AC blower mod...WAY improving air flow (could be coming) - LotusTalk - The Lotus Cars Community
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post #1 of 137 (permalink) Old 08-24-2006, 04:27 PM Thread Starter
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AC blower mod...WAY improving air flow (could be coming)

So...I'm working on getting details, but it looks like SPAL can supply me with a a different unit to replace the factory setup. It'll push 600CFM vs 400. That should make a NICE improvement. Only issue...it'll draw about 33amps vs 12 amps of the stock setup. Soooo....need some help for some wiring experts. I looked at the diagram.... What is the minimum gauge wire needed for a 40amp run? Could we use the existing harness and just up the fuse rating?
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post #2 of 137 (permalink) Old 08-24-2006, 05:04 PM
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33amps could probably use 14ga, but 40amps will need 12ga. I think some of the primary wiring looks to be around 14ga, but that should be checked.

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post #3 of 137 (permalink) Old 08-24-2006, 05:10 PM
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If the stock system doesn't use a relay, a relay might be something that might be good to include. This is just a thought and I may be way off base..... http://www.1728.com/project3.htm

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post #4 of 137 (permalink) Old 08-24-2006, 06:30 PM Thread Starter
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Quote:
Originally Posted by Stan
That's a lotta current...maybe try getting more voltage to the fan first. Check voltage under load, bone stock. Sometimes a better ground or more wire gage really help. If need be give it a power supply voltage boost is what I'd try first. A bit more voltage goes a long way....it's a squared relationship.
How are you gonna get more than about 14 volts though? Most car systems only crank about 14-15 volts....
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post #5 of 137 (permalink) Old 08-24-2006, 06:41 PM
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Quote:
Originally Posted by Žob
So...I'm working on getting details, but it looks like SPAL can supply me with a a different unit to replace the factory setup. It'll push 600CFM vs 400. That should make a NICE improvement. Only issue...it'll draw about 33amps vs 12 amps of the stock setup. Soooo....need some help for some wiring experts. I looked at the diagram.... What is the minimum gauge wire needed for a 40amp run? Could we use the existing harness and just up the fuse rating?
I don't get it. I have a SPAL fan in another custom car that pulls well over 1000 CFM and draws 7.5 amps. What the heck kinda fan is that?
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post #6 of 137 (permalink) Old 08-24-2006, 07:55 PM
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So how do you plan to step 12 v to 16 v. The alternator makes up to 16 v but usually there some kind of regulator inline. If you get around 12.2 v by the fan, you can step it up with dc to ac stepup-transormer back to dc. But that would not be efficiant and draw about the same wattage. The original 12 v still needs to supply enough current to make it work. Would be better to have the right guage wire to supply the max current.
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post #7 of 137 (permalink) Old 08-24-2006, 08:26 PM
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Quote:
Originally Posted by foosh
I don't get it. I have a SPAL fan in another custom car that pulls well over 1000 CFM and draws 7.5 amps. What the heck kinda fan is that?
There's one critical bit of data missing here about these two fans, and that's the pressure they produce. Typically, max CFM ratings are in free air, assuming no restriction. Stick the fan in a high impedance system - like the HVAC system - and you will NOT get the max CFM. When sizing fans, there's always a 'fan curve' provided, that plots airflow versus air pressure. Depending on the design of the fans, that 600CFM fan may move more air in a particular system than the 1000 CFM fan.

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post #8 of 137 (permalink) Old 08-25-2006, 04:14 AM
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Amazing -- doesn't matter what the topic, there are experts on this board. Gotta love it!

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post #9 of 137 (permalink) Old 08-25-2006, 05:06 AM
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Is there any evidence that the limitation is on airflow vs. heat exchanger area/effectiveness?
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post #10 of 137 (permalink) Old 08-25-2006, 05:33 AM Thread Starter
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Originally Posted by Chococar
Is there any evidence that the limitation is on airflow vs. heat exchanger area/effectiveness?
It's both. Bottom line...some people like myself would LOVE a crap load more air coming out of the vents. So either you look at things you could actually change, or pipe dream about crap that no one would be able to.

Here's what I am thinking. Keeping the stock wiring in place to the AC control unit and going to the fan area. But instead, have a relay system in between (3 relays, 1 for each speed setting), and wire that up with the appropriate gauge wire. There is a battery post in the front portion of the car you could tap off.
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post #11 of 137 (permalink) Old 08-25-2006, 06:36 AM
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Quote:
Originally Posted by Žob
So...I'm working on getting details, but it looks like SPAL can supply me with a a different unit to replace the factory setup. It'll push 600CFM vs 400. That should make a NICE improvement. Only issue...it'll draw about 33amps vs 12 amps of the stock setup. Soooo....need some help for some wiring experts. I looked at the diagram.... What is the minimum gauge wire needed for a 40amp run? Could we use the existing harness and just up the fuse rating?
33 amps! That's a lot of current for a fan. With a constant 33 amps running through it, 14GA wire will get very hot (it better have some good insulation and be routed where there is cooling air around it), 12GA wire will get fairly warm, and 10GA wire will be just slightly warmer than ambient.

Is the 33 amps a continuous draw, or just a momentary spike when the fan starts up? If it's just a momentary spike, what's the continuous current?

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post #12 of 137 (permalink) Old 08-25-2006, 06:56 AM Thread Starter
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Waiting on spec sheet. I poked around the web and found some good sizing calculators. 9awg wire would be an appropriate size for that.
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post #13 of 137 (permalink) Old 08-25-2006, 07:07 AM Thread Starter
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Spec sheet is getting faxed over to me. Price of new blower is 76$ !! Sweet!

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post #14 of 137 (permalink) Old 08-25-2006, 07:54 AM Thread Starter
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Did some debating with a very knowledgeable tech. Here is what we've come up with. Running a new power wire from battery to front of crash structure is going to be the best bet. Getting to the positive binding under the dash royally sucks.
What I think might be easiest is to run a new wire (with loom around it) through the driver side chassis. Has anyone tried fishing something through there? I believe there is plenty of gap to fit wiring through there, but I've never tried....
Installing 3 relays. Use the power leads from the stock wiring harness for the 3 fan speeds to power the 3 relays. Connect those relays to the new resistor pack that comes with the new blower.
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post #15 of 137 (permalink) Old 08-25-2006, 08:01 AM
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I smell group buy Right now I would rather have this than a supercharger!
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post #16 of 137 (permalink) Old 08-25-2006, 08:04 AM
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I have one of these from my previous delSol project car:

http://www.pegasusautoracing.com/pro...asp?RecId=2771

It's cheap, provides a VERY nice stream of air, weighs almost nothing and only draws 2.6 amps.

Couldn't I just inline this somewhere for that extra oomph?

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post #17 of 137 (permalink) Old 08-25-2006, 08:16 AM
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Quote:
Originally Posted by darkSol
I have one of these from my previous delSol project car:

http://www.pegasusautoracing.com/pro...asp?RecId=2771

It's cheap, provides a VERY nice stream of air, weighs almost nothing and only draws 2.6 amps.

Couldn't I just inline this somewhere for that extra oomph?
This was my thought exactly. Anyone try something like this this yet?
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post #18 of 137 (permalink) Old 08-25-2006, 08:18 AM Thread Starter
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I did some more sizing. A 4 awg wire from the battery to the front of the car will cover the amperage. 8awg from the relays to the fan will cover the other. Next stop on my list...find relays and I want to find a project box I can mount these relays in and make water tight.
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post #19 of 137 (permalink) Old 08-25-2006, 08:21 AM Thread Starter
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Originally Posted by tesprit
This was my thought exactly. Anyone try something like this this yet?
When you put in front of fan what happens? It doesn't move more air...
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post #20 of 137 (permalink) Old 08-25-2006, 09:15 AM
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I measured the stock fan ( on high) at 20 amps. I was going to add a step-up power supply / transformer. Something around 16v but couldn't find one that would handle the 20 amps.

33 amps for a fan sounds real high.
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