Lowered rear 2" now getting worse gas mileage

[jtbwatson]

Well, I guess I kind of brought this upon myself...

I've got a chevy blazer that sits like a truck. When it's stock, the rear end sits 1" higher than the front. I found 2" lowering blocks and installed them only on the rear and it looks pretty level, but when I'm driving it, now my engine is having to work harder. I was getting 17.6-18.4 mpg per tank and now i'm down to 16.5 and 16.9 on my past two tanks. I dropped it with the intent of having it look more level (it's level when I'm sitting in it).

The thought came into my mind that I need to grab some coroplast and smooth out the bottom of the car, because it feels that air is grabbing the underside of the bumper and dragging. What do you think, ecomodders? Return it to stock height? find 1" blocks? make a belly pan for the rear end (is that a butt pan? :P). Feedback is wonderful!

[iveyjh]

Lower the front as much as you did the rear and install air dam/splitter. That ought to get your gas mileage back plus a few more. If you install belly pan you can leave the air dam off, but the air dam is a lot easier and cheaper and the gain is pretty much the same. Happy modding

[mcrews]

there are some discussions about the 'angle' of the front end...ie the direction it points down at the nose.

I improved my mpg on the 2002 Infiniti Q45 by lowering the front just 3/4 of an inch.
the pivot point for what you did is the front axle.
while it may 'look' level, you have changed the overall aerodynamics of the body.
just my 2 cents.
Cleaning up the underbelly might help....see the link on my sig

[UltArc]

I am not a scientist.

In my mental wind tunnel, I see this:
-Lower the rear end puts it more into the wind
--Increasing the frontal area
--Changing the angles air normally interacts [with the underbody]
-Changes the angle of the roofline
--Ruining the already damaged airflow

An air dam is the easy way out, but your best bet is to duplicate the stock stance, but as low as acceptable for your life/conditions, and then do an underbody.

[Cobb]

I returned to the original springs on my honda, but cut a half turn off the fronts. THe front looks the same lowered height as before on tanabe df springs. The rear is noticability higher. I didnt loose the 5 mpg lowering it gave me and I think it even handles better.

I love the fact I can easily throw 800 lbs of mulch, quikcrek, top soil, etc and it doesnt scrap the tow hook on the ground.

[NeilBlanchard]

By possibly exposing the underside to the air flow as the vehicle moves forward could introduce lift - which is drag. The 'attitude' (aka angle of attack) of any vehicle is an important factor to aero drag.

[oil pan 4]

With my suburban it sits a little nose down, when empty.
Its got old sagging half ton coilsprings up front and much newer 3/4 springs in back.
With the trailer and a load of tools it sits more level.

You want to keep air from getting under the vehicle.

[hamsterpower]

I also wonder about the front end alignment changing with the new nose high attitude. You certainly have changed the caster angle a bit and possibly toe in, and camber too.

[mcrews]

Originally Posted by hamsterpower

I also wonder about the front end alignment changing with the new nose high attitude. You certainly have changed the caster angle a bit and possibly toe in, and camber too.

this is HUGE!!!!!!

lowering the front end 3/4 inch on the Infiniti Q45 chewed up 2 front times!!!!!

(stupid me...should have done an alignment!!!!)