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DeWitts Fans - Performance & Wiring ???

 
Old 06-16-2019, 01:30 PM
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Default DeWitts Fans - Performance & Wiring ???

My SC'd C6 is not liking these Florida temps, even with the DeWitts radiator. Now I've gone and melted my fan connector so it's obviously time to upgrade.

The ProSpeed setup is nice with all of the wiring plug & play, but not for $500 more, and their PWM controller is (sorry Prospeed!) nothing more than a $30 solid state relay so no huge added value there. So I'm leaning towards the DeWitts which they say can re-use the stock controller, or make my own if necessary.

Does anyone have any real-world experience on the performance of these units on a car with an A2A intercooler in front of the rad? Leaning towards the DeWitts for less than 1/2 the price but am I missing something?

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Old 06-16-2019, 02:40 PM
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I went with the ProSpeed and it works great out here in Az Heat. From what I read those other setups don't cool well so that's why I spent the money on the ProSpeed.
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Old 06-16-2019, 03:38 PM
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Originally Posted by donnyt View Post
I went with the ProSpeed and it works great out here in Az Heat. From what I read those other setups don't cool well so that's why I spent the money on the ProSpeed.
Thank you for the quick reply! I wonder what the CFM difference is between the two?
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Old 06-16-2019, 04:07 PM
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Originally Posted by Pete2k_Z28 View Post
Thank you for the quick reply! I wonder what the CFM difference is between the two?
Pretty sure it's more about the shroud design between the two. Unreal on here was able to shed some light on this quite a bit from researching in this forum across the various threads
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Old 06-16-2019, 04:09 PM
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Originally Posted by donnyt View Post
Pretty sure it's more about the shroud design between the two. Unreal on here was able to shed some light on this quite a bit from researching in this forum across the various threads
Thanks, I'll search his threads or maybe just send him a PM.
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Old 06-16-2019, 05:15 PM
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Not even close to the same fans. Even though both are Spal, one is like a Chevy Cobalt, the other a Corvette.

You are better off just fixing you fan connector than downgrading, unless you goto the prospeed setup.

The "Dewitts" setup uses normal high performance spal fans rated at 525cfm at 25 mm pressure.
The Prospeed uses extreme performance spal fans rated at 1074cfm at 25mm pressure.

That is more air flow from one of the prospeed fans than both fans on the dewitts system. There is a reason is it cost more.

Last edited by Unreal; 06-16-2019 at 05:21 PM.
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Old 06-16-2019, 07:13 PM
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Originally Posted by Unreal View Post
Not even close to the same fans. Even though both are Spal, one is like a Chevy Cobalt, the other a Corvette.

You are better off just fixing you fan connector than downgrading, unless you goto the prospeed setup.

The "Dewitts" setup uses normal high performance spal fans rated at 525cfm at 25 mm pressure.
The Prospeed uses extreme performance spal fans rated at 1074cfm at 25mm pressure.

That is more air flow from one of the prospeed fans than both fans on the dewitts system. There is a reason is it cost more.
Thank you for the reply and the PM. I had not been able to find any good CFM data on the DeWitts unit so that really puts things in perspective. I had been a little suspect of the performance on the DeWitts unit since they claim it can use the stock PWM controller, which would tell me it can't be all that much more powerful than stock. I was also skeptical that ProSpeed was charging mostly for convenience, having a mostly "plug & play" solution. It seems that is not the case, but it doesn't make shelling out $900 on fans taste any better
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Old 06-16-2019, 08:44 PM
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PDF with flow specs are on spals site.
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Old 06-17-2019, 11:47 AM
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Originally Posted by Unreal View Post
PDF with flow specs are on spals site.
Thanks again, I see there is quite a big difference between the Spal "dual fan" https://webstore.spalusa.com/content...02052_SPEC.pdf and their highest rated 11" fan https://webstore.spalusa.com/content...02800_SPEC.pdf

That said, the "dual fan" (setup that DeWitts uses) is 2720 CFM base flow vs. factory which from what I gather is 1600-1700 CFM. I'm not arguing with your experience, and I absolutely agree the Prospeed setup is more efficient, I just want to understand how a fan with 1,000 more CFM than stock is downgrading. Of course I'm going from baseline flow vs. baseline flow because I cannot find a gradient chart for the stock fan, though I would assume it's rather poor since it's an open construction shroud.

I don't mind spending the money if I "need" to, but there's no point in spending money for more than I need, especially when you consider the Prospeeds may also require an alternator upgrade as well.
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Old 06-17-2019, 11:58 AM
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You shouldn't look at unrestricted flow because fans are used unrestricted. So quoting numbers for when there is no radiator or ac condenser or fmic doesn't mean anything. Plenty of people have seen increased temps with those fans. I fell for that trap. Real world results show they don't cool as well.

The only other upgrades are 17" nuova fan for $750-800 or dual pwm nuova setup but that is $1300+. Prospeed is very good price compared to competition.

If $1500 for fans and alternator is even something to think twice about then a blown Corvette maybe not for you. That's a minor drop in the bucket compared to the drivetrain, fuel system and other parts needed for a car at this level.

Last edited by Unreal; 06-17-2019 at 12:02 PM.
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Old 06-17-2019, 12:09 PM
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Originally Posted by Unreal View Post
You shouldn't look at unrestricted flow because fans are used unrestricted. So quoting numbers for when there is no radiator or ac condenser or fmic doesn't mean anything. Plenty of people have seen increased temps with those fans. I fell for that trap. Real world results show they don't cool as well.

The only other upgrades are 17" nuova fan for $750-800 or dual pwm nuova setup but that is $1300+. Prospeed is very good price compared to competition.

If $1500 for fans and alternator is even something to think twice about then a blown Corvette maybe not for you. That's a minor drop in the bucket compared to the drivetrain, fuel system and other parts needed for a car at this level.
What amp alt is required above the stock one ? I looked at the Derale 4000cfm set up ( had great reviews ), they were pulling almost 50 amps i think !
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Old 06-17-2019, 12:18 PM
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Originally Posted by Pete2k_Z28 View Post
My SC'd C6 is not liking these Florida temps, even with the DeWitts radiator. Now I've gone and melted my fan connector so it's obviously time to upgrade.

The ProSpeed setup is nice with all of the wiring plug & play, but not for $500 more, and their PWM controller is (sorry Prospeed!) nothing more than a $30 solid state relay so no huge added value there. So I'm leaning towards the DeWitts which they say can re-use the stock controller, or make my own if necessary.

Does anyone have any real-world experience on the performance of these units on a car with an A2A intercooler in front of the rad? Leaning towards the DeWitts for less than 1/2 the price but am I missing something?
I bought the Caspers Electronics fan controller, plug and play into existing connectors which allows you to set the fan to be either normally controlled by ECU , manual control of fan at low speed , manual control of fan at high speed. All 3 settings controlled by a switch you can change when you want. FWIW, I am dealing with the same issue here with Florida temps. To the point where I stopped driving it recently due to the near all time heat records we had. I am also changing to Royal Purple 10-40 HPS oil to see if it holds up better than the Mobil 5-30 which may be fine for stock motors, but throw in a blower along with meth inj and ridiculously hot outside temps and a higher viscosity / quality oil is needed in my opinion.
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Old 06-17-2019, 12:23 PM
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Originally Posted by Unreal View Post
You shouldn't look at unrestricted flow because fans are used unrestricted. So quoting numbers for when there is no radiator or ac condenser or fmic doesn't mean anything. Plenty of people have seen increased temps with those fans. I fell for that trap. Real world results show they don't cool as well.

The only other upgrades are 17" nuova fan for $750-800 or dual pwm nuova setup but that is $1300+. Prospeed is very good price compared to competition.

If $1500 for fans and alternator is even something to think twice about then a blown Corvette maybe not for you. That's a minor drop in the bucket compared to the drivetrain, fuel system and other parts needed for a car at this level.
Oh trust me, I'm well aware of what it costs to build / own a blown Corvette. I'm close to $20k in parts alone the past year and that's doing all the work myself. But spending $1,500 on anything is always something to think about, it's a lot of money by any measure. Like I said, I don't mind so much spending the money if it's worth it, but there's no point spending more than needed, and spending that much money without getting all the facts is foolish. Like you said on PM, "...or just too stupid to research". Well, this is research.

Thank you for sharing your experience.
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Old 06-17-2019, 12:27 PM
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Sorry if I came off harsh there. Just seen it too often lately as price on these cars come down too many people think a 609; hp reliable Vette is nothing but a 5000 blower.

Prospeed fans work and are proven in the most extreme environment and setups. Too many people including myself bought the spal dual and noticed a rise in temps.

Prospeed setup is buy once hurt once. I bought spal dual, ran hotter. Lost $300 on them as you are lucky to sell for $200 of that and then spent $800 on 17" fan setup. Prospeed wasn't out at the time 6 years ago otherwise would have went that way.

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Old 06-17-2019, 12:29 PM
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Originally Posted by Unreal View Post
Sorry if I came off harsh there. Just seen it too often lately as price on these cars come down too many people think a 609; hp reliable Vette is nothing but a 5000 blower.

Prospeed fans work and are proven in the most extreme environment and setups. Too many people including myself bought the spal dual and noticed a rise in temps.
No worries, and I agree.... I'm just the type that likes to have hard data before I spend hard money
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Old 06-17-2019, 12:33 PM
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Plus anything that just uses stock fan plug and wiring will be amp limited. I wouldn't consider anything that doesn't run new power wires and fuses direct to power source. I think maybe the spal dual fans could flow better than stock if you redid all the wiring and ran new fuses and power wires but both fans being fed off the single small wire probably limits them. 17" and prospeed just use the signal for pwm and then are new power setups directly to fuse box.
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Old 06-17-2019, 12:41 PM
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Originally Posted by Unreal View Post
Plus anything that just uses stock fan plug and wiring will be amp limited. I wouldn't consider anything that doesn't run new power wires and fuses direct to power source. I think maybe the spal dual fans could flow better than stock if you redid all the wiring and ran new fuses and power wires but both fans being fed off the single small wire probably limits them. 17" and prospeed just use the signal for pwm and then are new power setups directly to fuse box.
Great point and I had the same thoughts; running off the stock wiring could reduce performance, especially since it's about 40% more current (40A @ full load vs. 25A stock). I had actually planned to purchase a pair of 40 amp solid state relays to make my own PWM controller and hard wire the fans (similar to Prospeed). The factory fuse is 60A but I don't think that's quite a 60A circuit continuous duty.
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Old 06-17-2019, 12:50 PM
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I opted to go with these guy's coupled with the Dewitts radiator I do not go over 201 here in FL. Yes it is more expensive than the other guys but it is well worth it IMO.

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Old 06-17-2019, 01:01 PM
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Another great option is to get out of Florida. That would be my choice of what to do in this situation
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Old 06-17-2019, 01:57 PM
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[QUOTE=Unreal;1599597922]Another great option is to get out of Florida. That would be my choice of what to do in this situation [/QUOTE

Hey, we get nice weather about 4 months out of the year, come on now.I see you are in Arizona, land of the 100+ temps, but I hear it's a "dry heat" so its not that bad, lol.... Seriously though, its been hot as f*ck way to early this year. My home ac unit could not even keep up, and it is a fairly efficient set up. Between keeping the house cool and the Z cool , its a real task !!
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