Restricter plate

[brelandt]

So.....let me see if I am understanding where you are coming from...(I know there was a link to an article on this but I have not read it yet).

By gunning you engine up to higher RPM's you save gas because the pistons are least effective when the throttle plate is restricting the airflow and lower RPM's?

I understand this, however what I am not understanding is why this whould save gas?

On a internal combustion engine that uses a piston (modern anyways) the fuel comsumption is realitive to the position of the throttle plate. The more air that is let in, fuel must be added in order to keep a 14.7:1 air to fuel ratio.

This is opposite of how a jet engine works (also an internal combustion engine) were as the more fuel added (same as diesels) the faster it spins since there is NO throttle plate to control RPM's. But must also maintain a certain ratio to keep the combustion going.

By my way of thinking, revving an engine to a higher RPM would burn more fuel per distance than using less throttle. Not to mention the wear and tear of the parts in direct contact to the torque placed on it.

If there where a way to prevent the fuel from increasing while opening the throttle further (I don't no how since you need a air/fuel ratio or therre will not be any combustion) that would be great!

As I've said I did not read the article and if you would be so kind to as placing the link on this thread than maybe I will realize that I have no idea what I'm saying and then we will all have a good laugh at the end.

Just some thoughts and I am happy that there is a forum like this to further ones education. I love to learn about this stuff!

Thanks!

[DRW]

Originally posted by brelandt:"By gunning you engine up to higher RPM's you..."
Oopsie, he said he uses LOW rpm with 90% throttle. I believe it's been stated in other threads that low rpm with heavy throttle gives acceptable accelleration with better FE.

[brelandt]

that was the point to my question. Sorry that I went all the way around the world with it.

How do you maintain low RPM with 90% throttle? Hence why I wrote out those long explaination of my thinking.

[MetroMPG]

If you're driving an automatic, you can't keep RPM low with high throttle.

But if you're driving a manual, you just "short shift" when accelerating: use lots of throttle, but shift at a low RPM.

[brelandt]

Ah....Ok now that allows me to understand better.

Thanks for coming to my rescue MetroMPG!

[MetroMPG]

Is your Sidekick manual or auto?

[The Toecutter]

If his is an automatic, I can only imagine how horrendously bad its acceleration is. Oh the humanity!

[red91sit]

Originally Posted by MetroMPG

Is your Sidekick manual or auto?

I checked the garage, and his EPA numbers matches up to a 5speed manual version of this vehicle. Intesetingly, the 4wd, and 2wd have the same numbers

[brelandt]

yep, it's a manual, 2wd and with what I believe is a 5.61:1 rear gear!!!!!!
Lousy, but I achieved 33.1 today!

[GasSavers_Ryland]

I supose you can get away with running wide open throttle in a high gear/low engine speeds on some cars, but all of mine have either "power valves" in the carburator that give it more gas at low intake manifold vaccum, or vacum adjusted fuel presure regulators, that when you have low intake manifold vacum it increases the fuel presure going to the injectors, so you step on the gas, vacum drops, fuel presure increases, fuel/air mix gets richer.

I would think that if you have a restrictor plate that you would want it after the fuel injection, because didn't restrictor plates start out either on carburatored cars, or on throttle body injection? with TBI I could see how if you had a plate with a whole that was slightly less area then the throttle body when it was wide open, that would help to even out air flow, and cause just a bit of turbulance at the same time (if that's possible) to help the fuel mix better with the air, and keep the air velosity higher.