Bypass A/C compressor on 3.1 litre

[hforcier]

Hey there all and greetings from Quebec, Canada ...

I am trying to locate instructions, and a diagram, to bypass the A/C compressor on a 1994 3.1 litre engine. I am not sure what controls what in terms of the pulleys, I don't have a diagram under the hood, and dealerships are less than helpful here.

I did this with a 1995 Beretta and gained 30% in gas savings as well as the full extent of the engine horse power capability that I did not have before. It was a pretty extreme result, but I don't expect as much from this ... I just want to give the engine a chance to survive a little longer, and I can use any edge I can get to do that. You know how it is ... Gotta see those girls through colledge!

Anyway, thanks in advance for all the help and replies and help. Diagrams, instructions, a Jpeg of the hood diagram would all be welcome.

Best regards.

Henri

[richtazz]

With the way the belt is routed, you cannot eliminate the AC compressor without installing an idler pulley in it's place. I know they make a pulley kit for the GM 4.3 and 5.7, but I don't know of a kit available for the GM 60 degree V-6's. Unless you're able to fabricate, you're SOL I'm afraid.

[jeffcoslacker]

Here is the routing.



You can see that without a pulley there, you'd have to go around the other side of the water pump. Then it would be turning backwards. I can't really see a way to do it without a pulley there, like rich said.

[hforcier]

Originally Posted by richtazz

With the way the belt is routed, you cannot eliminate the AC compressor without installing an idler pulley in it's place. I know they make a pulley kit for the GM 4.3 and 5.7, but I don't know of a kit available for the GM 60 degree V-6's. Unless you're able to fabricate, you're SOL I'm afraid.

I think you may be right ... I found a belt for no A/C from a store, but I don't see how the thing can be installed without causing it to touch. I wonder where you found these pulley kits. Maybe I can check to see if there is one availlable. Do you have the name of the parts manufacturer? Maybe a store we might have here too?

Thanks so much for that reply.

Henri

[hforcier]

Thanks for the image that is a great help. A buddy of mine suggested that I move the Alternator from it's current position to the place occupied by the A/C compressor. It'S a good idea, but it makes it easy to get wet. I'm still looking at all options.
Thanks again.

[Manny_boy]

Check out this link about A/C Delete:

http://www.w-body.com/forum/viewtopi...ghlight=delete

[hforcier]

Originally Posted by Manny_boy

Check out this link about A/C Delete:

http://www.w-body.com/forum/viewtopi...ghlight=delete

Now ... This, is something I have to check out further!! Thanks again! I will see what is availlable with regards to that part. And, I might just try it! It looks simple, and the mounting hole is on the engine at the same place as the image (I checked). I now see it in the Haynes manual too. I will let you know if it works.

Excellent resourse here!

Henri

[hforcier]

Originally Posted by Manny_boy

Check out this link about A/C Delete:

http://www.w-body.com/forum/viewtopi...ghlight=delete

Ha HAAA!! Yeah!! Witness a 343 lbs fatman doing a moonwalk ...
This was the answer for sure.

I got the part number quoted in the thread you sent me and went to the largest GM part distributor in Montreal (GRAVEL) to get it. The guy there had been in the parts department for 18 years, and never had one ordered or knew what to do with it ... But it was in the catalogs; GM part# 10044867 Idler pulley. After getting the proper Power Torque belt part# 14-0887-8 (600K6) SAE J1459 it was installed in the pre-bored engine block hole (as in the images) with some minor grunting in about 30 minutes. This applies to 2.8 and 3.1 liter engines. The A/C compressor was not removed and does not interfere with the rest ... I am refering to a Pontiac Trans Sport 1994, it may vary according to the vehicle.

I have yet to do the cap to cap liter per 100 kilometer count, but since installing it this afternoon there is a marked increase in throtle from a full stop, a change in the power to pass, and about a 300 to 500 RPM less at cruising speeds of 100 km per hour!! I was driving at 80 to 90 km with some difficulties before. It was just dying slowly, now ... Babys got bouce!!

I will post fuel consumption results later.

Thanks again!!

Henri

[cdru]

Originally Posted by hforcier

since installing it this afternoon there is a marked increase in throtle from a full stop, a change in the power to pass, and about a 300 to 500 RPM less at cruising speeds of 100 km per hour!!

The 300-500 is just you. At cruising speeds, the torque converter would be locked, essentially making a solid connection between the engine and wheels. Any variance in engine speed would directly relate to a variance in wheel speed. It may require less fuel/throttle to maintain that 100km/hr speed after your mod, but it wouldn't drop the engine RPMs at that speed. With slower driving when the TC isn't locked, it's more of a possibility.

[hforcier]

Originally Posted by cdru

The 300-500 is just you. At cruising speeds, the torque converter would be locked, essentially making a solid connection between the engine and wheels. Any variance in engine speed would directly relate to a variance in wheel speed. It may require less fuel/throttle to maintain that 100km/hr speed after your mod, but it wouldn't drop the engine RPMs at that speed. With slower driving when the TC isn't locked, it's more of a possibility.

Sounds logical, you are probably right ... I am no mechanic, nor an engineer, and it is difficult to estimate as my tach has a "twitching" problem right now.

I don't know how the fuel consumption will turn out, but I recommend this to anyone with a 3.1 liter and no need for A/C.

Thanks for the input, once again.

Henri

[hforcier]

Great News!! I just did the average of yet another tank of Gas and it is better, yet again ...

I started with an average since purchasing the vehicle of 14.4 liters to 100 km (very high) and now have an average of 12.022 liters to 100 km since modifications. This means an improuvement of 2.378 liters over the begining results and a 16.51% savings in fuel. I must note that the van show inprouved peerformance and ease of use. The steering wheel actually turns without whining at a full stop.

This is the second GM that I modify to bypass the A/C. In both cases, it involved vehicles that had small engines compared to the bodyweight they needed to pull. Very usefull if you can do without the A/C ... In Canada, no problem ... Elsewhere, you decide.

Best regards,

[LMP]

I used to bypass the A/C too in winter with my 3.8, but not for economy, since the A/C pulley free wheels in winter. In fact I used to shroud the A/C compressor in a tight plastic blanket to prevent salt from ruining the tubing, clutch, seals etc. I used a shorter belt (not listed for transport but listed for Olds 1988 )that would fit in without any modifications at all.

[comptech_69]

I would see aproblem running w/o an a/c in the winter because the compressor runs when the defogger/defroster is on to de-humidify the car and defog the windshield. I've been in a car with a non-working a/c in the winter and there was litterally ice on the windshield and in another car with a non-working a/c the window would just not defog or defrost.. well it wouldm but it took a long time.

[Schurkey]

I need someone to explain the power difference between running a belt over the existing A/C compressor pulley, when it is freewheeling on it's bearing, and running a belt over an aftermarket idler pulley, freewheeling on it's bearing. We're still talking about a pulley, and we're still having that pulley spin on a bearing. So where does the power increase come from?

Wouldn't it be a hundred times easier, and cost exactly ZERO dollars to just unplug the electrical connector from the A/C compressor? This would result in improved power and/or mileage in hot/warm/cool weather. (A/C compressor will not run) Remember, IF you open the windows for ventilation at highway speed, you will cause aerodynamic drag approximately equal to--perhaps greater--than the mechanical drag of the compressor. And you'll still be hot 'n' sticky 'n' uncomfortable.

Certainly they make an aftermarket idler pulley: For people who have their compressor/bearing explode, and they're too cheap to replace it.

YES, the A/C compressor is set up to run in cool weather, to de-humidify the air. And yes, that does make the defroster more efficient. In actual COLD weather, however, the compressor will NOT run, because refrigerant pressure is too low. Refrigerant pressure is linked to temperature, and when the temperature of the refrigerant is low enough the compressor will not engage. So in COLD weather, you will gain NOTHING by disconnecting the compressor, unless under-hood temperature would rise enough to offset all that frigid air blowing through the condenser.

[Manny_boy]

I would think the power increase would come from running a smaller, lighter weight pulley, just like running an underdrive pulley on your crankshaft.