Don Terrill’s Speed-Talk

If you could only have too much or too little valve area which would you prefer for making power and what's the maximum percent of too big or too small?

If it's a racing application, I would always rather be too big.
If you're too big, you will lose some torque, but there's things you can do with the cam profiles, to get back the torque.
If you're too small, you lose Top-end power, and there's nothing you can do, to get that back.

I have no idea, about max %. It's not something I would ever want to calculate. If it's wrong, fix it.

What if i have an engine that requires 3.065 and the after market head is 3.676? Is that too much to fix with a cam?

Depends on the application.
25 years ago, the -12 Brodix heads they ran on the 410" sprint cars, were way too big for the engines, but they worked fine in the application.

Mike,

Assuming the valve area is correct do you always design the cam for 300fps or do you ever increase it beyond that?

learner1 wrote: ↑Fri Jan 08, 2021 10:21 pm Mike,

Assuming the valve area is correct do you always design the cam for 300fps or do you ever increase it beyond that?

Let me know when you find a 2-valve race engine that has the correct valve area, for what they want it to do. You'll have a better chance, finding a unicorn.
300fps works for the street/strip or bracket racers that aren't pushing the limits.
With the serious race engines, even if it's built with the correct valve area, for it's design goals, before it's off the dyno, those goals have changed.

Understood. With my lack of knowledge i may not be asking the correct questions but i've got to start somewhere.
What are the design velocities for engines that are pushing the limits?

Mike,
I recall talk of a cam program in progress that would eventually be available for purchase. Is that still in the works?
Thank you.

pastry_chef wrote: ↑Sat Jan 09, 2021 6:56 pm Mike,
I recall talk of a cam program in progress that would eventually be available for purchase. Is that still in the works?
Thank you.

No. We use to sell a cam program I wrote, that calculated the optimum cam, and picked the closest lobe profiles, from all our designs.
I did this, to reduce the amount of time, I would spend on figuring out what cams my customers needed. It turned out to be the opposite. The program would pick the same profiles, I would most likely pick, but the customers would either not believe the results, or have 20 questions on why the program picked the profiles. I spent more time answering questions, then I would spend calculating what they would need for a cam.

learner1 wrote: ↑Sat Jan 09, 2021 12:35 pm What are the design velocities for engines that are pushing the limits?

It depends on multiple factors. There is no one answer.

How about a pro stock engine?

learner1 wrote: ↑Sun Jan 10, 2021 2:20 pm How about a pro stock engine?

With a name like "learner1", you sure want a lot of answers given to you.

I appreciate his enthusiasm and tenacity and obviously he has come to believe that this site is one of his best opportunities to get some of his questions answered.
Learner 1, if you stay tuned in, you will indeed get many of your questions answered. If you stay connected and are diligent, you will began to grow in your knowledge and realize, that you are now asking questions and learning things that before you didn't even think to explore.
I personally believe we are all "learners" to some degree, carry on and good luck. The journey it's self is exciting and rewarding!

Just trying to learn something. Learning starts with asking a question whether you're asking someone else or yourself. If it's proprietary that's fine just say so.

Couldn't agree more Tom

I came here as a bit of a cocky t%@t fifteen years ago and was soon humbled by the real knowledge on offer

When the site went toes up and was resurrected couple years back I decided it was too good to lose so will pay to help fund it, despite being as 'cheap' as most other people ...... it's a commodity that's just too good to lose, unique even

I don't really benefit any more from what that brings, I'm the other side of the pond ...... I don't even get my free T shirt, lol (can it be sent to someone in the US who's at least paid a years subs?)

I'd encourage anyone who regularly looks in here to maybe think about the upkeep