Electric fans suck!

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454cid

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The 454 fan is a steel hub with 9 aluminum blades. I swapped it out for a later design 11 blade nylon that I think came in 610 Van's and 800 trucks, but also lists the 454, now.
 

L31MaxExpress

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The 454 fan is a steel hub with 9 aluminum blades. I swapped it out for a later design 11 blade nylon that I think came in 610 Van's and 800 trucks, but also lists the 454, now.
My buddies has and always has had a 5 bladed fan. I have worked on several TBI, Vortec and 8.1 big blocks with this fan.

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Carlaisle

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Now I'm curious. What year was the 6.5 with the 7 bladed fan? Did any of those 5 bladed fans cool adequately? I have owned 3 454 engines and worked on multiple 8.1s and 6.5s and have yet to see a 5 or 7 bladed fan on any of them. I apparently stand corrected.
 

L31MaxExpress

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Now I'm curious. What year was the 6.5 with the 7 bladed fan? Did any of those 5 bladed fans cool adequately? I have owned 3 454 engines and worked on multiple 8.1s and 6.5s and have yet to see a 5 or 7 bladed fan on any of them. I apparently stand corrected.
I think the 7 blade I have may have been on a 96 P30 van without air.

My buddies 99 454 cools pretty good but the thing sounds like a single engine Cessna almost all the time. His truck has the pusher condenser fan on it. I programmed it to come on a little earlier than stock when I tuned his black box for LS1 injectors.
 

letitsnow

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I have learned so much from guys and really enjoy reading stuff like this thread - thanks for posting.

I have also learned that gm used whichever parts were convenient. Most times when people use words like "never and always" when referring to what parts came on what vehicle - they end up looking like fools.
 

L31MaxExpress

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So I had to break out my step drill and ever so slightly open up the bolt holes on the Ford fan. It runs with zero vibration so must have centered up well. That being said, replaced the 34x19 radiator with a TYC factory replacement for an Express van with a small block. 31.5 x 17 x 1.25 core. The Ford fan is extremely quiet and pulls good CFM. Idling with the a/c blasting the clutch did fully engage a few times. It sits right between 178 and 182°F now with the 170°F thermostat.
 

stutaeng

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It looks like the 8.1 engine I have has a 5 blade. It was from a 04 HD truck mated to an Allison.

IIRC, the HD trucks have a deeper radiator. The entire front grill is deeper vs the Non-HD variants.
 

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Ehall8702

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I would think 6000 CFM would be enough to keep it cool at idle. I don't have any data but that feels like a high number for a mechanical fan to achieve at that rpm.
I had two 16" 9n my 97 with stock rad, it did well pulling my camper. We don't get real hot here but it was a tad higher than the stock fan temps. Never overheated tho, if I'd have made a shroud with only holes for fans prolly woulda been better. I pulled it and put stock fan back.
 

gearheadE30

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Every 8.1 has a 5 blade steel fan, unless it was installed in a Kodiak. Internet lore is they are good for 11,000 peak CFM on that engine/that FEAD pulley ratio.

The trailblazers use a plastic fan with an outer ring that is the same diameter and pulls even more air than the stock 8.1 fan, but it is probably overkill for most cases. Not a lot of other 21.5" fans out there. GMT400 stuff, at least with small blocks, are 19.5" fans. The bolt pattern is different on the Trailblazer fan and most of them have electric fan clutches, but for 2008-2009 they had a standard mechanical fan clutch with the same thread pattern as all the other GM stuff of the era.

As far as I can tell, the Kodiaks actually use the trailblazer fan setup, or something visually very close to it. Depending on what you look at on Rockauto, some of the part numbers interchange.

For some reason, every aftermarket fan clutch I've had seems to engage earlier and cycle more than the OEM GM stuff, which is a bit of a bummer for fuel economy.
 
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