Electric fans or Flex fan

RaysZ71 · February 24, 2006

Looking to help the mpg a bit on the '99 Sub.

What do you recommend for the money?

Electric Fans

or

Flex fan with clutch.

For the elctric fans, what CFM do I need.

Mr. Smith · February 25, 2006

Looking to help the mpg a bit on the '99 Sub.

What do you recommend for the money?

Electric Fans

or

Flex fan with clutch.

For the elctric fans, what CFM do I need.

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If you can afford it I would go electric. There is zero drag on the motor vs drag even with a low drag fan and clutch.

Go as much as you can and will fit under the hood. It can't hurt.

redvett · February 26, 2006

Along with the fans get a PCM tune and remove the cross bars on the roof rack.

facn8me · February 26, 2006

Since aftermarket elec fans have become so reliable it's a no brainer. I agree with mrsmith as big as you can afford. Cover the entire rad if possible. A custom tune can ( i believe) be programmed to run the fan also.

redvett · February 26, 2006

You can only make fans be controlled by PCM on 05 up PCM's. Make sure you use a fan system that has two fans like Camero or Corvette.

facn8me · February 26, 2006

I knew someone would know on the pcm tune. There are several good fan controllers availible also, including relay and temp sensing.

redvett · February 26, 2006

I used C5 Corvette fans and wired it with a controller with temp sensor in fins of the core. Got controller & relays from Jegs.

BlueTahoe · February 27, 2006

Just to Clarify on the PCM. You can tune older PCM's to controll on and off based on coolant temperature. I had this set up on my 03 tahoe. You still have to tap into an A/C wire to get them to come on with A/C. Nelson performance sells a harness that does it all. You just have to buy the fans, get PCM tune, and buy his pre-made harness.

RaysZ71 · February 27, 2006

ok.. I like the electric fan idea.

How big a fans do I need?

How many CFMs?

redvett · March 1, 2006

I believe GM uses 1200-1500 cfm but aftermarket uses a formula with engine displacement.

99Silver6.0 · March 2, 2006

You can only make fans be controlled by PCM on 05 up PCM's. Make sure you use a fan system that has two fans like Camero or Corvette.

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Wrong. You can do it on any 99+ PCM. Allen Nelson makes a harness just for it. Although you do need the ability to set up your on/off temps. EFILIve, HPTUners or LS1Edit.

You can use LS1 fans or the FlexALite 292's which are a direct fit for the 28" radiator.

RaysZ71 · March 2, 2006

I found a fan /shroud setup. It comes with a adjustable thermastat. Moves 2000 CFM. However this is a single fan, not dual.

redvett · March 2, 2006

Most fan MFR's have a formula and it goes with cubic inches say 350 but i can tell you if you have A/C and a 350 your going to need a 2 fan unit. One should be for no A/C normal operation and the faster one for A/C i my self put a diode in between the two fans so when A/C is on the primary fan runs also.

99Silver6.0 · March 3, 2006

I found a fan /shroud setup. It comes with a adjustable thermastat. Moves 2000 CFM. However this is a single fan, not dual.

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You want dual fans man!!! You can get LS1 F-body fans off ebay for around $100 bucks. Just peek around. And they are easy to install. Look for 98-02 LS1 fans.