Aerocivic - how to drop your Cd from 0.31 to 0.17

[MetroMPG]

I was wondering that as well.

Mike, on a typical highway trip, do you mostly drive with load (DWL) , or employ pulse & glide (P&G)?

If your existing numbers are DWL, the lean burn will make a significant difference. But I'm guessing from your initial 5 mpg boost and comment about the time delay for lean burn to kick back in after engine off that you're more of a P&G driver.

[basjoos]

I'm pulse and glide in that I'll FAS whenever I hit a downhill steep enough to maintain a coast (and it takes a very minimal downhill grade to maintain coasting speed), but otherwise I'll DWL. So I'm doing a lot of P&G in the mountains of NC and in the hillier parts of upstate SC, otherwise its DWL. Today's trip through upstate SC where I used to get 72mpg, today I gave me 85mpg and I spent about 65% of the distance in lean burn. On one fairly flat section of highway I sent my DWL cruise control for 100mpg at a speed of 55mph and it maintained a speed of 50 to 57mph over 8 miles of highway while maintaining 100mpg. Of course all these great mileages assume that the SuperMID is accurate and doesn't need some recalibration for the new engine, which I won't know until I run a few tanks through the car and compare the MID and calculated mileages.

The hardest part about driving with lean burn is learning to live with 2 different accelerator sensitivities. The car is also coasting several mph faster then it used to, so the old transmission must have something dragging inside it. My main adjustment to lean burn is that I've stopped FAS'ing onthe shorter downhills and I'll keep the throttle below 6.1 usec on the MID to stay in lean burn once I enter it. The throttle setting drops by 1.6 usec and the mileage jumps from 64mpg (4.6 usec) to 100mpg (3.0 usec) at 55mph when entering lean burn.

[Clev]

That's amazing. Excellent work.

[MetroMPG]

Thanks for the clarification and looking forward to more! (More news, I mean, as you gain experience & get a few tanks in.)

[basjoos]

I'm gradually getting the hang of keeping it within the throttle limits to stay in lean burn and knowing when to idle on a downhill and when to FAS. If the SuperMID is to be believed, I'm getting 100mpg at 55mph and 120mpg at 35mph. I'll have to run through a tank and get a calculated mileage when I fill up before I'll believe it.

[jkp1187]

The work you've done is nothing short of amazing. Was the engine swap done purely for fuel economy, or was the old engine starting to get worn out?

[basjoos]

The old engine and transmission were starting to wear out.

[TomO]

The injectors are the same size between your original cx model and the vx model (190cc) as well as the CDs pulses are the same. Your supermid should be as accurate as you had it set from before.

Good to hear that you're hitting the 100+ for instantaneous mileages!
I can't help feeling a little proud in having a hand in all this. And I'm glad it's working out well for you mike!

So did the person that replaced the rings and valve stem seals say what the condition of them were? When I rebuilt the Z1 that went into my vx, the rings were absolutely cruded up and worn.

[Crono]

I've always thought that someone should make a business of selling aerodynamic body kits, because they could appeal to both misers and performance seekers alike. I mean, I realize that the aerocivic as it is, isn't big on aesthetics, but I was talking more the kind of thing you see people order and typically put on their Civics, except one that just minimized aero drag. (Though I'm inclined to believe it would be a bit more complex than a typical body kit).

I know I saw someone on here try to get something like this going in regards to trucks, but has anyone (yourself included) considered commercializing something like the aeorocivic as a body kit? (I could bet that one for Geos would probably be fairly popular among this site's membership if it were a reasonable price).

[basjoos]

Refilled for the first time since installing the B15Z1 (VX lean burn) engine in my car and got 81.2 MPG over 438 miles of mostly interstate driving with a fair amount of driving on wet roads. Its been up to 75mph on a level road without it dropping out of lean burn. At that speed, it was showing 5 usec on the SuperMID, the ceiling for lean burn is at 6.1 usec, so I still have some headroom left. I'll have to find a highway with a higher speed limit before I can continue trying to find the upper speed limit for lean burn operation (the max speed will probably will be RPM limited rather than load limited for lean burn). On a flat road, its getting 100mpg (at 3.0usec) at 55mph and 120mpg (at 2.5usec) at 35mph. The results on the SuperMID were close enough to the calculated that I'll want to average a couple of tanks before making a change to the MID's calibration.

If the car has the correct shape, you don't need a hybrid system to get good mileage on the highway. I think even an Insight-I would be hard pressed to match my highway mileage at normal highway speeds now and its a much smaller car.