how to get more milage out of a 240sx

[nismo1003]

It's a 90 240sx, stock SOHC motor with no mod but manual transmission swap .w/ auto ecu. I am trying to save as much gas as possible . mainly I will be on the highway most of the time so I want to lower the gear ratio, hopfully I can get 300-370 miles for a 13 gallon tank. I know the J30 Diff got highter gear ratio so it will lower the rpm rev at high speed, I want something like 80 mph at 2.5-2.7k RPM . on top of that I will lean out the A/F w/ the wideband so I can get more . what other option do i have? right now I"m getting 250 miles max out of one tank

[supra brit]

I'm getting around 350-375 to the tank on an SOHC. I have removed the power steering and A/C components, and mine is also 5-speed swapped. I also have a cone filter from AutoZone and an exhaust and I always run 93 octane gas...

I'm about to install a J30 diff as well, but not for gas reasons...

[cdlong]

why are you doing this first of all? if you're doing it for money reasons, it will take a long time to pay off the modifications with the money you save.

your best bet for the diff would be a J30 ring and pinion like you said or one from an S15 r-type, 3.69:1 i think. that's the only thing that will get you close to your rpm goal. but then your car would be dog slow.

other mods help mileage too. getting more power often happens because the mods make the engine more effecient. as long as you don't use the power to go faster, gas consumption will drop. i'm not sure where it comes from but my car usually gets about 30-31 mpg on the highway doing 75. i've gotten as much as 32 on 100% highway. the epa spec is 28 and that test is conservative so doing 75 should give you about 26 mpg. click my sig for a full list.

there's free stuff you can do like keeping your tires inflated to 32-35 psi, keeping the car cleaned out (hauling crap around wastes gas). you can also keep the speeds down, drive like a grandma, and shift at around 2500 rpm. that will probably help the most. also, if you replace your tires, get some with low rolling resistance, narrow ones with a high tread wear. if saving money is the issue, use regular gas, there's no need to use premium, the car runs fine on the cheap stuff. (at least most do, some people have problems when using the cheap stuff)

fyi, the s13 tank is 15.5 gallons.

then again, you could just sell your car and buy a CRX HF. my old roommate had one, it was fun to drive and got about 50 mpg on the highway. i doubt your 240 would be much fun to drive anymore if you did all that stuff to it.

[bloodspread]

wow my milage sucks compaird to you i get like 120 miles to the tank on my SOHC but then again i do have warn lifters.

[tonynalli]

the tornato is your friend....just kidding

[HaveBlue]

in my sohc i got 320 out of one tank driving with cruise control on the entire time (highway). I normally get 250 out of a tank running around town. by 'tank' i mean until the light comes on the dash which is about 13 gallons. when the light goes on you probably have 2.5 more gallons left.standard tune up will help: oil, sparkplugs, wires, o2 sensor, etc.if you get less than 200 per tank you probably have leaking injectors or a broken o2 or a huge exhaust leak before the o2.you can get a different rear end or larger tires, improving aero may help if you cruise at high speeds. but the faster you cruise the lower your MPG.you can not lean out the car with just a wideband sensor. you need something to control the fuel like a SAFC or other electronics. if you lean it out too much it will blow up or overheat.

but like it was said, spending $1000 on a different rear end, tires, electronics and whatever could be better spent on a $1000 crx hf which will get WAY better mileage anyway.

[zukitek]

I average 21-26 in city and 28-30 on my s14 ka-de if this makes ya feel better.

Ricky

[tonynalli]

fully advanced timing and few other half *** mods....decent mileage....but definatly to at least get a new exuast sensor...best 18 bucks you will ever spend

[jdm_master_X]

i remember driving to santa barbara from fairfield last july (it was a 456 mile trip). i drove to santa barbara for 5 hours that night, never stopping for gas or anything. and behold, it was an SR.

as mentioned, a good idea is tire inflation. under inflation will increase the rolling resistance and cause a nasty wear pattern on both sides of the tire while overinflation will get you a little more gas mileage due to its lack of rolling resistance, but with that, you lose a little more traction and u get a nasty wear pattern in the center of the tire.

i pumped 91 octane + octane booster (which brought the octane rating to 103). i was also running the stock 7 PSI driving there and my car was fully of baggage. the trick was to drive at low RPM and gradually gain speed in the over drive gears (5th gear primarilly). the car finally died out as soon as i touched down in santa barbara, just yards away from the closest chevron. haha.

engine efficiency is also key. help the thing breathe, burn gas a little better, and fart all that nasty gas out ASAP. light throttle is good yet boring gas mileage, while full throttle is terrible but exciting gas mileage. my car is completely gutted and has no A/C or P/S. i dont even have most of the electronics in my car (seatbelt motors, all that shiz behind the dash, radio, etc.)

finally, reduce the friction in ur motor. get some great motor oil. the extra pennies will save you in the long run!

[Neejay]

Man my mileage sucks compared to you guys'.

I can go about 227 miles, but this is with the needle on E and I have never driven until the light came on (heard that lets debris get into the tank and it isnt good for the car).

I came a long way though, because when I bought the car I was only getting like 185 miles per tank filling.

[ddgsxr504]

wow my milage sucks compaird to you i get like 120 miles to the tank on my SOHC but then again i do have warn lifters.

Wow you serioulsy need to find out what's wrong with your car if you are getting milage that $hitty. I can drive about 400-420 miles highway on a tank of gas. Thats with no cats and running rich.

[bloodspread]

Wow you serioulsy need to find out what's wrong with your car if you are getting milage that $hitty. I can drive about 400-420 miles highway on a tank of gas. Thats with no cats and running rich.

i know, i just dont know where to start

[cdlong]

spark plugs/wires, air filter, O2 sensor.

also, calculate your mileage, not just how many miles you get per tank. miles per tank depends on mow long you wait to fill up.

[bloodspread]

i already have new spark plugs/wires, and a new air filter, i will see about my 02 sensor, where is it located?

[ddgsxr504]

lol, well if you have the stock exhaust manifold then it will be on the back of that right next to the firewall.

[bloodspread]

thanks for all the help

[ddgsxr504]

That's why we're here my brudda!

[JesusLikesKFC]

tune it all, lean out fuel, cut out cat. reduce wieght less restriction

[jdm_master_X]

reduce drag and tire resistance.

...and everything else Jesus enlightened us with. har har.

[nelson8708]

I am getting about 20mpg and that is mostly city driving. From full to empty i probably get 300 to 350 miles depending on how i drive that week. I also have a sohc. Soon to be chipped and then i will have to run premimum gas. It advaces the timing and changes the fuel maps. Should be an easy 5 to 10 crank horse power.

[1990flatblack240]

Dont use A/c. And drive with all your windows up. Thats like 1-2 MPG

[rsmithdrift]

Hmph. I have a DOHC and I always get 22mpg. That's half city, half highway. This tank I've got in it right now is all highway and I've gone 200 miles on a half tank. So that would mean 400 miles on a full tank (my gauge is very accurate)400 mi / 13 gal = 30.7 mpg

12.5-13 gallons to to full is when my gauge hits e. The light comes on at 14.8-15.2 gallons from e. I got 16.1 gallons in the tank once when I ran it completelly dry and it died on me. (I expected the light to stay on longer before it died lol)

[Neejay]

Man, thats crazy to get 300+ miles per full tank. I wonder wtf is wrong with my car....hmm...

[rsmithdrift]

Ever clean your AIV valve or MAF??

Ever disconnect and clean all of your elect. connections under the hood??

Ever replace your 02 sensor??

Ever replace your air filter?? lol sorry couldn't resist. When I got my car it had never been replaced in 140k miles. It was NASTY!!

Ever replace your fuel filter??

Ever check for vacuum leaks??

Ever check for egr valve functionality??

Ever check your engine codes??

Ever adjust your TPS sensor??

Ever replace your plugs/wires/cap/rotor/coil??

Ever run fuel injector cleaner??

Ever seafoam your engine??

Ever checked the lead content of your right foot?? LMAO Sorry, again, couldn't resist.

Ever check for leaking injectors??

When I got my car it was getting 16mpg and this is what all I did to it and now I get 22mpg average and 30mpg highway only.

FYI. When I check the mpg, I calculate the actual miles driven from completely full, divided by the amount of gas that I put into it to fill it all the way up and start over, I do this every tank and the lowest sense all of this tune up that i did was 20.8 mpg (full throttle, mostly city, lots of high speed runs) and the highest was 24.1 (driving like a granny lol) This is the first time I've driven all highway and usually I'm at 160 +/- at half tank, but this time I'm at 192. So that's a big difference.

More FYI..................MPG = Miles driven on 13 gal of gas 12mpg = 156mi14mpg = 182mi16mpg = 208mi18mpg = 234mi20mpg = 260mi22mpg = 286mi25mpg = 325mi28mpg = 364mi30mpg = 390miIf you are getting less than 20mpg driving it normall, then there is something wrong with your car. You should be getting 18mpg if you are driving like a mad man and racing the whole time, 22mpg is normal, 28-30mpg if you are a true granny and/or only drive highway.

*This is only relavent to your MPG if it takes around 13 gallons to completely fill your car up when you stop for gas.

Modified by rsmithdrift at 12:47 AM 2/27/2006
Modified by rsmithdrift at 1:05 AM 2/27/2006

[180fan]

Get a tune up. With a tune up, you get better mileage along with better power. Ignition wires, spark plugs, distributor cap and rotor, fuel filter, pcv, fluids, and air filter should be replaced. Clean your intake tubing, injectors, mafs, and carbon deposits with something as simple as a seafoam treatment. Check your TPS, CTS, MAFS, and timing.

My old KA24E was getting 25-30mpg with a little leaning out with an AFC to boot.

My SR20DET is getting 30mpg as long as I'm staying off boost.

Drive like a granny to save gas and your wallet will forgive you.

[benemorius]

You folks need to be calculating your miles per gallon. Miles per tank is damn near useless. And don't use your tank size to calculate it either. Use the figure on the fuel pump when it cuts off automatically. Do it any other way and you could end up with some pretty useless figures.

[HashiriyaS14]

I can't believe no one else said this, but check your TIRE PRESSURE!

Low tire pressure will severely impact your gas mileage. Keep them properly inflated.

[Neejay]

Ever clean your AIV valve or MAF?? REMOVED AIV, cleaned MAF (at least I thought Ive cleaned it)

Ever disconnect and clean all of your elect. connections under the hood?? NO

Ever replace your 02 sensor?? YES

Ever replace your air filter?? YES

Ever replace your fuel filter?? YES 300ZX

Ever check for vacuum leaks?? Not throughly

Ever check for egr valve functionality?? NO

Ever check your engine codes?? YES

Ever adjust your TPS sensor?? YES

Ever replace your plugs/wires/cap/rotor/coil?? YES

Ever run fuel injector cleaner?? YES - Seafoam + Marvel Mystery Oil

Ever seafoam your engine?? YES

Ever checked the lead content of your right foot?? YES

Ever check for leaking injectors?? NO - but not gas smell of any sort

I get about 19 mpg. I removed my AIV though. I used to only be able to drive about 185-192 miler per tank. Ive come a long way from 192 to 227

[Neejay]

You folks need to be calculating your miles per gallon. Miles per tank is damn near useless. And don't use your tank size to calculate it either. Use the figure on the fuel pump when it cuts off automatically. Do it any other way and you could end up with some pretty useless figures.

I've been hesitant to run my tank down to at least when the gas light comes on. But I may have to do that. What do you mean "Use the figure on the fuel pump when it cuts off automatically"?

[rsmithdrift]

like what I was saying, those figures apply to 13gal of gas exactly. They only apply to your gas mileage if you put between 12.8-13.2 gal of gas in your car when you fill up. All gas pumps tell you exactly to the x.xxx how many gallons you just put in your car.

Divide the miles number on your trip meter (only if you set it when you filled up last) by the number on the pump for gal. when you are done filling up to get your specific gas milage for that particular run. It isn't always possible to read it because it's easy to forget to do one of those things.