THe NAC Lots-O-BFG KO2 Thread

[5spd_xj]

Re: THe NAC Lots-O-Post Thread

No, going to be running 4.88s. If I do end up going full widths I may change to the 5's but otherwise it will be 4.88s.

Right now I am at 33s (worn down to a measured 31") on stock 3.07s. So 35 or 36s on 4.88s would be comparatively better than what I have now. Plus when I was DDing the Jeep I averaged 18+ mpg due to lots of highway driving on the oversize tires. I would rather have a larger tire and have it be less "fun" but get better fuel economy. I will probably also have the set of 33x12.50 Trxus MTs for "fun" street/trail tire, and the 34" LTBs for my trail only tire.

I think you'd do better with 34s or 35s on the street with 4.88s, even with knowing that you're intending to do highway driving often... Read up on some of the fuel economy threads here, lots of info and knowledge on all of it, mostly first hand which is awesome. Low RPMs, whether or not on the highway, hardly ever (if ever) helps the 4.0 get better mileage. It's happy somewhere between 2300-2600 IIRC... just fwiw

 

[ROBZ95Xj]

Re: THe NAC Lots-O-Post Thread

i had my 93 sit at 2500 all the way to upstate ny and i got 17mpg with my 33's, gps confeirmed, let the 4.0 sing

 

[5spd_xj]

Re: THe NAC Lots-O-Post Thread

i had my 93 sit at 2500 all the way to upstate ny and i got 17mpg with my 33's, gps confeirmed, let the 4.0 sing

Exactly. Last night driving the red Jeep home, I didn't track the distance exactly, but for about an hour and a half I held a pretty consistent 2500-2600RPM at 65mph (GPS), and after getting home, driving maybe 20ish miles around town, then another 30ish miles mixed mileage today, and I just dipped below half-tank.

 

[kastein]

Re: THe NAC Lots-O-Post Thread

yeah from what I've heard 2450rpm is the sweet spot for cruising, not sure where that number was pulled from but I suspect it was a lot of statistics or some dude's ass.

 

[5spd_xj]

Re: THe NAC Lots-O-Post Thread

taken from http://www.go.jeep-xj.info/HowtoSpeedoGears.htm :

Gearing for best MPG​

Most people think that less revs will equal better MPG. That is not always the case as less revs can also mean more strain on the engine which causes more fuel use. According to a engine design text‚ maximum fuel economy occurs with open throttle and at a piston speed of 1200 – 1500 ft/min. So if you know the stroke of your engine‚ you can calculate the rpm for best fuel economy. Usually comes out somewhere between 2000 – 3000 rpm. Dino provided me with the following numbers. The 4.0L has a stroke of 3.411" and a 4.5-4.8L stroker has a stroke of 3.895" so the numbers would be as follows: 1200-1500ft/min piston speed = 2110-2640rpm on a 4.0, 1848-2310rpm on a stroker. So use the table above to pick the right gears for your tyre size. Above gives the average cruising speed of 65 mph or 105 kph. The more weight you carry the more revs you need to stop the extra fuel use through engine strain. The extra revs is also better for the auto and even engine temperature with less strain and the water pump running faster to circulate the coolant.

You can also use the gear chart to work out what axle ratio is needed to return you to stock gearing by finding your stock gear tooth number under the new tyre size. Below is also a guide to what revs you will have with different combinations. This is about what you will have in overdrive or forth in a auto, ( 0.75 ). Pre '91 will be slightly slower at 0.70, Peugeot ( BA-5/10 ) had a 0.72 and faster for a AX-15 manual at 0.79 or a AX-5 with 0.85.​

RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 28's: 2,076 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 30's: 1,938 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 31's: 1,876 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 32's: 1,817 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 33's: 1,762 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 35's: 1,661 RPM​

RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 28's: 2,398 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 30's: 2,238 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 31's: 2,166 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 32's: 2,099 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 33's: 2,035 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 35's: 1,919 RPM​

RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 28's: 2,668 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 30's: 2,490 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 31's: 2,409 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 32's: 2,334 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 33's: 2,263 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 35's: 2,134 RPM​

RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 28's: 2,855 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 30's: 2,664 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 31's: 2,579 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 32's: 2,498 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 33's: 2,422 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 35's: 2,284 RPM​

 

[Begster]

Re: THe NAC Lots-O-Post Thread

So it looks like the chain in the 231 I took out of the red jeep is stretched, so I don't think I'll be able to put that in. Looks like I'll have to put the other 242 I have sitting around.

Got the starter in, and about to pull the Jeep into the garage, then start pulling the old case out. Can't wait to see whats inside.

 

[RCman]

Re: THe NAC Lots-O-Post Thread

as a few already know i just blew up the motor in the 98, nice hole on the drivers side of #6 cyl

I got the second text and told Colin who was standing right next to me and we both went "Oh S---!" at the same time.

we need M&G at pitstop

Yes. I'm in.

 

[billyjp2]

Re: THe NAC Lots-O-Post Thread

So it looks like the chain in the 231 I took out of the red jeep is stretched, so I don't think I'll be able to put that in. Looks like I'll have to put the other 242 I have sitting around.

if you will be looking to get rid of the junk 231 i'm interested. i'll also have the money for the high steer arms with me next weekend.

 

[ROBZ95Xj]

Re: THe NAC Lots-O-Post Thread

I got the second text and told Colin who was standing right next to me and we both went "Oh S---!" at the same time.

haha thats exactly what i was thinkin when it happened, but good thing it happened tonite and not tomorow when my mom has to bring my sis to her horse ridin lesson 30 mins away

 

[foxwar71]

Re: THe NAC Lots-O-Post Thread

poop skittles rob

 

[themangeraaad]

Re: THe NAC Lots-O-Post Thread

Billy, you still got the extra 3rd and shims for the 9" that you mentioned at the UJ party?

And apparently my last post I typed up didnt post for some reason.. but long story short I have figured out where my XJ seems to like to drive for good fuel economy and I am planning around that. idc if I could get better... if I can get a proven 20mpg at a certain RPM on the highway, I will do so..

Though I am going to wait to get some miles on 4.88s with my current tires before I make any decisions. Once I get some feedback from the Jeep I will pull the trigger on the street tires.

 

[Begster]

Re: THe NAC Lots-O-Post Thread

[size=+3]YAYYYY!
[/SIZE]

I think the green Jeep needs a head gasket. There is greenish residue around the muffler, and the coolant level is pretty low.
[size=+3]
F*ck, I mean YAYYYYYY!
[/SIZE]




Damn, I just realized I reached 5,000 posts.

 

[Dundy]

Re: THe NAC Lots-O-Post Thread

i have to work!!!

Ross, ill call you when i'm out.

Mark, your head gasket is fine. shut up.

 

[5spd_xj]

Re: THe NAC Lots-O-Post Thread

shalamalacka!!

 

[foxwar71]

Re: THe NAC Lots-O-Post Thread

I think the green Jeep needs a head gasket. There is greenish residue around the muffler, and the coolant level is pretty low.

Dude its fine, the green is just tryin to keep the same color theme throughout the entire vehicle.

Ross, ill call you when i'm out.

Oh-tay.








Time to go show up at Anthony's house in Grafton. Its snowing out pretty good, nothing like a fun adventure in black jeep.

 

[kastein]

Re: THe NAC Lots-O-Post Thread

Anyone know if Jeff is at Crown right now? I'm gonna hopefully be there by closing time or before

 

[Dundy]

Re: THe NAC Lots-O-Post Thread

I'd say the best way to find out is to call the store.

 

[JrTxJ]

Re: THe NAC Lots-O-Post Thread

Here til 1:30

781-821-2276

 

[foxwar71]

Re: THe NAC Lots-O-Post Thread

i have Crown on speed dail:thumbup:

 

[asp]

Re: THe NAC Lots-O-Post Thread

if you will be looking to get rid of the junk 231 i'm interested. i'll also have the money for the high steer arms with me next weekend.

dooouuubleeerrr... if you don't buy it i want it....