What is more important during break in a tachometer or a heat meter heat sensor?
What brand would you recommend and why?

Tach.. hands down..

anyone. I have a Thunder Tiger model. I'm sure there are better ones... this one dosen't work too well in shade, the garage, dusk or dawn.. Needs quite a bit of light

Temp sensor is a nice thing too, but so far, haven't really needed one..

Personally, I wouldn't buy either. Just follow the recommended break in proceedure for your engine, and you shouldn't need either one.

I use the GloBee tach for the last three years,but'm sure there are as good or better on the market.

Granted, with yer average 2 stroke engine, using yer average recommended break-in prop, you should be fine with no fancy gadgets....
However, with a 4 stroke engine, a tach is more or less a necessity.
DO NOT buy a H9 DVT. I've currently got a Glo-Bee and seems to work for me... The best tach (within reason) would be the TNC sensortach.
The only reason I can think of why you'd need a heat sensor would be if you're experimenting with fuel, plug and prop combos to get the very last scrap of performance out of the engine for racing for example...

Trig, you must be a Tach salesman.

I have broken in more engines that I care to think about, and I used a tach for the first time last summer. The only reason I bought/used it, is that I was doing an engine review, and I wanted a picture showing the tach reading. And that is still the only thing I would ever need to use one for.

What difference does it make what RPM you're turning? Use a break in prop, and set it a little on the rich side. I have broken in every engine I own this way, and every one runs beautifully.

I have used a tach for getting the length of a tuned pipe right, and for some of my racing birds, but for the normal joe flyer, both the tach and the heat sensor are toys. Both a waste of money as far as I am concerned. You will use it once and then it will sit in the flight box and rot. Do as MNF says. Use the recommended procedures and don't waste your money. If you need to tach it, borrow one from someone that got one. He will be more than happy to get some use out of it.

LOL, so true! Come on over to my house, I'll let you use mine just to watch it work!

I have a tach and do use it. Saito tells you to keep it under, I think, 4000 rpm for the first 10 minutes or so of running. The tach helped me do that. Even with recommended props the engines don't always turn the way they're advertised, high or low. I use the tach to make sure my YS's are in the right ballpark, on the ground, when changing props. Maybe y'all are better than me in sensing RPM. I don't use a tach all the time, but do use it occasionally, and need it when I use it.

I guess I'd say, keep it running at as low an RPM as you can. That would be under 4,000.

I do have a tach that I bought a few years back. I haven't used it in a couple of years now. The only reason I ever DID use it was out of curiosity.
Dennis-

I have broken in a number of 2 strokes and a fair number of Saito's. I have a tach, it came in a swap of stuff I traded another guy with. I don't even know if it works. Never had it out of the box. I do it all as Minn and others do. I go by the instructions and by ear. I am also an ASE certified master auto technician, that helps some. I have never had the need,so far. Just follow the instructions and your engine will turn out fine.

Mark Shuman