[Isaac Zachary]

Originally Posted by JulianEdgar

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.

I suppose because I was thinking more along the lines of boat-tail since I've been under the impression there's more to gain from boat tailing than front end-mods. And with a boat tail there's the angle on the top, angle on the bottom and angle on the two sides. Not to mention the question as to where to start the boat-tail in the first place, from off the trunk or start up at the top of the car above the rear window. How do you make a mock-up that's easily and acurately changed for testing.

Plus you keep mentioning the work "optimal" here. If following a one-size-fits-all rule-of-thumb or template has zero value, then following a one-size-fits all design and just moving it up or down a few inches to see where it's optimal doesn't sound like it would improve much either. It sounds, to me anyhow, like taking a template shaped car and then slighly lowering or raising the front and/or rear to see what gives you an optimal angle after a little testing and calling it good.

Originally Posted by JulianEdgar

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.

Maybe it was just coincidence, but I found that starting with the rule-of-thumb (or just a guess from my intuition) made the biggest difference (end result 24mpg to 30mpg). Trying to fine-tune from there didn't seem to help very much (30mpg to 30mpg)

Not only that, but with my testing I really felt that I was at the end of my measuring techniques. Throttle stops, coast downs, and other such rudimentary testing are nearlly impossible to get consistent results from. Do the test 10 or 20 times and then average the results... But it also gets kind of weird having neighbor folks watch you go up and down the same street day after day doing testing.

If I ever did an engine again I'd want access to a dynanometer. But would it be worth the $700 for just one testing session?

Originally Posted by JulianEdgar

[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.

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.

I would like to say to most everyone else's credit is that rarely do you find people on here who don't do any testing at all. What I mean is doing a mod and then seeing if you get better fuel mileage or not and then deciding to leave it on or not is still a form of testing. Sure, such a person may not get "an optimal" design, but if he or she gets better fuel mileage I think we can all be proud of him or her, can't we? Maybe in a few months or years they'll try out a slightly different version of the same thing and compare which of the two helped the most.

Originally Posted by JulianEdgar

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.

It's not the idea, it's the wording. As Freebeard mentioned, it seems you say one thing and then another. Not that you do, but this is what I was trying to get at earlier. What does the average Joe reading your posts understand from them?

This is what an average Joe will think, at least on the posts I've read (or tried to read):

1. Hey! I found a template that looks like a very aerodynamic shape on this site called Ecomodder. Cool!
2. A guy named Julian hates the template... So much hate, it sounds like he has no faith in aerodynamic shapes.
3. But wait a minute Julian says make a mockup and try it. But what's the difference between making a mockup based off of the template, and just making a mockup based off of my own guess and trying it? (Did he say try one mock up or two...??)
4. But wait again. Julian is now directing his disdain towards an individual. So maybe he's here for personal reasons...
5. Trying to read through the mudslinging...
6. More mudslinging...
7. Is this an ecomodding forum or a political debate?
8. Hey! Another topic on VW diesels! Maybe I'll move out of the aerodynamic forums for a while...

I'm not saying you said anything of this sort. But that's what the average Joe will understand from it all. Stick to your facts, be nice, don't direct thing personally towards others. Show a possitive before a negative

For an example, "I see you like this template here. A car shaped like the template both front and rear and everything in between may be more aeordynamic than your average car. But you're not going to be able to make your car exactly like it. My recomendation is, if you want mods that make your particular car much more aerodynamic than justfollowing that template then try this! I think you'll be much more pleased with the results!"

IF you learn to talk properlly you can learn to talk in a languange more average Joe's will understand.

Take me for an example. I'm finally understanding what you mean. But only after how many posts and threads? Forced ideas always become interpreted as something they don't mean. Persuasion gets more people to understand you.