Valve Seat Angles and Flow Area

General engine tech -- Drag Racing to Circle Track

Moderator: Team

user-9274568

Re: Valve Seat Angles and Flow Area

Post by user-9274568 » Fri Mar 09, 2018 8:08 pm

Walter R. Malik wrote:
Fri Mar 09, 2018 5:48 pm
* wrote:
Fri Mar 09, 2018 3:00 pm
groberts101 wrote:
Fri Mar 09, 2018 1:21 pm


Could you elaborate?
Increase port pressure.
Increase port harmonics.
close the valve faster..
OR Decrease the steady state flow.
If it is the same thing, I guess that would mean that increasing low lift flow also means the valve spring requirement is not as much. I don't think so.
It is much, MUCH easier to hurt only the low lift flow than to increase the flank rates of a cam lobe profile and keep RPM in check.
When you get to the point where you can not increase the cam lobe aggressiveness any further, yet you still wish to keep your required torque while increasing horsepower ... what would you do ...?
Put a better head on it?

Walter R. Malik
Guru
Guru
Posts: 3957
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: Valve Seat Angles and Flow Area

Post by Walter R. Malik » Fri Mar 09, 2018 11:32 pm

* wrote:
Fri Mar 09, 2018 8:08 pm
Walter R. Malik wrote:
Fri Mar 09, 2018 5:48 pm
* wrote:
Fri Mar 09, 2018 3:00 pm


Increase port pressure.
Increase port harmonics.
close the valve faster..
OR Decrease the steady state flow.
If it is the same thing, I guess that would mean that increasing low lift flow also means the valve spring requirement is not as much. I don't think so.
It is much, MUCH easier to hurt only the low lift flow than to increase the flank rates of a cam lobe profile and keep RPM in check.
When you get to the point where you can not increase the cam lobe aggressiveness any further, yet you still wish to keep your required torque while increasing horsepower ... what would you do ...?
Put a better head on it?
A better head would show less low lift air flow with an increase above .250" and not have any larger cross section so, I could make good use of more camshaft.
http://www.rmcompetition.com
Specialty engine building at its finest.

randy331
Guru
Guru
Posts: 2939
Joined: Mon Dec 04, 2006 7:30 pm
Location: N.W. MO.

Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 10:19 am

groberts101 wrote:
Fri Mar 09, 2018 2:48 pm

For a mostly street oriented motor would your cam guy rather grind spec's around a cylinder head that flows like gangbusters in the <.200" lift ranges or another that flows like horsepoo in that same range because eliminating reverse flow was the entire basis for port/seat design? What differences would each grind have on the powerbands average power production?
I want my cam guy to just grind what I tell him to.

And if your cam guy asks for flowz,...get a new cam guy.

Randy

user-9274568

Re: Valve Seat Angles and Flow Area

Post by user-9274568 » Sat Mar 10, 2018 11:36 am

Walter R. Malik wrote:
Fri Mar 09, 2018 11:32 pm
* wrote:
Fri Mar 09, 2018 8:08 pm
Walter R. Malik wrote:
Fri Mar 09, 2018 5:48 pm


If it is the same thing, I guess that would mean that increasing low lift flow also means the valve spring requirement is not as much. I don't think so.
It is much, MUCH easier to hurt only the low lift flow than to increase the flank rates of a cam lobe profile and keep RPM in check.
When you get to the point where you can not increase the cam lobe aggressiveness any further, yet you still wish to keep your required torque while increasing horsepower ... what would you do ...?
Put a better head on it?
A better head would show less low lift air flow with an increase above .250" and not have any larger cross section so, I could make good use of more camshaft.
Ok, a better valve job? Or blend it differently. You can kill 10+ down low by how hard you get into the 60 or 65.

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 11:54 am

randy331 wrote:
Sat Mar 10, 2018 10:19 am
groberts101 wrote:
Fri Mar 09, 2018 2:48 pm

For a mostly street oriented motor would your cam guy rather grind spec's around a cylinder head that flows like gangbusters in the <.200" lift ranges or another that flows like horsepoo in that same range because eliminating reverse flow was the entire basis for port/seat design? What differences would each grind have on the powerbands average power production?
I want my cam guy to just grind what I tell him to.

And if your cam guy asks for flowz,...get a new cam guy.

Randy

Sounds a bit inflammatory but it's very true and I mean absolutely no disrespect when I say.. you need to keep in mind that not everyone is as smart and experienced as you are when it comes to spec'ing the "right cam" for any given application. More informed details make for a better designed part in the little bubble I live in. Also consider that not everyone has the cash to buy extra cams and swap towards the ideal grind for that specific application so the closer to the mark the first time around the better, IMO.

Was just making a general statement. And seriously, how the hell does my cam guy know if I have a well prep'd and heavily ported head that flows 25 more cfm than another out of box design which he's already made dozens of cams for in the past? Will he give me his "usual design" for that out of box bolt on parts application without factoring in my ported heads extra port efficiency? Maybe I just tell him they are "ported" and he knows what to do?

Seems almost the same a telling the cam guy, "my springs have 155lbs seat/412lbs open pressure" and leaving out the fact that they are conical springs with ultralight 5gm Ti retainers. If he doesn't care to ask(or maybe I'm ignorant enough to not even mention it).. or take that into consideration?.. then I'll go find another cam guy who will do the grind to take full advantage of that considerably lighter spring mass. Might not be the correct anaolgy but hoipefully you get my drift here. Knowledge is power and not every cam guy has the same knowledge base to work from when it comes to certain combo's with higher marks in some area's of the build.

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 12:04 pm

* wrote:
Sat Mar 10, 2018 11:36 am
Walter R. Malik wrote:
Fri Mar 09, 2018 11:32 pm
* wrote:
Fri Mar 09, 2018 8:08 pm


Put a better head on it?
A better head would show less low lift air flow with an increase above .250" and not have any larger cross section so, I could make good use of more camshaft.
Ok, a better valve job? Or blend it differently. You can kill 10+ down low by how hard you get into the 60 or 65.
I get what you're saying here Walter but avoiding/foregoing a backcut on the valves can also do near similar to reduce reverse flow as well. Yet we still trend towards a backcut to aid mid and high lift flow even though that just inevitably encourages reverse flow.

IMHO, in the end not one thing being mentioned here completely transforms a cylinder head on its own merits. We can only "tune it" towards that direction by adding a "few tricks" together in cumulative fashion. Bore size and OEM port locations limit us a great deal too.

Walter R. Malik
Guru
Guru
Posts: 3957
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: Valve Seat Angles and Flow Area

Post by Walter R. Malik » Sat Mar 10, 2018 12:24 pm

groberts101 wrote:
Sat Mar 10, 2018 12:04 pm
* wrote:
Sat Mar 10, 2018 11:36 am
Walter R. Malik wrote:
Fri Mar 09, 2018 11:32 pm


A better head would show less low lift air flow with an increase above .250" and not have any larger cross section so, I could make good use of more camshaft.
Ok, a better valve job? Or blend it differently. You can kill 10+ down low by how hard you get into the 60 or 65.
I get what you're saying here Walter but avoiding/foregoing a backcut on the valves can also do near similar to reduce reverse flow as well. Yet we still trend towards a backcut to aid mid and high lift flow even though that just inevitably encourages reverse flow.

IMHO, in the end not one thing being mentioned here completely transforms a cylinder head on its own merits. We can only "tune it" towards that direction by adding a "few tricks" together in cumulative fashion. Bore size and OEM port locations limit us a great deal too.
EXACTLY ... and that, in a round-a-bout way, is what I was trying to allow others to realize.
"BETTER" is not always "BETTER" in every application; heads, cams or otherwise. Different combinations require all sorts of different parameters in order to work well TOGETHER and reach the wanted end results.
http://www.rmcompetition.com
Specialty engine building at its finest.

user-9274568

Re: Valve Seat Angles and Flow Area

Post by user-9274568 » Sat Mar 10, 2018 12:32 pm

Both are 45º radius exhaust cutters. One on right is a 042 Sunnen. One on left is a custom. One makes a really big throat, one doesn't. One makes more power than the other. Both are the same seat..

Image

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 12:36 pm

Walter R. Malik wrote:
Sat Mar 10, 2018 12:24 pm
groberts101 wrote:
Sat Mar 10, 2018 12:04 pm
* wrote:
Sat Mar 10, 2018 11:36 am


Ok, a better valve job? Or blend it differently. You can kill 10+ down low by how hard you get into the 60 or 65.
I get what you're saying here Walter but avoiding/foregoing a backcut on the valves can also do near similar to reduce reverse flow as well. Yet we still trend towards a backcut to aid mid and high lift flow even though that just inevitably encourages reverse flow.

IMHO, in the end not one thing being mentioned here completely transforms a cylinder head on its own merits. We can only "tune it" towards that direction by adding a "few tricks" together in cumulative fashion. Bore size and OEM port locations limit us a great deal too.
EXACTLY ... and that, in a round-a-bout way, is what I was trying to make others realize.
"BETTER" is not always "BETTER" in every application; heads, cams or otherwise. Different combinations require all sorts of different parameters in order to work well TOGETHER and reach the wanted end results.
And hopefully to correctly embellish on that same thought process.. not every trick we have available to us will even FIT on every casting/shape/size anyways. So, just because we know a particular trick will/has/would potentially help power, or torque or dynamic response or whatever the goal, doesn't do squat to make the combo better if we can't physically implement it and make it fit into the overall design and play nice with other tricks. Million's of various and potential combo's available without even getting into machining tricks!

randy331
Guru
Guru
Posts: 2939
Joined: Mon Dec 04, 2006 7:30 pm
Location: N.W. MO.

Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 12:41 pm

groberts101 wrote:
Sat Mar 10, 2018 11:54 am

Was just making a general statement. And seriously, how the hell does my cam guy know if I have a well prep'd and heavily ported head that flows 25 more cfm than another out of box design which he's already made dozens of cams for in the past? Will he give me his "usual design" for that out of box bolt on parts application without factoring in my ported heads extra port efficiency? Maybe I just tell him they are "ported" and he knows what to do?
What makes you think your cam guy woulda had the right cam before the 25 cfm was added ?
What makes you think your cam guy would make the right changes to the cam for a 25 cfm increase?

Randy

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 12:45 pm

* wrote:
Sat Mar 10, 2018 12:32 pm
Both are 45º radius exhaust cutters. One on right is a 042 Sunnen. One on left is a custom. One makes a really big throat, one doesn't. One makes more power than the other. Both are the same seat..

Image
Then there's the little known fact that you can run both those cutters on several head designs and end up with differing results because of other limitations which have now reared their ugly heads to greater degree because those cuts interfered with the incoming masses movement. Which is of course why you spent the money and development time to come up with them for YOUR PORT DESIGNS in the first place.

Plus, you(figurative) could go even further yet on some castings by employing a non-symmetrical/non-round throat design via additional hand grinding. Probably preaching to the choir here.. but a completely round throat isn't ALWAYS best either. One of those things you tend to learn early on when doing this stuff. :D
Last edited by groberts101 on Sat Mar 10, 2018 12:57 pm, edited 1 time in total.

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 12:46 pm

randy331 wrote:
Sat Mar 10, 2018 12:41 pm
groberts101 wrote:
Sat Mar 10, 2018 11:54 am

Was just making a general statement. And seriously, how the hell does my cam guy know if I have a well prep'd and heavily ported head that flows 25 more cfm than another out of box design which he's already made dozens of cams for in the past? Will he give me his "usual design" for that out of box bolt on parts application without factoring in my ported heads extra port efficiency? Maybe I just tell him they are "ported" and he knows what to do?
What makes you think your cam guy woulda had the right cam before the 25 cfm was added ?
What makes you think your cam guy would make the right changes to the cam for a 25 cfm increase?

Randy
Taht was my exact point.. I don't know if and what he comes up will be better or not. But why would I hamstring him by not supplying as much info as possible?

Like I said.. not everyone is as smart as some of you guys around here. But at least I have a good inkling as to what's required so I can cut through some of the advertising and cookie cutter BS forced down my throat when I walk into a shops front door. And part of that BS would be not even considering all those hard fought designs to come up with a better mousetrap! Working on Fords lately.. so that's supposed to be a funny!
Last edited by groberts101 on Sat Mar 10, 2018 12:49 pm, edited 2 times in total.

user-9274568

Re: Valve Seat Angles and Flow Area

Post by user-9274568 » Sat Mar 10, 2018 12:48 pm

Speaking of camshafts, I have one engine builder customer that told me, "we run this cam in our 316 cid engines because it goes down the track the fastest, it has .990 intake lift and .950 exhaust, port your head to make it work." OK, I like you....

groberts101
Guru
Guru
Posts: 1905
Joined: Sat Mar 08, 2008 3:08 pm
Location: Minneapolis

Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 12:56 pm

lol.. build to the camshafts requirements. Ain't that the truth when it's all boiled right down.

Erland Cox
Guru
Guru
Posts: 3265
Joined: Sun Jan 29, 2006 9:46 pm
Location: Lund in Sweden
Contact:

Re: Valve Seat Angles and Flow Area

Post by Erland Cox » Sat Mar 10, 2018 1:19 pm

If possible I would use the chamber to make the head flow less att low lifts.
With steep top angles above the seat the head flows less at low lifts.
The reason I woulld want less low lift flow is because that lets me use a longer duration camshaft without loosing torque.
A long duration camshaft allows me to have higher lift and more duration at high lift where the head flows more.
The engine that I am talking about is valve acceleration limited by its bucket diameter.
When I decrease low lift flow I also decrease reverse flow.

Erland

Post Reply