About a month ago, the install was completed of a F20C in my S2000 from the same year of S...a 2001 with 22K on the clock... due to my previous engine dying on me at 97K. Since then, my MPG has noticiably gone down 2.5 to 3 miles per gallon. I used to get 25-26 combined city and highway, now I am getting 22.5 to 23.5. Though its not much, its irritating to me.

There are a couple things to note:

1. I usually have the top down, which obviously creates more drag.

2. I do drive the car a bit more spirited these days...I installed an Invidia exhaust the same day I brought the car home with its new heart and the sound is intoxicating. However, I really don't think I drive it hard enough to lose this much on the MPG. The only time I have ever gotten this low of mileage was during a group drive when the speeds exeeded 90+ the majority of the time and there were lot of shifts at 9K.

3. The temparture outside has cooled considerably here in Kansas, but, even in the dead of winter the worst mileage I have seen from this car combined city and highway was 24 MPG.

4. The engine installed sat for 2 years after the salvage title was issued on the car it came out of in 2004, and was not used at all after 2004 until installed in my car last month. That being said, the oil was changed after I put 1K on the engine to ensure any crap inside the motor would be removed.

I guess my question is there something I can do or check? Should I run a fuel injector cleaner or an octane boost of some sort through it?

Its not that big of a deal, it just makes me curious....especially since a Z06 cruising on the highway is getting better fuel economy than I am.

 

You know the change to gasaohol (E10, 10% alcohol) has cut fuel economy across the board (something they don't advertise but, it's true). If you were running real gas before and are now using E90 gasahol, that reduction in fuel economy would be normal. Even in place that don't normally use E90, they sometimes use it as a winter gas to reduce emissions.

 

aftermarket exhausts can sometimes decrease your fuel economy, has to do with backpressure. Anyone have any insight on this theory?

 

Check the basics first...intake air filter (make sure its clean). The Invidia may be robbing you of some mpg. I noticed a difference when I put on my HKS. It wasnt big but my MPG isnt the same as when it was stock.

 

Let me summarize here and see if I understand what you stated - "So I put a new engine in my car and the mpg is different."

That part about the new engine might explain the mpg, everything else is just conjecture since not all things are constant.

 

hmm new engine maybe? I think so, no engine is the same.

Also we are talking about 2mpg, it can be anything really. Plus its an s2000 not a prius, who cares enjoy the car! I get 18mpg fwiw.

 

I'm thinking:

1. winter blend of gasoline. This usually kills my mileage by about 2mpg to 3mpg on all my cars.

2. Did you replace the plugs, filters etc. on the new engine?

I'd bet strong money on 1.

 

my guess is the temperature and spirited driving.

 

I don't know what to think....it has to be the engine. I guess I am wondering if a fuel injector cleaner of sorts would help the situtation??

I have a K&N drop in filter that came with the car when I bought it, I am thinking it might be time to change it since I have no clue how long it has been in the car.

 

My mileage has dropped about 2mpg over the last couple months and nothing about my driving has changed. I'm guessing it's my fuel.

?