a2matik

I have made a LOT of n00b errors over the relationship between me and my Civic.

I have a 97 Civic EX with 152,200 miles and is in need for some service:
-Tranny (most likely synchro going out, maybe clutch?) Grinds from 2nd to 3rd gear if RPM above 2k. Sometimes kicks it out 3rd gear when rpms lower to 1k.
- Brakes are another issue; pads, rotors, lines, fluid each are about 4 years old. working fine!
- Has HP racing 4to1 solid piece headers, KN oe box filter, pacesetter hi flow cat, 2.5in piping after cat, and ahem.... stock muffler that insurance put on after an accident.
- I use quaker state synthetic 5W30 with Quaker State Oil Filter. (every 2700-3000mi)
- Use Marvel Mystery Oil every 3 fillups to clean injectors, fuel delivery system.
- AEM fuel filter and housing.
- Stock distributer but with bosch rotor, cap, and nology hotwires, about 1 1/2 years old.
- Always keep tire pressure at recommended levels (30F/29R)
- Tranny Fluid was changed 10,000~miles ago w/ valvoline 10w30 Standard.
- Stock Steel wheels (hubcaps still on yea!) Goodyear Viva Touring Rubbers
- besides a Sony Xp 60x4 Headunit and two polkaudio components in the front..(see below)
- this car is stock.

My Question:

I know there is a good deal of work to get done to make this car run better. It runs great right now but I know there are ways to do a lot more out of it. I average 34mpg @ 70mph, and around 25-30mpg in town/freeway usually driving back and forth to work.

A new engine or Forced induction are out of the question. Thanks.

What types of performance upgrades can I perform that would reduce gas consumption and add performance? Cold air Intake? a new muffler on? A tune-up of course but what recommended parts? Any chemicals or services I should go thru (ie. oil systems flush)? Lighter rims? Pulleys?

Pull out your knowledge and help me find ways to have a more "green friendly" performance vehicle.

MoSeS

definately new exhaust, not just new muffler. you have way too big of piping for a na d -series, Discount Car Parts Stuff - Car Accessories & Truck Accessories - Cheap Auto Parts - Car Cover - Floor Mats - Cargo Liner carries a lot of different parts that can help. i would suggest 2" piping because with 2.5" piping you are killing your exhaust velocity and scavenging which is lowering your mpg.

MoSeS

AEM also makes just about everything you could ask for a d16. intakes, pulleys, cam gears. if you have the intake manifold that has the throttle body on top i would reccomend replacing it for one that has it side mounted, a d16y8 intake manifold would work. fuel rail, fuel pressure regulator, basic bolt-ons. you won't be able to pull much HP out of the d-series without forced induction though

YBLEGAL

does too large an exhaust affect preformance? such as 2" opposed to 2.5"?

MoSeS

yes, very much. you need to find the happy median inbetween too big and too small. the reason you don't want exhaust too small should be obvious, too much resistance against the exhaust flow. too big is a little more complicated. you want velocity, with good velocity your exhaust system will actually pull the spent gases out. its like if you were to try to drink something through a coffee stirrer (the ones that are like tiny little straws) its hard to get anything out of it because its too small. you also wouldn't want to try to drink something through a shop-vac hose, because you would be trying too hard to get just a little bit out of it again. for d-series 2" piping will be good, b-series 2.25", h-series 2.50", turbo 3" and up

a2matik

Thanks for all the advice Moses.

Citizen_Insane

If you want to increase your milage, you're going to want your motor to produce the last amount of HP possible. Performance and fuel consumption are on opposite sides of the scale. While a turbocharger or supercharger will increase the overall efficiency of a motor, when added to an N/A motor, you'll end up burning more gas. The reason you can have efficent turbo cars is because they use engines as small as 800cc to propell a car. With your 1.5L engine, forced induction will only add to fuel consumption since your motor already has enough torque to move your car. The equation for hp is pretty much:

bhp = (displacement)x(a/f ratio)x(latent heat of combustion)x(efficiencies)

This means that there is a linear relationship between how much fuel you add and how much power you get out of an engine. Therefor you can see that it is impossible to increase an engine's performance without adding fuel. You might argue, upon seeing this equation, that there are other ways. You could increase displacement right? Wrong, more fuel must be added to compensate for the added air. Why not increase the efficiency? Well, honda isn't stupid. Their engines are already about as efficient as possible. The volumetric efficiency of a honda engine is probably arround 90% (avg). You're not going to increase this any more without forced induction, which will in turn increase it so much that you'll have to add more fuel to compensate as well. The mechanical efficiencies of modern motors is also at max (85% or so). There isn't really any way for you to reduce friction within your motor in an signifigant way.

So will that CAI help you? No. The added oxygen provided by the cooler air will only increase the fuel you need to add to make peak power. What you should do is the opposite. Intake warm air from your engine bay that is less dense, and you'll therefor make less power and use less fuel.

Sorry for the long rant, but there always seems to be this idea that you can have power adders that also increase gas milage and it just isn't so. To a point you can increase an engine's efficiency, but you'll net maybe 5% more power. After that you'll just be burning more fuel.

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No tech questions through PM please!

B16 CRX....you will be missed

MoSeS

DwnShftPrincess

i luv it when you guys post formulas and then explain them

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127 hp = 2 rabbitts and a squirrel

Turbo&Auto

I actually get better MPG's with my Accord after the turbo. It would take more effort and throttle to get up a hill before and now I can give it a quick burst and then ease the throttle and maintain my speed. I'm getting 32+MPG's now, about 325-350 miles per tank. Before I was getting less, not by much, but still less. 300ish to the tank if I babied the car all the time.

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www.BackyardTurbo.com