Cam Data from Well-Developed Engines

[Stan Weiss]

I like the title of this one.

"Cam data from well developed engines".


It's so easy, everyone can do it themselves (yes, I have) without having to ask any questions.

Just go find yourself a "well developed engine" at your local junkyard.
Turn the flywheel into a degree wheel.
Adjust the valve lash so it's zero or negative.
Use a dial gauge to measurevalve lift every X crank degrees.
Pull the cam, measure base circle and max cam lift.

4 important numbers, IO, OC, EO, EC.
ICL, ECL, LSA, overlap, they're nothing more than different combinations of those 4 numbers.
Once you've done that, you'll be asking even more questions, like.......... why isn't max lift half way between open and close?
How would you know if you've never made the effort to measure?



A flow bench is OK but full of limitations.
28 inches water, that's about 1 PSI.
Atmospheric pressure is more like 14.5 PSI so it's 1/14.5 away from reality at best.
A flow bench that works at atmospheric pressure drop would be a good upgrade.
Making more vac than 28 inches isn't really practical either.
Even a 2000W electric vac motor struggles to make 28 inch vac at max head flow, well it won't.
So you'd need other methods, like a turbo converted to a jet engine.

Joe,
Really?

NOT! I am sure you understand pressure deferential. To see the full 14.69 psi you would need absolute zero pressure / psi in the cylinder.

Also just what is the atmospheric pressure in the room when you are flowing the heads?

What does the pressure deferential on a running look like fro IVO to IVC and how does it change with an increase in RPM?

Stan

[GARY C]

The cam is just one part of the engine combo that needs to be factored in with heads, intake, compression, valve train, header and intent to name a few...

How do you use RPM to determine lift, duration and centerlines?

I don't, duration more effect where the peaks happen than total rpm for the most part.

[GARY C]

Try getting a human without a human and let me know how that goes, it takes two humans by the way, we have over 7 billion tests confirming this study.
Not sure what multiplying the lobe separation by 2 has to do with it.

Because LSA is just half the sum of the ICL and ECL.

106 lsa can have the same cam lobes but on different centerlines and behave rather differently

106 lsa. 100 intake centerline. 112 exhaust centerline
106 lsa. 110 intake centerline. 102 exhaust centerline

You think those cams will behave same in the same motor?

Moving the installed center line does not change the distance between center lines... I am well aware that different lobes on the same Lobe "separation" angle will effect valve motion by a few degrees.

[SchmidtMotorWorks]

The cam is just one part of the engine combo that needs to be factored in with heads, intake, compression, valve train, header and intent to name a few...

How do you use RPM to determine lift, duration and centerlines?

I don't, duration more effect where the peaks happen than total rpm for the most part.

So if you want to move the RPM of the peaks up what direction do you move the following:?
Lift
Duration
LSA
Index

[GARY C]

How do you use RPM to determine lift, duration and centerlines?

I don't, duration more effect where the peaks happen than total rpm for the most part.

So if you want to move the RPM of the peaks up what direction do you move the following:?
Lift
Duration
LSA
Index

Depends on where start from, they can all have an effect as they increase or decrease overlap, exhaust scavenging or window area to draw on the intake port.

[Stan Weiss]

Looks like this thread is nothing but one continuous pop quiz. Has anyone got it correct yet?

While it is OK to ask questions of others, some people really need to learn that they also have to answer questions ask of them.

Stan

[statsystems]

Looks like this thread is nothing but one continuous pop quiz. Has anyone got it correct yet?

While it is OK to ask questions of others, some people really need to learn that they also have to answer questions ask of them.

Stan

And there is the issue. Lots of question askers but no one will answer anything because it's all top secret shit.

[GARY C]

Looks like this thread is nothing but one continuous pop quiz. Has anyone got it correct yet?

While it is OK to ask questions of others, some people really need to learn that they also have to answer questions ask of them.

Stan

Most people here know that will never happen but it's fun watching people dig a hole.

[Stan Weiss]

Let me add telling someone that something does not work is not a technical answer.

Thomas A. Edison "I have not failed. I've just found 10,000 ways that won't work"

Stan

[CGT]

Over the years, studying the effects of cam positioning on my own and others dyno tests has led me to looking at valve events on a more individual basis rather than Lobe Separation...or at least trying to. Post's from ST members that were and are involved with DOHC engines doing positioning tests was also very inciteful to me.

There are some very interesting things being done with the Coyote engine...and others I'm sure, as far as playing with the camshaft actuators via software, in relation to rpm etc. as well. Want a lumpy idle in your Coyote? No problem..how does an instant 96 LSA at idle only sound to ya. There is definitely not one set of centerlines that are ideal through a broad rpm range.

[GARY C]

Over the years, studying the effects of cam positioning on my own and others dyno tests has led me to looking at valve events on a more individual basis rather than Lobe Separation...or at least trying to. Post's from ST members that were and are involved with DOHC engines doing positioning tests was also very inciteful to me.

There are some very interesting things being done with the Coyote engine...and others I'm sure, as far as playing with the camshaft actuators via software, in relation to rpm etc. as well. Want a lumpy idle in your Coyote? No problem..how does an instant 96 LSA at idle only sound to ya. There is definitely not one set of centerlines that are ideal through a broad rpm range.

Too many adjustments for my brain to deal with, it would probably get me in trouble.

If memory serves me right the one I saw ran a 106 through the meat of the pull moving to a 109 and ending with a 113... It might have been Jon that posted it years ago.

[digger]

One such engine I know has the ICL at 70 at 2500rpm and at ICL 125 at 7500rpm. Cam is about 230-235@0.050" if I recall. The exhaust cam doesn't move around as much though

Take a more typical fixed cam setup. Run the same overlap (ie fix evc and Ivo ) but change the evo and ivc it massively changes both topend and bottom end. Then investigate constant evo and ivc but vary the overlap. I've done this in engmod4t. Then do a sensitivity study on each event one at a time. Do it fir a bunch of different engine.

[user-23911]

I like the title of this one.

"Cam data from well developed engines".


It's so easy, everyone can do it themselves (yes, I have) without having to ask any questions.

Just go find yourself a "well developed engine" at your local junkyard.
Turn the flywheel into a degree wheel.
Adjust the valve lash so it's zero or negative.
Use a dial gauge to measurevalve lift every X crank degrees.
Pull the cam, measure base circle and max cam lift.

4 important numbers, IO, OC, EO, EC.
ICL, ECL, LSA, overlap, they're nothing more than different combinations of those 4 numbers.
Once you've done that, you'll be asking even more questions, like.......... why isn't max lift half way between open and close?
How would you know if you've never made the effort to measure?



A flow bench is OK but full of limitations.
28 inches water, that's about 1 PSI.
Atmospheric pressure is more like 14.5 PSI so it's 1/14.5 away from reality at best.
A flow bench that works at atmospheric pressure drop would be a good upgrade.
Making more vac than 28 inches isn't really practical either.
Even a 2000W electric vac motor struggles to make 28 inch vac at max head flow, well it won't.
So you'd need other methods, like a turbo converted to a jet engine.

Joe,
Really?

NOT! I am sure you understand pressure deferential. To see the full 14.69 psi you would need absolute zero pressure / psi in the cylinder.

Also just what is the atmospheric pressure in the room when you are flowing the heads?

What does the pressure deferential on a running look like fro IVO to IVC and how does it change with an increase in RPM?

Stan

I could quite easily go one or 2 steps further when I say I use turbos?
1 bar boost?

2 bar boost

Or more?


How much pressure differential is that?




If you've made the effort to measure all 4 events of the cam on cylinder 1, repeat with the opposite cylinder.
Are the events the same?
Should they be?
What about all the other cylinders?


They'll always measure a bit different.

[GARY C]

One such engine I know has the ICL at 70 at 2500rpm and at ICL 125 at 7500rpm. Cam is about 230-235@0.050" if I recall. The exhaust cam doesn't move around as much though

Take a more typical fixed cam setup. Run the same overlap (ie fix evc and Ivo ) but change the evo and ivc it massively changes both topend and bottom end. Then investigate constant evo and ivc but vary the overlap. I've done this in engmod4t. Then do a sensitivity study on each event one at a time. Do it fir a bunch of different engine.

I really thought a lot of the factory engines would have moved away from cams by now but I guess the technology didn't advance as was predicted.

Have you ever found engmod4t's predictions to match dyno results?

[MadBill]

...I really thought a lot of the factory engines would have moved away from cams by now but I guess the technology didn't advance as was predicted....Have you ever found engmod4t's predictions to match dyno results?

I met a guy at the Sonoma CA track in 1986 who was working on solenoid-operated valves. He figured his system would be fully operational in about two years. The plates on his Thunderbird read "EVA", for Electronic Valve Actuation...