How to make a 4cyl 7G Efficient

[arkaine13]

Hello everyone! I have found that there are a lot of mods here that pertains to increasing the power of the 7g, I was wondering if anyone had any tips or mods that can allow the 7g to eat less petrol. I was also wondering if there is a way to reduce the power output of the 7g through timing. Any thoughts on this?

Thanks in advance!

[Exhaust power]

To be more efficient the engine would need to utilize the fuel more efficiently wile doing less work.
Torque is what youll need to have at lower rpms so the engine will require less work to move.

A better flowing intake side will be more efficient like short ram, bigger TB, port match IM to the cylinder head.
For the exhaust side a better flowing exhaust would help example performance header, bigger cat and cat back.

In theory retarding the timing would most likely shift the torque to lower rpms which should help.

Tuning will be one of the biggest parts about being more efficent trying to obtain a perfect burn ratio 14:7 would be ideal.

This is just a little bit of info there's far more things to talk in theory about like aerodynamics , gear ratio , static weight, how to drive to save gas and suspension.

[Silvertune]

Retarding timing does not promote torque. It's as wrong as people saying backpressure promotes output. You have X amount of charge in the cylinders and it creates the same pressure no matter when you fire it. Increasing timing actually promotes torque because you increase the amount of charge burned for any given point in rotation. More total burn, more cylinder pressure acting at any given time and more torque for the same net mass of charge.

Neither is 14.7:1 is not a "perfect" ratio either, it's simply what the EPA wants from an emissions standpoint. You can run a point and a half leaner than that and be just fine.

Ultimately you aren't going to multiply the MPG of your car much past what it could do when it was brand new unless you're going to basically build the motor. If you want to restore some mileage than maintain the crap out of it and revise your driving habits.

[Exhaust power]

Retarding timing i said in theory will shift the curve backwards. I wasnt saying youll gain more torque overall but earlier which should help the car get around with less effort. Maybe i shouldnt of said perfect but thats the ideal ratio/stoichiometric for gasoline.

"In theory retarding the timing would most likely shift the torque to lower rpms which should help"

And im not sure how you say more mpg cant be achieved after the factory ratings? i dont understand your point. Of course mpg could be gain with simple mods.

Basically the concept was getting the torque you need at lower rpms will help the car work less to achieve it thus gaining better mpgs.

Just like a car can be tuned performance the same can be done to gain mpgs

[Silvertune]

Torque is output... If the engine is making output then it is burning gas. My cousins Corvette makes 250wtq at a thousand RPM's and he drives it like a grandma but I still get better mileage redlining my Accord all day long.

Fuel efficiency is VERY different than overall efficiency. Fuel efficiency is getting as much work as you can out of a unit of gasoline, how much work goes into moving the car for a given fuel consumption.

You can do this be reducing the work the engine has to do. Fluids, tires, all the wear items and more contribute to how much work is required. Lightweight aftermarket parts help here as well. However in the light of age chances are the lightweight materials will only make up for if not only a tad bit more than the efficiency lost over time. Driving style is huge.

The other increase in fuel efficiency is making more output per unit fuel. Moving the torque band down isn't going to do this, in fact it'll probably make your mileage worse and if you throw a bunch of breathing mods on it the thing will start adding fuel to compensate for the extra air and make your mileage even worse yet. Your ECU has a preset that it is looking for, it will add fuel to see that and as things wear it ends up adding more fuel because that's what happens when O2 sensors get old. In the scope of things unless you're leaning it out by tuning it the best thing you can shoot for is the factory preset because it never pulls fuel but under maybe one circumstance that really doesn't happen, it only adds.

If you're tuning you better be damn good at it to get an efficiency tune down. Dyno tuning is time consuming and that's tuning for one circumstance, tuning for every driving condition there is is a job that nobody but an OEM manufacturer takes on.

[Exhaust power]

a lot what you said i found similar saying here http://www.torquecars.com/tuning/tuning-mpg.php

I also want to talk about torque and rpms in theory later on after i get to work.

[wetamup2k3g]

I never knew 14.7 isn't actually the ideal AFR, they never taught us that at Lincoln Tech (I looked it up just now), they basically preached 14.7:1. No mention of the EPA changing stoich at all. Interesting.

OP, the quickest, easiest, cheapest way to increase your mileage is to change your driving style, maintain your car to the utmost and make sure your car is as stock as possible. Get your car as close to factory specs as possible. If you must mod, make your car lighter, that's only gonna save you gas as well as help performance.

[Silvertune]

They teach you a lot of stuff at school. Haha. Emissions in general is the most misleaded worthless piece of shit counsel we have in the government. None of them really understand how catalysts and engine theory work. Our cars aren't getting 60 MPG because we use piss for gas and put giant converters 3 inches away from the exhaust port. They don't last forever because we recirculate carbon through the engine again and again and again, use shit for gas.

I could write a 50 page encyclopedia on why the EPA is a bunch of tards but I'll stop there.

[Exhaust power]

The article I posted was saying on stock computer a small intake or stock intake is best for more mpg. Basically the computer senses less air so it spends less gas. So that's a very interesting read.

What's your opinion on 2 4g64 engines 4g64a makes 130lbft @ 1500 rpm and 4g64b makes 130lbft @ 2000 rpm given the same gear ratio which one would you think would be more fuel efficient?

My answer. 4g64a should get better gas milage because the engine should be using less gas since its not spinning as fast?

The reason why i made that example is for the reason why i said adding a inatke and exhaust and then retarding timing to shift the torque curve. Thats what i was thinking the ecu would have to be tuned though.

[arkaine13]

I have a Mirage (a 4G92 Lancer 1997 in my country) that has a modified intake and exhaust, I notice that it had an increase in acceleration, but has some relative difficulty going up to inclines after the exhaust and intake mods. Also, engine braking was not as effective as it was before, but nonetheless the fuel economy was quite good. Will this mod help my 7g? I'm asking because my wife wants to ditch the 7g for a smaller econo-car, I want to keep the 7g. If I retard the timing, will it help my fuel consumption? Also, I have been thinking of replacing the distributor cap, will this also help? Thanks a lot for the thoughts!

[arkaine13]

So if I were to restrict the air intake, I can in some way decrease my fuel consumption?

[Exhaust power]

I wouldn't restricted it pass the factory intake. You will decrease fuel consumption but also power and our cars don't make much of that to lose.

You should read the whole article I posted.

And retarding the timing Is a stretch that might not work. I can't give any evidence of this being beneficial yet so that's a no.

[wetamup2k3g]

They teach you a lot of stuff at school. Haha.

I know right? I think I've learned more from the forums than that damn school when it comes to engine management. And the forums haven't cost me $14K.

[Silvertune]

You're completely missing the point. Peak torque is meaningless, torque at WOT is meaningless in terms of fuel consumption. You never use it if you're concerned with fuel consumption!

The engine that makes torque lower is not going to magically get better mileage. The engine that gets better mileage is the one that produces THE REQUIRED AMOUNT OF WORK THE MOST EFFICIENTLY. That is NOT the engine that makes the most low end torque. The engine that makes torque lower is going to be more pleasurable to drive, it is going to move more easily given a certain throttle input BUT IT IS GOING TO CONSUME MORE GAS because it is making that more torque and doing so requires fuel.

It takes 15 horsepower to move your average car down the highway. My old civic revved to 3k on the road. My cousin's corvette revs to 1200. They both got around 30 MPG. The reason being they both make the 15 horsepower with the same amount of fuel. They have the same fuel efficiency at that load level given their respective gears.


The only reason retarding timing would increase torque under any circumstance is if the engine has excess timing advance causing the cylinder pressure to work while the piston is coming up. However no factory tune is going to be even remotely close to this threshold so it's inapplicable unless you've been to a shitty dyno tuner.

[Exhaust power]

I get what your saying. In fact I have read about similar talk when doing research on a more fuel efficient rotary engine concept couple years back. Unless i have a equation its a bit complicated.

[Isaurio]

You could make your afr for cruise to 15-15.3 safe

Im targeting for idle for that.

[mko]

you guys went all in detail. Its a 7g after all - all he can do is retard the mechanical timing by moving the distributor. That will change the entire hp/torque output and will not do much at specific rpms. You can do all that to your 8g Galants, but not to 7g with stock ECU.


@OP - We are not in the same game, sir. Here in the US, automotive fans care more about making more power than saving fuel.

Whatever you're wanting to achieve is easy, but costly and unless you plan on keeping the car and continue modding it for more power that you better off selling it. Its tough but its the ugly truth.

Here's a little breakdown:

1. Throttle body - you need 1g Eclipse TB and you have to modify the idle control.
2. Port match the 1g Eclipse throttle body gasket with the intake manifold inlet flange.
3. Intake - you need a MAS adapter, air filter, couplers and 3'' pipes. Best spot is to locate the filter a bit bellow battery. If you decide to stick with stock air filter box then at least replace the stock rubber intake pipe with metal one. Its very restrictive.
4. The stock exhaust is 2 1/8'' ID or 2 1/4'' OD. I know you wont upgrade that so at least make sure it doesnt leak and the cat converter isnt clogged.
5. New or properly working upper/front oxygen sensor and engine temperature sensor.
6. New spark plugs, wires, distributor cap
7. Change driving habits - slow and steady acceleration in 1st and 2nd gear. Do not go over 3000 rpms in any gear. No stopming on the pedal.
8. To be able to know what exactly is the air to fuel ratio, you need a wideband. It will feed you numbers in real time of how your engine is burning fuel. The best fuel economy is achieved at 15.2: 1 air to fuel ratio, as mentioned above. ($150-200)
9. To be able to change your stock ECU air to fuel ratios, you need a fuel controller. SAFC is commonly used. This will set you back $200-250.
10. Properly working PCV system. Besides the stock PCV valve, you may want to add a check valve in the same line. And to keep the oil out of the intake manifold, you should have an oil catch can in the PCV system too.

As you see its not cheap to have a car that eats less gas.

Ok, my car is heavily modded. I get 33 mph/gallon on the highway. How's that for you?

[arkaine13]

33MPG? That is amazing, it is like 14Km per liter for us! The most that I can get with my car is 10km per liter. One thing that I have noticed in USDM 7G's is that they have an EGR and lots of solenoids in their G's, the unusual thing about our 7g is that we don't have EGR's in our vehicles, and our 4cyl engines use a NA 4G63 instead of 4G64. Thanks for the comprehensive list mko, one more question though, is your 7g boosted?

[mko]

EGR is useless. You're better off not having one.

yes, boooooost.

[Galanttuner10]

my galant 5 speed non turbo, intake and only a cat back, had 2 cats because it was cali spec running 93 i got 35mpg highwat and around 27 city when driving right. boosted i got 32 highway and 22 city. its all in how you drive and take care or you engine and drivetrain, ie wheel bearings, tires etc