Don Terrill’s Speed-Talk

F-BIRD'88 wrote: ↑Thu Mar 21, 2019 9:31 am Are u flowzin the base+ head with a generous radius (putty) at the base inlet? Great thread.

About 3/8" clay. Thanks, Charlie

What cfm would you like to see for a 6,000 peak rpm 350, Charlie?

RevTheory wrote: ↑Thu Mar 21, 2019 11:02 am What cfm would you like to see for a 6,000 peak rpm 350, Charlie?

I have been thinkin about that Rev. I would like 250 cfm but at this point 220 cfm will have to do. I am only a few cfm from this on cylinder #1 which should be the worse runner. Thanks, Charlie

Quick test of 48 mm t.b. with radiused tpi runners. This throttle body only loses 4.7cfm @ .5" lift over larger aftermarket (bbk) throttle body. So not much of a restriction there. It did come with an ugly center filler piece. It would be of interest to see how drivability and tip in are different with the two. Thanks, Charlie

Can you say "Pushing your luck."? Can't kick me for trying. I would like some input on this new texture. I call it "Smear". 90 degree lines against flow with bumps. Super easy to do. Thanks, Charlie

Look closely at the left corner in that pic.

Carnut1 wrote: ↑Sun Mar 24, 2019 7:30 am Look closely at the left corner in that pic.

Water flowz

gmrocket wrote: ↑Sun Mar 24, 2019 8:37 am

Carnut1 wrote: ↑Sun Mar 24, 2019 7:30 am Look closely at the left corner in that pic.

Water flowz

Slp runner, just extra air until I tig it up.

Carnut1 wrote: ↑Sun Mar 24, 2019 10:27 am

gmrocket wrote: ↑Sun Mar 24, 2019 8:37 am

Carnut1 wrote: ↑Sun Mar 24, 2019 7:30 am Look closely at the left corner in that pic.

Water flowz

Slp runner, just extra air until I tig it up.

Do you not make any depth reference points when your grinding to reduce the chances of breaking through?

gmrocket wrote: ↑Sun Mar 24, 2019 1:53 pm

Carnut1 wrote: ↑Sun Mar 24, 2019 10:27 am

gmrocket wrote: ↑Sun Mar 24, 2019 8:37 am

Water flowz

Slp runner, just extra air until I tig it up.

Do you not make any depth reference points when your grinding to reduce the chances of breaking through?

I use my sonic but it is difficult doing corners. Other times on something like this I just get carried away trying to get area or a shape just right. I certainly pay less attention on aluminum that will get welded anyway. Thanks, Charlie

I should add that big aggressive burrs remove metal at a high rate of speed.

After some testing I think this is my winner for overall flow in the lift range this engine will see. 2.02 Manley straight stem with a 32 degree back cut done on my Sioux 2001. They flow an amazing 13 cfm @ .15 lift more than a pro flow design with a necked down stem. It beat the pro flow design @.5" lift and equaled the same valve without a backcut.
Just head flowed with 1204 radius
From my phone so it did not make nice rows, sorry.

Pro flow nbc Straight stem. Straight stem bc
. 05. 38.3. 36.9. 37.4
.1. 71.7. 70.3. 72
.15. 100.5. 106.2. 113.4
.2. 134.1. 143.2. 143.3
.25. 164. 170. 170.5
.3. 192.3. 197.2. 195.1
.35. 215. 217.3. 217.7
.4. 232.7. 235.1. 235
.5. 255.9. 257.3. 257.3

Carnut1 wrote: ↑Sun Mar 24, 2019 3:14 pm

gmrocket wrote: ↑Sun Mar 24, 2019 1:53 pm

Carnut1 wrote: ↑Sun Mar 24, 2019 10:27 am

Slp runner, just extra air until I tig it up.

Do you not make any depth reference points when your grinding to reduce the chances of breaking through?

I use my sonic but it is difficult doing corners. Other times on something like this I just get carried away trying to get area or a shape just right. I certainly pay less attention on aluminum that will get welded anyway. Thanks, Charlie

i used to do it like that too,, but unless you have photographic depth perception you just cant keep track of your cut depth unless you continually sonic over and over..way to tedious. especially if your shooting for the minimum wall thickness on a max port. doing about one sq inch at a time sure helps keep you focused on where you are in relationship to the original surface . ill never understand how some guys do a complete removal of the original cast finish, then go ahead and grind away on just about the whole surface area of the port at the same time.....its too much of an area to keep track of, unless its minor port work.

the way i do it now is actually way quicker and eliminates the chance of breaking through.... and it just about guarantees a uniform min.wall thickness. once you have you depth reference points done, you can go right at it with good pressure and an aggressive burr...

Carnut1 wrote: ↑Sun Mar 24, 2019 3:22 pm 20190324_152100.jpg
I should add that big aggressive burrs remove metal at a high rate of speed.

yup, and they bite more in the corners too.

gmrocket wrote: ↑Mon Mar 25, 2019 12:51 am

Carnut1 wrote: ↑Sun Mar 24, 2019 3:14 pm

gmrocket wrote: ↑Sun Mar 24, 2019 1:53 pm

Do you not make any depth reference points when your grinding to reduce the chances of breaking through?

I use my sonic but it is difficult doing corners. Other times on something like this I just get carried away trying to get area or a shape just right. I certainly pay less attention on aluminum that will get welded anyway. Thanks, Charlie

i used to do it like that too,, but unless you have photographic depth perception you just cant keep track of your cut depth unless you continually sonic over and over..way to tedious. especially if your shooting for the minimum wall thickness on a max port. doing about one sq inch at a time sure helps keep you focused on where you are in relationship to the original surface . ill never understand how some guys do a complete removal of the original cast finish, then go ahead and grind away on just about the whole surface area of the port at the same time.....its too much of an area to keep track of, unless its minor port work.

the way i do it now is actually way quicker and eliminates the chance of breaking through.... and it just about guarantees a uniform min.wall thickness. once you have you depth reference points done, you can go right at it with good pressure and an aggressive burr...

I can see that working for a port you have developed before but I can't see how that would work on a port you are still designing. Thanks, Charlie