Fuel economy

Post by **courtier** » Tue Mar 21, 2006 5:59 am

Hi I just want to know what is your kms or Mileage with a full tank, I know the J30 is hard on gas, but I am wandering if I have a leak somewhere !!! I made 250 miles or 400kms with one tank...

thanks

Post by **driverdriver** » Tue Mar 21, 2006 6:31 am

I average 20-22 MPG on Octane 91. Use only premium gas in the J30 for optimum performance and a number of other reasons.

Post by **yodawill2000** » Tue Mar 21, 2006 6:57 am

22 on 93 for me ..Unless I open her up more than usual :O)

Post by **driverdriver** » Tue Mar 21, 2006 7:20 am

I find my J is more lively when I'm running a full tank of Octane 93 or 94 and my mileage much better.

Post by **courtier** » Tue Mar 21, 2006 7:35 am

Looks like you guys are doind much more than me with a tank, what could be my probleme ?

Post by **yodawill2000** » Tue Mar 21, 2006 7:48 am

Air Filter(OEM) , Clean the Maf and new plugs is all Ive ever done.I also keep the tires at 34 PSI

Post by **driverdriver** » Tue Mar 21, 2006 7:51 am

A starting point would be to get the fuel system cleaned out. The fuel injector design on the J30 is different. Using the wrong octane is known to gum up the spray pattern.

A K&N air filter instead of a regular paper air filter also helps with fuel economy, since the K&N design allows the engine to breathe better.

Post by **Q45tech** » Tue Mar 21, 2006 8:22 am

How does the K&N allow the engine to breath better when the rpm where most drive [and consider MPG] has no measurable restriction.

True above 4,000 rpm there is a steady rising restriction but that doesn't come from the air filter [ the MAF and the protective screen are the major restrictions] until you get to 6,000 rpm and then it is only 1-2/28 or less than 1%.

Post by **driverdriver** » Tue Mar 21, 2006 8:32 am

Q45tech wrote:How does the K&N allow the engine to breath better when the rpm where most drive [and consider MPG] has no measurable restriction.

True above 4,000 rpm there is a steady rising restriction but that doesn't come from the air filter [ the MAF and the protective screen are the major restrictions] until you get to 6,000 rpm and then it is only 1-2/28 or less than 1%.

I don't what it does, but I can tell you this for certain (and other J30 drivers who use the K&N air filter on this forum will too) that there is a noticeable increase in both pick up along all rpm ranges and a noticeable improvement in fuel economy.

Originally when I switched to K&N air filter, just to make sure I wasn't having a "placebo" effect I stuck in a new normal paper filter. Noticed both a change in pick up and fuel economy. Both where negatively affected. I took the paper filter out and stuck the K&N back in.

When I switched back to a paper filter in order to see if there was a difference, I kept all my variables the same as when I was driving with K&N. Things like where I refuelled, fuel octane, brand and weight of oil, oil filter brand, frequency of oil change, commuting distance travelled, time frame of experiment, time of season, roads used, etc.

Post by **DominickJ30** » Wed Mar 22, 2006 1:56 pm

The filter itself was defenitely measured to have better air flow than stock filters, which means more air=more fuel.

I have done a few dyno runs with various cars, and on some cars there were noticeable 3-4hp gains, while other lost up to 15hp.

I wouldnt mind talking my car in for a dyno test with k&n and without.
Modified by DominickJ30 at 4:07 PM 3/22/2006

Post by **Q45tech** » Wed Mar 22, 2006 3:46 pm

My point is at the normal rpms [idle to 3,000 rpms] were most drive 95% of the time NOT A WOT DYNO TEST the clean oem filter is not a measurable restriction. Otherwise the factory would have changed it to gain even 0.01 mpg as they can add these increments up times number of cars sold to try to get a higher mpg rating and pay less tax fines to US government.

Post by **yodawill2000** » Wed Mar 22, 2006 3:50 pm

"Clean" being the key word

If Q45tech says it .I'll bet the bank on it ..

Post by **t-bay j** » Wed Mar 22, 2006 3:55 pm

When was the last time you replaced your fuel filter?

Post by **atlanta_shooter** » Tue Mar 28, 2006 7:08 am

recently 25+ mpg on interstate @ steady 70-75 mph, no a/c, 91 octane. '97 J, 140K.

Post by **93j30t** » Tue Mar 28, 2006 7:27 pm

i get 25 highway 23 city on (gasp) 87 octane

Post by **CustomJ30** » Tue Mar 28, 2006 10:01 pm

I Get 180 Miles From A Full Tank (93 Octane).....

Post by **DominickJ30** » Wed Mar 29, 2006 4:49 pm

93j30t wrote:i get 25 highway 23 city on (gasp) 87 octane

You must drive like a grandma.

Post by **93j30t** » Thu Mar 30, 2006 7:46 pm

yep, i try to stay at 2k rpms...

Post by **chiller** » Wed Apr 05, 2006 4:00 am

sorry for late reply but just to add a reply that may help you out:

i usually refuel when i get down to about 1/4 of a tank on the gauge, at that point i usually have approx. 450km on the tank (i have pushed upwards of 550km with no fuel light on yet), i would fill approx. 45-47L (say avg 46L) into the tank... means 9.782 L / 100km converted to MPG is approx. 23.01mpg... this is using PetroCan 91 octane, using Sunoco 94 would get me approx. 44-45L, the difference between 91 and 94 I have found is not of consequence so I just go with 91 because its cheaper...that's with the 15" stock rims with snow tires mounted...and obviously since its winter time with snow tires, there is no a/c on

with the 17" rims with tire size 235/45/17, my mileage takes a very small bit of a dip, i'm guessing because it takes just a bit more gas to get the bigger wheel turning in traffic, not by much 450km is still read at 1/4 on the gauge but the amount needed to pump in is approx. 46-48L (say avg 47) would net 9.57L / 100km and converts to 22.51mpg...since these are summer tires i run with the a/c on and off about 1/2 the time, hot muggy days the a/c is on, sunshine warm days the windows go down with the roof open...

also of note, KN filter has been put in from about 20,000km and cleaned regularly, so i don't have any exp. with how it would be with a stock element...exhaust is stock, injectors get a pour in tank injector cleaner every 3 tanks of gas and the injectors are cleaned by the dealership once every 48,000km with throttle body cleaning done at the same time and fuel filters are also swapped out at that point...

hope that helps...

Post by **gr8scott72** » Sat Apr 08, 2006 10:47 am

just filled the wife's 93 up last night and got 19.5 mpg. We always use 93 gas. Car has 187,000 miles on it.

Post by **DominickJ30** » Sun Apr 09, 2006 6:38 am

Yea my avarage is 19-20 and 22 hwy

Post by **gr8scott72** » Sun Apr 09, 2006 8:32 am

I just put a new Wix fuel filter on and got a new wix air filter. About to go change the oil and also in the middle of a coolant flush. Going to flush it all the way out and switch to dexcool.

We'll see if any of that will help the MPG any. I think the fuel filter was pretty bad.

Post by **texalmighty** » Sun Apr 09, 2006 4:08 pm

i'm getting like 16mpg city

Post by **driverdriver** » Mon Apr 10, 2006 8:21 am

gr8scott72 wrote:Going to flush it all the way out and switch to dexcool.

Isn't there a lot of complaints about Dexcool not lasting as long or protecting as well as GM claims resulting in engine damage?

I'm sure there is a class action lawsuit against GM/Dexcool from people who formely used it and damaged there engines.

Stick to the green coolant.

Post by **DominickJ30** » Mon Apr 10, 2006 10:03 am

Yes there is a lawsuit. Its about the dexcool eating away the head gaskets on all the GM enignes. I know this first hand since my friend owns a 99 grand prix and had to swap the gasket.

I would stick with ethylene glycol and call it a day.

Fuel economy

Fuel economy

Re: (driverdriver)

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Re: (courtier)

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Re: (93j30t)

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Re: (chiller)

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Re: (DominickJ30)

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