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-   -   My goal is to get 25+ mpg from my 99 XJ with 30 x 9.5 R15 ATs (https://www.jeepforum.com/forum/f11/my-goal-get-25-mpg-my-99-xj-30-x-9-5-r15-ats-1551782/)

morrie 02-05-2014 10:24 AM

Quote:

Originally Posted by mschi772 (Post 20070817)
In the tranny, stay with Dex/Merc III. I've heard far too many stories of people using more modern/synthetic ATF in the AW4 with unpleasant consequences, and I've never heard a story where it had an overtly positive outcome. There appears to be nothing to gain and plenty of risks.

Regarding synthetic motor oil...you can use it. Tons of us use it. That whole myth of not being able to change between dino and synthetic is just that--a myth. It's a long story, but it's basically just a mess of many of misconceptions with the only one remotely resembling truth is the concern that synthetic and its usually higher detergent levels will reveal leaks (reveal--NOT create; syn doesn't make an engine leak--it just cleans it out which can unclog leaks you already had and didn't know about). A dino oil with lots of detergents will do the same thing.

Motor oil can help with your MPG, but synthetic vs dino is not really what does it. Thinner oil (but not too thin as to sacrifice needed protection) can improve MPG. Basically, just use a good oil no thicker than necessary. I'm not about to discuss this further or what oils are "good." We've been over this in this thread already; you can go back and read it or do you own research.

Thanks for your time. I will definitely heed your advice...lots to learn on this forum.

morrie 02-05-2014 10:26 AM

Quote:

Originally Posted by 970001zj (Post 20069305)
:PopCorn:

Just curious....Did you get the popcorn with lots of butter? Enjoy!!!

tamnoz 02-05-2014 01:16 PM

25 mpg
 
I'm not saying there going to make 20 hp but anytime you can increase the velocity of incoming air you should see an improvement. We race Formula Vee racecars, they use a 1200 cc VW engine and the guys that ram air their carbs see a noticeble increase. Even if it creates the equivalent of 1-2 lbs of boost you should see it. If you look there are youtube videos where they used leaf blowers on vehicles that were on the Dyno and the numbers were impressive.

scottspott99 02-05-2014 01:29 PM

more air in more exhaust out is a good recipe for any motor+ high octane fuel= power and mpgs . gunna try the snake oil myself and see
sounds interesting...

Charley3 02-05-2014 05:11 PM

More air in, more exhaust out means more power, but not necessarily more mpg.

scottspott99 02-05-2014 07:04 PM

every bit counts tho.. more air/exhaust,rotating
restrictions,tires,non dilluted gas,smaller mirrors,wieght reduction,strip out a/c...etcetc not 1 thing makes much diff... but everything done at once hmm ...

green97xjsport 02-06-2014 04:33 AM

The reason it's snake oil is because it's just a stupid fan, not forced air like a turbo or blower, a bilge pump is just going to bilge your wallet and rightfully so if you fall for it, stick your hand against any small fan, the air will cease to circulate forward, not enough force to be effective, and with a real forced air setup, you would need more fuel supply, not just a heavier foot.

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scottspott99 02-06-2014 09:45 AM

that makes sense...and we looked at how it could be set up...were tryin to keep watertight an more a pain than gain thats 4 sure. how would cpu react to a turbo on a 4.0?

green97xjsport 02-06-2014 09:54 AM

I'm guessing you would need someone who's familiar with flashing your cpu with values according to a turbo's boost capability, and you would probably need some fuel delivery upgrades, possibly with larger injectors capable of handling the demand when necessary. Probably has been done, you might google search and see. Here's an example; http://www.fourwheeler.com/how-to/13...-turbo-system/

scottspott99 02-06-2014 10:55 AM

awesome link!! id like to find the alt relocate bracket they use.. i keep drowning mine (3in2 years) gotta link 4 one of those green?

green97xjsport 02-06-2014 12:27 PM

Quote:

Originally Posted by scottspott99 (Post 20109250)
awesome link!! id like to find the alt relocate bracket they use.. i keep drowning mine (3in2 years) gotta link 4 one of those green?

Yeah, I'm kind of torn between repairing my AC, but not quite sure what I'm going to need just yet besides a new condenser for sure, or relocate my alt to where the AC compressor is and upgrade to the 130 something plus alt as well.

as far as the power plant, I'm happy with the 4.0l design and power just the way it sits, love the longevity of these engines, a few minor upgrades like maybe a larger throttle body and 4hole injectors and that will be about the extent my engine upgrading, being a 97 I don't have the head woes, I like the single coil setup better than the newer coil banks, I think the 97-99 are probably my favorite of the XJ's. I think most people look to enhance the power of these things more so out of boredom, I'd just concentrate on suspension, aesthetics, and upgrade/mods that actually serve a purpose.

scottspott99 02-06-2014 01:00 PM

i upgraded my alt and put dual battery (stereo install) and everything electrical improved .. lights pw windows locks works effortless now and can crank tunes all day with no fear of killing battery. it been -30c here and my 99xj has never let me down starting in the morning
even heater fan motor seems more powerfull now.i just gotta get it higher in the engine bay now. ive got 3 alts that work but bearings in them howl so bad im fedup lmao

DunmerBoy 02-06-2014 01:05 PM

has anyone tried a 60 mm Throttle body? I've read a lot about these being a big improvement on a non heavily modified engine. especially in concert with a CAI

mschi772 02-06-2014 02:11 PM

65 Attachment(s)
Quote:

Originally Posted by DunmerBoy (Post 20113626)
has anyone tried a 60 mm Throttle body? I've read a lot about these being a big improvement on a non heavily modified engine. especially in concert with a CAI

I'm sure someone has, but keep in mind that this isn't not a power thread--it is an MPG thread. CAI will not improve MPG and will likely hurt it. If maximum MPG is the goal, a warm air intake is actually the way to go.

Regarding the 60 mm tb...I've read mixed results. Much of it is confounded no doubt by people wanting to believe that it has a positive result even if it doesn't (placebo effect)--on subjects like these, misconceptions and wishful thinking really makes a mess of the quest for truth.

Does it have a positive effect on its own and, if so, how much? I'm skeptical that it even does anything on its own; I have a hard time believing that the throttle body is a bottleneck on a stock 4.0. My first suspect would be the downpipe followed by the head itself, the header, and the cumulative restrictions in the stock exhaust. Only after that would I start suspecting the intake/throttle body of significantly restricting the system, but these are just my semi-educated guesses.

Regardless, the topic at hand is fuel efficiency, and I'm especially skeptical that a lone throttle body enlargement would have a positive, if any at all, effect.

DunmerBoy 02-06-2014 02:26 PM

Quote:

Originally Posted by mschi772
I'm sure someone has, but keep in mind that this isn't not a power thread--it is an MPG thread. CAI will not improve MPG and will likely hurt it. If maximum MPG is the goal, a warm air intake is actually the way to go. Regarding the 60 mm tb...I've read mixed results. Much of it is confounded no doubt by people wanting to believe that it has a positive result even if it doesn't (placebo effect)--on subjects like these, misconceptions and wishful thinking really makes a mess of the quest for truth. Does it have a positive effect on its own and, if so, how much? I'm skeptical that it even does anything on its own; I have a hard time believing that the throttle body is a bottleneck on a stock 4.0. My first suspect would be the downpipe followed by the head itself, the header, and the cumulative restrictions in the stock exhaust. Only after that would I start suspecting the intake/throttle body of significantly restricting the system, but these are just my semi-educated guesses. Regardless, the topic at hand is fuel efficiency, and I'm especially skeptical that a lone throttle body enlargement would have a positive, if any at all, effect.

Oh sorry, I went back to the article I saw a realized that they didn't notice an MPG difference.


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