Restricter plate
 

Anyone every intall a restricter plate too see if mileage improved?

I was thinking of doing it if there was proof it worked. If it does would it be better to install the plate under the TB or before it?

It seems to me that a restrictor plate would hurt mileage due to pumping losses. Am I missing something?

Tried it -- Failed for me
 

I tried restricting the intake on the Integra and it just took more throttle input and no appreciable gain:

Thread.

It could vary from vehicle to vehicle, but compared to old carbeurated vehicles of the past, the ECU will adjust accordingly. More importantly, intake temperture should be optimized.

RH77

If there isnt proof you should test it and tell us the end results.

rh77....I just finished reading most of the 2 page thread on this subject. Of course I never noticed the thread to start with until I had already started this one.

However the old thread ended with no new/further results on the testing.

So you say you did do it then, correct?

Instead of a restrictor plate you could create some sort of throttle stop that would never allow you to go over 25% throttle.

I would think a restrictor plate would allow you to add more gas, but would restrict the air flow causing a rich condition. If I am wrong someone please correct me.

A throttle stop would be the cheapest and easiest to apply.....however designing a bypass system for emergency/needed situation would require some further thought on my part.

Maybe placing a heavy spring on the floor that would normally keep you from pushing it down any further but will allow the pedal to go all the way to the floor when you press down harder????

Mostly Guidance
 

No big deal about not noting the thread -- I try to recall what I've tried over the last year or so and that was one failed attempt. It turns out that the thread turned out to contain less info than I remembered.

What I used to restrict the air was to plug the intake with a stopper-like device that had a small-diameter hole in the center. To get up to speed, maintain speed, or drive with load, required a considerable amount of throttle input and resulted in more fuel consumption. I don't have anything scientific or an A-B-A test, but it did free up power and consequently less throttle input. Scanguage values were used and showed that no gain was attained, and sluggish engine operation resulted.

I welcome another test for maximum scientific attainability.

I have implemented a 20% maximum-throttle-input cruise control apparatus that takes less attention while cruising on the highway. Whatever 20% throttle gives me, is what I'll take on the Interstate. Once up to speed, it may reach 70 downhill and slow to 55 uphill -- the result is the "Driving with Load" technique.

A spring-loaded throttle is a good idea -- one I've wanted to try.

RH77

I have a restrictor of sorts on my car, it's in the form of an alluminum can in the exhaust (flattened with a hole in it) It's whisper silent, but really cuts down the power. I wild estimate is %50 percent less power. It has actually helped my gas mileage around town. I used to always floor it and come sliding around the corners (bad habit) With this in there, my exhuast no longer encourages me to rev it up to enjoy the sound. If it was a manual, DON"T DO IT, you can't proper pulse and glide with it. On the highway ( low load) it seems to get nearly the same gas mileage (judged by odometer/fuel gauge only)

For most gas engines, lots of throttle at low RPMs is the most efficient. This is because of the pumping loss across the throttle restriction. Why would you want to limit your throttle stroke to 25%? I use 90% throttle all the time and my MPG has improved since I started doing it.

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!

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.

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.

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.

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

Thanks for coming to my rescue MetroMPG!

Is your Sidekick manual or auto?

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

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 :confused:

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!

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.

Ryland.....

Your 1st paragraph IS exactly what caused me to wonder how this would work at all.

Apparently it will work on newer vehicles?

I run 90% (not 100%) for exactly the reasons you stated. With fuel injection the computer thinks you want max power if you give 100% throttle and goes into open loop control (ignores the oxygen sensor) and dumps in lots of fuel. That is bad.

brelandt,
Your comment about deisel engines being regulated by fuel delivery and not a throttle plate... that is one of the reasons they get better mpg than gas engines at partial throttle. No pumping losses across a throttle pate.

the problem of pumping loss as I understand it:
A partially open throttle reduces the manifold pressure, which reduces the pressure on top of the piston as it is travelling downward, sucking in air/fuel. Since the pressure on top of the piston is much less than the crankcase pressure, the pressure force is working against the piston (slowing the engine). At 90% throttle opening the manifold pressure is higher and it isn't as bad.

I agree!