Lower Shrouds on Turbo?

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CtCarGuy
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Lower Shrouds on Turbo?

Unread post by CtCarGuy » Thu Mar 28, 2013 10:07 am

My 65 Corsa came from Louisiana (rust free!) without the lower shrouds. I replaced the heater hoses but the lower shrouds, doors and thermostats are missing. I am more concerned about engine cooling than heat. I figure that if I really need to defog, there will be enough heat to work. My last Corvair just had a fan. I do plan on getting the missing pieces at some point when I find (and can afford) them. Any issues I should be aware of? The top shroud and and seal are in excellent condition.

I am hoping to be ready for the road is a few weeks. it's just starting to warm up here.

Larry
Simsbury CT

USAF_vair
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Re: Lower Shrouds on Turbo?

Unread post by USAF_vair » Thu Mar 28, 2013 12:41 pm

i have had my engine running and on the road for two years with no issue with over heating and such. your engine will run cooler but you do lose some engine heat for heating inside the car.

make sure you jugs have the heat shrouds because these reduce the air flow for better heat transfer.

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bbodie52
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Re: Lower Shrouds on Turbo?

Unread post by bbodie52 » Thu Mar 28, 2013 1:03 pm

There are several issues that you need to consider:

1. Without the shrouds in place, the engine will take longer to reach proper operating temperature. Too much airflow causes too much cooling. In a water-cooled engine, a thermostat is used to restrict the flow of coolant so that the engine will reach proper operating temperature quickly and will maintain proper coolant flow to maintain the desired operating temperature. This is optimum for good engine performance. The same principals apply with an air-cooled engine. The lower shrouds in a Corvair engine contain the thermostats and thermostat doors that are needed to regulate engine heat.

2. With no lower protective shrouds, water from wet streets can splash freely up onto the exhaust manifolds -- INSTANT STEAM GENERATOR! With the heater and defroster turned on, some of that steam and moisture will be drawn into the passenger compartment heater/defroster ducts. Instead of clearing a fogged windshield, the system can apply an unexpected dose of instant fog!

3. Fuel mileage. When the thermostatic coils that actuate the automatic chokes are exposed to outside cool air, and the engine takes longer to reach proper operating temperatures because of the missing lower shrouds and thermostat doors, the automatic choke butterfly valves will remain closed longer. This will cause the engine fuel/air mixture to run rich for an excessively long period of time after the engine has been started. This will worsen fuel mileage performance.

I would recommend that you obtain the missing shrouds, thermostats, fasteners and doors needed to return the engine back to its original design specifications. These components are not as important in a racing engine operating with tubular headers, because the operating parameters and environment for a racing engine are significantly different than they would be for a street engine.

The parts you need can probably be obtained from Corvair Ranch in Gettysburg, Pennsylvania, which specializes in use Corvair parts.

:link: http://corvairranch.com/
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

morevair
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Re: Lower Shrouds on Turbo?

Unread post by morevair » Mon Nov 06, 2017 8:25 pm

Brad, I realize I’m replying to a very old post but it had factors that I’m very curious about. I’m about to receive 1966 corsa that’s been living in Northern California, I’m moving it to Phoenix Arizona and our temperatures here to say the least are extreme 120 during the summers in the coals we get is 70 during the winter would be traveling will benefit me, I’m probably gonna look into a better oil cooler just want to make baby happy, plus I’m probably going to spend extra bucks And put AC and do it after market under – which means more of a load, any opinion is appreciated

morevair
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Re: Lower Shrouds on Turbo?

Unread post by morevair » Mon Nov 06, 2017 8:27 pm

Plus, since I live in the desert we don’t really have a rain or water problem here

morevair
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Re: Lower Shrouds on Turbo?

Unread post by morevair » Mon Nov 06, 2017 8:28 pm

All, any ideas on how to keep my baby cool would be appreciated…

morevair
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Re: Lower Shrouds on Turbo?

Unread post by morevair » Mon Nov 06, 2017 8:34 pm

My original 1966 500 never had any heat issues here in Phoenix back in 1970, but this car is a lot older now and I just want to do the best For the new course at 140 Which I’m sure generates more heat

63Spyderd
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Re: Lower Shrouds on Turbo?

Unread post by 63Spyderd » Wed Nov 08, 2017 2:57 pm

Adding to Brad's legacy comments in the area of fuel economy, I believe that the lack of lower shrouds would rob horsepower as GM Engineering designed the system with a known degree of back pressure. I am not an expert in fluid dynamics but removing the shroud may destroy the efficiency of the fan through cavitation and other ill effects. I know when I restrict the inlet or outlet to my shop vac, the motor RPM increases, indicating there is less load on the motor. Translating this to the Corvair engine, wouldn't there be slightly better fuel economy and less wear and tear on the fan belt and pulleys if the shrouds were properly installed? It's possible that the fan noise may be also be reduced with the shrouds on but I have no supporting data.

Frank DuVal
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Re: Lower Shrouds on Turbo?

Unread post by Frank DuVal » Sun Nov 12, 2017 12:29 pm

The path through the cylinder fins past the lower cylinder baffles is of greater resistance than the lower shrouds and thermostat doors.

My 64 turbo ran fine without lower shrouds in summer, and made plenary of heat in winter without the damper doors, but lower shrouds were on.

Yes, no lower shrouds plus rain/ puddles is steam on windshield generator!

Middle Atlantic area.

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