Built-in FE

[GasSavers_DaX]

This is what I'm mostly about now - adding built in FE. Once I get the built in FE (for me, in the form of HF transmission, OBD-1/MPFI conversion w/Hondata), then I'll really start stressing on things like technique.

[krousdb]

This is prolly the best thread to put this in. My latest built in FE mod was to replace the 15" wheels and tires with 14" HX and Insight rubber. Here is what the car looks like now...


The tire diameter is 2" less than the previous tires so the car is 1" closer to the ground as a result. The old wheel/tire weighed 34.5 lbs each, the new ones are 24.4 lbs each for total unsprung weight reduction of 40 lbs!

I made a quick calculation and changed the SuperMID distance parameter before going out to finalize the calibration by 40 miles of highway driving via the milepost method. After another small tweak, methinks I am calibrated.

Initial driving impressions...
Good stuff
- Easier to steer, less rubber on the road
- Easier to start from a stop and easier to accelerate according to the buttometer
- Quieter ride, bumps are less sharp even at 62 PSI.
- Rolls much farther when coasting
Bad stuff
- Less rubber on the road
- Cornering ability greatly diminished, oversteer !!!
- Nearly spun out on two occasions, need to reduce speed on curves
- I can only imagine what it will be like in the rain.

Initial FE impressions...
- Good stuff
- The trip to the inlaws was 73MPG (warm start) vs 62MPG (cold start) (pre belly pan) similar temps (52F) and winds.
- The trip around the park was 82.9 MPG vs 72.0, again similar conditions although I made one of the lights this time.

So far I am happy as long as I don't kill myself on a guardrail. We shall see what the commute data looks like. Next two days should be dry and moderate temps. I will update in the FE update thread.

[Compaq888]

Since the wheels are thinner now you can make a better wheel skirt for the rear wheels. It can go further down.

[SVOboy]

- Cornering ability greatly diminished, oversteer !!!

How did you manage that? You're lucky!

Anyway, if you want I'll find you a front sway bar that's a little bigger than stock to reduce your oversteer.

[Compaq888]

I wouldn't do that if I were you. Yes the bigger sway bar will improve his handling but you need to make sure the tires hook up. Since his tires are thinner and overinflated a bigger sway bar will make him oversteer like crazy if he has traction or make him crash.

My advice is keep the stock swaybar and slow down a little. Bigger swaybars are meant for cars that have grip, using thinner tires and overinflated will just fuel the fire.

[krousdb]

Originally Posted by SVOboy

How did you manage that? You're lucky!

Anyway, if you want I'll find you a front sway bar that's a little bigger than stock to reduce your oversteer.

Many of my long engine off downhill coasts have curves in them. Approaching those curves at the highest possible speeds means in some cases that I will have enough momentum to get me over the next hill and onto the next downhill without bump starting, thusly increasing FE.

The culprit might be that there is very little weight on the rear tires and the coilovers. If I hit a bump rounding a curve the coilovers bounce and cause the wheels to lift. Another time it was prolly because I was braking also and the tires started to lock up. I took the corners slower today and had no problems. Because of the decreassed RR, I still had the momentum I needed to get over the next hill. I might go back to the stock springs now that i have smaller tires. Unfortunately with the smaller tires i am constantly trying to shift into 6th gear.

An example of the decreased RR. I normally take one curve at 35mph, engine off and then coast down a gradual hill for over a mile before bump starting. At the very end of the coast, at the 25MPH speed limit sign, my speed has dropped to 27MPH with 40-50F temps and as low as 20MPH in 20's F. Today, at 32F I took the curve at 33 MPH and ended up actually gaining speed to 35 by the time I got to the speed limit sign. That is quite a significant difference.

[krousdb]

Here is my route...

Elevation at home:1187 ft
Elevation at work:1056 ft
High point:1260 ft (top near where route crosses I-79 for the first time)
Low point: 692 ft (Bridge over Ohio River)
Distance: 39.83 km, 24.69 miles.

[Compaq888]

Elevation at home: 56 feet
Elevation at college: 36 feet
Distance: 3.55 miles

Trips to college and back on a single tank 44.788
1 tank of gas is enough for 14 weeks of college.

[SVOboy]

Originally Posted by Compaq888

I wouldn't do that if I were you. Yes the bigger sway bar will improve his handling but you need to make sure the tires hook up. Since his tires are thinner and overinflated a bigger sway bar will make him oversteer like crazy if he has traction or make him crash.

My advice is keep the stock swaybar and slow down a little. Bigger swaybars are meant for cars that have grip, using thinner tires and overinflated will just fuel the fire.

How will a bigger front sway bar increase his oversteer. Possinly a bigger rear bar would do this, but he has no rear bar and I am not suggesting he get one.

[kickflipjr]

I never knew google earth had the elevation on it. I just redownloaded it.

The first time i used it i never really liked it (i didn't think it was any better than google maps). But seeing the elevation is really cool.