Don Terrill’s Speed-Talk

Forgivin-ness prease if this has been smashed before, I had a good lookie around for it.

Can someone please explain why an engine makes more power off a burr finish in the intake port/runner.
All literature of flow in pipes whether turbulent or not results in an energy loss down stream if the surface is not as smooth as possible.
I understand boundary layers (turbulent and laminar) from Fluid Mechanics by Frank M. White etc.

I'm assuming it has to do with the increased shear from the increased boundary layer (due to surface roughness) doing something with the fuel that is suspended in air resulting in a net power gain?

Please don't hold back with the technical stuff

Thanks again
F.P.

golf balls!

Have a look through this thread.

viewtopic.php?f=15&t=34837

That all depends upon whether or not the runner is flowing just air, (which is simply about surface tension), or also fuel, (which takes atomization into account).

It doesn't my engine builder of 30+ years proved it.

69434 wrote:It doesn't my engine builder of 30+ years proved it.

Can you tell us more about how he went about proving it?

This summer in the heat I went to the track with a fully smooth ported manifold I had done. I took my tools and burr marked it out in his trailer after we got a base line. Put it back on the engine, AT THE TRACK, same day, and made more runs.

ALL of my manifolds are burr marked because it works.

cspeier wrote:This summer in the heat I went to the track with a fully smooth ported manifold I had done. I took my tools and burr marked it out in his trailer after we got a base line. Put it back on the engine, AT THE TRACK, same day, and made more runs.

ALL of my manifolds are burr marked because it works.

Interesting, so Im assuming the difference was significant enough with DA and conditions taken into consideration to make you a believer? Nice test. Maybe the heads should be roughed up next?

CGT wrote:

cspeier wrote:This summer in the heat I went to the track with a fully smooth ported manifold I had done. I took my tools and burr marked it out in his trailer after we got a base line. Put it back on the engine, AT THE TRACK, same day, and made more runs.

ALL of my manifolds are burr marked because it works.

Interesting, so Im assuming the difference was significant enough with DA and conditions taken into consideration to make you a believer? Nice test. Maybe the heads should be roughed up next?

I have fully burr finished heads out there.

I have several members on this forum with my manifolds, maybe they will chime in.

I even do it to sheet metal and tunnel rams!

Cool stuff. This is new to me.
What tool do you use to apply the burr?

CGT wrote:

69434 wrote:It doesn't my engine builder of 30+ years proved it.

Can you tell us more about how he went about proving it?

Many years of R&D with porting & a flow bench.
I'm not a head porter, so to get into the intricate details of head porting he would know.
He's taught me a lot, but he's not going to give out all his secrets, even to me.

cspeier wrote:

CGT wrote:

cspeier wrote:This summer in the heat I went to the track with a fully smooth ported manifold I had done. I took my tools and burr marked it out in his trailer after we got a base line. Put it back on the engine, AT THE TRACK, same day, and made more runs.

ALL of my manifolds are burr marked because it works.

Interesting, so Im assuming the difference was significant enough with DA and conditions taken into consideration to make you a believer? Nice test. Maybe the heads should be roughed up next?

I have fully burr finished heads out there.

I have several members on this forum with my manifolds, maybe they will chime in.

I even do it to sheet metal and tunnel rams!

Do the sheet metal manifolds have a burr finish?

Do the sheet metal manifolds have a burr finish?

mine do

Let's see a pic, every company I have looked at that make sheet metal manifolds don't have a burr finish, why is that?

No burr finish here