Generally speaking, for most car

For example, say if i down shift from 3gear(3000rpm) to 2gear(~4rpm?)
Is it going to waste more gas due to the rpm goes up?

Or not, cause I didn't step on the gas?

 

i don't know i always wondered it? but i don't always down shift cause im too lazy to brake lol

 

No, when you are downshifting it cuts off and fuel for the engine and creates a vaccuum in the injectors in order to bring down rpms

 

Generally, fuel consumption is related to throttle position.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sleeperrex &raquo;</TD></TR><TR><TD CLASS="quote">No, when you are downshifting it cuts off and fuel for the engine and creates a vaccuum in the injectors in order to bring down rpms</TD></TR></TABLE>

So, even match revving wont have a negative affect on gas huh? I always questioned myself for doing it, wondering if Higher RPM's would mean more gas consumption. Nice to know its not like I thought.

 

If you're touching the throttle to rev match when you down shift then yes, if your just letting the clutch rev match for you, then no, but your clutch probably isn't a big fan of you doing that all the time.

 

I try to balance using the motor and brakes to stop. If my brakes are starting to wear out, I down shift more often to help out the situation. Otherwise, I'd rather use the brakes to keep my tranny in better shape

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ice78transam &raquo;</TD></TR><TR><TD CLASS="quote">Generally, fuel consumption is related to throttle position.</TD></TR></TABLE>

true, but you need to keep engine load under consideration as well.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drSquish &raquo;</TD></TR><TR><TD CLASS="quote">I try to balance using the motor and brakes to stop. If my brakes are starting to wear out, I down shift more often to help out the situation. Otherwise, I'd rather use the brakes to keep my tranny in better shape</TD></TR></TABLE>

If your brakes are wearing out, you should probably go buy new brakes. They cost like $30 and it takes less than an hour to change the front pads.

 

Load and throttle position are what effect your gas mileage. This is an obvious over-simplification, but you get the point.

 

what about injector pulse? a higher RPM will it not spray more fuel/time?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MegaPower &raquo;</TD></TR><TR><TD CLASS="quote">Generally speaking, for most car

For example, say if i down shift from 3gear(3000rpm) to 2gear(~4rpm?)
Is it going to waste more gas due to the rpm goes up?

Or not, cause I didn't step on the gas?</TD></TR></TABLE>

When you down shift without stepping on the gas. You are not wasting any type of gas. Unless you plain to heel-to-toe then that's a different story.

 

It depends on the accumulated length of time the ECU makes the injectors spray fuel

 

2500 for my EG coupe, (EJ2) primor, has a sohc vtec zc

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drSquish &raquo;</TD></TR><TR><TD CLASS="quote">I'd rather use the brakes to keep my tranny in better shape</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigsyke &raquo;</TD></TR><TR><TD CLASS="quote">what about injector pulse? a higher RPM will it not spray more fuel/time?</TD></TR></TABLE>

Nope, no throttle + negative load on the engine = no fuel being burned

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IslandSi &raquo;</TD></TR><TR><TD CLASS="quote">

Nope, no throttle + negative load on the engine = no fuel being burned</TD></TR></TABLE>

what i said was actually in response to this

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">Load and throttle position are what effect your gas mileage. This is an obvious over-simplification, but you get the point. </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigsyke &raquo;</TD></TR><TR><TD CLASS="quote">what about injector pulse? a higher RPM will it not spray more fuel/time?</TD></TR></TABLE>

If your @ 5k cruising in 2nd, your hardly on the throttle. But if your going the same speed say 1k in 5th, you will be at a higher load/throttle, but less injector pulse. So where do you find the sweet spot?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DarkGenesis &raquo;</TD></TR><TR><TD CLASS="quote">

When you down shift without stepping on the gas. You are not wasting any type of gas. Unless you plain to heel-to-toe then that's a different story.</TD></TR></TABLE>

heel-toing or at least rev-matching is the best way to downshift. if you're just engaging the clutch while in gear with out matching your tranny speed with your engine speed, you just asking for your clutch to wear out prematurely.

i usually only downshift if im gonna gas it through a turn or on-ramp, and have some fun. but other than that, i'd rather go through some pads then overhaul my tranny. brake's are there for stopping/slowing.

 

brand new pads are only $37 from honda! Brake away!

 

Such a long thread for simple answer! LOL

 

I'm not sure if it's really so simply.

If load stays the same, and the engine runs at higher RPM than previous gear, then it will use more gas over time.

If you are rev-matching, then throttle is being used, and you are using gas there.

If you pull out of one gear, coast or brake to slow down, and then run a lower gear at the same previous RPM, this would be the way to not be using any more gas.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigsyke &raquo;</TD></TR><TR><TD CLASS="quote">brand new pads are only $37 from honda! Brake away!</TD></TR></TABLE>