Is this used car worth it? What does it need?

[gammasphere]

Hi,

I am looking at a used 1998 Honda Accord Sedan that has been modified . The owner put on a DC Sports 4-2-1 Header, a stainless Greedy catback system and an AEM cold-air intake. First of all, I test drove it and found it to be actually quite fast, but WAY TOO LOUD! He also installed a straight thru muffler of some kind. Anyway, this guy says that he has lost some fuel economy after the modifications. Is this always the case when modifying an exhaust system to a more free-flowing system??? Normally, a 1998 Honda Accord supposedly gets 500 miles to the tank on the highway. Well, this used car seems to get 400 at best. So, where did all of that go? I thought that performance parts also got you better fuel economy because it created a more efficient engine. What's wrong with this picture? All of the theoretical info says that performance and fuel economy go hand in hand in today's cars. So why is it that this performance car has lost over 100 miles per full tank??? I am at a loss. Also, what muffler would you recommend. I heard Merit and Flowmaster 50 series are good mufflers. Do you agree?

Thanks for any help you can provide me with, as I am going to be making a decision about the car soon.

[AccordCodger]

If you USE the performance increase then you won't save gas. A more efficient motor only helps if you drive it with the same accel & speed as the stock version.

500 miles per tank is a shade shy of 30 mpg. I've had 3 accords, and most of my driving is highway. I'm not heavy-footed, and I've NEVER gotten that gas mileage. 26-28 typically. Where did you get the 500 number from?

Also, who knows what else he did. Could be anything, even brakes binding.

Is it worth it? Worth what? I wouldn't pay more than book price.

[andrewken]

well obviously the headers and straight through muffler decrease gas mileage by creating less back pressure. You can replace the muffler with a stock one for like 100 at advanced auto which will eliminate the loud sound and improve fuel economy.

CAI on the other hand, do increase performance and gas mileage

I do not reccomend buying a car from somebody who has modded it like that. This means that they prolly beat on it.

[gammasphere]

Originally Posted by andrewken

well obviously the headers and straight through muffler decrease gas mileage by creating less back pressure. You can replace the muffler with a stock one for like 100 at advanced auto which will eliminate the loud sound and improve fuel economy.

CAI on the other hand, do increase performance and gas mileage

I do not reccomend buying a car from somebody who has modded it like that. This means that they prolly beat on it.

Wait a minute. How does less back-pressure decrease mpg? I thought that less backpressure decreased the amount of residual exhaust gas in the piston chamber and thus made the car engine more efficient. I have heard so many variating opinions on this topic, that i don't know where to start... I was also thinking that a Cold Air Intake might reduce the mpg in this case, because it might be letting in TOO much air. I mean, I've never understood how cold air intakes help. Isn't the O2 sensor supposed to tell the valves how much oxygen and fuel to put in?

[gammasphere]

Originally Posted by AccordCodger

If you USE the performance increase then you won't save gas. A more efficient motor only helps if you drive it with the same accel & speed as the stock version.

500 miles per tank is a shade shy of 30 mpg. I've had 3 accords, and most of my driving is highway. I'm not heavy-footed, and I've NEVER gotten that gas mileage. 26-28 typically. Where did you get the 500 number from?

Also, who knows what else he did. Could be anything, even brakes binding.

Is it worth it? Worth what? I wouldn't pay more than book price.

Thanks for the mpg info, it gives me a better idea. The EPA lies anyway. Do you think if I take out the Cold Air Intake or by adding a fuel injector kit that it could help with the mpg? By the way, the car's going for $5900.

[AccordCodger]

EPA? There's not a car on the planet that hatches the EPA numbers. Dunno about the price. What does Kelley's Blue book say?

And I'm not sure the car has a problem with the gas mileage.

[andrewken]

The stock intake is very restrictive. By putting on a cold air intake, it allows the engine to breathe better. This causes a faster throttle response, more MPG(because you can ride at a lower rpm) and more hp because the engine can take in more air and more fuel.