well im not happy with the way my single fan cools my motor, so im swapping to a dual TPI fan setup soon. Ive never owned a tpi car or any car with dual fans, so i dont really know what all i need. obviously im gonna need the fans and the mounting brace that runs along the top of the radiator and the required nuts/bolts. is that all i need? what about the wiring harness? do i need a new harness or do i just need to modify my current harness. the primary fan will be wired to operate when the key is in 'run'. the secondary fan will be wired just as the old single fan was (on when A/C is on and/or when fan switch turns it on).

this is going on a 91 firebird with an L03 btw.

 

I would strongly advise you go with either a 4th gen dual fan shroud and either the stock fans that would come with it or go with after market fans. Spal makes an excellent dual fan shroud unit with dual 11" fans.
That would probably be your best and cheapest way to go. You get install directions with it which takes all of the guesswork out of it. If you need or want wiring diagrams for your car, pm me with your address and zip and I will mail them to you. I switched my `88 Iroc 383 TPI over to a dual fan shroud set up and it was the only way I finally got my temps down consistently without spending a ton of money. I still use the stock radiator and water pump. I did change the thermostat to a part # EMP-301, it`s a 180 thermostat with 3 3/16s bypass holes in it so there is always some coolant flow, replaced the fan switch with a Jet # 60600 which turns the fans on at 200 and off at 185. Also got a new radiator cap, installed a spring in the lower radiator hole so it can`t collapse and I run 1 bottle of Red Line Water Wetter along with a 60% distilled water to 40% antifreeze mix. Make sure to check your lower air dam/deflector/diffuser/baffle to see if it is still there and check the area between the radiator and condenser to make sure no debris like leaves or dead critters are blocking your air flow.

 

the reason i was going with the TPI fans was because i knew it would be a direct replacement with no modifications needed.

another reason i chose the TPI fans was because of price. how much is the spal fans you mentioned? im on a tight budget and i know i can go to the local f-body junkyard owner and get what i need real cheap.

 

86bird, keep in mind that I have an `88 Iroc that had dual factory fans that worked the way they were supposed to from the factory and I could not keep my engine cool. It took the addition of a fan shroud to get the temps down. The fans by themselves are not going to get the job done. Look for some pics of 4th gen fan shrouds or after market ones so you know what I am talking about. Sometimes the upper and lower mounting brackets on cars like mine with dual fans are called shrouds but they are not. I just checked the price on Spal dual fans & shroud from Jaycorptech.com and they want $239 without tax or shipping. I paid $15 or $20 for my LT1 type dual fan shroud which needed some modifications to work and $99 each for my fans. There are not many cheap fixes on cars these days. Go back and read my first post and you will see the few other changes I made, they all work together. If you are determined to stay with factory fans, go for a 4th gen LS1 type with both the fans and shroud. There are some on this site that have done this mod and they love it and their cars run cool.