[JulianEdgar]

Originally Posted by Isaac Zachary

The phrase: "there comes a point of diminishing returns." comes to mind. The question I'd have is how much would I benefit from the work involved. To get everything "optimal" in my mind requires not only redesigning the rear window and trunk area, but also making my own windshield and hood. At what point does optimal become OCD?

I really don't know why you take a simple example and then extend it to something quite different, as if that were being discussed all along. We are discussing the use of the template as purporting to suggest an optimal boat-tail shape. I don't know where that suddenly turns into reshaping the entire car.

If all it takes is a "little testing" "simple testing" that makes sense. However, in my mind it sounds like a lot of work. I'd be tempted to see if I get good mileage with the first mockup and then leave it on permanately if it does.

I've tried testing fuel/air ratios and degrees of advancement. And even though with those it's just a small twist of an ajustment screw or a distributor it's still a lot of work.

Now building not just a 3 dimentional mock up but several of them sounds a bit harder than just twisting a screw, at least for me. Or maybe I just don't understand the concept of "simple testing of mockups."

However, I'm still interested in trying a boat tail at some point as it seems to be the best way of getting better fuel mileage. So thank you, I'll keep these points in mind.

Turning air/fuel ratios and ignition timing is a good parallel. How would you react if someone said that for best power, you must have 12.5:1 AFR, for best economy, 15.7:1? I hope that you would say, "On what car and engine?" Because, as you are probably aware, suggesting that such rules of thumb should be universally applied is also rubbish. You can find these optimal values only through testing.

Re testing. It's the same with any car modifications - engine management, sound systems, suspension, cylinder head work, engine intake systems, aerodynamics. You can follow some rules of thumb - that may or may not work - and accept whatever results. Or you can do some testing and development and 90 per cent of the time get much better results.

Why? Because it's easier to just go with something predesigned. And if it produces possitive results, it stays on the car. If it doesn't it gets taken off.

But you make it sound like the level of effort isn't much different either way, template or mock-ups.

[shrug] Is fitting whatever springs Fred says will work best (because he has a completely different car but they work on his car) better than making some measurements of the existing springs and then developing new ones from that starting point? Pretty obviously, no.

It's not a radical idea - actually making a car modification through measurement and development, rather than guesswork.

Sounds like he can't be happy with someone trying something that's not optimal, even if it ends up giving them a small benefit.

I've done aero modifications that either worked or didn't (ie made drag better or worse) through a 3 degree change in the angle of a spoiler. That's stuff you'll never know through blindly following someone's guesswork.

That's what makes it hard to follow his posts, for me anyhow. It's kind of like one guy saying he's going to lean out his carburetor and another ridiculing him for not installing fuel injection and tuning each cylinder's AFR.

It's nothing like that at all. A much better parallel is ridiculing someone for following the AFRs and ignition timing given to him as being optimal by someone who didn't even know what engine he is using. That's how stupid The Template is as a guide to aero car modification.