Meaning? You thought they would be further apart, closer, more flow, less flow?
Great effort, kudos on finding out what's what and close to the casting limits in some cases.
Moderator: Team
Meaning? You thought they would be further apart, closer, more flow, less flow?
Yes, I was expecting much more from the slp modified runners. Now that may just mean the obstruction is somewhere else. I need to take some more airspeed #s. Thanks, Charlie
The chamber side of the valve is much more likely to lead you down the wrong path, than the port side of the valve.
I took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
I've done a lot of long runner development, what you are saying is right. You don't want large airspeed changes in a given runner/port section. Your fastest air should ALWAYS be in the head, at least from an average velocity standpoint. This will produce a responsive engine with good transition response between middling load to high load. This isn't always the easiest thing to see in a static flow bench test.Carnut1 wrote: ↑Tue Mar 19, 2019 12:11 pmI took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
Sorry, meant to say the flow bench will lead you down the wrong path on the chamber side, much easier than the port side.Carnut1 wrote: ↑Tue Mar 19, 2019 12:11 pmI took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
Thank you!LoganD wrote: ↑Tue Mar 19, 2019 12:26 pmI've done a lot of long runner development, what you are saying is right. You don't want large airspeed changes in a given runner/port section. Your fastest air should ALWAYS be in the head, at least from an average velocity standpoint. This will produce a responsive engine with good transition response between middling load to high load. This isn't always the easiest thing to see in a static flow bench test.Carnut1 wrote: ↑Tue Mar 19, 2019 12:11 pmI took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
So Randy, I will admit I did not expect such a large flow gain by some chamber deshrouding. Do you think the shrouded chamber had the ability to make more power with less flow? If you do what do you think some of the reasons that would happen? Thanks, Charlierandy331 wrote: ↑Tue Mar 19, 2019 12:28 pmSorry, meant to say the flow bench will lead you down the wrong path on the chamber side, much easier than the port side.Carnut1 wrote: ↑Tue Mar 19, 2019 12:11 pmI took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
Chasing flowz on the chamber side is likely to take you backwards.
Randy
That's easy, a shrouded valve will cause more charge motion, generally in the form of tumble. This will help BSFC and knock resistance. Most modern tumble port 4-valve heads deliberately shroud the area of the intake valve near the cylinder wall to cause a low pressure condition that forces tumble.Carnut1 wrote: ↑Tue Mar 19, 2019 12:45 pmSo Randy, I will admit I did not expect such a large flow gain by some chamber deshrouding. Do you think the shrouded chamber had the ability to make more power with less flow? If you do what do you think some of the reasons that would happen? Thanks, Charlierandy331 wrote: ↑Tue Mar 19, 2019 12:28 pmSorry, meant to say the flow bench will lead you down the wrong path on the chamber side, much easier than the port side.Carnut1 wrote: ↑Tue Mar 19, 2019 12:11 pm
I took a long look at that as well. I know the system flows more with a bigger port but is that wise? Having fast air in the runners and a lazy port may not be a great combo. What I think would work well is have each section close to flow and csa so the airspeed is similar. I haven't done any long runner applications so I don't know. Thanks, Charlie
Chasing flowz on the chamber side is likely to take you backwards.
Randy
Logan what does the D stand for? David?LoganD wrote: ↑Tue Mar 19, 2019 12:55 pm That's easy, a shrouded valve will cause more charge motion, generally in the form of tumble. This will help BSFC and knock resistance. Most modern tumble port 4-valve heads deliberately shroud the area of the intake valve near the cylinder wall to cause a low pressure condition that forces tumble.
I have seen that, now often on ST pros will state they will rather have higher flow than swirl or tumble. As far as a wedge chamber from what I have tested (flowbench with swirl meter) they actually have too much swirl and a step back would be better. Thanks, CharlieLoganD wrote: ↑Tue Mar 19, 2019 12:55 pmThat's easy, a shrouded valve will cause more charge motion, generally in the form of tumble. This will help BSFC and knock resistance. Most modern tumble port 4-valve heads deliberately shroud the area of the intake valve near the cylinder wall to cause a low pressure condition that forces tumble.Carnut1 wrote: ↑Tue Mar 19, 2019 12:45 pmSo Randy, I will admit I did not expect such a large flow gain by some chamber deshrouding. Do you think the shrouded chamber had the ability to make more power with less flow? If you do what do you think some of the reasons that would happen? Thanks, Charlie
If done like Cosworth 60's patent tumble is made with port bias - port is at different angle than valve and at high lifts flow detach from SSR and makes SSR side of valve low pressure area, which with upper valve part flow directed downward with chamber creates tumbling motion in cylinder. More valve lift than what is needed for max port flow increases tumble even more so its usual to lift valves much more than what is needed for max flow. Modern eco-heads have skijump in port floor to detach flow from SSR without high valve lifts.