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

[Rick360]

If the cam was correct for the 45° seat, it would seem logical that a couple of degrees more for both IVO and IVC could be required with a 50° one (and thus no change in ICL or LSA) to compensate for the reduced low lift flow.

This would be a good investigation for someone with a recent version of Dynomation or a similar/higher level simulation software program. m ke I believe is one Speedtalker with same..

I did some Dynomation 5 simulations testing some steep seat flow curves and ran the cam iterator to find what it wants but the sim always showed less power with the steep seat flow curve, no matter the cam events. Makes me doubt the accuracy of the info.

Rick

[NewbVetteGuy]

If the cam was correct for the 45° seat, it would seem logical that a couple of degrees more for both IVO and IVC could be required with a 50° one (and thus no change in ICL or LSA) to compensate for the reduced low lift flow.

This would be a good investigation for someone with a recent version of Dynomation or a similar/higher level simulation software program. m ke I believe is one Speedtalker with same..

*Paging CamKing*

I'm curious what the magic Jones algorithm says, especially since my current cam with 45 degree valves is a Mike Jones cam, I'd be curious what, he'd change if I went to 50 degree valve seat angles.


Adam

[MadBill]

If the cam was correct for the 45° seat, it would seem logical that a couple of degrees more for both IVO and IVC could be required with a 50° one (and thus no change in ICL or LSA) to compensate for the reduced low lift flow.

This would be a good investigation for someone with a recent version of Dynomation or a similar/higher level simulation software program. m ke I believe is one Speedtalker with same..

I did some Dynomation 5 simulations testing some steep seat flow curves and ran the cam iterator to find what it wants but the sim always showed less power with the steep seat flow curve, no matter the cam events. Makes me doubt the accuracy of the info.

Rick

Interesting Rick! Disregarding the lower predicted power, how were the similarly-optimized cam specs affected?

PS: How did your steep seat flow input data compare to the 45° values? If it exhibited the commonly-reported reduced low lift flow, less power would be the opposite of the conclusions noted in the "too fast over SSR" thread...

[Warp Speed]

The area where you hang your curtains.

Dude, if you don't get it by now, never mind!

If you conclude a partial test as conclusive I would have to say the same to you.

Should I have added that the curtain area is the area that covers the window and the terms are used interchangeably?

Are you trying to learn or just being a tool?
I think I know the answer, and it's not doing this discussion any good.
You were talking valve angle, NOT valve seat angles! How would "valve angle" change curtain area?
If you don't want to believe any of this, stay with your tried and true 45 or 30!
Can you change the cam and and increase benefits? Of course, but why would it need differing lobe separation?
Quit being so hung up on one person's views!

[Warp Speed]

I'm almost afraid to reference the other "rule of thumb" thread, but I do want to ask: Are there any "rules of thumb" about how a cam recommendation changes with the move from a "typical" 45 degree set of valve angles to a "typical" 50-degree profile?

The other thread started looking at discharge coefficients and from this thread, we know moving to 50 degree profiles makes the discharge coefficients increase fairly significantly.

-Is there any sort of generalization that can be taken away between what's ideal for the cam for two otherwise identical motors with only the valve angles changed from a typical 45 to a typical 50? -I thought I saw some discussion that with improving discharge coefficients, the recommended LSA widened, but the other thread was just too painful to read for me to spend much time in it... -I could see you wanting to actually DECREASE the LSA with 50 degree seats to get more overlap to take advantage of the decreased reversion so I'm all sorts of confused...



Adam

IMO the seat is altering the flow at low lifts which is on the opening and closing side which leads me to believe that the LSA reqd wouldn't change but the ideal duration would probably be a little longer with the steeper seats.

Rick

THIS^^^^^^^

[cjperformance]

^^^^^ and being able to use some more dutation for the same lift can allow a more endurance friendly lobe and a slower seating velocity

[Warp Speed]

^^^^^ and being able to use some more duration for the same lift can allow a more endurance friendly lobe and a slower seating velocity

Or you can keep it at the same limit you have, and increase area.............win/win!

[cjperformance]

^^^^^ and being able to use some more duration for the same lift can allow a more endurance friendly lobe and a slower seating velocity

Or you can keep it at the same limit you have, and increase area.............win/win!

50 deg seats for all !

[Warp Speed]

^^^^^ and being able to use some more duration for the same lift can allow a more endurance friendly lobe and a slower seating velocity

Or you can keep it at the same limit you have, and increase area.............win/win!

50 deg seats for all !

Not sure about all of that, but there are positives that can be taken advantage of for sure.
Optimise the compromise...........

[cjperformance]

Or you can keep it at the same limit you have, and increase area.............win/win!

50 deg seats for all !

Not sure about all of that, but there are positives that can be taken advantage of for sure.
Optimise the compromise...........

Agreed, im just having a laugh, not converting the ark to 50* seats!
I like the "Optimise the compromise" quote, i guess with engines being a huge bunch of compromises he who stacks the most compromises in his favour wins!

[Warp Speed]

50 deg seats for all !

Not sure about all of that, but there are positives that can be taken advantage of for sure.
Optimise the compromise...........

Agreed, im just having a laugh, not converting the ark to 50* seats!
I like the "Optimise the compromise" quote, i guess with engines being a huge bunch of compromises he who stacks the most compromises in his favour wins!

[GARY C]

Dude, if you don't get it by now, never mind!

If you conclude a partial test as conclusive I would have to say the same to you.

Should I have added that the curtain area is the area that covers the window and the terms are used interchangeably?

Are you trying to learn or just being a tool?
I think I know the answer, and it's not doing this discussion any good.
You were talking valve angle, NOT valve seat angles! How would "valve angle" change curtain area?
If you don't want to believe any of this, stay with your tried and true 45 or 30!
Can you change the cam and and increase benefits? Of course, but why would it need differing lobe separation?
Quit being so hung up on one person's views!

It's a seat angle thread, all I have talked about on here is seat angles mostly in favor of the 50, the only thing I am hung up on is comprehensive testing, it seems the guys that preach the importance of testing would understand that.

[hoffman900]

I’ve seen this with a phenomen in a class that restricts valve sizes and lift, but with the exhaust. Get the header working waayyy better and you can keep feeding in more duration and it’ll make more up high and on the overrev, without giving up the midrange. The valve seat angle can further enhance this phenomenon.

As Calvin Elston alluded to here over a decade ago, think what (in his world) what else the header can do for you. No different than adding crankcase vacuum in ring tension. Nothing works in isolation.

[Rick360]

If the cam was correct for the 45° seat, it would seem logical that a couple of degrees more for both IVO and IVC could be required with a 50° one (and thus no change in ICL or LSA) to compensate for the reduced low lift flow.

This would be a good investigation for someone with a recent version of Dynomation or a similar/higher level simulation software program. m ke I believe is one Speedtalker with same..

I did some Dynomation 5 simulations testing some steep seat flow curves and ran the cam iterator to find what it wants but the sim always showed less power with the steep seat flow curve, no matter the cam events. Makes me doubt the accuracy of the info.

Rick

Interesting Rick! Disregarding the lower predicted power, how were the similarly-optimized cam specs affected?

PS: How did your steep seat flow input data compare to the 45° values? If it exhibited the commonly-reported reduced low lift flow, less power would be the opposite of the conclusions noted in the "too fast over SSR" thread...

IIRC it wanted a little more duration like you'd expect. It's been a while now so I don't remember for sure.

The flow data was numbers I made up to approximate the effect of steeper seat with less low lift flow.

Rick

[Stan Weiss]

If we were to look at this using Blair's time area. The great the seat angle the less time area we would see in these areas (looking at intake only).

Intake BTDC (IVO to TDC)
Intake Ramming (BDC to IVC)
Intake Overlap (IVO to EVC)

Stan