Don Terrill’s Speed-Talk

Check out http://www.somender-singh.com/ It seems that the jury is still out on this one. Lots of folks claim they have noticed improvements but no dyno quantification yet. This thread has some limited info: https://www.speed-talk.com/forum/viewtopic.php?t=4069 . These grooves were on the heads of ...

I still up in the air about the port design. But I can say this, CFD is here to stay in racing and it's only going to get better. I know there are teams that don't even have a head porter to design ports and manifolds. They design it all with computers. I've heard about some teams and engine builde...

Hmmm... Since the target inlet peak velocity is typically derived from the local speed of sound, e.g. "0.6 Mach" and a blown engine's charge temperature might be anything from 60° F. to 250° F. , thus substantially altering the speed of sound, seems like the port CSA should also take into...

caddycarlo wrote:14.7 lbs of boost that is a easy one ....... you would need 41% more flow so if it is a stock head that flows 300 cfm you would need 423 cfm ......

How are you coming up with that number???

The port does not exit into an infinite volume like the straw, but a fixed volume that eventually builds to the same pressure as the port. ... That is why I made the distinction between a mechanical blower vs. an exhaust gas-driven one. In the S/C case, with a suitable exhaust valve, port & hea...

J-Rod wrote:I have to say this is a fantatic topic. Please keep the information coming.

Is there anything your looking for infoormation on?

Feed Forward is pretty much a GE Fanuc term... but is found elsewhere in other CNC Control systems... Feed Forward describes a system that reacts to change or disturbance. Basically it's when a CNC control system becomes off target... the control has the ability to move "back on target" o...

Just as has been mentioned... Boost Pressure is just an indication of Back Pressure in the intake tract. Turbos are so misunderstood still I think... much to be learned yet... ;) I'm not guru, and I find it hard to convince people this is the case. Any pressure reading is resistance to flow. They l...

i seem to remember that my 1380CC A-Series with Scatter Cam, anda "stage 4" head... made something like 120 or so Wheel HP... sure was a fun little car...

I'll see if I can find the dyno sheets...

Speaking again to the original quote, if the port velocity is similar (at least arguably roughly true for some turbo applications) and the density greater (no argument possible) then the inertia of the charge is also greater and quite apart from pressure ratio considerations, the valve timing event...

On a related note, I would like to hear the different means used to convert a port mold (or finished port) into a form suitable to obtain code from. Are you probing with the cnc machine (like Carl Hinkson does his blocks), or something like a CMM? How long does it take? What converts the point clou...

If you are looking for info on the British Leyland A-Series engine... then you can't beat the classic by David Vizard... I think the title is "Tuning the A-Series Engine" David goes into much detail on head work, as well as cam design and everything else along the way... I have a lot of ex...

Aaron, You discussed inverse time relating to feed rate and surface speed. Where does feed foward control fit into all this? Is "feed foward" just a proprietary marketing trademark of GE Fanuc, or it it an industry wide accepted term for servo tuning? Feed Forward is pretty much a GE Fanu...

Just as has been mentioned... Boost Pressure is just an indication of Back Pressure in the intake tract. I've had a lot of interesting conversations with Curtis on just this subject... If you increase the flow in the port... you will increase HP at the same boost level.... or, you can lower the boos...

The definition of 5-Axis simultaneous machining is pretty much as had been mentioned... but that doesn't explain WHY we need to use it for machining geometry such as that found in a cylinder head. The main reason is that it's the only way to actually machine around corners as found in a port. The sh...