whether or not a port will work well for a given engine combination? I'm always looking to learn.

No offense taken. We're all here to learn.

Can you give us a better explanation of how you determine whether or not a port will work well for a given engine combination? I'm always looking to learn.

There is no simple answer to your question. I suggest you study the basic fundamentals of how engines move air. Unfortunately these basics are fairly complex in practice, as are many things in nature. The sticky Books 101 has some good reference material.

It seems to me that many people in the "engine building" business either don't understand how engines "move wind", or simply ignore it and try to get engines to do what they, the builder wants them to do, rather than what the engine itself wants to do.

There is a reason we call her Mother Nature and not Father Nature. :)


Jon

So back to the original posters question which I am also wondering about which heads flow better stock and ported? I have a set of 243's on my ls1 right now and I also have a set of 241's sitting on the shelf I was given. Anyone have any real world experience?

ported 241's will flow better than ported 243's when ported correctly, up to .400, after that its the 243's for the win.

I guess I should rephrase. It's really not safe to say flow in any one area is more important than another, and I feel that people often ignore the low and mid lift numbers in favor of peak numbers. I see people that buy which ever head has the best peak numbers, and end up with an engine that doesn't make the power it's expected because the intake ports are lazy in the low and mid-lift ranges.


Bingo.

I would say that they spend more time in the top 10% of lift than any other 10% area.(Other than closed:nod:):engarde:

Look at the lobe on a cam:secret2:

Nice avatar!

Jon

Nice avatar!

Jon

This asshole I know built it:angel::secret2:

Airflow of a cylinder head is still relavent to the hp potential. Now, in saying that, there are a lot of people that think that airflow is everything. If you are talking about an all out drag engine that lives life in a very small operating RPM range, then yes, peak numbers are where it is going to make the most sense.

I believe for the rest of the world, it is all about having the correct flow for your camshaft. Don't make the port so big that you loose the velocity, but don't make it to small and sacrifice flow.

You have to look at airflow from a changing displacement aspect. If you graph piston velocity vs. angle, you will see that the peak velocity occurs roughly 70-80 deg. before and after TDC. So, this means that the greatest change in displacement is happening around there.

So, in order to take advantage of that it is best to have your peak flow numbers just before peak velocity, gives the air time to catch up.

But, again, this is dependant on RPM. Sorry, I think I am rambling on here, but chime in with input.

Airflow of a cylinder head is still relavent to the hp potential. Now, in saying that, there are a lot of people that think that airflow is everything. If you are talking about an all out drag engine that lives life in a very small operating RPM range, then yes, peak numbers are where it is going to make the most sense.

I believe for the rest of the world, it is all about having the correct flow for your camshaft. Don't make the port so big that you loose the velocity, but don't make it to small and sacrifice flow.

You have to look at airflow from a changing displacement aspect. If you graph piston velocity vs. angle, you will see that the peak velocity occurs roughly 70-80 deg. before and after TDC. So, this means that the greatest change in displacement is happening around there.

So, in order to take advantage of that it is best to have your peak flow numbers just before peak velocity, gives the air time to catch up.

But, again, this is dependant on RPM. Sorry, I think I am rambling on here, but chime in with input.

I would never change a head to fit a camshaft for an engine. I would do it the other way around.

As for the average flow versus peak flow, on LS6 headed small displacement engines with .590 lift the engines really only respond to increses in flow over .400 lift, and especially .500-.600 for the largest increase in power. Having lots of low lift hurts power substantially on the bottom end and has a small benefit of helping to carry power a little better after peak. Average power suffers when you use "Internet Logic" to port heads.

Most of the time, on an LS6 head, if you do something to increase the .500-.600 flow it will hurt the low numbers if you are doing it with the valve job.

Making peak flow just before peak velocity sounds like it makes sense. I used to actually think that too. It is easy to believe because it's logical in a basic sense. In reality, it absolutely won't work and can't be made to happen anyways.

What is the most you have seen a stock valve size 241 and 243 casting flow? Stock port as well as ported.

Stock valve size 243 321cfm on a 3.900 bore 221cc port. Stock 243 port 282cfm(valve job only)

This is getting interesting now.

I don't port heads, but I listen to some very successful guys who do. The ones who I know who do extremely successful LS endurance engines pretty much agree with what Cascazilla posted, which seems to disagree with what Schwanke posted.

My own opinion is that you design a cam to work with the rest of the engine, especially the ports, intake manifold, exhaust headers, etc...that stuff that moves the wind, rather than try to make the heads "fit" the cam. This applies to daily drivers, drag only, endurance. sprint or 'bout any engine. Heck, even if you race in a "lift rule" or "duration rule" cam class, this still applies. It just makes the cam guy's job a little more difficult.

FWIW, I am impressed by the numbers quoted above. I don't think everyone with a die grinder can get there. I certainly couldn't.

Jon

Having lots of low lift hurts power substantially on the bottom end and has a small benefit of helping to carry power a little better after peak.

is this because having more low lift flow will increase reversion at lower rpms?
i used to think it was all about low-mid lift flow nos...but i have seen in the last couple years that is not really what you want,at least for most applications..i don't understand exactly why,but the guys making the big HP go for flow in the higher lift range..

is this because having more low lift flow will increase reversion at lower rpms?
i used to think it was all about low-mid lift flow nos...but i have seen in the last couple years that is not really what you want,at least for most applications..i don't understand exactly why,but the guys making the big HP go for flow in the higher lift range..

The engine knows what it wants and that is what is important. Those folks who are making the power try to explain what works, but if their theories are wrong, they change theories and keep giving the engine what "she" wants. Unlike many other "shes", the engine tells you if what you gave it is what it wanted.

Jon

The engine knows what it wants and that is what is important. Those folks who are making the power try to explain what works, but if their theories are wrong, they change theories and keep giving the engine what "she" wants. Unlike many other "shes", the engine tells you if what you gave it is what it wanted.

Jonok,but that doesn't answer my question,lol..

ok,but that doesn't answer my question,lol..

My guess is that those who have figured out what works and why it works aren't going to be too forthcoming with the details. IOW, you may not get a valid answer to your question here.

If I knew any of the details I wouldn't compromise my sources. I encourage folks to keep thinking about what happens in an engine and not parrot what they have read from internet "experts". Everything in the operating engine is interconnected which often makes it difficult to understand the "why".

ported 241's will flow better than ported 243's when ported correctly, up to .400, after that its the 243's for the win.

i have to disagree with you there..i have flowed a few seats of heads and both of the sets of ported ls6 heads i flowed out flowed the ported 241's and 5.3 heads at every valve lift. They significantly outflowed them in the mid lift ranges but the peak flow was within a few cfm. Mind you all these heads had runners that were within 2-3 cc's of each other as well. Also a machinist i know said that every set of ls6 heads he has ported has always outflowed the 241's he has done at every valve lift. The first three sets i flowed are on the first page and the second set of ls6 heads i flowed are on the second page of this thread i made

http://www.ls1tech.com/forums/showthread.php?t=832264

My guess is that those who have figured out what works and why it works aren't going to be too forthcoming with the details. IOW, you may not get a valid answer to your question here.

If I knew any of the details I wouldn't compromise my sources. I encourage folks to keep thinking about what happens in an engine and not parrot what they have read from internet "experts". Everything in the operating engine is interconnected which often makes it difficult to understand the "why".i respect that..if i was making a living from building motors,i wouldn't want people knowing my secrets,or knowledge i gained over the years...it's a hard business to make a buck in.
i used to parrot what some "experts" have said,and i've learned a lot from modding my cars,and had to change some of my "theories" about how an engine works over the past few yrs..i've also learned i how much i don't know as well,lol..

is anyone that actualy has the numbers going to answer the question?

is anyone that actualy has the numbers going to answer the question?


Post #20 had some numbers similar to what I have seen on the very best porting of 243 heads.

Which post has the numbers on the 241 heads?

Hey OLD SStroker.... probably a good thing your kids not allowed on here anymore huh? Probably would give old Schwanke a lesson on Blair's teachings. I have a funny feeling that you could probably too but choose not to for some reason ;-)

As for numbers.... what do they mean anyways? Flow benches seem to lie worse than hookers do about the size of a guys member.

Hey OLD SStroker.... probably a good thing your kids not allowed on here anymore huh? Probably would give old Schwanke a lesson on Blair's teachings. I have a funny feeling that you could probably too but choose not to for some reason ;-)

As for numbers.... what do they mean anyways? Flow benches seem to lie worse than hookers do about the size of a guys member.

About the only thing worth viewing in your posts are the set of tits for your avatar. Nothing but recycled motor head babble.

http://www.ls1tech.com/forums/showthread.php?p=8715823&highlight=#post8715823

Wow and infinte wisdom coming out of your pie hole here.... sounds like you can regurgitate what every other moron on the boards "thinks" is good. I highly doubt YOU have ever touched a ET or All Pro head let alone ran one on the dyno against something else or even come close to making 1000hp in a LS2 block.

Oh yeah you READ about it on a internet forum. I forgot :gtfo:

Thank god I'm actually screwing someone who knows something. Knowledge thru injecton!

Jess

I'm guessing "someone" has "lied" to you before, poor boys. Someone = Hooker

Well actually, not that I need quantify anything to you, I have been around failed LSX blocks from 1500+hp as of late, several all pro heads, and different options of LS2 setups with 95mm/F1R setups around 1K hp. When someone asks a simple and straight forward question, you give a simple answer. Point of the matter, I have an o-ringed all pro/LS2 block being put together right now. So keep screwing and get back when you have something neat to put out there.

I would never change a head to fit a camshaft for an engine. I would do it the other way around.

As for the average flow versus peak flow, on LS6 headed small displacement engines with .590 lift the engines really only respond to increses in flow over .400 lift, and especially .500-.600 for the largest increase in power. Having lots of low lift hurts power substantially on the bottom end and has a small benefit of helping to carry power a little better after peak. Average power suffers when you use "Internet Logic" to port heads.

Most of the time, on an LS6 head, if you do something to increase the .500-.600 flow it will hurt the low numbers if you are doing it with the valve job.

Making peak flow just before peak velocity sounds like it makes sense. I used to actually think that too. It is easy to believe because it's logical in a basic sense. In reality, it absolutely won't work and can't be made to happen anyways.

Just for informational purposes, are your comments directed at intake, exhaust, or both?

Just for informational purposes, are your comments directed at intake, exhaust, or both?

The same thing applies to both, exept the exhaust is much more area sensitive. I changed the valve job on an SB2 head on the exhaust and it picked up 12 cfm, along with 48 hp@8200. It was the area that mattered. We flow exhaust ports at 1 psi. Exhaust ports have much higher pressure differentials than that. There is no way to accurately quantify results of an exhaust port exept on the dyno. Intake ports are much easier to predict what the change will do.