Does anyone know which moves the most air, or do they both move the same?

 

I would say LS1's I have read where LT1's move more than TPI ones. So I would say LS1's will be close to the LT1's or better. Mabey some who knows for sure will chime in.

 

The LT1/LS1 fan assemblys are very similar(the LT1 assembly have openings cut into them).They even share motors in most cases with 3rd Gen dual and single fan setups.The 4th Gen fan assemblys have the big advantage over the 3rd Gen setip being built into a shroud that covers the radiator.I have a LT1 assembly on my '95 Jimmy(S-series radiators are almost exactly the same size)and there is a noticeable difference in the amount of air movement in and out compared to my '83 Z28 with 3rd Gen open dual fans.I intend to upgrade my '83 down the road to a LT1/LS1 fan assembly.
Hope this helps but I'm sure someone has more info on the LT1/LS1 setup for you.

 

I have wondered though, if the shroud on later fan systems would negatively affect the airflow patterns created by the air dams on our cars?

 

Thats a very good question...I would like to know myself because I was looking at getting an electric fan...I have seen a nice kit that comes with radiator and aluminum shroud with electric fan but I am doing my homework first.

 

I never thought about the shroud affecting the airflow. I'll let you know how it works out for me in my firebird when I get them. I can't wait to see the difference, right now my fans basically run all the time, and they run for longer than I like after the engines off . I'm running a 180/170 switch with an aluminum radiator.

 

That's one of the reasons I went with the dual fan setup vs. LS1. A shroud is a nice idea when there is no air moving through the radiator (low speed/stopped), but at speed it hinders airflow. You could always cut and install flaps that can open at speed and allow more air through.

 

I always thought a shroud balanced the air coming through the radiator.
But does anyone know the stock fan CFM ?

 

i have an LT1 fan in my 90 firebird and ill tell u I ( for the time being ) only have one fan hooked up and it keeps my car cooler then the old stock junk.

 

This is just my .02 but I believe the cutouts in the LT1 shroud assembly was GM's thinking of the needed airflow thru the radiator above 40mph.But the LS1 shroud assembly doesn't have these so they may have found them unneccessary.Look at it this way,on an engine driven fan you have a shroud,and as soultron stated,the shroud can also be used to drirect or funnel air flow when the fans aren't running/needed.Without a shroud the fan(s) pull air from thru over and around the radiator so effective cooling abilty is down.

 

i jus bought a 2001 dual setup havnt put them on yet...i jus want nice cold a/c in traffic...

 

Well think about it this way.
My Dual Thermo fans flow 2,700CFM thats $#!t loads through the two holes in the shroud and when they are not moving they may block about 10% of that flow so thats still 2,430CFM.
I have a 180'F T/Stat, 190'F "fan on" temp switch, Custom Airdam and on a 35'C/95'F day I don't pass 200'F normal and 220'F under load (up hill).

 

Checker Auto has a dual fan set-up for 3rd gen's, that has a shroud. ($220) Anybody ever tried one of these.

I can tell you for sure that the original single fan set-up on my '86 was a ridiculus piece of innefective s__t, compared to the stock dual-fan set-up, I ugraded to, off of an '87 dual-fan car.

 

I'm disappointed, once again I took someone elses word. I didn't notice any difference in the cooling capabilities yesterday when I swapped the stock duals for the ls1's. It still takes the same ammount of time after the engine is off to cool down. I can't believe I just spent 125 on these fans for no reason at all. I read that they have a higher amperage motor, but I don't believe it, they seem to flow the same ammount and they are the same exact blades, and the motors look the same. Whoever is thinking of switching don't waste your time and money. Anyone want to buy mine?

 

off course it will take the same time when the car is off the water pump isnt going nor are the fans.

 

It is the same when the engine is running also. And wouldn't you think if the motors are higher amperage that it would cool the engine faster running/not.

It also runs hotter at cruising speeds now, because the shroud blocks air flow.
I'm going to most likely end up switching back.