200 CFM Research

[jfholm]

Another thing about turbos and superchargers is the whole intake is pressurized. I don't think you can treat it the same way as a N/A engine. My way of thinking is that port in a a turbo'd engine is packed full before you even start the valve to open. In a N/A engine you have to kind of talk it into moving. I don't know if that is a valid way of thinking but seems there should be some correlation along that line.

John

[200cfm]

Here is the extracted mold made this week from the red head. I straightened the headbolt turn wall a lot from where it started. And got a more gradual radius on the PRt wall side. Using filler now to try and fill in some of the bulge after the PRt. That wall will always have that turn by design but I am hoping the filler will reduce some of the expansion zone. And I wasn't to please with the mold shape of the bowl. Looked more like a tree stump than a bowl.

What makes a good bowl shape? Should the bowl ever be bigger than the throat or any of the angle cuts? What about the depth and angle of approach on a bowl?

Here is a before and after.



For some reason when I made a clay ridge between the one big channel (making it two channels) I gained a few cfm. That's why there is that cut in the roof mold. And I overlooked a pit cut made too deep on the roof while grinding. Mold shows it clearly needing a filler.



Side views, roof entry was raised a lot. the mold was poured to the very start of the seat which is why is shows more turn after the SSR. I still have lot of metal in that SSR base. Does it need to be laided back more. I made it wider but didn't take it back to far. (tom)

[jsa]

[jsa]

[jfholm]

[jsa]

[jfholm]

That is part of the trouble with email, forums and blogs etc. You can't tell with what "voice" the writer is using

I wasn't implying but really asking a question as I am not sure of the answer - can anyone tell me will the size of the port change the speed of sound?

John

[200cfm]

John, I going to guess that the port size itself will not affect the speed of sound. I see the port as just a medium or enviornment for the wave. But I do believe that the mach number is higher if the temperature is higher. Not sure about the density or mass causing the mach number to change in a gas. Might change at higher altitude because of the temperature change. Pretty cold at 30,000 ft so a sound wave would travel at a different speed.

I spent the whole day on the bench testing new shapes in my mock up head and finally hit 200.6 cfm at .500 lift this afternoon. So sound the alarms, ring the bells, and everybody have a beer or glass of wine and celebrate!

But to make sure I am not seeing things I will recheck it all tomorrow. I believe it is correct because I had to use two plates to handle the air at 28" wc. It was maxing out the incline on the largest single plate at .350 lift so that got me really excited.

That's one small step for a chevy port, one giant leap for a stude port . :p

[bruce]

New user name: 250cfm

[jfholm]

[49-1183904562]

Tom,

Great thread and real success.

It sound like your bench is ready for a PTS-DM, just put the 300CFM plate in and flow

Bruce you are a real Half Full Thinker, maybe 215CFM

Rick



Edited By 1960FL on 1238266137

[bruce]

I'd have to keep changing Tom's user name then, 250 might take him a tad longer to reach :;):

[jfholm]

No it won't Bruce. I am just going to end mill straight into his head for him with a 4" mill and press in some sewer pipe

[200cfm]

Thanks guys. I have the PTS plans and got 6 Surplus motors on stand by here. So a new bench is on the list here. No racing this weekend due to rain showers. But I just got back from VMP with the car from NHRA chassis recertification. Sportsmans qualified and good to go down to 8.50.

John, I like the idea of milling the port entry. Might be a good way to raise the roof for the first 2 inches and be consistent on the cuts.

[jfholm]

We have done that. Takes time. Poor man's CNC (my right arm)

John