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probably a similar compressor, but there's another 944 guy with a 12V AC system in his 944 on Pelican. he had a 100 amp alternator that couldn't hack it. he went to a 145 amp and it seems to work ok.
a belt driven AC compressor can take 5-10hp - 3500-7300 watts - but there are both losses in there as well as the belt-driven pump probably has a higher cooling capacity than the 12V one
even at 100 amps the 12V (or 13.6 running) compressor is only taking ~1300 watts - less than 2HP equivalent
Got it torn apart this weekend, pilot bearing failure which in turn toasted the clutch. Luckily the input shaft looks salvageable, just a nice groove in the center now. The picture makes it looks worse with all the nasty grease on it. I think it was mostly likely caused when the torque tube was mated to the bell housing as it was tough getting it aligned.
I am going to try and design a new adapter to use a ball bearing like the factory 944 engine. Just for peace of mind and as recommended by @Constantine over at Black Sea R&D. According to him the shaft isn't hard enough to act as a bearing surface for a roller bearing.
Not sure what happened here, maybe over tightened or something.
So I ended up designing a new pilot bearing adapter which utilizes the factory 944 6202 ball bearing. Boost Brothers had apparently already done this and is having them made but I didn't feel like waiting. They offered to send me one for free so props to them.
My shaft depth seems to be off about 5.5mm here which explains the groove that was worn into the center of the shaft. The thing is, the adapter can't be spaced back anymore as it would start to run into the clutch disc hub. I believe I have some adjustment to push the shaft forward in the torque tube though. Everything is within spec according to Boost Brothers so I am not sure why it is off. The initial failure was most definitely caused by this as well as me not aligning the shaft enough during installation. I should of checked this before just smashing everything together... oh well. I will post an update when I get to correcting this.
I had the adapter CNC turned in 4340 alloy steel through pcbway.com. Wasn't sure on how the quality would turn out considering it only cost me $63 but holy crap was I surprised!
I applied some gun blue to hopefully add a little bit of corrosion resistance. 4340 is supposed to have good atmospheric corrosion resistance already though.
Lastly, the GM clutch slave cylinders have a plastic support/retainer for the release bearing. This can apparently fail if it gets too hot. A number of companies make metal replacements. I will be doing this for additional piece of mind.
I had to grind/clearance the new clutch disc hub down slightly as it was hitting the tube that the throw out bearing rides on. Boost Brothers was talking to SPEC about this but I never heard back. Something to definitely check before you bolt the bell housing tight. It would destroy the throw out bearing assembly and probably take the clutch with it.
This is the shaft at the correct depth, I was able to bash the shaft from the transaxle side forward enough.
I also converted to E-Throttle as it really is the best way to go. Idle control is so much easier. Pedal is from a Porsche Panamera but I think they used it in other models as well. Throttle body is a Bosch 0280750156 which bolts right on. I bought it under a Ford part number because it was cheaper, 1R1E9E926AA.
Lastly, I converted to a bar and plate dual pass oil cooler. I went through two stacked plate coolers because they were cracking. The way I had done the lines was causing the issue though, the force of the air was putting too much stress on them.
Nice work so far mate - interested to see how the AC Compressor goes as Ive been looking at that same unit for my car. Have considered mounting it in battery area [and relocating battery] or moving it reward and mounting it in one of the wells in the rear corner of the car. Only concern I have is the routing of the lines to/from, and where Im going to squeeze a decent core in for cooling given that the front will be taken up by oil cooler and intercooler. Speaking of oil coolers, whats the cooler off? Looks like an RX7
Nice work so far mate - interested to see how the AC Compressor goes as Ive been looking at that same unit for my car. Have considered mounting it in battery area [and relocating battery] or moving it reward and mounting it in one of the wells in the rear corner of the car. Only concern I have is the routing of the lines to/from, and where Im going to squeeze a decent core in for cooling given that the front will be taken up by oil cooler and intercooler. Speaking of oil coolers, whats the cooler off? Looks like an RX7
N-
I installed it in the battery tray and moved the battery to the rear, there is pictures in this thread. It works pretty damn good actually. Obviously not as good as a belt driven compressor but plenty to keep the cabin comfortable. I used a universal 21" x 12" parallel flow condenser in the stock location by cutting the brackets off the stock condenser. I'm using the stock 944 Turbo radiator and intercooler and there is no cooling issues so far.
Gents..AFAIK, has anyone tried an electric compressor from a Tesla? Or is this the same unit? They have to have a pretty low drain compressor, but still have to keep everyone comfy. Just thinking outside the box here. Quite pricey unless you get one out of a wreck..😀
Gents..AFAIK, has anyone tried an electric compressor from a Tesla? Or is this the same unit? They have to have a pretty low drain compressor, but still have to keep everyone comfy. Just thinking outside the box here. Quite pricey unless you get one out of a wreck..😀
I’d like to know as well. I think the Tesla use heat pumps which are much more efficient.
Great write up and documentation. How has the car been performing?
Do you have a wiring diagram for the DBW throttle pedal to TB?
I am starting this swap and getting everything together. Luckily it is a track car so I do not need to worry about AC and heat.
Have you had any of the belt issues Boost Brothers have had?
Thanks
Pete
No belt issues at all. I am running the TTRS harmonic balancer and Boost Brother's tensioner pulley that has the lip.
The DBW throttle body and pedal wire into the ECU, so it will be specific to whatever ECU you are running. I am running a Link G4X FuryX ECU and not the Performance Electronics or Haltech that Boost Brothers was/is selling.
Here are the pinouts though.
Pedal - Part Number 997-423-021 - Like I said, they use the same pedal for many models so the part number varies. If you get one that comes from an automatic car it will have a tactile spring button thing that acts like a bump stop. It's so you can feel the "kick-down" point for downshifting. You can pry the button off though as it doesn't do anything electrical.
Pin 1 - 5 Volts
Pin 2 - 5 Volts
Pin 3 - Sensor Ground
Pin 4 - Signal 1 Out
Pin 5 - Sensor Ground
Pin 6 - Signal 2 Out
The two signals are inverted. So one goes from 0 to 5 Volts and the other is 5 to 0 Volts. I don't remember which is which but it doesn't really matter, any ECU that supports DBW will have a calibration tool.
Throttle Body
Pin 1 - Motor Negative
Pin 2 - Sensor Ground
Pin 3 - 5 Volts
Pin 4 - Motor Positive
Pin 5 - Signal 2 Out
Pin 6 - Signal 1 Out
Originally Posted by Tiger03447
Gents..AFAIK, has anyone tried an electric compressor from a Tesla? Or is this the same unit? They have to have a pretty low drain compressor, but still have to keep everyone comfy. Just thinking outside the box here. Quite pricey unless you get one out of a wreck..😀
@V2Rocket is correct. They typically operate around 350-400 Volts.
The unit I have does come in different voltages though, including high voltage. I suppose you could run two batteries and run the 24 Volt one.
02-09-2023, 08:25 AM
