Cylinder head porting claims...
01-14-2007, 03:36 PM
#41
11 Second Club
iTrader: (3)
Join Date: Feb 2005
Location: Covington, LA
Posts: 687
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Studytime
Please... I'm not even going humor you with a response.
Ben T.
Ben T.
01-14-2007, 04:30 PM
#42
TECH Enthusiast
iTrader: (1)
Join Date: Oct 2006
Location: pensacola, florida
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Adrenaline_Z
I'm not going to argue anything posted because I don't own a dyno, or a flow
bench.
Reading a couple of sources states otherwise however. I found an article on
Wikipedia which was also backed up by an R-M reference that stated:
Smooth surfaces impede air flow due to a thin boundary layer. This slow moving, or static air promotes fuel separation from the air stream.
Rough lines, or small grooves that run perpendicular to the air stream reduce
fuel separation and improve air flow within the intake port.
Quoted from Wikipedia:
"within intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished port and a rough textured port is typically less than 1%"
I would imagine track testing would show a larger margin once fuel has been
introduce along with dynamic pressure changes in the runner during a 1/4 mile pass.
bench.
Reading a couple of sources states otherwise however. I found an article on
Wikipedia which was also backed up by an R-M reference that stated:
Smooth surfaces impede air flow due to a thin boundary layer. This slow moving, or static air promotes fuel separation from the air stream.
Rough lines, or small grooves that run perpendicular to the air stream reduce
fuel separation and improve air flow within the intake port.
Quoted from Wikipedia:
"within intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished port and a rough textured port is typically less than 1%"
I would imagine track testing would show a larger margin once fuel has been
introduce along with dynamic pressure changes in the runner during a 1/4 mile pass.
01-14-2007, 11:01 PM
#43
Registered User
iTrader: (15)
Join Date: Aug 2005
Location: BTR, La
Posts: 1,363
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Greg Good
Ben, the cfm gain should have yeilded some substantial power. There is something else at play here. What is the runner volume of that head? Open carb or 390?
Maybe the manifold is truncating the additional airflow and the motor is not seeing it?
Ben T.
01-15-2007, 07:46 AM
#44
TECH Resident
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
Maybe the manifold is truncating the additional airflow and the motor is not seeing it?
connected?
01-15-2007, 12:19 PM
#45
Registered User
iTrader: (15)
Join Date: Aug 2005
Location: BTR, La
Posts: 1,363
Likes: 0
Received 0 Likes
on
0 Posts
No, but I would like to see results from exactly what you suggested. It probably won't happen because the motor is needed for an event, but I'd like to see the flow data with the intake connected.
Ben T.
Ben T.
01-15-2007, 05:02 PM
#48
Originally Posted by Studytime
No CNC marks and a perfectly smooth finish gives the best power. As for as emissions, possibly something else? A slick wall shows the best power on an engine dyno. There are also companies that coat the intake runner at the same time they're ceramic coating the chamber and valves. The smoother the better. Besides the master head for any CNC head is slick in the runners because that slick surface digitizes better.
It contradicts fluid dynamics I know, but which one do you believe? Theory or a lying engine dyno.
Ben T.
It contradicts fluid dynamics I know, but which one do you believe? Theory or a lying engine dyno.
Ben T.
Originally Posted by Studytime
I'm beginning to put less faith in head work. Just Friday I saw a motor go from the mid 280s to 320 cfm head flow on a 23* head. It was a 355 ci SBC that picked up zero on a DTS engine dyno at 7400 RPM with an additional 30 cfm at peak and with improvements all across be board from valve job technology and back cutting the valves. Flow quality went from good to beyond great (for a 23* head) and power didn't change. These were pontiac SBC heads fwiw.
I've also seen atleast two other 355 chevy motors in the last two weeks not pick up anything from an additional 20 cfm. Really baffles me. With all this said, the difference in gains from a slightly low relative surface roughness to a higher one (such as a CNC) would be even less.
This data is coming from a DTS dyno and a SF600. With all this said, if you want more power increase your camshaft size and spin your motor higher. I'm beginning to put less faith in what I thought was the most critical aspect of a performance motor- the cylinder heads.
Ben T.
I've also seen atleast two other 355 chevy motors in the last two weeks not pick up anything from an additional 20 cfm. Really baffles me. With all this said, the difference in gains from a slightly low relative surface roughness to a higher one (such as a CNC) would be even less.
This data is coming from a DTS dyno and a SF600. With all this said, if you want more power increase your camshaft size and spin your motor higher. I'm beginning to put less faith in what I thought was the most critical aspect of a performance motor- the cylinder heads.
Ben T.
It seems to me that with the amount of wins and championships that have been enjoyed by TEA customers…and the wins that have been made in every head dyno article that TEA has ever taken part in…that you might believe what I say….but now you’re the expert…please teach on.
01-15-2007, 06:19 PM
#49
TECH Resident
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Greg Good
Find someone with a flow bench that will let you use it and just jump in with both feet. That's the only way you'll learn. Forget about surface finish for now because you're hunting elephant. Debating surface finish is akin to the "What's the best wax" debate. If you get up to the Pro Stock level then it'll be a concern. Go to speedtalk andread all of Larry Meaux's posts. While I don't agree with everything he says, he does has a good handle on port sizing.
is to dress a port to resemble a Pro-Stock motor (port volume and application
considered of course) and use these tricks on the average street-strip motor.
Whether that's out of budget is another discussion totally.
Larry is a great guy. I have read several of his articles and have been lucky
enough to trade PM's with him as well. One day I'd like to start playing with
heads and port shaping just for interest sake.
01-15-2007, 06:41 PM
#50
A Pro Stock engine and a hot street engine are two entirely different games, two different head porting philosophies.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
01-15-2007, 08:34 PM
#51
TECH Enthusiast
iTrader: (1)
Join Date: Oct 2006
Location: pensacola, florida
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Greg Good
A Pro Stock engine and a hot street engine are two entirely different games, two different head porting philosophies.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
01-15-2007, 09:11 PM
#52
Registered User
iTrader: (15)
Join Date: Aug 2005
Location: BTR, La
Posts: 1,363
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Brian Tooley
So you teach us that best power on the dyno is achieved by an ultra smooth surface….then you tell us how your heads aren’t making power on the dyno?
It seems to me that with the amount of wins and championships that have been enjoyed by TEA customers…and the wins that have been made in every head dyno article that TEA has ever taken part in…that you might believe what I say….but now you’re the expert…please teach on.
It seems to me that with the amount of wins and championships that have been enjoyed by TEA customers…and the wins that have been made in every head dyno article that TEA has ever taken part in…that you might believe what I say….but now you’re the expert…please teach on.
Funny how you work at a company that sells CNC heads. Guess I could understand where your'e coming from not wanting to lose any sales.
Did you read what Greg Good was just saying? It's the same thing that I'm saying about smooth intake surfaces for race engines.
I was just adding my 2 cents like everyone else Brian. No need to be assinine.
Ben T.
01-17-2007, 11:50 AM
#53
Originally Posted by Greg Good
A Pro Stock engine and a hot street engine are two entirely different games, two different head porting philosophies.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
I'm not saying that surface finish doesn't matter. It does, but it's so low on your list right now that you can ignore it. There are several schools of thought on surface finish these days. One, the oldest, says that the surface should be rough so that seperated fuel can become atomized again. Another says that's wrong, and that a rough surface "grabs" or "collects" fuel out of the mixture, so make the surface smooth. The third is from CNC shops that draws from engineering text to claim their surface is the best. When I start seeing headers with "cnc like" grooves then maybe I'll take notice.
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock, so I tend to lean that way, especially on the EFI stuff.
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
Per the wikipedia quote earlier, that 1% on an intake port that flows 300cfm will be 3. I'll take that extra cfm...won't you!?
01-17-2007, 11:55 AM
#54
There's a couple of old timey Pro Stock racers that disagree with you.
Let me ask you this. If a relatively smooth intake port finish is good for a carbed engine, why is it bad for a fuel injected engine?
Don't think that wikepedia is the last word on head porting either. You'd be making a big mistake. The subject is much deeper than one webpage can go into.
Let me ask you this. If a relatively smooth intake port finish is good for a carbed engine, why is it bad for a fuel injected engine?
Don't think that wikepedia is the last word on head porting either. You'd be making a big mistake. The subject is much deeper than one webpage can go into.
01-17-2007, 12:19 PM
#56
TECH Resident
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Greg Good
A Pro Stock engine and a hot street engine are two entirely different games, two different head porting philosophies.
tuning. There are details an engine of this caliber contain that our street/
strip motors probably wouldn't respond to, nor register on a dyno/track.
If you have specifics on which parts of the port you are referring to when you
state, "two different head porting philosophies" I'm interested.
I would have thought what you do to the seat angles, SSR, valve job, etc. would be similar
(again keeping port volumes application specific). Having said that, I don't
know that the seat angles of ProStock port profile would work with the average
street head port shape.
Originally Posted by Greg Good
Who's right? I don't know for sure because I have seen them all go fast, so take your pick. But I'm faced with the fact that ultra smooth is competitive in Pro Stock
be for their specific engine however. As mentioned, there's more than one
way to get results.
Originally Posted by Greg Good
Good luck, and don't ever think that you're too smart for anyone to tell you anything. You'll always be a student like the rest of us, or at least most of us.
there would be no such thing as R&D correct?
If I was faced with a decision to polish, or stay rough I would opt for the
rough surface based on my research. Whether it works for my motor, or not
is another story. It's possible that my runners would work better with smooth
finishes...I don't know? It's very difficult for me to work against my findings and
try the opposite. That's my position. There's no wrong or right until the
time slip says otherwise.
Last edited by Adrenaline_Z; 01-17-2007 at 12:26 PM.
01-17-2007, 12:25 PM
#57
I would have though the seat angles, SSR, valve job, etc. would be similar
Nope. Totally different than what you run on a street head.
I have a source from Reher-Morrison which says rough is optimal. That may
be for their specific engine however. As mentioned, there's more than one
way to get results.
Kinda what I was getting at, hey? If there are different finishes running fast then how much difference can it really make?
Nope. Totally different than what you run on a street head.
I have a source from Reher-Morrison which says rough is optimal. That may
be for their specific engine however. As mentioned, there's more than one
way to get results.
Kinda what I was getting at, hey? If there are different finishes running fast then how much difference can it really make?
01-17-2007, 12:33 PM
#58
Originally Posted by Greg Good
There's a couple of old timey Pro Stock racers that disagree with you.
Let me ask you this. If a relatively smooth intake port finish is good for a carbed engine, why is it bad for a fuel injected engine?
Let me ask you this. If a relatively smooth intake port finish is good for a carbed engine, why is it bad for a fuel injected engine?
This is the area that the fuel mostly doesn't hit.
The fuel injector is pointed directly at the top of the valve. It'll still hit a decent amount of the intake runner though. You can also see a ridge toward the middle of the valve guide. This is caused by the cnc machine not being able to reach from one end to the other. Hand porting this will help in flow.
01-17-2007, 12:34 PM
#59
TECH Resident
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
You beat me to the edit. I should have known better than to type that
originally. The port designs are so different, you couldn't possibly use the
same angles.
originally. The port designs are so different, you couldn't possibly use the
same angles.
01-17-2007, 12:38 PM
#60
If you have specifics on which parts of the port you are referring to when you
state, "two different head porting philosophies" I'm interested.
The intake to exhaust rato (valve size and according flow) is skewed to favor the intake side on a high rpm high compression engine. This applies to Pro Stock, Comp Eliminator, and any class that runs this configuration.
The valve jobs are set up to flow well in the higher lift range, 1" and over. This involves steeper valve seat angles and much larger throats. Less emphasis on mid lift flow.
The port taper is reduced, meaning the intake port at the manifold flange is not squeezed down as much, like we tend to do on lower rpm engines.
Another thing about the pro type stuff is that track testing comes more into play. Head porters make changes to the heads and test at the track. Stuff that may hurt flow on a flowbench can go faster down the track.
state, "two different head porting philosophies" I'm interested.
The intake to exhaust rato (valve size and according flow) is skewed to favor the intake side on a high rpm high compression engine. This applies to Pro Stock, Comp Eliminator, and any class that runs this configuration.
The valve jobs are set up to flow well in the higher lift range, 1" and over. This involves steeper valve seat angles and much larger throats. Less emphasis on mid lift flow.
The port taper is reduced, meaning the intake port at the manifold flange is not squeezed down as much, like we tend to do on lower rpm engines.
Another thing about the pro type stuff is that track testing comes more into play. Head porters make changes to the heads and test at the track. Stuff that may hurt flow on a flowbench can go faster down the track.