50 degree valve seats in modern hot street builds: is it finally time?

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Warp Speed » Tue Jun 12, 2018 11:17 am

Frankshaft wrote:
Tue Jun 12, 2018 11:05 am
CGT wrote:
Tue Jun 12, 2018 10:46 am
30 degree seat. 100k plus life expectancy in OE applicatons. Probably 1/2 that in a performance street strip app
45 degree seat. I've seen several hundred thousand in OE applications " "
50 degree seat 10 minute life expectancy in street strip application? :D
55 degree seat 3 minute life expectancy? ](*,)

Pretty sure your being sarcastic? 55 degree seats last just fine, and much longer than that. Same with 50 degree seats. Even 60's will.
Yep.
Valve control and heat are some major factors. Keep theses two in check, and it's surprising how long they can last.
Fuel used can also be a player.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by CGT » Tue Jun 12, 2018 11:27 am

Frankshaft wrote:
Tue Jun 12, 2018 11:05 am
CGT wrote:
Tue Jun 12, 2018 10:46 am
30 degree seat. 100k plus life expectancy in OE applicatons. Probably 1/2 that in a performance street strip app
45 degree seat. I've seen several hundred thousand in OE applications " "
50 degree seat 10 minute life expectancy in street strip application? :D
55 degree seat 3 minute life expectancy? ](*,)

Pretty sure your being sarcastic? 55 degree seats last just fine, and much longer than that. Same with 50 degree seats. Even 60's will.
It was sarcasm, I have projects with well over 20k on them on the street. .650 lift with 50 degree seats. No problems at all. A shitty valvetrain will beat the hell out of any seat angle.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by groberts101 » Tue Jun 12, 2018 12:14 pm

CGT wrote:
Tue Jun 12, 2018 11:27 am

It was sarcasm, I have projects with well over 20k on them on the street. .650 lift with 50 degree seats. No problems at all. A shitty valvetrain will beat the hell out of any seat angle.
Is the detail of that design proprietary.. or can you share any spec's that others may be able to cross reference for use on their street engines?

After all.. this thread started out with intention towards an actual tech discussion.. so let's talk tech.

What head castings.. and what seat and valve design?

Also someone mentioned fuels being used affecting longevity? Any specifics on that tech observation?

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Tue Jun 12, 2018 12:39 pm

CGT wrote:
Tue Jun 12, 2018 11:27 am
Frankshaft wrote:
Tue Jun 12, 2018 11:05 am
CGT wrote:
Tue Jun 12, 2018 10:46 am
30 degree seat. 100k plus life expectancy in OE applicatons. Probably 1/2 that in a performance street strip app
45 degree seat. I've seen several hundred thousand in OE applications " "
50 degree seat 10 minute life expectancy in street strip application? :D
55 degree seat 3 minute life expectancy? ](*,)

Pretty sure your being sarcastic? 55 degree seats last just fine, and much longer than that. Same with 50 degree seats. Even 60's will.
It was sarcasm, I have projects with well over 20k on them on the street. .650 lift with 50 degree seats. No problems at all. A shitty valvetrain will beat the hell out of any seat angle.
My guess is a 50 in an OE application would probably live long and prosper. If you can use a longer slower lobe on a 50 and get better lift for performance without beating on the valve train possibly gives it an advantage for long life on a performance street app.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by MTENGINES » Tue Jun 12, 2018 12:44 pm

groberts101 wrote:
Tue Jun 12, 2018 12:14 pm
CGT wrote:
Tue Jun 12, 2018 11:27 am

It was sarcasm, I have projects with well over 20k on them on the street. .650 lift with 50 degree seats. No problems at all. A shitty valvetrain will beat the hell out of any seat angle.
Is the detail of that design proprietary.. or can you share any spec's that others may be able to cross reference for use on their street engines?

After all.. this thread started out with intention towards an actual tech discussion.. so let's talk tech.

What head castings.. and what seat and valve design?

Also someone mentioned fuels being used affecting longevity? Any specifics on that tech observation?
Really man? It really seems like you want your hand held. did it ever occur to you that maybe valve material, seat material, valve weight, rocker arm ratio, spring rate, cam acceleration rate, guide material can be a huge factor? Some of this stuff might work, some of it may not. Do you build engines or not? Some things take refinement, and there has been some good tech here. If you want to know more, maybe buy a competitive engine from someone on here and disassemble it.

I have had 60 degree seats work on alcohol with moldstar seats.. have also had them not work. Get your valvetrain in line and it can last. I suppose you want to know who the parts were ordered from, how many people touched the product before it was shipped, what their mothers favorite color is.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by groberts101 » Tue Jun 12, 2018 1:02 pm

MTENGINES wrote:
Tue Jun 12, 2018 12:44 pm
groberts101 wrote:
Tue Jun 12, 2018 12:14 pm
CGT wrote:
Tue Jun 12, 2018 11:27 am

It was sarcasm, I have projects with well over 20k on them on the street. .650 lift with 50 degree seats. No problems at all. A shitty valvetrain will beat the hell out of any seat angle.
Is the detail of that design proprietary.. or can you share any spec's that others may be able to cross reference for use on their street engines?

After all.. this thread started out with intention towards an actual tech discussion.. so let's talk tech.

What head castings.. and what seat and valve design?

Also someone mentioned fuels being used affecting longevity? Any specifics on that tech observation?
Really man? It really seems like you want your hand held. did it ever occur to you that maybe valve material, seat material, valve weight, rocker arm ratio, spring rate, cam acceleration rate, guide material can be a huge factor? Some of this stuff might work, some of it may not. Do you build engines or not? Some things take refinement, and there has been some good tech here. If you want to know more, maybe buy a competitive engine from someone on here and disassemble it.

I have had 60 degree seats work on alcohol with moldstar seats.. have also had them not work. Get your valvetrain in line and it can last. I suppose you want to know who the parts were ordered from, how many people touched the product before it was shipped, what their mothers favorite color is.
wtf is it with you greedy ass attitude pro's around here. Someone asks for tech details and you get scrunched undies like I'm asking to share your wife or something. But yet you can write the equivelent of novels over time with all the smart assed arguments? Asking for details after being told how smart you are compared to the rest of us is holding my hand? Maybe take a look around at where you are here.... It's a TECH SITE! Not much is learned by.. "yeah, it works.. I do it all the time". Post that kind of shit on facebook where people will bow down to you and give thumbsups or whatever floats your boat but if you post it here be prepared to get asked questions relating to your words of wisdom.

Maybe Don can make a new speed secrets episode and you'll get paid for giving advice? Or I have to buy a 20k engine from you and reverse engineer it?.. is that all it takes? As it is I can walk into many local machine shops and custom boutique builders and do that fro free! :lol:

And yeah, I'm well aware that there are other variables. Want me to lay them all out for you so it proves I have an overview yet you can ignore them too? But wait.. then you'll bitch because you had to take the time to read more than 50 words or perfectly summed up... X2. #-o

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Rick360 » Tue Jun 12, 2018 1:13 pm

groberts101 wrote:
Tue Jun 12, 2018 1:02 pm
wtf is it with you greedy ass attitude pro's around here. Someone asks for tech details and you get scrunched undies like I'm asking to share your wife or something. But yet you can write the equivelent of novels over time with all the smart assed arguments? Asking for details after being told how smart you are compared to the rest of us is holding my hand? Maybe take a look around at where you are here.... It's a TECH SITE! Not much is learned by.. "yeah, it works.. I do it all the time". Post that kind of shit on facebook where people will bow down to you and give thumbsups or whatever floats your boat but if you post it here be prepared to get asked questions relating to your words of wisdom.

Maybe Don can make a new speed secrets episode and you'll get paid for giving advice? Or I have to buy a 20k engine from you and reverse engineer it?.. is that all it takes? As it is I can walk into many local machine shops and custom boutique builders and do that fro free! :lol:

And yeah, I'm well aware that there are other variables. Want me to lay them all out for you so it proves I have an overview yet you can ignore them too? But wait.. then you'll bitch because you had to take the time to read more than 50 words or perfectly summed up... X2. #-o
I think he's waiting for an explanation for why it works that agrees with his own theory.
CGT wrote:
Tue Jun 12, 2018 9:39 am
randy331 wrote:
Tue Jun 12, 2018 9:15 am
There would be those that would discredit the test, saying a better 45* would have done better or with xxx flowz speced cam the other valve job would be better.

A test more interesting to me would be do some window area figuring and use a larger valve with the steeper seats. That's kinda how I view the use of seat angles. What else it lets you do. (better compromise)
That's why the more I think about it, I would just do the test and keep it private. I've thought about it, there isn't a set of tests that wont get you picked apart by people while your feeding them free data. What's the point?
Maybe do the test and share the results with everyone but groberts. :lol:

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by NewbVetteGuy » Tue Jun 12, 2018 1:15 pm

Rick360 wrote:
Mon Jun 11, 2018 9:52 pm
Here's a link to an old Speedtalk thread from 2005 that might be useful for some. This post/thread was my initial inspiration as to a new reason other than flow "why" steeper seats might be better, although I already had a set of heads with 50º seats by then. This certainly got me thinking along new lines.

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=1257

Rick
Rick, I really appreciate you posting a link over to that thread, making the XLS, and making and posting the pictures.

I just used the XLS to look at the minimum window area of a 2.02" valve with 50/43/35 valve angles vs. 45/35/30 valve angles at 0.100" increments up to 0.700" and then also added one more data point at 1.000". I did not see what I expected and I think I'm more confused, but possibly on the cusp of understanding something new...

2.02" Valve "typical" 50 vs 45 degree valve job min window area at various lifts:
Valve Lift 45 50
0.100" 0.459 0.413
0.200" 0.975 0.855
0.300" 1.504 1.417
0.400" 2.075 1.984
0.500" 2.661 2.568
0.600" 3.254 3.16
0.700" 3.85 3.756
1.000" 5.649 5.555


I fully expected to see the 50 degree seat start out with less window area at lower lifts and then at some point transition to having a larger window area (much like we see the CFM flow #'s cross over in the HotRod article), but we don't see that actually ever happen. The 50 degree angle starts out with less window area and stays that way at all lifts... Did I do this right?

Is this correct that the 50 degree angle valve will have less actual curtain area at all lifts but still somehow flows more? (simply because the angle of the valve and seat let the air flow FASTER?) More air flow with the same area == more velocity, but this seems to be more airflow with less area -so potentially significantly higher velocities through the valve curtain area??? (At least at the lifts where the valve curtain area is still the bottleneck /choke point.)

On a related note, unless I totally screwed up something above (WAY more than possible): When calculating at which valve lift point the choke moves from the valve curtain area to the intake port's choke / minCSA, should we actually be using this more complicated Window Area Calculation? (If so it seems like it will take more lift with a 50 degree seat to reach the point when the throat becomes the choke, right?)



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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by statsystems » Tue Jun 12, 2018 1:16 pm

groberts101 wrote:
Tue Jun 12, 2018 1:02 pm
MTENGINES wrote:
Tue Jun 12, 2018 12:44 pm
groberts101 wrote:
Tue Jun 12, 2018 12:14 pm


Is the detail of that design proprietary.. or can you share any spec's that others may be able to cross reference for use on their street engines?

After all.. this thread started out with intention towards an actual tech discussion.. so let's talk tech.

What head castings.. and what seat and valve design?

Also someone mentioned fuels being used affecting longevity? Any specifics on that tech observation?
Really man? It really seems like you want your hand held. did it ever occur to you that maybe valve material, seat material, valve weight, rocker arm ratio, spring rate, cam acceleration rate, guide material can be a huge factor? Some of this stuff might work, some of it may not. Do you build engines or not? Some things take refinement, and there has been some good tech here. If you want to know more, maybe buy a competitive engine from someone on here and disassemble it.

I have had 60 degree seats work on alcohol with moldstar seats.. have also had them not work. Get your valvetrain in line and it can last. I suppose you want to know who the parts were ordered from, how many people touched the product before it was shipped, what their mothers favorite color is.
wtf is it with you greedy ass attitude pro's around here. Someone asks for tech details and you get scrunched undies like I'm asking to share your wife or something. But yet you can write the equivelent of novels over time with all the smart assed arguments? Asking for details after being told how smart you are compared to the rest of us is holding my hand? Maybe take a look around at where you are here.... It's a TECH SITE! Not much is learned by.. "yeah, it works.. I do it all the time". Post that kind of shit on facebook where people will bow down to you and give thumbsups or whatever floats your boat but if you post it here be prepared to get asked questions relating to your words of wisdom.

Maybe Don can make a new speed secrets episode and you'll get paid for giving advice? Or I have to buy a 20k engine from you and reverse engineer it?.. is that all it takes? As it is I can walk into many local machine shops and custom boutique builders and do that fro free! :lol:

And yeah, I'm well aware that there are other variables. Want me to lay them all out for you so it proves I have an overview yet you can ignore them too? But wait.. then you'll bitch because you had to take the time to read more than 50 words or perfectly summed up... X2. #-o

No offense groberts, but you act like a welfare engine builder. What I have said from the start has been proven correct several times over. You want a fool proof, guaranteed, works every time recipie for whatever you are building to keep your monetary exposure to the minimum.


This place is for an exchange of IDEAS. Not a place where everyone gives shit away for free.

You have been given ample information yet you continue to argue and find fault with everyone but yourself.

Personally, you aren't ready to move up to the 1990's (most likely earlier because I didn't develop the stuff but I damn sure learned it in the 1990's) as far as valve jobs are concerned.

Just do what you do and be happy.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Warp Speed » Tue Jun 12, 2018 1:40 pm

groberts101 wrote:
Tue Jun 12, 2018 1:02 pm
MTENGINES wrote:
Tue Jun 12, 2018 12:44 pm
groberts101 wrote:
Tue Jun 12, 2018 12:14 pm


Is the detail of that design proprietary.. or can you share any spec's that others may be able to cross reference for use on their street engines?

After all.. this thread started out with intention towards an actual tech discussion.. so let's talk tech.

What head castings.. and what seat and valve design?

Also someone mentioned fuels being used affecting longevity? Any specifics on that tech observation?
Really man? It really seems like you want your hand held. did it ever occur to you that maybe valve material, seat material, valve weight, rocker arm ratio, spring rate, cam acceleration rate, guide material can be a huge factor? Some of this stuff might work, some of it may not. Do you build engines or not? Some things take refinement, and there has been some good tech here. If you want to know more, maybe buy a competitive engine from someone on here and disassemble it.

I have had 60 degree seats work on alcohol with moldstar seats.. have also had them not work. Get your valvetrain in line and it can last. I suppose you want to know who the parts were ordered from, how many people touched the product before it was shipped, what their mothers favorite color is.
wtf is it with you greedy ass attitude pro's around here. Someone asks for tech details and you get scrunched undies like I'm asking to share your wife or something. But yet you can write the equivelent of novels over time with all the smart assed arguments? Asking for details after being told how smart you are compared to the rest of us is holding my hand? Maybe take a look around at where you are here.... It's a TECH SITE! Not much is learned by.. "yeah, it works.. I do it all the time". Post that kind of shit on facebook where people will bow down to you and give thumbsups or whatever floats your boat but if you post it here be prepared to get asked questions relating to your words of wisdom.

Maybe Don can make a new speed secrets episode and you'll get paid for giving advice? Or I have to buy a 20k engine from you and reverse engineer it?.. is that all it takes? As it is I can walk into many local machine shops and custom boutique builders and do that fro free! :lol:

And yeah, I'm well aware that there are other variables. Want me to lay them all out for you so it proves I have an overview yet you can ignore them too? But wait.. then you'll bitch because you had to take the time to read more than 50 words or perfectly summed up... X2. #-o
Waiting bandwidth AGAIN I see............ [-X

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by groberts101 » Tue Jun 12, 2018 1:48 pm

statsystems wrote:
Tue Jun 12, 2018 1:16 pm
No offense groberts, but you act like a welfare engine builder. What I have said from the start has been proven correct several times over. You want a fool proof, guaranteed, works every time recipie for whatever you are building to keep your monetary exposure to the minimum.


This place is for an exchange of IDEAS. Not a place where everyone gives shit away for free.

You have been given ample information yet you continue to argue and find fault with everyone but yourself.

Personally, you aren't ready to move up to the 1990's (most likely earlier because I didn't develop the stuff but I damn sure learned it in the 1990's) as far as valve jobs are concerned.

Just do what you do and be happy.
That's just it, stat. You misunderstand me asking questions towards greater detail as handholding and giving away your first born or leaking trade secrets or something. I will admit the "welfare engine builder" was pretty funny though.. my brain loves to come up with witty smart ass remarks like that too. After consideration for the degrading aspect of such remarks, it usually ends up with just me patting myself on the back though. :lol:

Your word IDEA's would be better translated into the word CONCEPT's.. because that 's all you guys are really giving out. Not highly specific info that can be added to the internal notes and chalkboards to cross reference over towards other designs. You want to see a guy that freely share's his wisdom when he has a moment to breath? Look at Larry Meaux's posts. That guy may not disagree with some peoples assessments or replies(pro's or plainfolk).. but he has CLASS and responds in like manner. Something to be learned there.

And here's the thing I've said over and over till I'm blue in the face saying it. All I want are specific's to what, where, when, and WHY you did something. I full well understand the variables involved and would never EVER assume that the stuff carries across all applications and architectures. In fact, if you say it does?.. I put a little yellow asterisk next to your inputted data that related to "data smells of shit.. add more salt to keep the stink down". It's ALL just data that get's accumulated for greater overview towards seeing a bigger picture is all. Don't know how else to explain it other than I don't really even care who the data originates from(mainly because there are some EXTREMELY sharp unknown individuals out there that should not be ignored).. it's all just used as building blocks to determine how I.. ME.. want to utilize it and all falls into my interpretation and fitment into any particular application.


The other thing I see quite often over a lifetime of experience, is some people being overly guarded with information because they never truly want others to know what they don't know. Pride's a funny thing and too much causes a tripping hazard for some guys.

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Rick360 » Tue Jun 12, 2018 1:49 pm

NewbVetteGuy wrote:
Tue Jun 12, 2018 1:15 pm
Rick360 wrote:
Mon Jun 11, 2018 9:52 pm
Here's a link to an old Speedtalk thread from 2005 that might be useful for some. This post/thread was my initial inspiration as to a new reason other than flow "why" steeper seats might be better, although I already had a set of heads with 50º seats by then. This certainly got me thinking along new lines.

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=1257

Rick
Rick, I really appreciate you posting a link over to that thread, making the XLS, and making and posting the pictures.

I just used the XLS to look at the minimum window area of a 2.02" valve with 50/43/35 valve angles vs. 45/35/30 valve angles at 0.100" increments up to 0.700" and then also added one more data point at 1.000". I did not see what I expected and I think I'm more confused, but possibly on the cusp of understanding something new...

2.02" Valve "typical" 50 vs 45 degree valve job min window area at various lifts:
Valve Lift 45 50
0.100" 0.459 0.413
0.200" 0.975 0.855
0.300" 1.504 1.417
0.400" 2.075 1.984
0.500" 2.661 2.568
0.600" 3.254 3.16
0.700" 3.85 3.756
1.000" 5.649 5.555


I fully expected to see the 50 degree seat start out with less window area at lower lifts and then at some point transition to having a larger window area (much like we see the CFM flow #'s cross over in the HotRod article), but we don't see that actually ever happen. The 50 degree angle starts out with less window area and stays that way at all lifts... Did I do this right?

Is this correct that the 50 degree angle valve will have less actual curtain area at all lifts but still somehow flows more? (simply because the angle of the valve and seat let the air flow FASTER?) More air flow with the same area == more velocity, but this seems to be more airflow with less area -so potentially significantly higher velocities through the valve curtain area??? (At least at the lifts where the valve curtain area is still the bottleneck /choke point.)

On a related note, unless I totally screwed up something above (WAY more than possible): When calculating at which valve lift point the choke moves from the valve curtain area to the intake port's choke / minCSA, should we actually be using this more complicated Window Area Calculation? (If so it seems like it will take more lift with a 50 degree seat to reach the point when the throat becomes the choke, right?)



Adam
Yes, I think you've got a pretty good understanding. One other thing about the area is that the steeper seats starts gaining back some area deficit to the 45 at about .100"-.150" lift depending on angles and widths. The rate of change in area per lift or "slope" of the area vs lift gets much better around that lift. Slower opening area at real low lifts where not much can happen yet then faster area opening at about the lift when the valve can really start to move out of the way. It acts like a faster lobe. Or thats how I see it.

Rick

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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by Stan Weiss » Tue Jun 12, 2018 1:53 pm

Rick360 wrote:
Mon Jun 11, 2018 10:06 pm
Here is a drawing I posted back then that is probably a dead link now so I'll put it here as an attachment. Shows where the narrowest point is at different valve lifts. If you can picture what a steeper seat does to the gaps at the different lifts.


ValveSeatDwg.jpg

Rick
Stan Weiss wrote:
Wed Jun 06, 2018 1:13 pm

From - INTAKE_PORT_FLOW_STUDY_ON_VARIOUS_CYLINDER_HEAD_USING_FLOWBENCH.pdf

1. First stage
For low valve lifts, the minimum flow area corresponds to a frustrum of a right circular cone where the conical face between the valve and the seat, which is perpendicular to the seat, defines the flow area.
The minimum area is;
Am = πLv cos β (Dv – 2w + (Lv/2) sin 2β)
Where: β = Valve seat angle [º]
Lv = Valve lift [mm]
Dv = Valve head diameter (the outer diameter of the Seat) [mm}
w = Seat width (difference between the inner and outer seat radii) [mm]

2. Second stage
For the second stage, the minimum area still the slant surface of a frustrum of a right circular cone, but his surface is no longer perpendicular to the valve seat. The base angle of the cone increases from (90-β)º toward that of a cylinder, 90º.
The minimum area is;
Am = π Dm [ (Lv – w tan β)² + w²]½
Where: Dm = Mean seat diameter (Dv – w) [mm]

Stan
Not sure how these calculations work out to your drawing?

Stan
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by GARY C » Tue Jun 12, 2018 2:08 pm

Rick360 wrote:
Tue Jun 12, 2018 1:49 pm
NewbVetteGuy wrote:
Tue Jun 12, 2018 1:15 pm
Rick360 wrote:
Mon Jun 11, 2018 9:52 pm
Here's a link to an old Speedtalk thread from 2005 that might be useful for some. This post/thread was my initial inspiration as to a new reason other than flow "why" steeper seats might be better, although I already had a set of heads with 50º seats by then. This certainly got me thinking along new lines.

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=1257

Rick
Rick, I really appreciate you posting a link over to that thread, making the XLS, and making and posting the pictures.

I just used the XLS to look at the minimum window area of a 2.02" valve with 50/43/35 valve angles vs. 45/35/30 valve angles at 0.100" increments up to 0.700" and then also added one more data point at 1.000". I did not see what I expected and I think I'm more confused, but possibly on the cusp of understanding something new...

2.02" Valve "typical" 50 vs 45 degree valve job min window area at various lifts:
Valve Lift 45 50
0.100" 0.459 0.413
0.200" 0.975 0.855
0.300" 1.504 1.417
0.400" 2.075 1.984
0.500" 2.661 2.568
0.600" 3.254 3.16
0.700" 3.85 3.756
1.000" 5.649 5.555


I fully expected to see the 50 degree seat start out with less window area at lower lifts and then at some point transition to having a larger window area (much like we see the CFM flow #'s cross over in the HotRod article), but we don't see that actually ever happen. The 50 degree angle starts out with less window area and stays that way at all lifts... Did I do this right?

Is this correct that the 50 degree angle valve will have less actual curtain area at all lifts but still somehow flows more? (simply because the angle of the valve and seat let the air flow FASTER?) More air flow with the same area == more velocity, but this seems to be more airflow with less area -so potentially significantly higher velocities through the valve curtain area??? (At least at the lifts where the valve curtain area is still the bottleneck /choke point.)

On a related note, unless I totally screwed up something above (WAY more than possible): When calculating at which valve lift point the choke moves from the valve curtain area to the intake port's choke / minCSA, should we actually be using this more complicated Window Area Calculation? (If so it seems like it will take more lift with a 50 degree seat to reach the point when the throat becomes the choke, right?)



Adam
Yes, I think you've got a pretty good understanding. One other thing about the area is that the steeper seats starts gaining back some area deficit to the 45 at about .100"-.150" lift depending on angles and widths. The rate of change in area per lift or "slope" of the area vs lift gets much better around that lift. Slower opening area at real low lifts where not much can happen yet then faster area opening at about the lift when the valve can really start to move out of the way. It acts like a faster lobe. Or thats how I see it.

Rick
Is there anything to the shape of the air flow around the valve as lift increases?

statsystems
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Re: 50 degree valve seats in modern hot street builds: is it finally time?

Post by statsystems » Tue Jun 12, 2018 2:57 pm

groberts101 wrote:
Tue Jun 12, 2018 1:48 pm
statsystems wrote:
Tue Jun 12, 2018 1:16 pm
No offense groberts, but you act like a welfare engine builder. What I have said from the start has been proven correct several times over. You want a fool proof, guaranteed, works every time recipie for whatever you are building to keep your monetary exposure to the minimum.


This place is for an exchange of IDEAS. Not a place where everyone gives shit away for free.

You have been given ample information yet you continue to argue and find fault with everyone but yourself.

Personally, you aren't ready to move up to the 1990's (most likely earlier because I didn't develop the stuff but I damn sure learned it in the 1990's) as far as valve jobs are concerned.

Just do what you do and be happy.
That's just it, stat. You misunderstand me asking questions towards greater detail as handholding and giving away your first born or leaking trade secrets or something. I will admit the "welfare engine builder" was pretty funny though.. my brain loves to come up with witty smart ass remarks like that too. After consideration for the degrading aspect of such remarks, it usually ends up with just me patting myself on the back though. :lol:

Your word IDEA's would be better translated into the word CONCEPT's.. because that 's all you guys are really giving out. Not highly specific info that can be added to the internal notes and chalkboards to cross reference over towards other designs. You want to see a guy that freely share's his wisdom when he has a moment to breath? Look at Larry Meaux's posts. That guy may not disagree with some peoples assessments or replies(pro's or plainfolk).. but he has CLASS and responds in like manner. Something to be learned there.

And here's the thing I've said over and over till I'm blue in the face saying it. All I want are specific's to what, where, when, and WHY you did something. I full well understand the variables involved and would never EVER assume that the stuff carries across all applications and architectures. In fact, if you say it does?.. I put a little yellow asterisk next to your inputted data that related to "data smells of shit.. add more salt to keep the stink down". It's ALL just data that get's accumulated for greater overview towards seeing a bigger picture is all. Don't know how else to explain it other than I don't really even care who the data originates from(mainly because there are some EXTREMELY sharp unknown individuals out there that should not be ignored).. it's all just used as building blocks to determine how I.. ME.. want to utilize it and all falls into my interpretation and fitment into any particular application.


The other thing I see quite often over a lifetime of experience, is some people being overly guarded with information because they never truly want others to know what they don't know. Pride's a funny thing and too much causes a tripping hazard for some guys.

You want something I can't tell you in words. I can't describe what I see when I look at a port, chamber and valve. In my head it makes sense, but to put it in words is nearly impossible for me.

Show me a head and most of the time I can tell you what I'd do with it. To type out why would be impossible.

Another engine builder where I used to live was working with a local Comp eliminator guy. We shared flow information and helped each other when we ran into issues. We even flowed each other's port work and would compare notes.

I stopped by his shop on the way home one night and I was looking at a set of heads off the Comp engine he was sending off to get updated. He didn't feel comfortable with that particular set of heads. He was sending them to a well know guy who had proven results.

Anyway...I just off the top of my head I said "I'd put the 55* seat I have on that and ditch the nail head valves and piss on the flow numbers". He just laughed it off.

A couple of months later the heads showed up and he had them apart sitting on the floor. I didn't know they were even back yet. I just needed to drop off some cranks I magged for him and there they were.

Bigger than shit, from 20 feet away I could SEE it had the exact same valve job I suggested. He came walking up and I told him "that's the same exact valve job I use and that's a 55* seat". He was stunned. The next day I gave him the seat cutters I had and he matched them up. It was the same, as I told him.

He spent many hours on the flow bench and finally gave up. The heads flowed less everywhere. But the heads made more power on the dyno and went faster in the car.

I tell this long story to make the point that I can't describe what I see. I suspect many can't so they try to find math to help explain it. I suspect my limited education keeps me from describing what you want.

My best advice to you is to stop overthinking it. Use your imagination and picture what the flow would look like if you stuck a hose in the port and you were watching water move through the port.

For me, it's a visual thing. When you can see the shape in your mind, you'll know when to use a steeper seat. I just cant put that into words but I will say it's about the shape of things as the valve moves through the lift curve and how the valve, seat angles and port and the shape they make as the valve moves through the lift curve that is important to me and almost impossible for me to describe.

It's about shape, shape, shape. And I'm sure there is something in the way the pressure in the port changes but I'm definitely not smart enough to explain that.

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