electric ac conversion/alternator upgrade?
07-04-17, 03:26 PM
#1
electric ac conversion/alternator upgrade?
the stock fd alternator from what i can see is 90-100 amps depending on who you ask. from the factory that alternator is tasked to run with everything in the car. headlights on, ac on full blast, radio on, wipers running, fans spinning, all that stuff at the same time potentially. now lets say we remove the entire ac system, use more efficient lights and remove a lot of other things that the electrical system is tasked with in stock form while adding a better performing battery and thicker gauge wiring everywhere. would this effectively make the alternator a "high output" since its now only having to drive a fraction of the things its rated for? as in it now has a greater differential from operating vs peak? is my logic correct?
now from that scenario, if i were to go back in install an aftermarket ac system, would it be necessary to upgrade the alternator? my conclusion is no, but i figure it would be better to ask.
the compressor i will be using is rated as follows
https://www.seanhylandmotorsport.com...ompressor-3753
Voltage Range 9-30 V DC
Current Draw 31.63 amp
the blower motor set up, i cant find the numbers for but i would imagine it would be about the same as stock. i just want to make sure im not putting too much of a load on the system
Vintage Air 66005-VUX-A: Gen II Mini Evaporator Kit | JEGS
now from that scenario, if i were to go back in install an aftermarket ac system, would it be necessary to upgrade the alternator? my conclusion is no, but i figure it would be better to ask.
the compressor i will be using is rated as follows
https://www.seanhylandmotorsport.com...ompressor-3753
Voltage Range 9-30 V DC
Current Draw 31.63 amp
the blower motor set up, i cant find the numbers for but i would imagine it would be about the same as stock. i just want to make sure im not putting too much of a load on the system
Vintage Air 66005-VUX-A: Gen II Mini Evaporator Kit | JEGS
07-04-17, 08:56 PM
#3
That's the point of the thread... why needlessly get another alternator when I'm potentially fully within the operating capacity of the stock one? It's easy to "upgrade" parts just to do it. I'm trying to make an informed decision.
I guess it really comes down to what the draw of the stock compressor is. If it's equal to or greater than the electric one then problem solved.
I guess it really comes down to what the draw of the stock compressor is. If it's equal to or greater than the electric one then problem solved.
Last edited by cr-rex; 07-04-17 at 09:00 PM.
07-04-17, 09:14 PM
#4
You are asking two antithetical questions.
Is reducing the load on the stock alternator a good idea? Yes.
Is increasing the load on the stock alternator with an electric A/C pump a good idea? No.
The stock A/C system is powered by the engine, not the alternator. The only draw on the alternator is the increase in radiator fan speed when the A/C system in on and the low draw of the solenoid in the A/C compressor clutch.
You are going to have a hard time reducing the electrical load by the 30+Amps the added electrical A/C pump requires.
If you removed your electric fans and put an engine driven fan clutch and shroud in there like an FC that would be the biggest help. But that is a poor idea compared to getting a higher output alternator.
You don't want to skimp on the electrical system of a boosted car because it really can effect the fuel pump outlet.
If you want electrical A/C or electrical P/S or an electric Air Pump then I say go for it, but make sure you upgrade the actual alternator output by at least as much as the increased Amp draw you are putting into the system.
And as you point out, upgrading the factory wiring would be good as it is only rated for factory output and marginal at best.
Is reducing the load on the stock alternator a good idea? Yes.
Is increasing the load on the stock alternator with an electric A/C pump a good idea? No.
The stock A/C system is powered by the engine, not the alternator. The only draw on the alternator is the increase in radiator fan speed when the A/C system in on and the low draw of the solenoid in the A/C compressor clutch.
You are going to have a hard time reducing the electrical load by the 30+Amps the added electrical A/C pump requires.
If you removed your electric fans and put an engine driven fan clutch and shroud in there like an FC that would be the biggest help. But that is a poor idea compared to getting a higher output alternator.
You don't want to skimp on the electrical system of a boosted car because it really can effect the fuel pump outlet.
If you want electrical A/C or electrical P/S or an electric Air Pump then I say go for it, but make sure you upgrade the actual alternator output by at least as much as the increased Amp draw you are putting into the system.
And as you point out, upgrading the factory wiring would be good as it is only rated for factory output and marginal at best.
07-05-17, 12:20 AM
#5
Ah yes, key point and an oversight on my end. The compressor is driven by the motor and not the electrical system. That kind of answers my question lol Thanks for that
Upgraded alternator it is. As you mentioned, cutting 30 or so amps from the factory electrical to supplement what the new compressor requires isn't really likely. One last thing, is a 12v a 12v battery? Does it matter that I use a small braille vs a full size optima red or yellow? So long as the alternator is doing its job, it shouldn't matter should it?
Upgraded alternator it is. As you mentioned, cutting 30 or so amps from the factory electrical to supplement what the new compressor requires isn't really likely. One last thing, is a 12v a 12v battery? Does it matter that I use a small braille vs a full size optima red or yellow? So long as the alternator is doing its job, it shouldn't matter should it?
07-05-17, 10:51 AM
#7
RX-7 Bad Ass
iTrader: (55)
At this point you're shooting in the dark. You need to have some data to back up what you're looking to accomplish.
You will need an ammeter to test everything out. See how much you're using with nothing on, then add loads to the system - fans on high, defroster, etc. You may want to go for a clamp-on ammeter to test this.
Watch a few Youtube videos on the topic as well.
That said, a lot of the vintage air stuff is really homegrown looking. Janky wiring and AC lines. Any reason you wouldn't just put the stock AC stuff on?
Also, a PROPERLY FUNCTIONING AC system on an FD puts VERY little load on the engine, like you can't even tell a difference driving at low/off idle speeds. Seems like a more straightforward way than going to an electric compressor and all the plumbing and electrical needs that will require.
Dale
You will need an ammeter to test everything out. See how much you're using with nothing on, then add loads to the system - fans on high, defroster, etc. You may want to go for a clamp-on ammeter to test this.
Watch a few Youtube videos on the topic as well.
That said, a lot of the vintage air stuff is really homegrown looking. Janky wiring and AC lines. Any reason you wouldn't just put the stock AC stuff on?
Also, a PROPERLY FUNCTIONING AC system on an FD puts VERY little load on the engine, like you can't even tell a difference driving at low/off idle speeds. Seems like a more straightforward way than going to an electric compressor and all the plumbing and electrical needs that will require.
Dale
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07-05-17, 10:53 AM
#8
From what I understand the battery has a small effect on current available when the engine is actually running.
The alternator provides almost all your instantly available current which is what you will need for a big spike in current draw as when your electric A/C compressor pump first kicks over.
The battery can act as a buffer to current draw,.
Having a battery with a higher available discharge rate (like LiFePo) than Lead acid should actually provide more buffer with the engine running even if the battery is smaller. It is more about how much energy the battery can provide instantly in this case (like a capacitor in a stereo system).
The alternator provides almost all your instantly available current which is what you will need for a big spike in current draw as when your electric A/C compressor pump first kicks over.
The battery can act as a buffer to current draw,.
Having a battery with a higher available discharge rate (like LiFePo) than Lead acid should actually provide more buffer with the engine running even if the battery is smaller. It is more about how much energy the battery can provide instantly in this case (like a capacitor in a stereo system).
07-05-17, 02:55 PM
#9
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Power budget
I just had to jump in on this topic. So far guidance has been spot on. Vintage air has a smaller compressor, but is engine driven, only power draw was for the blower. The main issue seems to be how much draw is on the alternator when all electrical systems are on, probably would not happen often. The question to consider is with the age of the stock alternator how much is it putting out. Last week on my way to the store it started to rain, I had my AC on, turned on my headlights and wipers. The cars performance began to fall off. High AFR, some bucking, etc, almost in a limp mode. I began shutting off electrical systems. Got home and started checking grounds, etc per the Forum post. Lastly checked my 1993 alternator. Not putting out enough juice to run systems. BTW I have a Braille 21 battery. Just food for thought.
07-05-17, 08:19 PM
#10
Constant threat
Stock alternator per the FSM is 100 amps if my memory is correct. I've looked into the IRP amp or having mine rewound for higher output as my stereo can draw 100 amps alone.
Also not sure what rpm it fully energizes at. I was talking to a fellow boater the other day and he has a very high power system; he had his alternators rewound for 250 amps and they energize at 700 rpm. He told me it wasn't cheap but the stock Mercruiser alternators didn't fully energize until 1500 rpm, so at idle his engines weren't charging his batteries fully.
Also not sure what rpm it fully energizes at. I was talking to a fellow boater the other day and he has a very high power system; he had his alternators rewound for 250 amps and they energize at 700 rpm. He told me it wasn't cheap but the stock Mercruiser alternators didn't fully energize until 1500 rpm, so at idle his engines weren't charging his batteries fully.
Last edited by bajaman; 07-05-17 at 08:22 PM.
07-06-17, 12:41 AM
#11
At this point you're shooting in the dark. You need to have some data to back up what you're looking to accomplish.
You will need an ammeter to test everything out. See how much you're using with nothing on, then add loads to the system - fans on high, defroster, etc. You may want to go for a clamp-on ammeter to test this.
Watch a few Youtube videos on the topic as well.
That said, a lot of the vintage air stuff is really homegrown looking. Janky wiring and AC lines. Any reason you wouldn't just put the stock AC stuff on?
Also, a PROPERLY FUNCTIONING AC system on an FD puts VERY little load on the engine, like you can't even tell a difference driving at low/off idle speeds. Seems like a more straightforward way than going to an electric compressor and all the plumbing and electrical needs that will require.
Dale
You will need an ammeter to test everything out. See how much you're using with nothing on, then add loads to the system - fans on high, defroster, etc. You may want to go for a clamp-on ammeter to test this.
Watch a few Youtube videos on the topic as well.
That said, a lot of the vintage air stuff is really homegrown looking. Janky wiring and AC lines. Any reason you wouldn't just put the stock AC stuff on?
Also, a PROPERLY FUNCTIONING AC system on an FD puts VERY little load on the engine, like you can't even tell a difference driving at low/off idle speeds. Seems like a more straightforward way than going to an electric compressor and all the plumbing and electrical needs that will require.
Dale
07-06-17, 07:55 AM
#12
Constant threat
the thing is, my car is RHD and the ac system in its entirety has been removed. every last part right down to the ducts in the door and under the dash. trying to source rhd ac parts would be hell and a half. realistically, my options are no ac or this method. do i HAVE to use an electric compressor? no.... but if im going to go this route then why not. your idea with the ammeter is genius. i will definitely do that. that will tell me everything i need to know.
07-07-17, 11:38 AM
#14
RX-7 Bad Ass
iTrader: (55)
You may be able to get parts from an imported RHD half cut, that would have all the parts in it.
The compressor and receiver/dryer are the same on US cars.
I'd ask around, I have a feeling some of those parts may not be that hard to source. Someone who bought a half cut would probably be throwing out the blower motor and things like that.
Or, find someone with a RHD car that's making it a track car and pulling all that stuff out.
Dale
The compressor and receiver/dryer are the same on US cars.
I'd ask around, I have a feeling some of those parts may not be that hard to source. Someone who bought a half cut would probably be throwing out the blower motor and things like that.
Or, find someone with a RHD car that's making it a track car and pulling all that stuff out.
Dale
07-07-17, 01:38 PM
#15
Easier said than done. Wiring comes into play with all that. Getting the factory wiring all working again for the ac and controls would be the next burden on top of getting the parts. Then pulling the dash, the door panels and installing all the pieces and parts of the system will be a hassle. The appealing thing to the electric conversion is that I don't have to do any of that. The blower runs off its own control panel independent of the cars wiring. The vintage air blower assembly is small enough to tuck right under the dash without removing it and the way the ports are made, I don't HAVE to duct it. It will just blow up through the defrost vents and blow cool air into the cabin. Even if I did want to duct it to just the center vent, that would be easy since it comes with ducting. The ease of install going aftermarket is worth the additional cost vs sourcing all the stock parts and dealing with that install.
I can't stress enough that everything ac related has been removed. All of it. Everything. Nothing related to the ac exists in this car. I would have to FULLY reinstall EVERY ac related part and wire it all in.
I can't stress enough that everything ac related has been removed. All of it. Everything. Nothing related to the ac exists in this car. I would have to FULLY reinstall EVERY ac related part and wire it all in.
07-07-17, 03:08 PM
#16
RX-7 Bad Ass
iTrader: (55)
No heater core in the car either?
The heater core has all the ducts/flappers/etc that move the air to where it needs to go, like defrost, foot, etc.
The wiring on the heater core, AC evaporator, and blower motor are all kind of part of the units. If you have those units you will probably have what you need unless they majorly gutted the dash harness or something. Do you still have all the AC controls in the center console?
Big thing here is custom jabbing that Vintage Air stuff is probably not the easy route it looks. TONS of fab work and from what I've seen the quality is hokey at best.
Dale
The heater core has all the ducts/flappers/etc that move the air to where it needs to go, like defrost, foot, etc.
The wiring on the heater core, AC evaporator, and blower motor are all kind of part of the units. If you have those units you will probably have what you need unless they majorly gutted the dash harness or something. Do you still have all the AC controls in the center console?
Big thing here is custom jabbing that Vintage Air stuff is probably not the easy route it looks. TONS of fab work and from what I've seen the quality is hokey at best.
Dale
07-07-17, 07:53 PM
#17
There's no nothing under the dash. If I pull the dash, I'll be looking at firewall and the single harness that runs across it. I still have the actual controls in the center. It's just for looks though. There's a bunch of little ducts and stuff that attach to everything to route the air everywhere it needs to go. Finding all of that and installing them is what I don't want to do.
Why do you say the vintage air stuff is hokey lol. From what I can see its pretty popular stuff to use. I've never seen any of it in person but just based on reviews and stuff, it seems legit to me =/
If my measurements are right, the mini vintage air blower should tuck right up under the dash with room to spare. There are a lot of studs and other mount points under there with all the stock stuff gone so making brackets shouldn't be all that hard. Same with running the lines. There's a lot of space under there.
Why do you say the vintage air stuff is hokey lol. From what I can see its pretty popular stuff to use. I've never seen any of it in person but just based on reviews and stuff, it seems legit to me =/
If my measurements are right, the mini vintage air blower should tuck right up under the dash with room to spare. There are a lot of studs and other mount points under there with all the stock stuff gone so making brackets shouldn't be all that hard. Same with running the lines. There's a lot of space under there.
07-08-17, 01:35 AM
#18
I honestly think that is not that hard finding all the AC parts for RHD , I very often see some RHD AC parts when I buy stuff locally.
And there is not that much to it anyways
I got a good feeling that all the AC parts are NOT NLA yet in Japan.
Which would be nice to have brand new S8 OEM AC system
Not too sure if the compressor would work since it's on a 16bit ecu.
Anyways, if you upgrade to a 130amp, then you get your electrical AC that draws ~30amp your back to stock at 100amp. Your good to go.
And you get extra 30amp not using AC.
I'm sure that is easier & maybe cheaper to go the route you want to go because there is nothing behind your dash.
I taught the only electrical connections was to the blower and compressor ,
I mean if all the connections are not on the harnesses.
It's still not that bad 2 or 3 harness , one is battery harness which is super easy(LHD is the same) Dash and Firewall maybe , at least you don't have to get the front one .
lol now that I think of it , it is a lot of parts to get, haha compare to your alternative.
Tough luck.
And there is not that much to it anyways
I got a good feeling that all the AC parts are NOT NLA yet in Japan.
Which would be nice to have brand new S8 OEM AC system
Not too sure if the compressor would work since it's on a 16bit ecu.
Anyways, if you upgrade to a 130amp, then you get your electrical AC that draws ~30amp your back to stock at 100amp. Your good to go.
And you get extra 30amp not using AC.
I'm sure that is easier & maybe cheaper to go the route you want to go because there is nothing behind your dash.
I taught the only electrical connections was to the blower and compressor ,
I mean if all the connections are not on the harnesses.
It's still not that bad 2 or 3 harness , one is battery harness which is super easy(LHD is the same) Dash and Firewall maybe , at least you don't have to get the front one .
lol now that I think of it , it is a lot of parts to get, haha compare to your alternative.
Tough luck.
Last edited by 7krayziboi; 07-08-17 at 01:48 AM.
07-10-17, 12:10 AM
#19
Another question to ask is pertaining to the compressor you linked to. The specifications say 9-30VDC. Is the 31 amps at 9-, 12-, or 30-VDC? If that amp rating is at 30VDC, then the draw at 12VDC will be higher. just a thought. From my research into this topic (I was hoping to convert to electric power steering and electric AC), many of these pumps seem to be designed for hybrid or electric vehicles, and like to run at higher voltage.
07-10-17, 08:25 AM
#20
I'm based in the UK, have a few spares laying about from previous builds, if you need RHD ac parts let me know, I can have a look and we can sort something out if interested.
07-24-17, 08:50 AM
#21
There's no nothing under the dash. If I pull the dash, I'll be looking at firewall and the single harness that runs across it. I still have the actual controls in the center. It's just for looks though. There's a bunch of little ducts and stuff that attach to everything to route the air everywhere it needs to go. Finding all of that and installing them is what I don't want to do.
Why do you say the vintage air stuff is hokey lol. From what I can see its pretty popular stuff to use. I've never seen any of it in person but just based on reviews and stuff, it seems legit to me =/
If my measurements are right, the mini vintage air blower should tuck right up under the dash with room to spare. There are a lot of studs and other mount points under there with all the stock stuff gone so making brackets shouldn't be all that hard. Same with running the lines. There's a lot of space under there.
Why do you say the vintage air stuff is hokey lol. From what I can see its pretty popular stuff to use. I've never seen any of it in person but just based on reviews and stuff, it seems legit to me =/
If my measurements are right, the mini vintage air blower should tuck right up under the dash with room to spare. There are a lot of studs and other mount points under there with all the stock stuff gone so making brackets shouldn't be all that hard. Same with running the lines. There's a lot of space under there.
