00siandrew

I have a 00 em1 with 137k miles on it and recently put on an apexi ws2 cat back. Before that I had some haggard exhaust that was made by a local exhaust shop. It was restrictive and I had an exhaust leak. I was getting consistent 27-28 miles per gallon with about a 50/50 mix of city and highway driving. I put on the cat back and with the same 50/50 mix of driving i got 32.5 mpg my first tank. All this is using bp 93 octane by the way. Then the last two tanks I'm back to getting 27-28 again and my driving habitts have not changed. Was that 32.5mpg a fluke? or is that common with a new more free flowing exhaust? I was really enjoying those 4-5 more mpg's and am bummed it only lasted one tank.

Vindicator9000

It was a fluke I think. In my experience, mileage can fluctuate +/-5 mpg based on all kinds of factors that you don't notice.

I have a mileage computer in my car, so I watch mine pretty religiously. I tend to get anywhere from 27-33 over the course of a tank, even though I'm driving the exact same routes every time. Sometimes I'll average 26-27 on a tank. Sometimes I'll average 32-33. There are dozens of factors in that small of a difference... If I just wrap it up to 8000 rpm 2-3 times, that'll kill my average mileage for the tank. Over the course of the past year, I'd say that the car, as a whole, averages 29mpg.

This is on a 00 EX with a 01 B18C1 and 99 Si transmission, with an apexi WS2 btw. I noticed NO difference in mileage before/after I put on the exhaust.

00siandrew

Yeah overall I would say 29 has been about my average. The very best I've ever got with my car was 33 and the very worst I ever got was 25. But to get that 32.5 right away without even trying with that exhaust on made me think that was going to make a difference. Thanks for the response.

BlackDeuceCoupe

Agreed!

I get 40+ MPG with a '99 Si engine, so it IS possible to get good mileage with a B16A2, but...

I keep close track of my mileage (too) and I've noticed a huge difference in how much gas I can get into my tank - depending on the angle the car is sitting when I fill it!

The best car angle for filling my car is slightly downhill and leaning toward the passenger-side. I can get almost another gallon in my car by finding a pump where my ride sits at this angle.

Sooo...

My theory is, when he filled his tank, his ride was sitting at a ***** angle and he couldn't fully fill the tank - even though the gas level was all the way to the top of the filler neck.

I've had that happen before... *thought* I got 44 MPG, only to have it *seemingly* drop to 40 MPG on the next fill - and ALL because of the angle(s) my car was sitting at when I filled it.

If you REALLY want to know what your mileage is (on every fill) - you need to use the SAME pump every time. Otherwise, the results will be a crap shoot!

Either that, or average your fills over the last 30 days - last 3 fills - or whatever...

00siandrew

I use the same station everytime...not necessarily the same pump though. What mods are done to your car, or what is it you do to get 40 mpg?

BlackDeuceCoupe

It's a full, bone-stock, swap...

I run a K&N panel filter, Mobil 1 HM motor oil, and Red Line MT-90 tranny oil.

I use 87-octane (regular) with a small amount of Acetone mixed in, and 50 PSI in my tires.

And, my HX shell is a lot lighter than a Si shell, so that helps too.

Other than that, nutiin' honey!

00siandrew

Yeah after I had posted the reply I noticed the car the motor was in. I run roughly 32 psi and may bump it up some...but not quite 50. I think that may make for a rough ride.

BlackDeuceCoupe

BTW, here's my fuel log... to show you what I'm talking about.

http://ecomodder.com/forum/em-fuel-l...vehicleid=1291 (Ecomodder.com - BDC fuel log)

If you'll look at my most recent entry, you'll see I got 44.35 MPG.

LoL!

I can guarantee you, that was a short fill.

Next fill, I'll probably log 40 MPG...

BlackDeuceCoupe

All depends...

I have Faulken ZIEX ZE502s mounted on my Si alloys, and they ride like a Cadillac @ 50 PSI.

On the other hand, I have Pirelli Cinturato P3000s on my HX alloys, and they ride rough, like a go-kart!

00siandrew

Yeah I've run both Falkens and Pirellis and know the difference in how soft and hard those tires are is huge. I'm currently on Yokohama TRZ's and could probably manage some more psi without sacrificing ride comfort. And this may be a silly question, but how important is it that you run atleast 91 octane i a stock b16? I know honda suggests because of spark knock, but if it's just a bone stock b16 does it really need 91 octane? I know you said you run 87 with acetone, so I was just curious what you thought that was like compared to running the 93 that I do.

Matt93eg

Damn 50psi? I might try this..not sure I can get away with it though. I am on stock 14" steelies with stock size tires..I think there 185/65-14 or something like that..bet they would ride rough as hell at 50psi. Would that make my tires wear un even or anything?

I know I let my tires get slack once awhile back..they were all around in the 26-28psi range..I put 35psi in them and noticed it didn't seem to drag as much..seemed I could tell throwing the clutch in and coasting in the same spots as before I wouldn't loose as much speed and have to end up using more brake to slow down and make the turn or whatever.

Thats why Trains use those big steel wheels on the steel tracks..less rolling resistance which means more efficiency which means lower diesel fuel costs.

BlackDeuceCoupe

Well... no reason to turn this into a white-paper report, right?

To put it simply, 'premium' has less power than 'regular'.

My B16A2 starts faster, and performs better on 'regular', but it wants to GO all the time. Put another way, running 87-octane in a B16A2 makes it drive kinda schizophrenic, manic, or whatever. 'Regular' gas is harder to modulate, when you're trying to take it easy, if that makes sense.

That's one of the reasons I mix Acetone with my 'regular' gas - it REALLY smooths things out! It's a whole different driving experience running Acetone - plus I get 5-10% increased fuel economy.

The only time I've heard my B16A2 ping (detonate) is when I do a warm motor start. About half the time, I get a single ping, just before it fires up. Never happens when the motor is cold, or when I'm driving down the road - racing someone, et cetera.

Sooo, IMHO, no, a stock B16 doesn't NEED 'premium'!

This has been discussed (and argued) several times, in many forums. The conventional logic is - the use of 'premium' fuel in the B16 Si is RECOMMENDED by Honda, NOT a requirement.

Personally, I feel that putting 'premium' in a B16 is like throwing quarters down a wishing well, but to each his own...

BlackDeuceCoupe

My tires wear MUCH better with 50 PSI, but it will cause some weird cupping (on the rear tires only) if you don't rotate your tires every 5000 miles. Rotating your tires on a regular basis is a MUST! But, you should be doing that anyway, right? It just becomes paramount at higher pressures...

Exactly!

The only eco-driving I do is "Motor-on Pulse n' Glide" (when I can) which is what you're describing. I can coast (in neutral) a mile or two on a very slight decline without losing too much speed. On a steep decline, I can coast further (9 miles is my record) and I will actually GAIN speed in neutral!

Heh! I've been thinking about doing a YouTube video of P&G - it's unbelievable, really!

Pulse n' glide is good for another 5-10% increased mileage, in my experience, if I got the time (and opportunity) to do it, e.g. light traffic conditions.

Matt93eg

Well..I just went out and put 50psi in my tires..hell I want to try it out anyways. And I will make sure I rotate my tires more often..i'm bad about not doing it anyways so now I have some extra incentive to do so which like you said, it needs to be done anyhow.

And the coasting thing..I use to not could do it...I was always in a hurry..now I just don't get in a rush. So I will coast when I can as long as I don't have traffic behind me.

I heard someone tell me one time..it wasn't on Honda-Tech or anything that you get worse MPG by coasting, that the fuel injectors used more fuel at idle coasting down the road than they do at WOT. I wanted to knock that stupid *** out. That makes no sense.

Vindicator9000

Yes, pulse and glide, and just avoiding braking as much as possible makes a huge difference in mileage. That's how I've achieved my personal best mileage (45mpg in an EX with d16y8), and it's really not that hard... just requires shifting your focus a little bit in how you drive.

Unfortunately, I don't really like to p&g mine now... I cruise at 4000 rpm at 70mph, and the car loses a ton of speed quickly through engine braking when I come off of it. P&G doesn't work so well for me at interstate speeds, although it does great at 55-60. I average about 37mpg if I can keep it below 60.

Matt93eg

Hey BlackDeuce, Check your PMs

ef-hatchcrap

I had a b16a2 with I/h/e and type r cams tuned by phearable tuning in tampa with 195/60/14 on hx wheels at 44 psi and I was getting like400 to 420 miles to 6 gallons in my 91 crx hf. Always ran it on 93 octane and 5w30 oil and did tranny flushes evrytime I did and oil change. Tranny was an jdm s1

Beverly Stayart

I have read all the posts here because I am very concerned about gas mileage, as is everyone these days. Thanks for all the informative and helpful posts.