what type of gas

Jeepin_it_real · **Posted:** Wed May 06, 2009 12:48 am

hey what type of gas does everyone use? i heard with the jet module II you must use 91 octance... without the module would it harm the jeep? how about 93 octance? :wink:

Diggerfreek · **Posted:** Wed May 06, 2009 12:50 am

well I usually run 87 with my stage 2, but I am a mile high in elevation... no problems... I just filled up with 91 tonight so I will let you know

Mr Nick · **Posted:** Wed May 06, 2009 1:09 am

You want to run the LOWEST possible octane your engine can handle. Anything more is wasting gas and money.

Mike08Liberty · **Posted:** Wed May 06, 2009 7:33 am

Anything more then 87 is a waste of money ... If you get the JET chip and they say you should use 91 then use 91 but other then that 87.

Diggerfreek · **Posted:** Wed May 06, 2009 8:32 pm

I notice a big difference between 85 and 87.... 1 to 1.5 mpg less with some "hard" idling at times... Seems to like the 91 so far

JeepinJarhead03 · **Posted:** Wed May 06, 2009 10:24 pm

i dont get enough mpg with 50/50 driving to warrant over 87 but i use 89 on mostly highway the mpg increase is worth it by about a gallons worth of gas and it drives up long inclines easier

Jeepin_it_real · **Posted:** Wed May 06, 2009 11:13 pm

i'll be filling up with 91 then, just incase... i put in 93 the other day cause i needed gas to go to school and the gas station was out of everything else... at 2.30 a gallon i was a little mad but i had to get to school... i did notice that my car's pickup and sensitivity is alot better though.

vmf · **Posted:** Wed May 06, 2009 11:17 pm

i tried em all just for the heck of it, i dont feel any difference at all. if you engine is designed for low octane fuel and has low compression ratios it would not have much perfomance boost whith higher octane fuels. my civic with a swapped k20 engine does need an a 93 or 95 or 100(when i go to racetrack) and once i had to put 87 into my LS430 and that thing just refused to move. so the verdict going up is ok, going lower is not:)

richd · **Posted:** Thu May 07, 2009 12:47 am

People keep talking about compression.
Here is a trick question ,which has a higher compression ratio,a 08 5.7 HEMI or a 08 3.7 V6?
the answer the 3.7.I been using mid-grade since new.I had this discussion on another Jeep forum.They said it made no differance.I tried regular for a couple tanks,I found less power,plus my MPGs went from 17+ all city with mid-grade,and about 15+ with regular.I seen and feel the differance,and you cant use compression as a excuse.

chava_olllllllo · **Posted:** Thu May 07, 2009 1:08 am

What type of gas would be good for towing? When I first got my car I used 91 over 87 but switch back when it got to expensive. Never noticed a difference except for on highway driving.

JeepinJarhead03 · **Posted:** Thu May 07, 2009 1:48 am

not to nitpick or anything but i thought the 08 5.7 had a 9.6:1 and the 08 3.7 was a 9.1:1

ive seen the 03's listed as 9.5:1 and 9.1:1

im not 100% convinced that the 3.7 heads don't have quench space either thats more of a question for Troy

since hemis dont have the quench space they're more susceptible to low octane pings

only other real difference i could think of would be the individual engines differing ability to adjust timing to mask or adjust for any pinging, i've driven about 7k miles in the last 2 months since changing plugs and i do notice a difference in 87 and 89 but the economy difference isn't enough buck to make me put in 89 when im doing any city driving

every bit of it will differ from driver to driver, condition to condition so naturally its very debatable since everyone drives differently

richd do you happen to have a link to something from chrysler that gives the compression ratios for say the 02-04 3.7's in comparason to the 08 3.7's as well as the 5.7? I've done some limited searching, and as i mentioned i keep coming up with differing results

SilverKK09 · **Posted:** Thu May 07, 2009 9:02 am

I do what the manual says
and it clearly says to use regular gas
thats what I use

JeepinJarhead03 · **Posted:** Thu May 07, 2009 9:35 am

mine says use 89 for towing, clearly

*snicker*

hope ya doin better Secret Silver Squirrel

zarinKK · **Posted:** Thu May 07, 2009 9:53 am

Jeepin_it_real wrote:

i'll be filling up with 91 then, just incase... i put in 93 the other day cause i needed gas to go to school and the gas station was out of everything else... at 2.30 a gallon i was a little mad but i had to get to school... i did notice that my car's pickup and sensitivity is alot better though.

Premium at $2.30? Must be nice; 87 octane here is $2.47 today

JeepinJarhead03 · **Posted:** Thu May 07, 2009 9:57 am

like 2.15-2.19 here

nightdrv · **Posted:** Thu May 07, 2009 12:16 pm

I've tried all 3, and was bummed (but kind of expected it) to see almost no difference in any of them (87-89-93). It did get up and go on the highway a little better with the 93, but not enough to warrant the cost of that with 15-16mpg.

>>edited for stupidity<<

richd · **Posted:** Thu May 07, 2009 1:54 pm

THE 08 5.7 hemi has 9.6:1
08 3.7 has 9.7:1
The manual states when towing use 89 for better towing WHY? because it gives you more power.Also the higher the grade of Gas ,the more detergent the gas has.Number 1 enemy for Fuel injection?dirty injectors.If you feel better performance on the Highway,then it has to give you more power all around.In '05 the 3.7 got a compression boost for better performance and MPGs.Its your choice what you want to run,I just know how my KK runs with 89,I will stick with it,to me not a waste of money,better power,more MPGs,and cleaner injectors."In 05 the 3.7 was treated to numerous economy and idle quality changes,with a new cam profile,lash adjusters,rings,and a 9.7:1 compression ratio ".This was stated on Allpar.

tjkj2002 · **Posted:** Thu May 07, 2009 2:49 pm

nightdrv wrote:

I've tried all 3, and was bummed (but kind of expected it) to see almost no difference in any of them (87-89-93). It did get up and go on the highway a little better with the 93, but not enough to warrant the cost of that with 15-16mpg.

Stupid 5600lb Jeep.

Your KK does not weigh 5600lbs,more like about 4000lbs.That little sticker on your door jam that say's 5600lbs is also followed by GVWR(Gross Vehicle Weight Rating) and is not the curb weight of the vehicle,which means that the total safe total capacity of the vehicle and all passengers/gear should not exceed 5600lbs.

nightdrv · **Posted:** Thu May 07, 2009 8:47 pm

I think therefore I'm stupid, right? Thanks for clearing that up for me.

According to www.jeephorizons.com it weighs 4222lbs.

Doesn't matter really. Can't find a useful/cost effective way to shed weight anyways.

Mike08Liberty · **Posted:** Thu May 07, 2009 9:39 pm

Regular is $2.06 here ... Last week it was down to $1.97

what type of gas

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