lvw

Ok, I expect to be flamed on this since most people here are removing ac. Rev9 is advertising a conversion kit for right hand drive cars only, using the ND compressor which is smaller and supposedly more efficient. Has anyone here heard of such a thing,or tried this themselves. This would be for na and nb right hand drives. It seems you would need custom lines at the very least for a left hand drive? I am interested because I drive to the track for now and would like to keep ac but my compressor failed and na6 compressors are notorious for failure . Thoughts?

HarryB

Quite popular in Japan AFAIK. Maruha also sells a conversion kit themselves.

gooflophaze

So I'll preface this with I am not an A/C professional, however, I've done quite a lot of research on the subject.

This is interesting - there are 2 basic automotive compressor types. Poppet valves, that compress the gas via a piston and swash plate through a 1-way valve, and a scroll compressor. Scroll types are the new hotness - they do compress the gas without injecting as much heat (which is then cooled by the condensor core). Since they're mechanically simpler, they can be a little bit more reliable, a bit more compact in size too.

The question is, does that efficiency translate to a "better" a/c? In the miata.. not really. The NA/NB's a/c system sucks "in general" - on top of being a soft top and not really insulating, the condenser size is really damn small, the airflow kinda sucks, the expansion valve is kinda crap. NB2's got a lot of things updated - a new cartridge type expansion valve, and a new condenser that is 2/3rd cooling area, then an inline drier, which then allows the last 1/3rd to cool the now liquid refrigerant which increases its potential cooling - which if you go parts scouting through a junkyard, almost all cars 2005+ use a similar system.

So is this compressor upgrade worth it? IMHO - no. There's way too much other crap in the miata's a/c system that sucks to make a scroll compressor a silver bullet. Since you mention you're NA6 - that means you're either still rocking R12, or you have a R134 in an R12 system - which means a really unfit condensor core for R134 cooling (R12 is serial flow, R134's are parallel flow and much finer fins). From a track reliability standpoint - You could buy 4x NA/NB rebuilt compressors for the cost of the kit, and I don't think the NA compressor is inherently unreliable - the Denso(?) compressor that the NA8/NB uses is in something like 30 other vehicles.

HarryB

Late NB2 compressors are also scroll type (and identical to RX8 ones) BTW

lvw

Thanks, HarryB , and gooflophaze, for the info. If I were going to do this, I would not buy a kit, way too expensive. Probably used compressor, custom lines, then fab a bracket to mount said compressor. If these new compressors are not better , why are they being used? Plus I have a 1.8 engine in an na6, my compressor almost touches the sway bar. A shorter compressor would be much good. and I would end up putting in a new valve an parallel condenser. Yes I am still talking money, not as much as the kits. Thoughts?

lvw

But yes , for a track car it will probably be a rebuilt compressor. Still, please comment.

gooflophaze

They are "better" but not significantly better to upgrade to, especially at the 1k price IMHO. Close to touching the sway bar isn't touching the sway bar - I have seen a few different electromagnetic clutch types with different stick out length, but you're always going to be limited by the belt line for positioning. But the problem with these types of upgrades, especially when you're changing so many parts at once - was it the new part that made the difference, or the fact that you sucked it down, cleaned it up, installed new expansion/drier, and recharged the system? Sorta like running an autozone fuel injector cleaner while you were in there buying spark plugs and an air filter, and suddenly the engine runs better because you did some basic maintenance - or was it the fuel cleaner?

In my LS3 NA, I have a GM scroll compressor, NB2 evap core, ducted to the mouth with ford focus fans pulling across - still have the NA evap core and expansion valve, with virtually all fabricated hard lines. It blows cold, but no colder than it did before (well, before I was turbo - intercooler definitely limited the condensers efficiency). So far in its 2nd summer it's held up to the Georgia heat - but it's not like I ever have to turn the A/C down.

The NB2 compressor is interesting though, since it looks like it might have the same mounting points - might be worth it to see what the rockauto prices are on the soft lines, but I'm positive that the hose ends would need to be modified to work on an NA.