Automotive Air Conditioning Information Forum

Just for fun, the TM31 or DKS32 has a 313cc/rev displacement. But it has a 152mm PV8 clutch.

So, about 34% slower. Multiply the capacity by .736 230cc "capacity".

It is 170mm "tall" from the mounting surface. Might be enough room on the 7.3 where it mounts.

Commercial grade unit with an oil sump, sight glass and gear pump for lubrication.

http://www.valeocompressors.com/en/tm31

Okay so thats intriguing.

Thats a monster. I think I have enough space I will measure tonight. I would have to figure out hoses for it. I guess I might even have to replace the condenser so I could have the correct connectors on it. My concerns would be connecting it to the Evaporator, rear AC lines and the dryer.

So maybe I have not had enough coffee this morning but can you walk me through you math to figure out the "actual" capacity? I would like to figure out how to do it myself and I would like to figure it for each compressor that I am looking at. Or at least the TM21 and QP25.

Wonder if that Cold Hose place in Florida could help with your connections, they have been suggested on here before by the heavy hitters

Custom hose set of course. GM style rear ports are an option on that unit.

Calculations are pretty straight forward. For any given belt speed over the existing pulley on the FS10 you get 170cc / rev. So if you change the pulley size by 25% you get a 25% change in compressor shaft speed. If you slow it down by 25% then you multiply the new compressor displacement by the inverse of 25% which is 75% or .75

You could of course add a larger condenser if there is any room left. There is a lot of back and forth over the benefit of a secondary condenser for sub cooling. Dodge did it when they added rear A/C on some minivans.

Something like an Omega 24-30505 mounted as liquid cooler after the main condenser comes to mind.

Like to hear Detroit's input on that stuff.

Lots to think about with a big increase in capacity.

Here is what I get:

My guess at Excursion crankshaft pulley is 172mm, I don't know what it actually is, this is what I could find quickly for the 6.8L, this is just an apples to apples comparison with this assumed pulley diameter

170cc FS10, 1.52:1 Ratio ==> 258 cc/engine revolution
200cc 10S20 1.51:1 Ratio ==> 302 cc/engine rev
210cc TM21 1.35:1 Ratio ==> 284 cc/engine rev
250cc QP25 1.22:1 Ratio ==> 305 cc/engine rev
313cc TM31 1.13:1 Ratio ==> 354 cc/engine rev

OP said he's looked and cannot find 8 groove Denso 200. TM21 is just too small an increase to be considered worth doing IMO.

So, really which one fits the best? QP25 or TM31? and is the QP25 actually available? I see it for sale by heavy truck AC wholesalers?
Will these pulleys (141 or 152mm) package in the engine compartment?

AC lines will be customized, but I picture a short adapter to get from the compressor ports to the existing lines with a compression fitting splice. It seems doubtful the existing lines would be able to be kept intact. I can also maybe help out with this, I'm fabricating adapter lines and fittings all the time.

Edit: I'd want to see how the existing condenser handles the load, it's a huge 6mm Visteon piccolo tube, probably also lots of airflow for the massive trailer towing capacity these things have. Personally, I'd live with a bit higher condenser pressures to keep the installation simple. I picture a kit with a compressor, a belt, compressor adapter mounts, an adapter fitting/pipe assembly, charging instructions. Could be an easy bolt on job?

Well if it had enough vertical clearance I could make a plate adapter with an idler and stack a pair of FS10's in that spot...

Just kidding.

Detroit:
Good to know you think the condenser is up to the job.

If the vehicle has the space for the TM31 it will have plenty of capacity at idle. Do you see any issue with the pump spun up?

I have converted a couple of CCOT F150's to TXV's over the years with good results. Just left the accumulator in place and added an R/D.

I think that the QP-31 has an internal oil sump with an oil pump and 500 cc oil capacity. Do any of you know if that would be the total oil charge, or would I need to charge the normal oil charge plus the 500cc.

500cc's of oil is max charge on the pump. You would fill the compressor and run the system, checking the sight gauge on the compressor to see if it needed any additional oil. Probably be close to full on the gauge.

The compressor manual also says that if you remove & replace the same compressor that you should put 350 cc's back in it after draining it - which kind of supports the 500 cc's as a system charge.

On a small system like the Excursion I would probably start with 350 - 400 cc's in the sump and run the system for a few minutes then check the sight glass.

Here is the service manual

http://www.valeocompressors.com/media/b ... manual.pdf

Detroitac here are some pictures detailing that line to the rear ac. Let me know if you need anything else.





I am using CAD (cardboard aided design) to build a mock-up of the TM31 that I will try and fit in the truck this weekend. I’ll keep y’all posted. Thanks for all the help!

Sorry for the delay. I had to drop the tank on the truck twice and replace the radiator before I left on a trip.

It looks like it will fit the factory location. That’s a huge compressor but I have a fair amount of real estate sale there. I may have to reroute a few things but it’s very doable.

When I get back in town I am going to call Tim about ordering a TM31 with rear ports. The top ports won’t clear the hood.

Thanks for all the help guys.