Project TOWTRUCK buildup... fan question big block

[camiswelding]

Nearing the end of my buildup of project TOWTRUCK...
89v3500 crew....

My questions is the radiator fan
The factory used a 5 blade 20 inch fan...pretty severe pitch
The shroud can accomodate up to a 22" fan with some trimming

I have heard some people use duramax fans or others,such as a medium duty truck fan, as a way to move more air to cool the hot bigblocks...
horsepower rob is not a primary consideration....cooling is

Aftermarket stuff?

Any comments

Thanks
cam

 

[nvrenuf]

For my crew cab I ditched the original 5 blade stuff for a 7 blade fan and a severe duty fan clutch (application = 83 K30 dually, 454, 4spd, 4.56's) and a 4 core radiator. My truck has a 350 so it cools fine but I also had this set up in my old K10 wheeler with a roller 454 and even without a shroud it cooled flawlessly. The K10 NEVER ran hotter than 200* (w/ 195* t-stat).

I have heard some talk of the possibility of using a 6.5 fan blade but have not researched it much. TARussell was looking into this but I'm not sure what he found.

 

[camiswelding]

thanks nvrenuf... I know about the 7 blade.... this is a good upgrade
Im interested in medium duty stuff.... anyone have some other ideas?

Obviously my setup is a part serp belt...so its a standard rotation


thanks
cam

 

[tarussell]

For my crew cab I ditched the original 5 blade stuff for a 7 blade fan and a severe duty fan clutch (application = 83 K30 dually, 454, 4spd, 4.56's) and a 4 core radiator. My truck has a 350 so it cools fine but I also had this set up in my old K10 wheeler with a roller 454 and even without a shroud it cooled flawlessly. The K10 NEVER ran hotter than 200* (w/ 195* t-stat).

I have heard some talk of the possibility of using a 6.5 fan blade but have not researched it much. TARussell was looking into this but I'm not sure what he found.

All the info I found on 6.5 stuff was reverse rotation 9 blade stuff.

From what I can tell GM replaces the 19" 7-blade piece with that severe pitch 5-blade part. Some of the medium duty applications were larger in diameter but I do not have such an application in my head - spend some time in the medium duty manuals at the local GM dealer to find superseded parts numbers alog with blade counts and diameter . I do not think they will indicate if the pitch is extreme or not but I do know they state the diameter.
HTH , Tom

 

[camiswelding]

Thanks Tom

I discovered today while at the gm dealer that I currently have the extreme pitch 5 blade fan.... 500 cm or about 19 1/2 inch...

We looked at medium duty stuff but the parts books doesnt say if they are extreme pitch or not.... Ill keep working on this...

thanks
cam

 

[70~K5]

Cam my '95 C3500 has a engine driven clutch fan plus a electric fan on the pass. side mounted as a pusher. All of this is stock.

 

[camiswelding]

I have an electric pusher fan on one side as well... a hayden

I just spent big bucks redoing the motor.... truck only had 50k on it but the P.O. grandpa had overheated it pulling his 5th wheel and I could never get it to cool right...during the teardown I discovered blown headgaskets...only pushing exhaust into the coolant and not the other way around...I was stymied as the thing ran super and didnt burn any oil at all
now I have spent a bazillion bucks on it and mucho hours... and I was looking at all the best ways to keep it cool....(all the normal tricks are already in place)
They put big block 454s in the medium dutys from 99 up.... Ive been looking at those fans (I have the room)... thinking there might be a better fan option..

cam