I have a few ideas of how to get better gas mileage on my newly acquired Crx HF.

I am planning to try and get the best Gas mileage i can out of it. I am debating putting in a VX motor but that won't be until this summer or maybe next summer.

I am wondering if a header will benefit me or go against my MPG needs. I found a relatively cheap one near me. I figure it would be lighter weight and less restrictive so it would in fact help out with mpg.

Also I was wondering if I were to port match the intake and exhaust (this wouldn't happen unless i got the vx motor) would that benefit me or play against me? my buddy was saying it would go against me because it would need to adjust my fuel. I think he is wrong and it would be less restrictive and would allow better mpg.

I am kinda a newb at the whole gas saver thing but i want to do it this way so it will benefit me at college.

I am aware of http://www.gassavers.org and http://www.ecomodder.com and http://www.crxmpg.com I am just asking your guys input and eventually will venture to those sites and start asking questions.


Thanks,
Shane

 

any thoughts?

 

Let me explain something to you. If the most MPG is what you are after, then most of the performance oriented things will not make a darn worth of difference.
The majority of mileage is during cruise. At cruise your engine is under VACUUM. That means that a ported or polished this or that won't help at all.
What you need is a good runing engine as close to stock as possible. No headers, or intakes or anything of that nature. Do a good tune up like a new distributor, spark plugs and wires. Make sure the PCV system is working well ( very important for good PMG) your tires are properly inflated. and drive the car gently.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Maxbore.com &raquo;</TD></TR><TR><TD CLASS="quote">Let me explain something to you. If the most MPG is what you are after, then most of the performance oriented things will not make a darn worth of difference.
The majority of mileage is during cruise. At cruise your engine is under VACUUM. That means that a ported or polished this or that won't help at all.
What you need is a good runing engine as close to stock as possible. No headers, or intakes or anything of that nature. Do a good tune up like a new distributor, spark plugs and wires. Make sure the PCV system is working well ( very important for good PMG) your tires are properly inflated. and drive the car gently.
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Drive the car as though there is a raw egg between your foot and the gas pedal that you cannot break.

 

understood. I was not looking for performance out of it. I was just thinkig it would be flowing a little easier and less weight in the car.. plus it was a cheap header that was available :D.

Also i was reading a bit on gassaver and it was saying something about how the hf/vx cat placement is a bad idea. not sure where i was going with that. lol

 

tune it
my ls got 40mpg and ran a 15.0 on street tires

 

Less restrictive engine would = less fuel consumption while getting up to speed?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civickiller &raquo;</TD></TR><TR><TD CLASS="quote">tune it
my ls got 40mpg and ran a 15.0 on street tires</TD></TR></TABLE>

In due time :D

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ~sp33~ &raquo;</TD></TR><TR><TD CLASS="quote">Less restrictive engine would = less fuel consumption while getting up to speed?</TD></TR></TABLE>

Thats what i was thinking.

 

google hypermiling. the best way to get some better mileage is driving habits. good luck

 

Driving habits are a must to maintain amazing gas mileage. Depending on my driving I range from 35mpg to 27mpg. Big difference.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by achubbs &raquo;</TD></TR><TR><TD CLASS="quote">google hypermiling. the best way to get some better mileage is driving habits. good luck</TD></TR></TABLE>

He did mention that he know's about Gassavers.org. Hypermiling is well discussed there.

 

Porting will hurt your mileage for sure. Intake and exhaust will help it. A header should help too, but intake and exhaust are the killers. On another car, I went from 32 mpg to 37 with I/H/E, then I returned it to stock to sell, and it was back down to 32 mpg

 

How?

 

I have a 91 CRX with a d15z6 engine with no other mods than header and exhaust and I get between 35 and 40 mpg. Much better than the truck I was driving I was only getting 17 mpg.

 

I'm thinking that a better transmission might help. At least around town. One of the things I REALLY hate about the HF transmission is the first to second shift. Specifically, the gear ratio goes from 3.25 in first gear to 1.65 in second gear, which basically cuts your RPMs in half AND seriously bogs the engine. All of this means that either (1) you will rev high in first gear so that the engine can actually pull second, and/or (2) you will end up flooring the throttle in second to keep up with traffic, which wastes gas. I don't know why Honda did this, but I find it interesting that this is something they corrected on the 1992-1995 VX transmission (which has exactly the same first gear and final drive, and about the same fifth gear). What you could do here is swap the HF fifth gear and final drive into a DX/SI transmission. The DX and SI transmissions have different final drives, but the same gears 1-5. So you might as well go for a DX, since you can get them dirt cheap or even free. This will give you a transmission with the same first, fifth, and final drive as the HF. But you will have more usable gear ratios for city driving. For instance, second will go from a horrible 1.65 to a MUCH more livable 1.894. And since you won't be flooring it as much around town, it will save gas. Of course, you will have a slightly bigger difference between forth and fifth gear. But since you are already moving pretty good on level ground when you make this shift, it is not such a serious issue.

 

Hypermiling and gassavers.org are your friends, vx swap should defintely help.

 

vtecn8ive: It also might help to know the following
- What kind of mileage are you getting from it now that you want to improve it?
- How many miles are on your engine?

You should keep a log of what kind of mileage you're getting now before doing any 'mods' or upgrades. That way you can have a baseline to see what improvements you are achieving.

I just took my 88 HF on a over 800 mile roundtrip and averaged 70-75mph and averaged 46.5mpg. I've only changed the oil (thanks to Lompoc Honda's $9.95 oil change special!) but I haven't done a full tune up yet but I will soon adjust the valved, replace the spark plugs, spark plug wires, dist. cap and rotor with Honda OEM parts, fuel filter, air filter, and valve cover gasket and seals with OEM Honda parts (leaks a little oil thru seals) to see what kind of difference I'll get.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Maxbore.com &raquo;</TD></TR><TR><TD CLASS="quote">Let me explain something to you. If the most MPG is what you are after, then most of the performance oriented things will not make a darn worth of difference.

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I disagree with this guy. The intake and exhaust were restrictive on the civic and crx's. They only made the exhaust small to keep the noise down. ANYTHING that makes the engine do less work makes gas mileage and power. Do some research before you post.

 

There was an article i read on yahoo once about gas mileage. There are a group of people out there that can squeeze out like 100+ mpg out of a hybrid and like 70 mpg out of a ford ranger.It really comes down to how u drive your car.Dont use your a/c , keep windows up if u can, turn off car in long idling periods and drive really really really slow. Maybe u can find the article i read if u look for it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by whiteknightef &raquo;</TD></TR><TR><TD CLASS="quote">

I disagree with this guy. The intake and exhaust were restrictive on the civic and crx's. They only made the exhaust small to keep the noise down. ANYTHING that makes the engine do less work makes gas mileage and power. Do some research before you post.</TD></TR></TABLE>


I agree somewhat. I just changed my OEM catback from my 89si to a muffler tech they did a cat back and muffler. I feel the engine is a little more spanky. It sounds better and a bit louder and the car also feels much better. This is an 89 si motor with si tranny. Stock everything! Car feels a little faster and less restrictive. I also changed the spark plugs to iridium plugs from bosch.

I am planing to get the k&N intake kit.

excellent gas mileage.

 

Bosch plugs. Eek.

Turbo it. Turbos get ridiculous gas mileage.

 

turbo won't do anything because it doesn't spool up until high RPMS which will 100% defeat the purpose of gas mileage.

 

"Restrictive" intake and exhaust systems can be useful in this application. The small ports, piping, runners, etc will optimize VE in the lower powerband, so you will not have to rev higher to get the car moving. Notice the small ports and valves on the d15z1 head, which is designed for fuel economy. Most aftermarket parts are designed for peak power output, which will sacrifice some of the lower powerband.

However, the most important thing you can do to your car is to keep it maintained well. Also, as stated, be VERY gentle on the throttle.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ZeroTraction &raquo;</TD></TR><TR><TD CLASS="quote">Turbo it. Turbos get ridiculous gas mileage.</TD></TR></TABLE>
Please explain...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 &raquo;</TD></TR><TR><TD CLASS="quote">"Restrictive" intake and exhaust systems can be useful in this application. The small ports, piping, runners, etc will optimize VE in the lower powerband, so you will not have to rev higher to get the car moving. Notice the small ports and valves on the d15z1 head, which is designed for fuel economy. Most aftermarket parts are designed for peak power output, which will sacrifice some of the lower powerband.

However, the most important thing you can do to your car is to keep it maintained well. Also, as stated, be VERY gentle on the throttle.


Please explain...</TD></TR></TABLE>

Thats true, look at the throttle body on an HF, Its like a 2" opening. But works wonders for MPG's

 

what kind of mileage are you getting now?
I used my V-AFC to lean out at less than 10% throttle, so while crusing on the highway (about 7-8% throttle) it was barely sipping any gas. I got 38mpg in my JRSC'd B18c5 powered hatch while on road trips. It would take a while for a V-AFC to pay for itself if its only purpose were fuel saving, though. Your best bet IMO would be to get some 155-80/13s at about 40psi, a good alignment, get the engine running tip-top, and don't be in a hurry to get anywhere. Keep this thread up to date on your progress, I am very interested to see some results!