Thread: fuel consumption - where did I read this!?!?

I know a LOT of you don't believe this.. so thanks for your input on previous threads where I've talked about this.. I'm looking for your devils advocate here.. I'm trying to find the horses mouth so to speak to debate you for the sake of finding out for sure.. because maybe this person has a point you don't know about..

So 'm trying to remember who told me this, or where I read it.. i must have searched injectors a while back and read this one theory on replacing fuel pump and injectors on a stock motor to help with an old car suffering poor gas mileage..

Anyway, the the theory was that even on a stock motor, a 255 LPH fuel pump regulated with a fuel pressure regulator would provide more consistent delivery and the new injectors would provide better spray resulting in better combustion and of course more power and better mileage...

I'm considering the Walbro fuel pump too, just to make sure. New injectors are expensive and I don't know how ''new'' they will get after cleaning them ultrasonic.

I'm told FPR get's old and doesn't hold up pressure very well, but on the other hand, when I got the car, sparks where lean like 17:1 and after a lot of work, MAF, lambda, neutral switch, PCV, vacuum, new filter, I seem to haven ended up with a leaky exhaust that will also be replaced from engine to cat, with an e-bay solution. Leaky exhaust also are a culprit for bad mileage.

But my sparks show coffee brown now and very little trace of lean. Fuel economy stayed about the same but for a car with the ''kick of boost'' @ 4000 rpm, which actually is a lack of power up to 4000 rpm, I shift the car in heavy city driving before 3000 and still get 23mpg, and for the heck of it, I make sure it is rather 19mpg. I expect highway driving to be 26mpg or better.

But there is a lot of gain to be found in the drivetrain. First, cleaning brakes or refurb them is not a bad idea and the state of bearings/CV joints also count. I've put Redline MT90 for the first time of my life in the tranny and wow, no cluncky reverse shifting after 3 miles, powerband < 2000 hugely improved, actually I finally found the straight pull of the SR20DE everybody seems to have

Of course my ignition is in top shape, I still have timing issues, I can adjust timing but bc of the pulley I don't know what my timing is and I use premium gas (detonation on normal gas so pretty advanced I suppose).

And the wheel alignment also did a lot. I don't know if you also know the commercial of that little man locked up in a BMW engine entering by the intake, notices car starts and gets blown out of the engine they show in 5.1 theatres overhere.

But that is the way you should look at your car

tbh,thats alot of work and money to try to get better gas milage....maybe 1-2 mpg??

It could have easily been me that mentioned that vqman.

If you get a higher pressure pump (doesn't have to flow more) and mate it with a FPR set for 4-bar instead of 3-bar you will get better fuel atomization, a more complete combustion, and better economy because of it.

That's the theory anyway.

drive 5mph slower everywhere and you will see a great mpg gain.

I am up to 44mpg and laugh at my coworker who is only getting 40mpg in his prius. This is on my $11k versa 1.6 btw.

Whut!?

So 125% fuel pressure won't give 25% more fuel in the combustion?

Woah yah... Uhh, I forgot a detail or two.

I was completely forgetting about the fuel control problem. You'll need an ECU where you can control fuel.

Or maybe you could go with injectors that are 25% lower flowing than stock. (Huge, giant generalization).

vqman I don't think there is any benefit from putting in a higher pressure or higher flowing fuel pump on a stock engine with or without a different FPR. It's not like the stock pump is real weak or anything.

I believe it will be a bit more then that, but my goals are dragging for fun since dynoing overhere is kinda wtf and of course I want to show wtf numbers, driving my car is so much fun now I won't complain much about fuel economy but still look in to that, that is just a simple ROI, and did I mention the fun.

And then I aim for a SR20VE (which atm will be a hassle for me) and be happy with 200+HP on a FWD

yup, 4bar will atomize the fuel much more then 3 bar, youll like ben said get better combustion wich will inturn turn into better efficency of the motor.

thats how it reads out on paper.

real world who knows.

i do know this 718r .86 @ 16psi, s4's, 740cc inj, 3 bar, 300zx fuel pump drinks fuel like a mack truck ! hahaha.

my 3 liter pathfinder is a pig, my all motor sr20's always got nice mpg.

you want good mpg's get a 91 ef sedan with the dual point injection, i could go forever on one tank.

stratton.

Lol my friend had a 90 hatch with the tbi set up. That car was great on gas not to mention the 4spd trans. you could leave it in first most of the time auto xing.

As far as the mileage thing i would have to agree. My 1st turbo set up at 4 bar with 370's would get close to 40 mpg or a bit higher or lower depending on speed and such. This was on the highway