don't use premium gas

[gearbox]

You know I've noticed on alot of cars (even civics) there is carbon buildup inside the exhaust pipe, like the tailpipe piece. I even found buildup in my stock header, enough to decrease performance. Since I started modding and tuned the fuel, I haven't noticed any carbon in the exhaust.

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[Jrfish007]

Originally Posted by gearbox

You know I've noticed on alot of cars (even civics) there is carbon buildup inside the exhaust pipe, like the tailpipe piece. I even found buildup in my stock header, enough to decrease performance. Since I started modding and tuned the fuel, I haven't noticed any carbon in the exhaust.

Carbon build up is a sign of one of two things, or a combination of both:

1. the motor is running rich (more common than you than you may think for stock cars) and
2. the use of higher octane than required and/or the use of to many cleaners in the fuel (this includes detergents)

[gearbox]

i'm betting they were running rich. Even after the mods my car was rich in lower rpms. It's excessive tho and honda needs to tune better from the factory. I doubt the cars I saw had any mods, and I bet they used regular gas since they were all stock.

[Titleist71]

Originally Posted by gearbox

You know I've noticed on alot of cars (even civics) there is carbon buildup inside the exhaust pipe, like the tailpipe piece. I even found buildup in my stock header, enough to decrease performance. Since I started modding and tuned the fuel, I haven't noticed any carbon in the exhaust.

our cars run rich in stock form.....thats ulev, fuel economy, and vtec for you!

[pon55]

Originally Posted by Titleist71

our cars run rich in stock form.....thats ulev, fuel economy, and vtec for you!

Lean= ulev. Stock should run slightly lean-never rich! (Thats why we get like 35+mpg)

[gearbox]

I'll have to disagree. Our cars do run rich to prevent engine damage at lower rpms. I saw it on the dyno and it's true, even with mods. You're thinking about the HX which is a lean burn engine, different from the lx/ex.

[Jrfish007]

^^^ yup

You get 35 miles per gallon because Honda has an extremely good head design that provides for a better flow of air inside the chamber (better for atomization of the air and fuel) and a more even flame wall unlike most engines. And of course things like gearing and all that come into play.

And yeah, the HX get such good gas mileage (my aunt get 48MPG in hers) because it has a reverse cyclic air flow pattern in the chamber that allows the engine to actually run lean. So why not use this on all Hondas? Because this air flow design robs power from the engine (the engine has to work harder to pull the air into the cylinder, hence less overall power is produced).

[pon55]

Originally Posted by Jrfish007

^^^ yup

You get 35 miles per gallon because Honda has an extremely good head design that provides for a better flow of air inside the chamber (better for atomization of the air and fuel) and a more even flame wall unlike most engines. And of course things like gearing and all that come into play.

And yeah, the HX get such good gas mileage (my aunt get 48MPG in hers) because it has a reverse cyclic air flow pattern in the chamber that allows the engine to actually run lean. So why not use this on all Hondas? Because this air flow design robs power from the engine (the engine has to work harder to pull the air into the cylinder, hence less overall power is produced).

I'll go away now! soory

[Jrfish007]

^^^lol, that's not like to give up that easily. Anyway, most people think all Hondas run lean, you are not alone. I must have explained this to 25 people now, no big deal.

[Excal]

Originally Posted by Jrfish007

^^^lol, that's not like to give up that easily. Anyway, most people think all Hondas run lean, you are not alone. I must have explained this to 25 people now, no big deal.

dont you wish everyone on here give up that quick.

[DaddyFatSacks]

I heared even with nitrous, if your not detonating, you should stick with the lowest octane you can. Don't quote me on that, but it does make sense.

[senseiturtle]

In addition to decent air management, part of the reason you get 35 MPG on a civic is because it's got only 1.7L (or less) displacement. Small motor, less gas.


Now, as far as running lean goes...

Running lean causes an engine to heat up faster. When turbo guys go nuts with a MBC and crank it too high, the injectors max out, and a lean condition ensues. The engine overheats. Same with guys who shoot too much nitrous on a dry system.

The only time an engine should run lean is just after a VERY cold start, when the secondary air injection system (if equipped) crams additional air into one or more cylinders, allowing the engine to warm up faster, as well as get the catalytic converter up to operating temps faster. Its operation is required for proper emissions testing.

[Jrfish007]

Originally Posted by senseiturtle

In addition to decent air management, part of the reason you get 35 MPG on a civic is because it's got only 1.7L (or less) displacement. Small motor, less gas.


Now, as far as running lean goes...

Running lean causes an engine to heat up faster. When turbo guys go nuts with a MBC and crank it too high, the injectors max out, and a lean condition ensues. The engine overheats. Same with guys who shoot too much nitrous on a dry system.

The only time an engine should run lean is just after a VERY cold start, when the secondary air injection system (if equipped) crams additional air into one or more cylinders, allowing the engine to warm up faster, as well as get the catalytic converter up to operating temps faster. Its operation is required for proper emissions testing.

huh? lean makes the engine heat up? I think its the other way around, when you start your car in cold conditions, the engine runs even richer so that unburned fuel can actually reach the cat, which then burns on the cat hence heating it up. If you don't believe, go stand behind a car with a larger engine (or even my 4 cylinder Accord) when it is started and you will smell gas for about 30 seconds. This was one of the major advancements between OBDI and OBD II, the ability to heat up a primary cat at a faster rate. And the platinum catalyst used in the breaking of hydrocarbon is immune to coking problems, hence they moved it closer to the engine to break down unburned fuel and carbon to try and make the remaining two catalyst (located in your secondary cat) more efficient and last longer.

[Jrfish007]

Originally Posted by DaddyFatSacks

I heared even with nitrous, if your not detonating, you should stick with the lowest octane you can. Don't quote me on that, but it does make sense.

That's true, but as discussed before the worst thing from higher octane is that you get carbon builds and maybe a little more noisy engine (assuming you only run the higher octane when your on the bottle, you probably won't get much of either of these). The alternative, if you run lean is that your engine will knock, if you don't realize it is knocking (which chances are high since the human ear can not hear knocking above 4000 RPMs, and most knock sensors are only good to about 4000-5000 RPMs and knocking becomes more likely as RPMs rise) you will blow your engine. If the knocking becomes serious, you will blow your head gasket or crack your head(s). Personally I would rather chance a little carbon versus the head or head gasket. IF you would like I can try to explian the chemistry behind all this.

[gearbox]

My car shakes back and forth at idle in drive when I slightly let go of the brake. Is this due to octane or just a higher compression problem with the head? Can you feel knocking or detonation?