Blower Motor Upgrades?

[Patrick C]

I know that we have easy access to the Siemens PM106 cross-reference blower motor for our cars, but has anyone found an upgraded motor that can be used? Maybe a different squirrel cage? I have a feeling that there have been significant advances in technology in this area since 1981, and I'm curious if there is an easy plug-and-play solution to increase airflow in our cars.

[DMCflux]

I too would be interested in a different squirrel cage.

[Delorean Industries]

I'm sure you could retro fit a unit with a higher cfm rating. Doing a general search of blower motor comes up with the classic design for the most part.

This would work in the proper power rating:
http://www.moog.com/products/air-moving-products/blowers/amp28/

[Patrick C]

It looks like the common way to upgrade that the C3 Corvette guys use is to put in a spacer and use a C4 Corvette cage which is taller. Unfortunately, I believe those are set up backwards from our motors and spin the opposite direction (fins are pointed wrong on the squirrel cage for use in a DMC).

I see Hervey sells a $40 squirrel cage...I wonder if these fin lengths/widths are any different than ours from the factory?

http://specialtauto.com/delorean-parts/images/blower-motor-cage.jpg

[David T]

I'm sure you could retro fit a unit with a higher cfm rating. Doing a general search of blower motor comes up with the classic design for the most part.

This would work in the proper power rating:
http://www.moog.com/products/air-moving-products/blowers/amp28/


What is meant by "upgrading" the blower motor? The CFM it moves is variable with the maximum on speed 4. This is not a random quantity. It is an engineered value. Too much air movement creates more noise, less time in contact with the coils and a lower Delta T. You probably could find a motor that can move the same amount of air with less amperage. Not that big a deal but if it is that important to you to keep the electrical loads low go for it. As for the design of the squirrel cage, not much has changed in the world of physics so that you can improve on the design of the fan.

[LordFly]

It looks like the common way to upgrade that the C3 Corvette guys use is to put in a spacer and use a C4 Corvette cage which is taller. Unfortunately, I believe those are set up backwards from our motors and spin the opposite direction (fins are pointed wrong on the squirrel cage for use in a DMC).

Yeah, it does spin the wrong way, but the motor isn't actually grounded anywhere, since everything in the area is plastic. You can just swap the wires and everything is fine.

[Patrick C]

Yeah, it does spin the wrong way, but the motor isn't actually grounded anywhere, since everything in the area is plastic. You can just swap the wires and everything is fine.

But the fins on the squirrel cage are reversed and would not supply proper airflow if spun the opposite way. That's why I don't believe the C4 Corvette cage is an option for us.

[LordFly]

But the fins on the squirrel cage are reversed and would not supply proper airflow if spun the opposite way. That's why I don't believe the C4 Corvette cage is an option for us.

Oh, sorry, I didn't realize the cage was being swapped as well. On my car, the PO had swapped the motor for the corvette one, but just bolted the original cage on. ...at least I'm fairly sure that's what was done, since when I got the car, the cage spun the wrong way. I didn't really look inside the whole to see if it SHOULD be going that direction or not. Well, if my cage is backwards, 3D printer to the rescue! :D

[Nicholas R]

Can you 3d print a stock cage with wider fins?!

Dave the question isn't about noise or temp change, it's strictly about increasing the volume of air moving. The resistors that control the speed only adjust the amperage; they don't care how fast the motor is moving. So a more efficient motor would rotate faster at the same amperage.

Also with regard to "Delta T" the temperature change will be greater (cooler) until you over power the AC system (which isn't likely if your system is balanced). It's forced convection. The compressor may just cycle a little faster because heat is being added to the evaporator at a greater rate. But unless you overpower the evaporator to the point that it's remaining the same temperature as the ambient air, you'll be pulling more "cold" from it.

[LordFly]

Can you 3d print a stock cage with wider fins?!

I don't see why not. I've actually been thinking about redesigning it anyways. I don't like the standard squirrel cage design, it just doesn't seem as efficient as it could be. At least to me it doesn't.

[Bitsyncmaster]

I've thought about replacing the blower motor with a motor I have that may be more efficient and provide more air flow. The motor is used for radio controlled airplanes and has cobalt magnets. I will have to do some testing to see what current it uses at 12 volts loaded. Your looking for more current than the stock motor draws. If that current is to high, you would PWM the current lower.

I think the only thing you will gain is a quicker cabin cool down after your car has been parked in the hot sun.

[David T]

I've thought about replacing the blower motor with a motor I have that may be more efficient and provide more air flow. The motor is used for radio controlled airplanes and has cobalt magnets. I will have to do some testing to see what current it uses at 12 volts loaded. Your looking for more current than the stock motor draws. If that current is to high, you would PWM the current lower.

I think the only thing you will gain is a quicker cabin cool down after your car has been parked in the hot sun.

The very best thing you can do for that is to get a cover to put on the inside of the windscreen to reflect the sun out. It helps ALOT.

[Nicholas R]

The very best thing you can do for that is to get a cover to put on the inside of the windscreen to reflect the sun out. It helps ALOT.

How do you see where you're going? :p ;)

[LordFly]

How do you see where you're going? :p ;)

:hysterical:

[MML]

I see the first post mentions a Siemens PM106 blower motor, I take it that's the exact same thing as this?

http://www.ebay.com/itm/HVAC-Blower-Motor-VDO-PM106-/321379964703?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ad3bd171f&vxp=mtr

[Elvis]

I work for ebm-papst and we build fans.
I once thought about replacing the motor but what would I gain ?

A little more efficiency ? Maybe 10% more airflow ?

That's not worth the trouble for me.


Less noise of the motor and brushes would be great, but then I bought a
new siemens motor for $25 and that helped a lot.

One would also have to modify the switch, programm the fan speed curve and so on.

I'm sitting at the source to do it but I see no sense in doing it. Too much modification
for a classic car. And not enough gain to motivate me.

[bfloyd]

Was there ever a solution found to increasing the volume of moving air? I just replaced my blower motor this weekend with the PM106, and I can't tell any difference at all. I don't want to plug up the door vents, but I really wanted a fairly steady forceful stream of air hitting me in the face.

[Chris 16409]

I've been happy with my blower motor:

52603

[Patrick C]

I’ve found the biggest improvement to my car was relocating the vents to the kneepads using Mitsubishi Eclipse vents. You get the full force of air being directed at the driver and passenger. It’s pretty remarkable how much airflow the stock fan can produce when you have adequate vents for the air to be directed from.

[papanoel]

I think my blower motor at autozone works just like the original one.
I find that my car actually stays colder if I reduce to fan speed 2 after a few minutes of full blast.

[bfloyd]

Correct me if I'm wrong, but the motor we want turns counter-clockwise Correct? Looking at my receipt, I ended up getting the blower motor for a 1980 Chevy Monza.
http://www.autozone.com/cooling-heating-and-climate-control/a-c-heater-blower-motor/4seasons-everco-a-c-heater-blower-motor/914044_0_6648_5281
It turns counter-clockwise, all of the screw holes are in the exact same spot, and the electrical connection is identical. I just thought changing out the 36 year old motor would make a huge difference, instead it's just exactly as it was before.

I'd just like the same volume of air I get out of my 2004 F150.

[David T]

If you move the air too fast over the coil it doesn't have enough time over the coil and you get less of a temperature drop, not more. Make sure the hole in the forward firewall. in front of the driver is blocked. The original foam falls out. Make sure the ductwork inside the doors are sealed and you are not losing air inside the doors. Make sure the boot for the center dash ducts is fitted correctly and not blocking or leaking. Make sure all of the ducts and actuators are working and move correctly. Make sure the mode switch isn't hissing. The biggest problem as I see it is you cannot aim the vents well and blow on the driver and passenger. There have been efforts in the past to make deflectors so the door vents can blow on the occupants. Make sure the fan motor is rotating in the correct direction. Some cross/overs run "backwards" and while they do move air, it is a fraction of the necessary amount. Park in the shade. Try MAX for initial cool-down. Make sure the compressor is cycling correctly. If it isn't you may have too much or not enough refrigerant and the evap coil can freeze, blocking airflow.

[Jason]

If you move the air too fast over the coil it doesn't have enough time over the coil and you get less of a temperature drop, not more.

Isn't that only true if you're trying to cool outside air? If you're recirculating air then I would think in terms of how fast you can remove heat from the cabin more air flow would always be better, at least up to the max capacity of the rest of the AC system, and then beyond that things would stay the same. Unless keeping the evaporator too hot would cause pressure problems in the refrigerant.

[Jason]

So, if you did want to increase air flow using the same motor but different fan design, how would you change the design? I can pretty easily make new fans. Just for fun I have one printing now with twice the blade area.
5261152612
But I have no idea if that's going to increase air flow or not.

[David T]

Transferring heat from a moving stream of air to a coil (and then to the refrigerant) requires the air to be in contact with the coil (the fins and metal) for a finite amount of time. You must transfer the heat from the mass of air to the mass of the coil. It doesn't happen instantaneously. The longer the air is in contact, the more heat can be transferred. Yes, you will get more air over the coil but the temperature change (delta T) is less. The curve is going down as the airflow goes up. You quickly reach a point of diminishing returns. At infinite airflow you get 0 delta T. Noise also increases as you increase airflow. Another factor is comfort. Too much air blowing in the cabin will become uncomfortable. So there is an upper limit to how much air you want to move. A normal Delorean with the cabin fan on high is about as much air as you should need. If you aren't getting a really good airflow on high, check the fan motor rotation, the actuators are moving the doors appropriately, and you aren't losing air from leaks or blockages.

[Josh]

Jason, I am very interested to hear about the results of your testing. Very cool that you are producing your own squirrel cage!

[Jason]

Transferring heat from a moving stream of air to a coil (and then to the refrigerant) requires the air to be in contact with the coil (the fins and metal) for a finite amount of time. You must transfer the heat from the mass of air to the mass of the coil. It doesn't happen instantaneously. The longer the air is in contact, the more heat can be transferred. Yes, you will get more air over the coil but the temperature change (delta T) is less. The curve is going down as the airflow goes up. You quickly reach a point of diminishing returns. At infinite airflow you get 0 delta T. Noise also increases as you increase airflow. Another factor is comfort. Too much air blowing in the cabin will become uncomfortable. So there is an upper limit to how much air you want to move. A normal Delorean with the cabin fan on high is about as much air as you should need. If you aren't getting a really good airflow on high, check the fan motor rotation, the actuators are moving the doors appropriately, and you aren't losing air from leaks or blockages.

But in the case of recirculating air the air repeats the contact with the evaporator more often. While I haven't worked through the math, I'm pretty sure that in the recirculating case if you take the limit as the air flow goes to infinity it reduces to the case where all the cabin air is in contact with the evaporator all the time. Which is different from the non-recirculating case where you don't get a temperature drop because each bit of air is only in contact with the evaporator for one infinitely small instance of time.

[David T]

Recirculating helps, that is why there is a recirc mode. But you still have a lower Delta T because of the time any particular particle is in contact with the coil. Bottom line, to high an airflow is not good.

[rickjames8]

Recirculating helps, that is why there is a recirc mode. But you still have a lower Delta T because of the time any particular particle is in contact with the coil. Bottom line, to high an airflow is not good.

I have been wondering this. I don't see a recirc/fresh switch like on most cars. How do I select if the air comes in from outside, or gets recirculated?

[nkemp]

I have been wondering this. I don't see a recirc/fresh switch like on most cars. How do I select if the air comes in from outside, or gets recirculated?

Max recirculates interior air (it does bring in some fresh air. 15%?)
Norm uses outside air

When the car has been sitting and is very hot inside, run on NORM for a while. Outside air is probably cooler so the AC cooling increases (the load is decreased). Once the car has cooled for a while, use MAX for maximum cooling. MAX recools interior air which should be cooler than outside. Humidity is also a factor. If outside air is very humid, even though the inside air is the same temp or a bit higher, then it is better to use the inside air (MAX). Humid air has a lot more energy in it and is a greater load on the AC.

If you really want to know more or to compare humidity load and temperature variations, use the psychrometric chart. Here is a description:https://sustainabilityworkshop.autodesk.com/buildings/psychrometric-charts

[nkemp]

So I'm going to throw some thoughts into the conversation and hope it doesn't feel like redirecting this thread.

What is the benefit that the OP (and subsequently others) is trying to accomplish?
- More air flow?
- Quieter air flow?
- Different airflow adjustment curve?
- Improved comfort?

I propose that comfort (thermal and auditory) should be the goal. BTW ... I'd prefer a different airflow curve. It would be nice to have something between 1 & 2. 2 is a bit much and also a bit noisy

If improved comfort is the desirable outcome, there may be another option. Backstory: I had an Astro and learned quickly that AC worked fine but the temperature in the car would stratify and I was uncomfortable. Air from shoulder'ish up would be warmer than the lower part. The front vents didn't stir up the air in the upper zone. My Tahoe has a similar problem. The Astro had rear AC mounted on the ceiling and you could direct the airflow forward horizontally along the ceiling. When the rear fans circulated the ceiling air it substantially improved the comfort. Very little airflow was needed. When your upper body is warm, it seems to bother you more.

The DeLorean behaves similar. The vents are not good at directing air such that it stirs the upper zone air sufficient to keep your upper body comfortable. Do we run the fans high in order to disturb the upper air? I've pondered adding small 12Vdc laptop fans such that they circulate/disturb the upper air. The question is where to put the fan/vents so that you don't alter the original design ... noticeably alter. Something in the parcel shelf might work. Maybe a small 12Vdc laptop fan behind each seat at the top of the trim, bottom of the rear window. Maybe something removable mounted to the ceiling at the rear. A nice printed box could improve the appearance as well.

Here is a fan example: 52614

There are caged 12Vdc fans that you plug into the lighter... but i don't like the look.

If additional fans for upper air movement has traction, then maybe this should be spun off as a separate thread.

[papanoel]

I've thought about putting a computer fan near the fuses box to help keep that area cooler. But not sure how a laptop fan would be useful in the cabin.

[nkemp]

But not sure how a laptop fan would be useful in the cabin.

Just to circulate the upper air and keep it from stratifying.

[David T]

Just to circulate the upper air and keep it from stratifying.

The position of the return air duct, under the dash, is supposed to prevent the stratification. As in most cooling systems the cold air is directed towards the top of the cabin at the hottest air and the return duct is low to pull in the air from the lower area to improve circulation. You may notice some stratification when you first start up the system but it should get better the longer you run the A/C.