Don Terrill’s Speed-Talk

I have a question in a similar vein to the one that Bigchief632 asked: How much power is a more efficient combustion worth? (Let's say you had a certain engine and you made changes to the chamber, or max quench velocity, or spark plug location that allowed you to reduce the ignition advance without ...

I have never been clear on the difference between Mach index and the percentage of Mach 1. Are they the same? ....I sure HOPE they're the same or I'm even more confused than before. I'm sure the caveat statement that Mach 1 at different temps is different still applies, though, but I'm happy enough...

I think my last major question; this one for the head-porters. When you're evaluating the cD of your head at a given valve lift, you're not using these theoretical calculations, you're actually just using a pitot tube and measuring the actual velocities around different parts of the port and then va...

Now I'll roll out my "jump to conclusions mat" and jump to some conclusions, as it's a lovely game! And here is one of those variables...ignition delay. The ignition delay refers to the time it takes to get the mixture burning at a self sustaining rate. Excessively rich or lean mixtures wi...

Valve size is more of a relationship to bore diameter. I only use a mach index 0.613 (690fps) when calculating MCSA in a port. I prefer to look at cfm/in2 at valve and throat area. Valve size is more of a relationship to bore diameter. If the valve/throat is the MCSA then I would use mach index.wor...

Valve size is more of a relationship to bore diameter. I only use a mach index 0.613 (690fps) when calculating MCSA in a port. I prefer to look at cfm/in2 at valve and throat area. Valve size is more of a relationship to bore diameter. If the valve/throat is the MCSA then I would use mach index.wor...

I'm curious about the implications of running a too small intake valve on an engine, how much attention to pay to the mach index calculators that look at intake valve size, and whether a head that flows more air with the same size valve makes the situation of a "too small intake valve" wor...

too much overlap makes for a poor cruise MPG. Why? And is it inherent directly to more overlap or dependent upon other factors that usually "come along for the ride" with more overlap? When it comes to pulling fuel out the exhaust during overlap, IF you're running a modern port injection ...

mag2555 wrote: ↑Tue Oct 18, 2022 5:08 pm Get a sheet of 40 grit sand paper.

Cut it to fit both the length and width of your short turn and then contact cement it down and make some flow test.

This is easily reversible.

Umm... This is a GREAT idea. I want to see the results already!


Has anyone actually done this before?

Adam

Vortecs in stock form flow better than any other stock GM head. Stock GM SBC IRON head maybe. The FastBurn heads do exist and flow a LOT better than any Vortec head out of box. 266cfm @ .500", 275 CFM @ .600". They ARE A LOT bigger @ 210cc, though and with raised ports, but they are a &qu...

Stupid idea: Can you run an old smog pump with one of the electric pulley drive water pump motors as a rule hack and rig it up as a vacuum pump only at idle? It's technically not a vacuum pump; it's just a SMOG A.I.R. pump... https://www.lethalperformance.com/mr-gasket-electric-water-pump-drive-kit-...

No idea if AR chambers improve idle vacuum (I could see that they might...), but to answer your previous question about where to place AR mufflers: Hendren Racing / Crate Insider advises that the longer the primary, the closer you want the muffler to the collector. -They teste the crap out of theirs...

Does quench matter? How much.? How much quench clearance is enough.? Does low rpm (eg stock engines) require tighter quench clearance than high rpm. to be effective? VERY good questions. My take on what I THINK I know: 1. "Does quench matter"/affect power? Yes. But helping to reduce ignit...

Sketch area calculator Which is what that is. I didn't put the results. I know very well what needs to be measured. My reply wasn't meant to imply that you didn't know. It was more of stating the obvious. And the sketch area calculator was the software I was referring to. If you're so inclined, you...

It's the task of calculating the area of the quench pad "crescent" and well as the remaining less than circular chamber. I could in there with a ruler and calipers but it seems to me there's software out there that could "scan" the areas in question and crank out the requisite n...