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Discussion Starter · #1 ·
Greetings All. Has anyone ever tried to open up the fender wells to improve air flow through the engine compartment? I have what most consider an optimum cooling set up but it overheats when sitting still (230 degrees + in hot weather). I am told that my engine set-up limits airflow through the engine compartment: BBC engine with larger headers, centrifugal blower on driver side, alternator above engine and Vintage A/C on driver side. It IS really tight in there. So, local experts suggest that louvering the hood or opening fender wells will provide more air flow. And I really don't want to louver the hood since the car has a really nice recent custom paint job.

https://www.dropbox.com/sh/s1pvmceqf6n5u6h/AADwKUCWbDZHytOZqhOBPAQQa?dl=0

Any thoughts or suggestions would be most appreciated.

Ken
 

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Fan & Radiator ??
 

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Air and coolant flow through the radiator cools the engine, hood louvers nor inner fenders will help enough to stop overheating. Hold a piece of newspaper or a rag in front of the radiator to check air flow. Bad fan clutch or some kind of high speed fan?
 

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Greetings All. Has anyone ever tried to open up the fender wells to improve air flow through the engine compartment? I have what most consider an optimum cooling set up but it overheats when sitting still (230 degrees + in hot weather). I am told that my engine set-up limits airflow through the engine compartment: BBC engine with larger headers, centrifugal blower on driver side, alternator above engine and Vintage A/C on driver side. It IS really tight in there. So, local experts suggest that louvering the hood or opening fender wells will provide more air flow. And I really don't want to louver the hood since the car has a really nice recent custom paint job.

https://www.dropbox.com/sh/s1pvmceqf6n5u6h/AADwKUCWbDZHytOZqhOBPAQQa?dl=0

Any thoughts or suggestions would be most appreciated.

Ken
What size is you AC Condenser. I have seen it were if the A/C Condenser covered all of the area in front of the radiator, that it could cause over-heating issues.

 

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Discussion Starter · #6 ·
As you can see from that photo, the A/C condenser covers the entire intake area of the radiator. But I have never heard that such coverage would interfere with cooling. Why would Griffin do that? And most of the modern radiators I have seen have the same arrangement. Maybe there are supporting opinions here. Or it might be worth a call to Griffin. There is more info on my radiator setup here:

http://www.classicchevy.com/chevy-cross-flow-radiator-kit-aluminum-griffin-1955-1957.html.

KEN
 

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If you are having the heating issue only during long idle times and no other time then the problem is your fan/fans are not moving enough air through the radiator.
 

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Discussion Starter · #8 ·
If you are having the heating issue only during long idle times and no other time then the problem is your fan/fans are not moving enough air through the radiator.
Bruce, I'm not sure where to go with your suggestion. Griffin tells me that I have the highest flowing Spal fans. So, increasing fan CFM does not seem possible. My first thought from what you say is that the local folks are correct, that there is not enough air flow through the engine compartment. If that were improved, I would expect that the overall flow through the fans would improve too. One bit of data: the engine will idle at 185 degrees for 30+ mins sitting in the shop - with the hood open and fans going, of course. But one comment earlier said that adding mods to the metal work to increase air flow would not make much difference. Where to go from here?

Ken
 

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You have to consider the system. It's like a box fan blowing into a small room. Even if you close all of the windows the fan will still move air as it cannot pressurize such a large space to the point the pressure stops airflow... Not gonna happen in your engine compartment either...
The engine compartment is open to atmosphere. It is not pressurized in any way other then by your cooling fans when they are running. The fans will move air through the compartment as there is nothing to stop the air flow.
Mark
 

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Bruce, I'm not sure where to go with your suggestion. Griffin tells me that I have the highest flowing Spal fans. So, increasing fan CFM does not seem possible. My first thought from what you say is that the local folks are correct, that there is not enough air flow through the engine compartment. If that were improved, I would expect that the overall flow through the fans would improve too. One bit of data: the engine will idle at 185 degrees for 30+ mins sitting in the shop - with the hood open and fans going, of course. But one comment earlier said that adding mods to the metal work to increase air flow would not make much difference. Where to go from here?

Ken
If the shroud built into the radiator is not deep enough the fans will only effectively cool the area of the core directly in front of them. The other area of the core will not be as effective. I would spend some time with an infrared heat gun on your core to see if you have hot or cold spots. You will likely need to remove or at least unbolt your A/C condenser to gain access to do that.
 

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Discussion Starter · #11 ·
".....The fans will move air through the compartment as there is nothing to stop the air flow."

But, Mark, I was trying to address that point in my original query. There are significant large bodies in the engine compartment that are impeding the flow of air. You can feel the flow restriction of these bodies with your hand in that there are only a couple of specific channels with significant air flow over the engine and no flow in the majority of areas behind the fans. And evidence for that restriction is also provided by extended running of the engine with the car sitting still and the hood open, where you find no problem with idling for long periods. On the other hand, running the engine sitting still with the hood closed produces elevated engine temperatures (220+). To me, it seems that there must be restrictive elements to fan air flow with the hood closed to produce this difference.

Ken
 

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Discussion Starter · #12 ·
If the shroud built into the radiator is not deep enough the fans will only effectively cool the area of the core directly in front of them. The other area of the core will not be as effective. I would spend some time with an infrared heat gun on your core to see if you have hot or cold spots. You will likely need to remove or at least unbolt your A/C condenser to gain access to do that.
So you are saying that there may be a design flaw (not deep enough) to the shroud that will impede uniform cooling of the radiator. Is it possible to make some physical measurements (e.g., the traditional 1/2 the depth of the fan blade) or do you think that I can only answer your question with temp measurements with the A/C condenser removed (harder to do)? Also, the condenser is spaced very close to the radiator so I wonder if your temp measurements can be made in front of the condenser?

Ken
 

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So you are saying that there may be a design flaw (not deep enough) to the shroud that will impede uniform cooling of the radiator. Is it possible to make some physical measurements (e.g., the traditional 1/2 the depth of the fan blade) or do you think that I can only answer your question with temp measurements with the A/C condenser removed (harder to do)? Also, the condenser is spaced very close to the radiator so I wonder if your temp measurements can be made in front of the condenser?

Ken
The only way you will find hot or cold spots in the radiator is to take temp readings directly on the core, Not on the A/C condenser. Short of randomly changing things the temp readings is your next step if you want an accurate answer.
 

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Discussion Starter · #14 ·
The only way you will find hot or cold spots in the radiator is to take temp readings directly on the core, Not on the A/C condenser. Short of randomly changing things the temp readings is your next step if you want an accurate answer.
I certainly don't want to randomly change things, hence my inquiry here. In that regard, can you provide me with some concept of what exactly you mean by a shroud that is "not deep enough." Can you discern the difference between a shroud that is too deep from a shroud that is not deep enough? And can you get the same variation in radiator temps with a shroud that is too deep? And how do you define "hot spots" and "cold spots?" How do you establish what is the "right" temperature? How big should a "spot" be to justify making a mod - does a single spot that is off temp over only 1-inch square justify modifying the shroud or do you need at least 4-inch square? In other words, can you quantify the size of the total surface area temp anomalies that justify shroud modification?

Sorry for all the questions (I can think of a lot more). I can see this investigation leading to some very complicated issues and expense and, being a novice in this area, I am concerned about how to go about it, interpret the temp measurements and then translate the results into needed mods. Furthermore, I suppose that, if a mod is called for, I may have to get Griffin to build a one-off shroud.

Finally, I thank you for your interest in my problem and your willingness to help me.

Ken
 

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I certainly don't want to randomly change things, hence my inquiry here. In that regard, can you provide me with some concept of what exactly you mean by a shroud that is "not deep enough." Can you discern the difference between a shroud that is too deep from a shroud that is not deep enough? And can you get the same variation in radiator temps with a shroud that is too deep? And how do you define "hot spots" and "cold spots?" How do you establish what is the "right" temperature? How big should a "spot" be to justify making a mod - does a single spot that is off temp over only 1-inch square justify modifying the shroud or do you need at least 4-inch square? In other words, can you quantify the size of the total surface area temp anomalies that justify shroud modification?

Sorry for all the questions (I can think of a lot more). I can see this investigation leading to some very complicated issues and expense and, being a novice in this area, I am concerned about how to go about it, interpret the temp measurements and then translate the results into needed mods. Furthermore, I suppose that, if a mod is called for, I may have to get Griffin to build a one-off shroud.

Finally, I thank you for your interest in my problem and your willingness to help me.

Ken
Ken, PM me the number and best time I can call you at.
 

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Something else to consider is the alternator output. Modern vehicles w/electric cooling fans normally have around a 100 amp alternator. If your alternator doesn't have enough amperage, the voltage won't won't be enough to run the fans at full speed & the crowded engine compt will compound the problem.
 

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could be as simple as increasing idle timing to help engine run cooler. retarded timing increases engine heat.
 

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Discussion Starter · #19 ·
Something else to consider is the alternator output. Modern vehicles w/electric cooling fans normally have around a 100 amp alternator. If your alternator doesn't have enough amperage, the voltage won't won't be enough to run the fans at full speed & the crowded engine compt will compound the problem.
I am not sure I have any data on my altenator since it was installed by a shop. I will check into that and get back.

Ken
 

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At how many degrees would you recommend setting the idle timing?
depends on the compression ratio and cam profile some BBC like as much as 20 degrees initial and only 36 total.
 
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