help me with aerodynamics in my Chevrolet Blazer truck

[aerohead]

Originally Posted by guillermoariast

Hello, i have a Chevrolet Blazer which is not aerodynamic at all. Hence i need to modify several things.
I would like you to help me with ideas.

regards,
Guillermo Arias
Lima, Peru

Guillermo,I've located some figures for your truck,but need to dig a little longer.I think I can pull them together by this coming Saturday.
*You might tell us about your driving conditions there in Lima.If you do a significant portion of steady high-speed highway driving the aero mods should really help you.
*Also,it would be good to know about the Blazers gearing,and the kind of engine RPMs she turns at highway speed.
*I presume you have a thermo-clutch on the engines cooling fan?
*Is the original fan shroud still in place?
*How often do you use the 4-wheel-drive?
*Could you do with narrower tires?
*Could you get by with less ground clearance?

[guillermoariast]

Thanks for your post.

Originally Posted by aerohead

Guillermo,I've located some figures for your truck,but need to dig a little longer.I think I can pull them together by this coming Saturday.

Originally Posted by aerohead

*You might tell us about your driving conditions there in Lima.If you do a significant portion of steady high-speed highway driving the aero mods should really help you.

I drive the truck only on highway and off road ways because i have a car for the city. I use the truck only for travels.

Originally Posted by aerohead

*Also,it would be good to know about the Blazers gearing,and the kind of engine RPMs she turns at highway speed.

I do not know how are the gearings set.
The average RPM on highway is 3000

Originally Posted by aerohead

*I presume you have a thermo-clutch on the engines cooling fan?

Yes i have one

Originally Posted by aerohead

*Is the original fan shroud still in place?

I have not the original, but i ordered making a new one.

Originally Posted by aerohead

*How often do you use the 4-wheel-drive?

Not very often.

Originally Posted by aerohead

*Could you do with narrower tires?

I think it was not necesary buy the 31" tires. But I did. I could put some narrowers on.

Originally Posted by aerohead

*Could you get by with less ground clearance?

Maybe 1 or 2 inches less

[Debonair]

ah i love the K5 blazers, i was highly considering one.

Perhaps you can remove the cap and either make or buy an aerocap

[botsapper]

Many years back, sport truck customizers lowered, shaved & cleaned up a few Blazers & CK's. A new aero shell would be good.

[aerohead]

Here are some data on the Blazer:
* The Cd for the pickup on which the K5 is based is 0.535.The K5 will be higher due to exposed underbelly,wider tires,etc..
* The frontal area is 34.3-square feet
* CdA will be above 18.35-square feet
* Road Load 'dynamometer' @ 50 mph = 19.9 horsepower ( front axle not measured)
* Actual road load @ 50 mph approx. 24.142-horsepower
* Engine load @ 50 mph approx. 26.824 brake horsepower
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* 1974 C10 pickup @ 55-mph steady,with 250 cu in 6-cyl,4-speed manual,and 3:07 rear axle = 17.7 mpg.
* same truck,with softened hood leading edge,front airdam,and tonneau cover = 18.6 mpg.
* 1982 C10 w/ 6.2-liter Diesel 2WD = 31 mpg EPA HWY
* 1982 C10 w/ 6.2-liter Diesel 4WD = 29 mpg EPA HWY
* 1982 C10 --------------------- = 19 mpg EPA HWY
* 1986 C10,350 cu in V-8,Turbo-hydramatic w/ lockup,mild cam,performance intakemanifold,275X 60R-15 tires = 20 mpg @ 65 mph
* 1987 C1500, Cd 0.45,31.899-square feet Af (est), VORTEC V-6,M-5,@ 65 mph,with air conditioning and 1/2-tonneau cover = 23 mpg
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If you are very attached to the Blazer,anything you do to mimic the form of contemporary pickups and SUVs will pay you savings at the pump.
* JEEP has gone to air suspension on the new Grand Cherokee to lower it on the HWY.
* You see how all the 'noses' of current vehicles have been rounded.
* Drip edges have been eliminated
* Windshields and glass is more flush to the body
* The sides of the body are flush with the wheels,or vice versa
* Wheels are more 'enclosed' either as a wheel or with wheelcover
* Fenders and hoods slope downward
* Bellys are smoothed
*Airdams scoot the air over and around the vehicle
*Electric fans replace engine-driven units
*Grilles are blocked to restrict the amount of airflow through the cooling system
*Vehicles are 'longer' in relation to their height
*Rooflines are now mimicking the early Hungarian and German low drag forms of the 1920s-30s.
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The Blazer should respond very well to streamlining,however,since it is a carb'd engine,it's fuel metering system and BSFC will be more affected than fuel-injected vehicles.

[qbone]

Hey aerohead,

Bit late but I was wondering if you would be able to provide any sources for the pickup drag figures as I'm doing some research on that vehicle.

Thanks

[aerohead]

Originally Posted by qbone

Hey aerohead,

Bit late but I was wondering if you would be able to provide any sources for the pickup drag figures as I'm doing some research on that vehicle.

Thanks

The 1980 C-10 is around Cd 0.535 according to GM's reporting on the circa 1987 C-1500, with the all-new truck design.
The C 1500 is Cd 0.45, and GM reported this to be 20% lower than the out-going design; which back-figures at Cd 0.535.
Member 'bondo' ( Brett Herndon ) was able to get his 2012 F-150 down to Cd 0.31, from Cd 0.408, using his 'Aerolid' and' Aerotail'. Both wind tunnel tested ( and I believe that Ford Motor Company underwrote the testing, and was very interested in what Brett had done ).
You should be able to back-track to his threads to have a look at his tech.
With all the configurations tested on 'Spirit', if you're willing to live with extra length on the open road, the drag coefficient of the Lightyear Zero could be achieved with the Blazer.
On four 'good' road trips, Spirit has seen 39.9-mpg @ 65-mph, which pencils out at over 55% higher than OEM mpg.
It's not rocket science, but you've really got to want it. Work for it.