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Air Baffle Project

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steveg

steveg

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Started with a smaller baffle to attempt to isolate the fresh air intake from recirculated hot air, then morphed into a project to surround the radiator with baffles to prevent forward recirculation of hot air in general.

GerowAirBaffles.JPG
If anyone's interested, have photos:
https://www.pbase.com/stevegerow/healeyairbaffles
 
steveg said:
Yes, but with temps in the 50s-60s will have to wait for a warmer day to report back. Am looking for air from the fresh air vent to be same temp as ambient - not feeling like another heater vent.
Click to expand...

Have you seen the mod where folks place a bilge fan in the fresh air vent to increase air flow?
 
Hi All,

When installing the bilge blower with variable speed control and under-dash baffle to redirect air flow, it was my presumption that the air secured by the powered cold air vent would be pulled through the grill. Although that may be the case when under power, it definitely does not seem to be true when experiencing the warmer air flow when standing for a traffic light. Since Steve also experienced this heated air, it was concluded that the air now PULLED into the cold air vent was being drawn from inside the engine compartment and not from the outside through the grill. Since the cold air flow prior to the blower implementation happened only with the car underway (air pushed through the grill by the car's forward motion to the duct opening), now with the bilge blower, air was being pulled into the duct at all times and did not need forward motion to create a flow.

So, where is this air being drawn from? Since air was being pushed into the engine compartment through the use of aggressive radiator fans implemented by many, it was not a far jump to consider that a stopped car was probable pulling warmed air through the cold air inlet that was escaping the produced pressure of the engine compartment forward through the many openings in the radiator support. Since no compensating air was flowing via forward car motion through the grill and with the engine and other blocking engine components diminishing rearward flow, a partial path of least resistance was through the porous forward bulkhead.

So, why didn't it happen without having installed the bilge blower. With a non powered cold duct, air is only pushed into the duct when the car has forward motion. However, a bilge blower pulls air into the duct when the car is moving forward or at rest and at rest is when the engine compartment air migrates forward for the most part. However, it is also conceivable that some portion of this hot air migration and duct injection could happen when the car is underway as well.

Hopefully, this issue will be rectified by only a small part of Steve's total implementation. However, by effectively sealing the radiator support barrier, engine compartment air will no longer move freely toward the cold air duct and be drawn in by the bilge blower. With his extension of the cold air duct opening to the grill, cooler air will be pulled from outside the car rather than taken form inside the car. Although I hopefully anticipate that only a cold air duct extension will be sufficient to correct the cold air issue, I have no doubt that Steve's fully sealed radiator bulkhead, separating the forward section of the radiator area from the engine compartment (as in all modern cars) will work.

As one who recommended the implementation of the bilge blower to power the cold air duct, I very much appreciate that Steve had the insight to recognize, define, and now address a potential solution to this unexpected issue. If, extending the cold air duct opening to the grill proves successful, then we may still see the promise of cool air flowing into the cabin via the cold air duct on a warm day while waiting for a traffic light.

Sorry for being so long winded,

Ray (64BJ8P1)
 
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Rick,

I considered water injection to allow cooling via the elimination of heat through vaporization as air traveled down the duct to the cabin. However, air flow produced by the bilge blower substantially shortened the time in the duct for vaporization and, when researched, those that have tried this approach for other conditions usually experienced the development of rust. Since I had no desire to introduce rust into my (or anyone else's) Healey, I eliminated it as something to consider. I do believe it would work.

Ray (64BJ8P1)
 
I've offered this before, but it may help someone. Here in Florida it is commonplace to keep the heater valve on the block closed. Since one end of my 4" heater-side duct was already disengaged from the heater fan, I decided to detach both ends of the other duct, at the heater fan and the heater box inside the footwell. I then slid the smaller rear duct inside the front section that runs to the engine grill and directed the rear end inside the car in the driver's (my) direction. This thing really brings in a lot of air while underway. I've also removed the "screen" where the fresh air duct emerges in the driver foot well. These are only a couple of things I have done to make the car sufferable in the hot weather we experience here, which have included insulating the car interior, to include the under dash area, putting insulating tape on the exhaust pipes from the manifold to the muffler, building an air box around the recored radiator, and, more recently shimming the bottom of the radiator away from the frame member that runs behind the bottom tank. I've also installed the asbestos-like (quarter-inch Hardy Backer) insulating pieces above the muffler and the several pieces on the engine side of the foot well, etc. Oh yes, I have put a blocking tube in the thermostat housing and added a coolant reservoir. When it's really hot, I drive the Porsche with its AC.
 
Hi Steve,

I'm amazed at your tenacity in sealing off the front bulkhead, it is an arduous task. I too have made similar improvements, though less difficult since with the vintage air system I decided not to keep either of the 4 inch ducts. That allowed me to simply block off those areas with flat pieces of aluminum.

Since your premise is that the air from the engine compartment is moving forward at idle this should certainly eliminate that contribution to the warm air entering the cabin. But have you also thought of the heat that is coming from the tubes themselves? It seems to me that when stopped the engine compartment becomes akin to an oven, and is baking the exterior of the tubes, and since the tubes are a dull black in color (a heat sink for radiation) and are very thin and therefore can conduct heat fairly efficiently, the tubes may be contributing to the heating of the air also. So, once complete with the bulkhead mods, and it doesn't satisfy you perhaps insulating the tubes would be your next step?

If you are thinking also of improving the air flow through the engine compartment, the addition of a texas cooler fan should be better than the flex fan you have shown in your pictures, and it has the extra bonus of being yellow. I have one on the wall I could loan you if you want to try it. A further improvement over the texas cooler is a fiberglass flex flow fan, which I currently run on my BJ8. It flows about double what the texas cooler fan does at idle (my testing - not documented), but not for the C crowd.

I enjoyed the pictures, thanks so much for sharing!!
 
Jerry,
I believe the hot air moves forward with the car in motion, too. When driving along on a warm day, the air from my fresh air duct was noticeably warmer than the ambient air.

Using a bilge blower, I'm not too concerned about the air sitting idle in the tube long enough to heat up.

Thank you for the offer of the loan of a Texas cooler - may take you up on it in the future at some point.
 
Reporting back on the fresh air temp in hot weather:
Have driven several times lately in 80+ degree weather. Can report that the air from the fresh air vent feels like ambient temperature at speed and only a little heated while stopped. Have not been able to entirely close off the openings around the front shocks.
 
Last edited:
Steve, a besides the adition of the bildge blower, did you do anything to the hoses? Are you using the stock type black paper hose?
 
Rob Glasgow said:
Steve, a besides the adition of the bildge blower, did you do anything to the hoses? Are you using the stock type black paper hose?
Click to expand...

Rob,
Am using the stock hoses, which IMO look better than clothes dryer hoses.

Don't think the hoses are much of a concern, as with the blower going, the air doesn't stay in the duct long enough to pick up much heat from the engine compartment.

If there is hot air, it's being recirculated forward around the radiator into the duct opening.
 
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