Question: Heavy Duty Cooling- How did this work?

[KANE]

So, I've seen references for '80-82 Vettes with a "heavy duty" cooling configuration.

Was this a combination of a bigger radiator and a different fan or an additional fan? Not sure what that option entailed.


Anyone know what that was?


Eckler's has a 7 blade GM replacement. The OEM fans I have seen on my '80 and '82 were 5 blade fans.


Eckler's 7 blade fan...
Corvette Cooling Fan Blade, Clutch Style, With Air Conditioning, 1976-1982 | 469580

 

[kpic]

Kane,
As you mentioned radiator....

1977-1982 Aluminum Radiator | DeWitts Direct Fitâ„¢ Aluminum Radiators

30% more is a nice increase.

Unless you want to stay original; however, I know from reading, yours is about as stock as mine.

 

[KANE]

Kane,
As you mentioned radiator....

1977-1982 Aluminum Radiator | DeWitts Direct Fit™ Aluminum Radiators

30% more is a nice increase.

Unless you want to stay original; however, I know from reading, yours is about as stock as mine.

^ Already there- did that last summer!


Yeah, I have that radiator.


I'm looking to pull a little more air though it. Hence the ask about the 7 blade versus the 5 blade. Sitting in completely stopped traffic today for almost 30 minutes brought me slowly up to 200 degrees today at almost 80 degree weather.

FWIW- I'm not running the OEM puller fan- in fact, I've removed it entirely because the motor didn't work on it anyway.

The fan clutch is fairly new- only about two years old. I have a 185 thermostat that is working properly.

Any thoughts Kpic you have or anyone else would be great.

 

[bill81vette]

the rise in temp sitting in traffic,is not uncommon,Kane
as near as I can find the Heavy duty cooling was a 7-blade fan,with the gymkhana
suspension...
I've seen mine kick the aux cooling fans on in my vette on a hot summer day,but cool right off as
soon as I start moving again.Short of a direct drive fan ,I'm not sure what else you could do...

 

[KANE]

Thanks for the insight, Bill!


Yeah... I am probably a bit paranoid. :ugh

The only thing I might be missing at this point are some seals on the sides of the radiator that attach to the support.


It was very slow to heat up and has a 180 T-stat and a factory clutch on the fan. The car runs a little rich at idle- like 1-3% over depending on the conditions (air temp, coolant temp, etc) and advance is about 21 degrees at idle (which is about right for iron production heads). I idle in gear at 750rpm to offset the cam and run closed loop.

We'll see...

 

[bill81vette]

It may help some but the seals are more for directing air through the radiator while driving down the road as opposed to over it and over heating...
However putting back on can't hurt.

 

[KANE]

Bill- that's what I figured... the seals were more for directing air while moving. It cools off once I start to move. It will drop almost 20 degrees in a quarter mile.

There is a chunk missing from the shroud about 4 inches deep by 6 inches wide at the end of the shroud by the crossmember. Otherwise the shroud looks good. It looks like someone took a bite out of it.

Perhaps that could create a problem- I'm not sure at this point- and I doubt it since it is almost behind the blades. I have a rectangular piece of aluminum that I could undercoat and rivet in place to close that gap. I think it would look okay and like it was a reinforcing plate- shrouds are pricey and other than that it is still a good shroud.

The water pump does't leak and I have pretty good circulation when the T-stat opens. It is a new engine and I've drained it a few times between the engine install and swapping out radiators.

Would a high flow water pump help? How about the 7 blade fan? I already have a DeWitts radiator.

I struggle with how it would start to push 200 degrees in traffic when it is only 80 degrees outside- even if I was sitting for almost 1/2 hour in gridlock.

Maybe I am just paranoid...

 

[Vettehead Mikey]

If it's only reaching 200 in traffic, you're already doing very well. That temp and considerably higher is well within acceptable levels for an SBC.

 

[bill81vette]

Overall I wouldn't worry about it... Mine runs close to 200 with the ac on in the summer on the highway....more if I'm in traffic...I'm not concerned...

 

[kpic]

Kane, Air can do some weird stuff. Just out out curiosity, I'd tape a few pieces of ribbon around the missing piece to see what the air is doing there.. Air is similar to water, looking at a rock in a creek. A 6" rock affects the water 10-12" around it. If it sucks the ribbons in, it is blocking flow through the radiator's cores.

I have a 160F and the inter cooler (really an after cooler) is in front of the radiator; plus the air cleaner so I lose a lot of area. So after few miles in traffic and she comes up 20F, as soon as I am moving she is fine. I use a water wetter agent to help cooling.

In 100F in traffic the fans hit high. I run synthetics which are more tolerant to temperatures than regular oils. I dislike seeing the temperature gauge go up.

 

[minifridge1138]

The rule of thumb I always heard for engine temp was outside air temp + 110*. So if you're running at 200* while sitting still on 80* days, then I'd say you're doing pretty good. Especially since you said it cools down quickly when start to move.

You want the oil to be 190*+ anyway to boil the gas out of the oil anyway. I think you're fine.

 

[kpic]

It isn't the number of blades; it is the pitch and shape of the blades.

FYI:
Re: Why are radiator fan blades non-symmetrical?

American V8's - Curious - Mechanical engineering other topics - Eng-Tips

Back in the day, all high HP engines ran 5 blade and most hydraulic lifter engines ran 7. My guess is the 7's parasitic losses were greater than a 5's. It isn't the number of blades; same as a boat propeller it is the pitch of the blades. A lower numeric pitch is a great hole shot and limited top end. The warning is too high a numeric pitch is harsh on the engine and increases wear.

Simply said, an aggressive pitch with pull more air than a less aggressive pitch or more blades while increasing parasitic losses. The correct pitch will cool the engine and have less losses.

The factory guys actually know what they doing; as it is all they do 8 hours a day for years and years, they ought to know.. Unless the bean counters get in the loop; however, the bean counters fear warranty.

Here is a good read from Hayden: Hayden - Fan Clutch Tutorial - Part 1

You want the oil to be 190*+ anyway to boil the gas out of the oil anyway. I think you're fine.

Gas, acids and water from condensation so probably a bit higher than 190F That is regular oil; I don't know about synthetics.

 

[kpic]

Kane,
You're making this feel like work.

 

[bill81vette]

Kane,
You're making this feel like work.

Guess its time for a Happy Hour!!!:hijack

 

[KANE]

I guess... what concerns me is a slow creep over 200 degrees and where the stopping point might be- or NOT be!

I have a new fan electric fan that I'm going to try. Thank goodness for EBL... I can program it where I want it.



Also, I have a 7 blade coming. Yes- the "heavy duty" fan. From what I understand... at some point they were used on cars with AC as a replacement for the 5 blade version.


I understand the part about blade pitch- thanks guys! . I'd like to see and compare them both. There must have been a reason GM stated supplementing cars with these and using them as part of a heavy duty option.


I've had cars overheat and had to wait on the side of the road until traffic subsided and the car cooled off. That's not an experience I'd like to have again. Ever. LOL :ugh


Last option... go to 4th generation F-body dual fans & assemblies and wire them into the EBL and let the ECM run the show.

 

[Vettehead Mikey]

Back in the day, all high HP engines ran 5 blade and most hydraulic lifter engines ran 7.
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There is no correlation between number of blades and type of lifter. The deciding factor is the presence of A/C and/or optional HD cooling system.

 

[KANE]

Mikey- do you think the seven blade fan moves more air?

 

[Vettehead Mikey]

Mikey- do you think the seven blade fan moves more air?

All other things (size and pitch of each blade) being equal and turning at the same speed, yes. Otherwise, maybe.

 

[kpic]

There is no correlation between number of blades and type of lifter. The deciding factor is the presence of A/C and/or optional HD cooling system.

The 7 blade has more drag, weighs more therefore has a greater parasitic loss than a 5. Think about it, you'll get it.

https://www.drclassic.com/images/catalogs/pdf/Camaro/Underhood.pdf

There are 5 and 7 blade fans here on pages 14 and 15. You'll notice the spacing is not symmetric; I'll let you explain why.

 

[Vettehead Mikey]

The 7 blade has more drag, weighs more therefore has a greater parasitic loss than a 5. Think about it, you'll get it.

The number of blades still has nothing to do with the type of lifters. No idea where you got that idea. Go look at some Corvettes.