Thread: Neutral Coast Not So Great for Fuel Economy

I bet if you got a RR SR20DE it woould get an average of 3-5 miles per gallon more than a standard DE.

RR Adavtages Over Standard DE

7 pound lighter crank, less rotational mass

4 less counter weights for bette windage ( less friction going through oil )

1-2 pound lighter crank pully.

Roller Rockers for less friction.

Slightly higher compression for better fuel efficency

Thinner rings for less friction.


Now just think how much money you would have saved if you had bought a RR DE when you first noticed your motor was sludged up. You would not have wasted about $200-$300 on all the stuff you had done to the car. You would have been able to sell some of that DE for parts like the head $100, Intake manifold $100 and so on once cleaned up. Lastly the money you would have saved on gas would have been alot by now. Lest consider you have a tank that holds 13 gallons and you get 3-5 miles more per gallon that would be 39-45 miles per tank full.


Oh well.

I've established that the bad gas mileage is not because of my bad engine, but because of the 99 evaporative system parts failing.

So even if I bought an RR, I would still then have to spend money on the evaporative system parts.

Lack of cams, being called the weakest of all SR20 motors, not so good for boost, etc. etc. is what is driving me away from RR's slowly but surely.

As intelligent car enthusiasts we like to see engines working efficiently. All engines.

Engine braking, while giving better fuel economy and saving wear on your brakes isn't the end-all be-all of driving techniques. What you save in wear on your brake system you move to the engine's frictional components (bearings, piston rings, etc.). The higher rpms sustained by engine braking increase wear on these items. Frankly I'd rather replace my brakes one more time in the life of the car and avoid having to do an engine rebuild then "saving" the brakes by engine braking. I still engine brake for fuel economy's sake, but it's not a free ride and I certainly wouldn't do it to save wear on the brake system when the brakes are a lot cheaper, easier and faster to replace.

I have a spare RR engine you can swap in. Needs to have the crank turned as it spun a rod bearing. I have an 8cw crank I will sell with it haha.

But like ben said, you wear other components, but I don't think it is that big of a deal. My buddy always drove his integra at 4-5k everywhere. I always wondered why he drove like that, but he put on over 240k and still didn't burn oil. Overall that car was a champ. The added friction of engine braking isn't on of my concerns. After all, it is an investment. All the money you save in gas will build you a 500+hp SR when the time comes

Thats a very good point, most of the car mods are good for both power and MPG's, that is if you keep your foot off the right pedal.

Like a good set of spark plugs that are indexed properly will give you more power and better MPG's. A Intake, header, exhaust, all help both power and mpgs.

The only mods that really affect the MPG's but give more power is bigger injectors and bigger cams.



Very good point there.

The only thing I see wrong with over using the brakes is, when they over heat they start slipping. I've had that happen to me and it's scary when you press the brake and yet your still rolling.

That is like saying "I rather push the car than accelerate, so the engine will last longer", You start wearing components if you engine brake at high RPMs, if you keep it in between 1500-3500rpm it is gonna be fine, also you are cooling down the engine because the injectors send no fuel while engine braking, so you wont have combustion, but the water pump is moving a lot faster than at idle, cooling down the engine.

Some of the engine braking advantages:

-Keeps engine cool.
-Better MPG.
-Helps protecting the brakes.
-Provides better vacuum, making brakes more efficient for an emergency stop.

Keeping more vacuum will produce better gas millage. When you accelerate the vacuum goes down as you need more fuel. Taking off slower and staying in gear when coasting will help this.
Now MPG's are a concern to everyone if you like it or not. To over dramatize this point consider this.
If everyone drove cars that got actual 30MPG's or better in the US out oil prices would drop in half (estamated). Now the actual practical side of this is that everyone drive more MPG conscious than i would be willing to bet our gas prices would drop another $.50 or more. Oil prices are directly proportional to demand. So less demand, less per gallon. Im not saying we all grow vagina's and start to drive Prius's but be a little more conscious and drive a little less aggressive. But still have fun once in a while.

Good points there squirlz

I bet with a RT ecu you could really take advantage of engine braking. cough cough.

Working on it