Valve Seat Angles and Flow Area

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 2:17 pm

"BETTER" is not always "BETTER"
If better is not better then by definition it is not better.

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Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 2:41 pm

groberts101 wrote:
Sat Mar 10, 2018 12:46 pm
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?
I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy

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Re: Valve Seat Angles and Flow Area

Post by maxracesoftware » Sat Mar 10, 2018 3:10 pm

Erland Cox wrote:
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
Erland ,
that's exactly what i'm doing on all the higher HP engines we are doing :)
8)

most of our highest HP engines have horrible Low-Lift Flow :)
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Re: Valve Seat Angles and Flow Area

Post by hoffman900 » Sat Mar 10, 2018 4:03 pm

maxracesoftware wrote:
Sat Mar 10, 2018 3:10 pm
Erland Cox wrote:
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
Erland ,
that's exactly what i'm doing on all the higher HP engines we are doing :)
8)

most of our highest HP engines have horrible Low-Lift Flow :)
I believe the fallacy in looking at low lift flow on a constant depression flow bench is that it's actually going to flow in the correct direction on a running engine - and this at peak VE, this doesn't account for what's happening before or after that point. IMO, there has been (accidentally) misinterpreted data shared that furthers this.

Neglecting the valvetrain in this discussion does all of this a disservice. As Erland points out (and Larry, Walter, and RDY4WAR) , you need a certain amount of duration to reach a certain amount of lift, if this is an endurance application, then this has to be more so. Talking in terms of a flat tappet or a bucket OHC application, you're velocity constrained by the diameter of the lifter. On a roller, you're constrained by the base circle diameter and acceleration. All except Moto GP and Formula 1 are constrained by valve springs. If you integrate your lift curve and break it up, you'll notice you'll spend more total time in the middle / high lifts for a given valve lift curve than the low lift. Except for EVO, flow will likely be going the wrong way at the most extreme of low lifts (coming off the seat). If you wait to open it, you'll never be able to get the valve open fast enough to when it's needed most.

The builders working with hemispherical chambers learned long ago about all of this - Porsche, Alfa, Chrysler, vintage Japanese motorcycle engines, etc.

As for camshaft designers not knowing the flow curve, that's silly. Lots of chest beating going on here :roll: . Someone, somewhere in the decision making process has to know the flow curve in order to pick out the events. I don't think any cam designer is going to say they get it 100% out of the gate - that's stupid. It's their first, best guess. Where to go from there is contingent on testing. I know Mike Jones has laid out what he wants the customer to do.
CamKing wrote:
Fri May 13, 2016 3:37 pm
hoffman900 wrote: Ideally, what would you want to hear from the customer?
I want to see the dyno sheets for every move, and I want as much info being recorded as possible, including CFM.
After running the cam on the numbers on the cam card, I'd go .004" tighter on Intake lash, then Exhaust lash. If the power picked up, I'd go another .002" at a time, until it hurt the power. If going tighter hurt the power, I'd go looser by .002".
After you find best power, I would advance the cam 2 degrees at a time, until it hurts the power. When you get the ICL to the point it's making the best power, now re-set the lash to what's on the card, and run it again.
If you sent me all those dyno sheets, I'd have a really good idea of what's going on.
Playing around with pressure dynamic simulation software has been pretty enlightening. Jon hit the nail on the head...
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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 4:23 pm

randy331 wrote:
Sat Mar 10, 2018 2:41 pm
groberts101 wrote:
Sat Mar 10, 2018 12:46 pm
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?
I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?

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Re: Valve Seat Angles and Flow Area

Post by Walter R. Malik » Sat Mar 10, 2018 4:26 pm

Erland Cox wrote:
Sat Mar 10, 2018 1:19 pm
If possible I would use the chamber to make the head flow less at low lifts.
With steep top angles above the seat the head flows less at low lifts.
The reason I would 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
I see that someone understands that concept ... :-k

I think you probably mean VELOCITY limited by bucket diameter.
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Re: Valve Seat Angles and Flow Area

Post by hoffman900 » Sat Mar 10, 2018 4:30 pm

GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm
groberts101 wrote:
Sat Mar 10, 2018 12:46 pm
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?
I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
Someone still has to know the flow - whether that's measured in CFM, discharge coefficient, or some other metric. It's either the engine builder or the cam guy, it doesn't matter.

If we didn't, a 358ci wedge chamber head that peaks at 7500rpm would have the same cam as a 358ci hemispherical chamber head that peaks at 7500rpm or a 358ci 4 valve pentroof chamber head that peaks at 7500rpm. We know that not to be true ;)
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Re: Valve Seat Angles and Flow Area

Post by Walter R. Malik » Sat Mar 10, 2018 4:45 pm

GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm
groberts101 wrote:
Sat Mar 10, 2018 12:46 pm
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?
I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
Are you here to simply agitate or do you really have something constructive to add to this subject ...?
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Re: Valve Seat Angles and Flow Area

Post by groberts101 » Sat Mar 10, 2018 5:05 pm

hoffman900 wrote:
Sat Mar 10, 2018 4:30 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm

I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
Someone still has to know the flow - whether that's measured in CFM, discharge coefficient, or some other metric. It's either the engine builder or the cam guy, it doesn't matter.

If we didn't, a 358ci wedge chamber head that peaks at 7500rpm would have the same cam as a 358ci hemispherical chamber head that peaks at 7500rpm or a 358ci 4 valve pentroof chamber head that peaks at 7500rpm. We know that not to be true ;)
Thank you! All I was trying to get at is that you'd want to give your cam guy the best chance to be closer to the bullseye. And most of us know that durations will average out in such contests because much is about the time needed within that specific rpm range. And I ain't buyin' for 1 millisecond that all those various engine platforms have same valve lift plots over the entire lift curve simply because seat timings are in the same place. Obviously not everyone runs same rocker ratios either, so...

Randy of all people should know that's not an entirely true blanket statement. Memory ain't what it used to be and may be mistaken but didn't one of his motors with gmpp heads have some ridiculously non mainstream exhaust splits to make most power?

Ok let's hypothesize. I tell my cam guy I have xx motor with traditional bolt on modifications and it needs to run in xxxx rpm range. He asks what heads and I say xx heads that have been ported by myself in a garage. He immediately thinks they're probably just like a thousand others he's spec'd cams for and maybe even weaker cause obviously.. who the hell am I? Cam runs good and makes decent power like most of the other "typical combo's".

Then I tell him that same thing but include more detailed info about how I produced some of my very best work but tend to port up exhausts to nearer their full potential, I/E ratio be damned. Should he grind me the same cam with similar exhaust splits to the other for which he assumed flowed somewhere's in the low 200's when this combo flows over 250?

PS. I don't come here to waste all my free time on bs cookie cutter answers with rhetorical "roundy round we go" questions from pro's. I come to learn new tricks and develop better rounded engine building viewpoints, so please be specific if you think you may have the correct answer. It would be greatly appreciated simply because that's the exact situation I'm in. My 1st instinct is to spread the lobes a tad more than typical for similar combo's and/or run less exhaust duration with less lift?
Last edited by groberts101 on Sat Mar 10, 2018 5:30 pm, edited 2 times in total.

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Re: Valve Seat Angles and Flow Area

Post by JoePorting » Sat Mar 10, 2018 5:23 pm

cspeier 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
How much more power does the custom bit make?
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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 5:25 pm

Walter R. Malik wrote:
Sat Mar 10, 2018 4:45 pm
GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm


I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
Are you here to simply agitate or do you really have something constructive to add to this subject ...?
No, it's a serious question.

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Re: Valve Seat Angles and Flow Area

Post by CamKing » Sat Mar 10, 2018 5:37 pm

groberts101 wrote:
Sat Mar 10, 2018 5:05 pm
My 1st instinct is to spread the lobes a tad more than typical for similar combo's and/or run less exhaust duration with less lift?
You leave the intake centerline alone. You reduce the exhaust duration, and you move the exhaust centerline to keep the same overlap. This will give you a narrower LSA.
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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 6:37 pm

hoffman900 wrote:
Sat Mar 10, 2018 4:30 pm
GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm


I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
Someone still has to know the flow - whether that's measured in CFM, discharge coefficient, or some other metric. It's either the engine builder or the cam guy, it doesn't matter.

If we didn't, a 358ci wedge chamber head that peaks at 7500rpm would have the same cam as a 358ci hemispherical chamber head that peaks at 7500rpm or a 358ci 4 valve pentroof chamber head that peaks at 7500rpm. We know that not to be true ;)
I agree, each person has their method that they have perfected that works and they all have merit.

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 6:40 pm

CamKing wrote:
Sat Mar 10, 2018 5:37 pm
groberts101 wrote:
Sat Mar 10, 2018 5:05 pm
My 1st instinct is to spread the lobes a tad more than typical for similar combo's and/or run less exhaust duration with less lift?
You leave the intake centerline alone. You reduce the exhaust duration, and you move the exhaust centerline to keep the same overlap. This will give you a narrower LSA.
It seems that would also give a better indication of what helps or hurts vs changing all 4 events with each cam test.

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Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 9:15 pm

hoffman900 wrote:
Sat Mar 10, 2018 4:30 pm
If we didn't, a 358ci wedge chamber head that peaks at 7500rpm would have the same cam as a 358ci hemispherical chamber head that peaks at 7500rpm or a 358ci 4 valve pentroof chamber head that peaks at 7500rpm. We know that not to be true ;)
That's a little different and the cam difference isn't really because of what you see on the flow bench.

But calling up a cam guy and saying my heads flow 280cfm and thinking you should get a different cam than if they flow 260 cfm for the same application is silly.

Most street/street strip guys calling a cam guy with flowz to get a cam speced are already giving up a lot of power with lack of lift/valve acceleration/duration/street manners, so thinking a few deg duration or duration split is gonna make any real difference is silly too.

Randy

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