AHA! Somebody who actually *asked* for a widget example this time. I love the new guys, they havn't had it up to thier eyeballs with my widgets as of yet,lol.
Let's just focus on your immediate "pro's" and "con's" as a hobbyist, shall we? Often time we are limited in funds, space and ability. This is nothing new. One thing we have plenty of is time to play with all sorts of neat toys. This is a good thing to encounter on the IR path if you have large parts. Being a fellow car enthusiast, I see your plight. Perhaps you'd rather spend the thousands of dollars ( it could reach that high considering elements, controllers, wiring, insulation, metal, time involved, etc... or even the outright purchase of said "large" oven) on your car instead of an oven that takes up valuable space. One might even argue the point that maybe at the moment at least, you don't foresee yourself doing any more than 6 sprint car frames a year at best. This is where a manipulative system such as an IR source comes into play. The advantages are this : low cost, low storage structure, ease of use and lateral use within your coating shop for other purposes (they can be used to dry a part after phosphating rather quickly, or as a heat source if you have a cold garage and you need it momentarily near you). Disadvantages of the system include : tough work status if you intend to coat for everyday use, longer time spent on car frames and such compared to an oven because one must "move" the source around to get a cure, uncured portions of substrate due to the IR wave not being able to see around corners effectively. As you can see... you have some thinking to do.
We'll get back to your car frame in a minute. Let's flesh out your other parts first, shall we? For valve covers and the like.... I'd get a second hand used kitchen oven. It's not that you can't use the IR light without great results.... but I see them as an "add on" to the smaller ovens. Use the kitchen oven for the intake and valve covers, bracketry,etc..... use the IR for frames and parts that won't fit into the smaller oven. Chances are, you'll be using the smaller oven quite a bit, and the IR only once in a while. ( many small things on one car, only one frame per car,etc). Think of it this way.... a "marriage" of the two methods of heat, if you will. One is a smaller chamber and indirect so that it heats a given void of space, the other is direct and more focused. You can coat a bridge if you really desired to do such a thing. Now are you seeing how they both have thier purposes? Now... with that said, back to your car frame.....
An IR light only heats what it can see, as stated above. Therefore, logic dictates that if you can see it, so can the light wave. Where this comes into play on your tube chassis is this..... standard coat in say... matte black for example purposes. Position the IR light over the front section of the frame and you'll notice momentarily the cure process begin to take shape. Once a predetermined amount of time has passed (as dictated by your powder guidelines) you move the light to the next area and so on down the line until you part is cured. It may take a little more time this way, but I'm willing to bet you don't have the space or money right now to just go buy or build a large oven to fit it all. Another use for the IR that is an advantage is "on the spot" repair. Let's just say that you have a major coating failure in an area due to say.... you had to reweld in a new section from a hit. Well..... this is where an IR would be a lot better. As anybody here can tell you, to re-coat in an oven means sanding everything for adhesion and then coating it all over again. An IR light can simply be moved to said welded area and you can coat just what you need to without having to heat the entire mass. Pretty sweet,huh? When you're done with the lamps, you can just fold them up out of the way and save some space for something else without having to work around a big oven forever. Call it a "collapsable oven" if you will. It may take you longer for the overall cure, but you make up for it in square footage and money saved. Who knows, down the road if you find yourself doing more and more frames, you can actually get a bigger shop and build or buy that large oven. I whole heartedly endorse you to do just that if you have the means. The IR will still be there as a back-up and forever ready for those jobs needing touch up and such. (not to mention, a quite effective parts dryer after phosphating even after you have your big oven).
Personally, I recommend for your purposes, 2 of PRODM2000 listed on this page :
http://www.caswellplating.com/powder/caswell_lamp.html or even one PRODM9000 and one PRODM2000 for your purposes. Set the lamps facing one another (in the M2000 instance) and the light refelcting into each other will negate and anything inbetween will be cured having been trapped in the midway. The fold easily and out of the way and lemme tell ya, you can't even compare the price between a huge industrial oven and the price of the IR's (2 ea. of M2000 cost 600 bucks). The gap between the two is just that large. We're talking thousands saved here as well as the above mentioned space. The only thing it costs you is a little extra time. But like I said... if that's even a huge factor, go for the M9000..... bigger work space = less time adjusting lamp position. Plug em in, use em, then move them out of the way. Quick, clean and cost efficient. All of the above holds true for your headers as well. Just hang them on something that will swivel and keep the lamp in one position. When one area is cured, rotate 1/4 turn, cured again, another turn. Keep doing that until you've rotated the part 360 degrees and it will be done. Typical distance for short wave IR is 12 inches, and medium wave is approx 16 inches from distance to part. Hope that helps answer your questions bud.... keep us posted as to what you finally settle on,k? .... Russ