before/after 383 dyno results

[CGT]

This thread is still salvageable. It may be getting trolled a bit(FACT) but big deal. Im looking forward to the results all politics aside . No need in being so easily offended.

[paulzig]

The incorrect conclusion to draw from that is that too much low lift flow is bad.

If I have a camshaft that is optimally managing cylinder pressures in the engine, and you then go increase low lift flow which increases the effective overlap shooting all the torque out the exhaust pipe then why not draw the conclusion that low lift flow is bad...

When you say a cam is optimal are you saying this based on the cam matching the flow numbers low to high or the cam effectively managing cylinder pressures?

[Carnut1]

I don't think there can be an apples to apples low low lift flow vs, high low lift flow because for that application it needs a specific amount of overlap flow. If the low lift flow is different than optimum the lobe centerline angle must be changed to bring the low lift flow back to optimum. Thanks, Charlie

[zums]

Looks like this thread has finally gone the direction it was intended to go from the beginning.

They normally get there one way or the other. Surprisingly this one did take a little longer.

Stan

Maybe you could make a chart about threads that get locked because of fan boys vs threads that dont, they would be about as useful as your other charts
Tom

[Stan Weiss]

This thread is still salvageable. It may be getting trolled a bit(FACT) but big deal. Im looking forward to the results all politics aside . No need in being so easily offended.

Does trolled mean someone has a differing idea on how to make the different parts (head flow, cam events, etc) work together. I know for some of you "Discussion is a dirty word".

Stan

[Stan Weiss]

The incorrect conclusion to draw from that is that too much low lift flow is bad.

If I have a camshaft that is optimally managing cylinder pressures in the engine, and you then go increase low lift flow which increases the effective overlap shooting all the torque out the exhaust pipe then why not draw the conclusion that low lift flow is bad...

When you say a cam is optimal are you saying this based on the cam matching the flow numbers low to high or the cam effectively managing cylinder pressures?

If that is the case why would I change anything? If that is not the case then you are saying if I have more low lift flow that I can not have a camshaft will optimally managing cylinder pressures in the engine?

Stan

[PRH]

My suspicion is that those individuals who are putting together the pushrod v8 engines that make the most hp/ci......... are not focused on how to improve the low lift flow in their cylinder head program.

[CGT]

This thread is still salvageable. It may be getting trolled a bit(FACT) but big deal. Im looking forward to the results all politics aside . No need in being so easily offended.

Does trolled mean someone has a differing idea on how to make the different parts (head flow, cam events, etc) work together. I know for some of you "Discussion is a dirty word".

Stan

No. We have a couple suspicious new members posting on this that sound like old members. Besides, this isnt a theoretical magic overlap thread. Real stuff.

[Orr89rocz]

The ideal camshaft would have a completely square valve event.

I dont believe this is correct. I think The Air column takes some time to move and build speed. It is drawn in by piston motion which creates cfm demand and that changes as the piston picks up velocity and drawn in as well by the depression across the cylinder by the exhaust scavenging. If we had instant valve motion from some kind of solenoid valve, i dont think just snapping open at peak flow would build air velocity and increase ve. I might be wrong here but i think i recall something like this from an old thread on valve motion and solenoid or pneumatic valves. I’d have to look for it

[cgarb]

Formula 1 has or has had pneumatic operated valves at some point. I'm not sure if the air was used as a spring or if the valve was completely pneumatic operated by solenoids. I would think if you weren't limited my the geometry constraints of a camshaft lobe, opening and shutting a valve faster would make more power. Not to mention you could probably vary the amount it opens and when with rpm and throttle demands.

[Orr89rocz]

Formula 1 has or has had pneumatic operated valves at some point. I'm not sure if the air was used as a spring or if the valve was completely pneumatic operated by solenoids. I would think if you weren't limited my the geometry constraints of a camshaft lobe, opening and shutting a valve faster would make more power. Not to mention you could probably vary the amount it opens and when with rpm and throttle demands.

Yeah it be truly variable valve event/cam lobe technology but i still not sure they would be just opening straight to a set lift point like a square lobe. Maybe they would but i cant picture it with balancing port and cylinder pressures and air velocity. Interesting idea and totally off topic lol

[cgarb]

If you had a square valve event how would increasing low lift flow effect that?...lol

Joking...but seriously I do look forward to dyno results on this, I find Randy's builds interesting and informative.

[Walter R. Malik]

Seat angle threads end up revolving around CFM on a bench. A lot more people have access to a flow bench than to a dyno. It's hard to accept something flowing less but making more power after we've been around stuff that was ported for CFM only and it ran better than the as cast heads. But,...that don't mean something done differently won't be better. I've seen less CFM heads beat others flowing more at every lift more than once. It's not easy (or at least wasn't at one time) to know you can do something to a head that will gain CFM, but choose not to do it. I haven't re flowed these heads down low since the valve job, but I'm certain they will flow less below .300-.400. I'm sure grinding the throat out will flow more. A bigger valve and blowing the chamber out will flow more, and it's up to me, I could do all of those things and the owner will fund it, but how would it run ?
Some of those have their place,...

Randy

Way back almost 50 years ago, there is a small tidbit in the Bill Jenkins Chevrolet book where he says, "Anytime I do something which requires me to take cam out of it, I go slower".

What is the reasoning behind that...?

This just might be what happens with a greater percentage increase at low lift flow vs. flow percentage increase everywhere else.

[smeg]

My suspicion is that those individuals who are putting together the pushrod v8 engines that make the most hp/ci......... are not focused on how to improve the low lift flow in their cylinder head program.

This is spot on the money.

[randy331]

For the vast majority of engines that have physical limitations on lifter diameter, journal diameter, etc, how do you just "cam it right" for improved low lift flow ?

How do you keep the time/area up top if you just keep improving low lift flow and taking duration out to compensate?
Lift becomes a limit as duration goes down.

The problem is, we are always confronted with the choice of best compromise. The valves don't have unlimited motion. We are always confined by the architecture of the engine, class rules, budget, etc.
The best cam for a certain application isn't a perfect cam, it's just the best compromises.

There are other reasons steeper seats are used than the flow we see on a bench.

So far the thread has been for the most part very civil even though there has been disagreement on ideas,...as it should be.
For the few that think this thread had some sinister motive to go down a certain path and have nothing to contribute,... read other threads and stay out.

Randy