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Discussion Starter #1
Hello all. I'd like to introduce myself to the forum. I'm here to learn, plain and simple.

I drive a 1989 Civic LX with 145k miles on it. Before you tell me that I'm inthe wrong forum, or on the wrong website, I already realize this.

A bit of background:

I used to drive a Sentra. I bought it brand new in 2000 and mileage was always a big deal to me. I have no idea why. Maybe it's because I'm cheap... or maybe it's just because I actually care about being efficient. That car was rear ended by a jeep while on a road trip.

Being the stupid twenty-something I am, I decided to "live a little" and get a 2000 Jeep Wranger. I loved it... except it had a 6 cylinder, 4.0 liter engine that got around 15.0 mpg. I remember being so happy the day it got 20mpg when I drove from Southern California to Las Vegas.

Now that I work at home, I had no reason to have a car payment and high insurance. So I sold it for a minimal loss and picked up a 1989 Civic LX for two reasons: Fuel economy and lower insurance.

Besides, chicks dig classic cars, right? Okay, it's not classic, but it's a car.

I was getting 38 mpg in the city and I was shocked at my 45 mpg on the way from Salt Lake City to Southern California. I made a wise choice... I couldn't have been happier.

Until my radiator hose blew outside of vegas on teh trip back, causing my engine to overheat and my headgasket to blow. $800 and 3 days later I was on my way back home. My car only got 33mpg after this. I'm thinking the timing was screwed up when they put the cylinder block back on or the head was warped due to the high heat.

Back to my point.

I love fuel efficient vehicles, but I just can't afford an insight or a civic hybrid. In lieu of buying a new car with higher insurance and payments, I've decided to modify my 1989 LX to get much better mileage. My planned modifications are as such:

1. I'm first going to switch to MPFI. My car runs on DPFI now and DPFI is nothing more than a glorified carb system. I have the parts ready to install, but I'm going to finish painting it first.

2. The next major modification will be to swap the cylinder head from the Civic VX (the d15z1 head) onto my Civic LX (d15b2) block. As I'm sure you know the Civic VX had about 55mpg due to it being a vtec-e engine. The insights also use a vtec-e engine, just a smaller one.

3. I want to make custom rear wheel well covers like the insight has. If anything this will help with a little drag that the car experiences at higher speeds.

4. On the same token, I'm thinking of cutting out the bottom half of the rear bumper and replacing it with a metal mesh so that the bumper doesn't restrict airflow.

5. Oh, I want to put a HF (The CRX HF) transmission into the car. It will make accelerating take longer, but will definately help my mileage in the long run. My understanding is that the HF transmission and the VX transmission had the same gear ratios. I'll go with the HF transmission and iwill not have to swap out my axles when I do it.

there are a few other modifications I want to do, such as a K&N air filter or a K&N CAI, but I'm starting to get mixed reviews about if this is a wise idea. I've read a little about a Warm Air Intake on this forum. Which is better for mileage?

I don't have too many places to turn to, as all of the honda message boards are full of people who want to make their car more powerful and less fuel efficient. It's difficult to have a conversation about fuel efficiency with these people when every time I ask a question I'm answered with, "yeah, forget the efficiency, why don't you just drop in a bigger engine?"

So I come here for answers from people who have similar goals as myself.

So, this is my introduction. If you can think of anything that can help me achieve my goal for this car (50mpg+ in city driving) please let me know. I'll be lurking around the forums here trying to get ideas for making my old civic more like your newer civics.

Oh, and I'll soon start a blog listing my modifications and will be using statistical analysis to determine if in fact each marginal modification returns statistically significant benefits in fuel economy.
 

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As a starting point, what tires do you have and what is the inflation pressure? You may want to consider LRR tires like those on the current Civic hybrid (two different brands for the automatic & manual transmissions, names escape me at the moment) or even a narrower tire inflated to sidewall plus psi.

If you are truely cheap, you would forgo all of the expensive engine / transmission work and just drive SLOW. 50 % of you mileage is in your right foot.
 

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Discussion Starter #3
Kevin Dougherty said:
As a starting point, what tires do you have and what is the inflation pressure? You may want to consider LRR tires like those on the current Civic hybrid (two different brands for the automatic & manual transmissions, names escape me at the moment) or even a narrower tire inflated to sidewall plus psi.

If you are truely cheap, you would forgo all of the expensive engine / transmission work and just drive SLOW. 50 % of you mileage is in your right foot.
I'm using stock rims, but I can't remember which tires exactly. I will eventually switch out to LRR tires and use the correct PSI rading for them.

As for the engine/transmission work, I'm also using this as a hobby. I've always wanted to learn how to work on cars, and this is the perfect excuse. Since I'm doing all of the world myself, all I'm paying for are parts. For example, the DPFI->MPFI swap is only costing me $100 in parts from the junkyard. The d15z1 head is probably going to cost me around $100. You get the idea.

Oh, and I rarely go above 70mph on the freeway, so I'm already a "slow" driver by today's standards.
 

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You might consider using the lightest weight oil that's recommended by Honda. The engine and transmission oil in the Insight are both pretty thin. At low speeds, drag from tire and engine friction is the main issue.

Another help would be to get a vacuum gauge, which gives pretty much the same information as the instantaneous mileage gauge on the hybrid cars. That will help you keep your foot out of it.

"Driving slower" is indeed a big, big part of it. 70 MPH is fast! Since the aerodynamic drag goes up as the sqaure of the speed, there's a big difference between 55 and 70.

Are you aware that if you follow the shifting recommendations from the Insight computer, you'll rarely run the engine at over 2000 RPM? Lugging the engine along at 1000 RPM is standard driving procedure...
 

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Discussion Starter #5
Dougie said:
You might consider using the lightest weight oil that's recommended by Honda. The engine and transmission oil in the Insight are both pretty thin. At low speeds, drag from tire and engine friction is the main issue.

Another help would be to get a vacuum gauge, which gives pretty much the same information as the instantaneous mileage gauge on the hybrid cars. That will help you keep your foot out of it.

"Driving slower" is indeed a big, big part of it. 70 MPH is fast! Since the aerodynamic drag goes up as the sqaure of the speed, there's a big difference between 55 and 70.

Are you aware that if you follow the shifting recommendations from the Insight computer, you'll rarely run the engine at over 2000 RPM? Lugging the engine along at 1000 RPM is standard driving procedure...
I was looking at one of those vaccum gauges last night online. It was actually designed for mileage calculations. Unfortunately, it only went upto about 30mpg. I couldn't understand why someone would make a gas-mileage gauge and have it max out at 30mpg.

I was considering getting one of those computer from sweden that also tell you the proper time to shift, give instant gas mileage, etc. I'm not sure if anyone has actually used one, however, or even how much they cost. For this reason I'll wait on the computer and maybe I'll just get a vaccum gauge for now.
 

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Dougie said:
You might consider using the lightest weight oil that's recommended by Honda. The engine and transmission oil in the Insight are both pretty thin.
If the engine isn't designed for this type of oil, I suggest not using it. If it were as simple as using a 20W oil then all engines would be using it, but it's not.
 

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Rather than driving slowly, think about driving smoothly, and think ahead of where you are. Rather than dashing up to a red light, then slamming on the brakes, you can back off the gas and coast in. On the freeway, use the slight grades to help: if traffic allows, gain speed on the downhills, lose a bit on the ups.

Learning to do things like this is where the Insight's real-time mpg display is a big help.
 

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Discussion Starter #8
james said:
Rather than driving slowly, think about driving smoothly, and think ahead of where you are. Rather than dashing up to a red light, then slamming on the brakes, you can back off the gas and coast in. On the freeway, use the slight grades to help: if traffic allows, gain speed on the downhills, lose a bit on the ups.

Learning to do things like this is where the Insight's real-time mpg display is a big help.
I've been a big time coaster in all of my cars. In my fiance's 87 CRX Si I get about 7 more mpg than she does based solely on driving style.

I've always thrown it into nuetral (on a five speed) and coasted. I've always assumed this was better than leaving it in gear, but I may have read a few contrary things on this site regarding this. Then again, that could be specific to the Insight and not standard cars.
 
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