CFM + Airspeed = mass flow rate, assuming of course there's no density changes to the fluid. Remember when that flow starts going faster than 350ish feet per second, you will start getting changes in air density, which means that CFM starts to matter less, because the stuff in that cube isn't constant, but your velocity(how fast you move those cubes) then starts to matter more.
The valve, the seat and the throat radius, all form one continuous variable duct. Therefore they cannot be seen independently of each other. Cut aways of the ports are great for this reason, as you can see the venturi tunnel in 2 dimensions, you can get a better idea of what shape you want with the valve installed how it conforms to the chamber. You can use your technique of using a wire to shape the radii on a cutaway, then transfer it to full head itself? Most of the gains and losses are going to happen on that throat radius, as you've clearly seen. Now you have the chance to use epoxy to reform that throat radius, although with this heat I wouldn't blame you if you took the weekend off. But I'll keep watching and learning if you keep making vids.
@@luckyPiston Absolutely, the valve and the seat are the inlet to the exhaust port, and the radius is essentially the expansion for the flow after the seat and valve. It almost works like a steam ejector. ruclips.net/video/N-1MrAABFIA/видео.htmlsi=3GYhXDO8rkkjncq4
I feel like the change led to the airflow separating from the throat wall behind the seat, possibly because the shortside not being ideal to the new throat ratio. Pushing the air where it doesn't want to be.
@@servediocylinderheads honestly we should be thanking you for have the patience to actually do one change and record the results in the most scientific way possible.
I would be interested in seeing what happens with valve angle changes same bowl ratio or possibly chamber mods. My thinking on a higher rpm application a different seat could be the ticket.
You need to work on the guide more, stop playing with the Short Side radius of the exhaust port. I have seen larger gains by simply shaping the Guide and making the Guide "blend" into the Valve stem so the air will just naturally flow by it as it's is exiting. Also you need to widen the exhaust port (on the furthest side of the exhaust port in the Bowl away from the intake port) almost to the point of Undercutting your exhaust guide but keeping it blended nicles with a gradule "round Over" and you need to try a 45 Main valve seat sealing point with an additional 30 degree cut
CFM + Airspeed = mass flow rate, assuming of course there's no density changes to the fluid. Remember when that flow starts going faster than 350ish feet per second, you will start getting changes in air density, which means that CFM starts to matter less, because the stuff in that cube isn't constant, but your velocity(how fast you move those cubes) then starts to matter more.
Important information! Watching your successes and failures is good! You saved me from ruining ex ports on the heads for my project!
@@user-mm9ol9oi1i Glad to read that! Thanks
You lost all the radius going to the seat that kills flow, good info
Sinking the valve a decent amount and adding a substantial top cut would probably help a bunch + radius the edge of the valve
@@roberthollinshead2325 I agree. Thanks
Very interesting!
@@bcbloc02 Glad you like it. Thanks
The valve, the seat and the throat radius, all form one continuous variable duct. Therefore they cannot be seen independently of each other. Cut aways of the ports are great for this reason, as you can see the venturi tunnel in 2 dimensions, you can get a better idea of what shape you want with the valve installed how it conforms to the chamber. You can use your technique of using a wire to shape the radii on a cutaway, then transfer it to full head itself?
Most of the gains and losses are going to happen on that throat radius, as you've clearly seen. Now you have the chance to use epoxy to reform that throat radius, although with this heat I wouldn't blame you if you took the weekend off. But I'll keep watching and learning if you keep making vids.
so u think the throat radius is a player too , not just its diameter ? secondly would that factor into v/v sizing to maintain desired radius angle ?
@@rolandotillit2867 The wire helps keep each port very close in shape. Thanks
@@luckyPiston Absolutely, the valve and the seat are the inlet to the exhaust port, and the radius is essentially the expansion for the flow after the seat and valve. It almost works like a steam ejector.
ruclips.net/video/N-1MrAABFIA/видео.htmlsi=3GYhXDO8rkkjncq4
I feel like the change led to the airflow separating from the throat wall behind the seat, possibly because the shortside not being ideal to the new throat ratio. Pushing the air where it doesn't want to be.
@@lucascb750 Stay tuned, it gets more work. Thanks
@@servediocylinderheads honestly we should be thanking you for have the patience to actually do one change and record the results in the most scientific way possible.
@@lucascb750 A whole weekend for this series. Thanks
Volume is everything when it comes to exhaust. Don't pay attention to flow. More room, the better.
@@approachingtarget.4503 I have heard that before. I agree for high rpm race engines but not for street applications. Thanks
I would be interested in seeing what happens with valve angle changes same bowl ratio or possibly chamber mods. My thinking on a higher rpm application a different seat could be the ticket.
@@bobbyhaskell2048 Sure, just give me extra work.
@servediocylinderheads 😆
Those airspeeds look great. Is there anything left of the venturi? It seems odd that the CFM is noticeably down everywhere. Great video.
@@briantayes2418 A little. Thanks
I'm thinking cfm is down because of non laminar flow in the absence of adequate venturi , there is velocity but its not clean air so flow is down ?
@@luckyPiston Good question, I was not expecting shuch a big loss with such a small change. Thanks
Hi charlie can i use dv low budget flow bench manometer to compare ports after porting?
I would say yes. Thanks
Must have lost laminar flow somewhere in the port. Did it get noisy?
@@jamesandannschmitt6835 If it did I would have written that on the flow sheet. Thanks
How thick is the port wall at this point?
@@mikkokuorttinen3113 Thin spot is .140"
Still usable
Don’t keep flogging dead horses
@@copisetic1104 Noted. Thanks
You need to work on the guide more, stop playing with the Short Side radius of the exhaust port. I have seen larger gains by simply shaping the Guide and making the Guide "blend" into the Valve stem so the air will just naturally flow by it as it's is exiting. Also you need to widen the exhaust port (on the furthest side of the exhaust port in the Bowl away from the intake port) almost to the point of Undercutting your exhaust guide but keeping it blended nicles with a gradule "round Over" and you need to try a 45 Main valve seat sealing point with an additional 30 degree cut
@@trxtech3010 The roof and guide have very little work done. Thanks