Having fought this battle for over 15 years in 4 different conversions, I
offer some observations.
Removing some of the lip at the rear of the hood & eliminating the rubber
seal while slightly rasing the rear of the hood makes a slight bit of
improvement, but looks really stupid.
Rubber bumper cars especially, benefit from a spoiler, either the ST or LE
style. Years ago, we dribbled motor oil along the leading edges of my 1977
roadster, then proceeded to drive at various speeds up to well over 70 MPH.
When we stopped, there were very visible oil tracks all the way to the
windshield on the hood, but no oil on the grill or radiator. The rubber
bumper is very streamlined in use & improves airflow over the hood,
increasing speed, but drastically reduces air flow through the radiator.
Spoilers force air through the lower part of the radiator & create a lower
pressure in the area below the engine which also improves airflow through
the radiator & out of the engine compartment on any car. Early cars present
a flat front to the air when moving which results in better airflow through
the radiator compared to rubber bumper cars. Lots of race only cars use
fiberglass replicas of rubber bumpers for better streamlining.
Louvers in the inner fenders behind the block hugger headers do increase
airflow out of the engine compartment. Louvers or other openings in the
outer fenders coupled with openings in the inner fenders also aid air
transfer out of the engine bay. I used a set of Trans Am ducts in the outer
fenders.
RV8 headers, especially when JetHot coated reduce under hood temperatures
compared to block huggers, & the hole in the inner fender opens into a LOW
PRESSURE area in the wheel well. I cut my holes in the inner fender on the
generous side.
Moving the radiator as far forward as possible increases airflow at speed
and allows for a PULLER fan, which is 15-20% more efficient than the same
fan as a pusher.
Ducting the valance or spoiler opening to the radiator, eliminating air
leaks, maximizes air flow through the radiator, by not allowing the air to
go around the radiator.
Optimizing the timing, air/fuel mix, & spark gap will lower engine cylinder
head temps resulting in lower water & oil temps.
25% antifreeze cools better than 50%, but does not give as much boil over
protection. 100% water cools better than any mix- add a can of water pump
lubricant/acid neutralizer. A 15-17 lb cap reduces the possibility of boil
over & will help you find which hoses you should have replace at the start
of the driving season & which hose clamps need to be tightened. A 160`
thermostat is not a help in cooling, a 180-190` thermostat is. Once the temp
climbs over 160`, it will never drop to a level where the thermostat closes,
so you might just as well use the higher rating & get your engine to correct
operation temperature a bit faster. Our V8's all should run at 180` minimum,
190-95' ideally, up to 210` without problems. I confess, I prefer to see
190-200 on the gauge. I have experienced temps as high as 230` without loss
of water & no resulting engine damage, but an engine that hot is hard to
start.
Increased radiator surface area is more helpful than additional rows. More
than 4 rows of tubes (copper brass) results is less cooling. Finned tubes
cool better than no fins. Louvered fins on the radiator tubes cool best of
all. Too many fins per inch of tubes reduces air flow- see a really smart
radiator designer, not necessarily your local shop.
Oil coolers can help but should only be used with an oil temp gauge. You do
not want your oil under 200` F or you will loose performance & start sludge
buildup. This is really a problem with winter driving. I have an oilstat
that only allows flow to the cooler starting at 200`.
All the above is based on my personal experience, your results may differ.
Whew! I didn't mean to talk/write that much.
Jim Stuart
1977 215 270,000 miles & sold
1974 1/2 4.2 GT 240,000 miles & rusted away
1966 215 53,000 miles & looking good
1974GT Buick 300 1200 miles looking ugly as sin but fast enough to scare
me( a little)
Reply to <jimbb88@usa.com>
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