My goal is to get 25+ mpg from my 99 XJ with 30 x 9.5 R15 ATs - Page 38 - JeepForum.com
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Unread 08-27-2013, 11:39 AM   #556
JSahara00
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You get all of the electrodes pointing the same way so the flame is more consistent in every cylinder HOPEFULLY making it more efficient.
Not sure if it would work but a pack of indexing washers is cheap and it will not take to long. I know its normally used for piston clearance but who knows...



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00 TJ, OME shocks, all currie control arm, OME steering damper, Brown dog MML, VIAIR OBA with 2 quick disconnects at the doors, jks quick discos, Kolak exhaust, 30 spline D30 w/ ARB and 4:56, 8.8 w/ super 88 and ARB, home made F/R bumpers and tire carrier,OME zj front springs and OME Lj rear springs, CB w/ firestick, DIY highline fenders/hood, 35 pro comp mud terrains, cragar soft 8s .. .

95 XJ 4.0 4x4 Auto, V8 ZJ steering linkage
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Unread 08-27-2013, 12:04 PM   #557
Newtons3
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Originally Posted by Charley3 View Post
OK. I'll get a new down pipe made.

Is the stock headers/manifold good enough performing to keep using, or replace?
You already have a tubular exhaust. A really good header would be better but the real-world numbers would show minimal measurable gain, if any. If its not cracked, run it. If it does crack, upgrade then.
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Unread 08-27-2013, 12:15 PM   #558
Newtons3
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Quote:
Originally Posted by JSahara00 View Post
You get all of the electrodes pointing the same way so the flame is more consistent in every cylinder HOPEFULLY making it more efficient.
Not sure if it would work but a pack of indexing washers is cheap and it will not take to long. I know its normally used for piston clearance but who knows...

http://www.youtube.com/watch?v=B7cxRl89yPk
Ive done this, but only on extremely high compression engines usually with exceptionally small combustion chambers. The thought was, and we had been told, that we would see power gains. We didnt see anything definitive or repeatable. Id predict that it wouldnt make any difference on the Jeeps, but who knows? Id be willing to give it a try.
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Unread 08-27-2013, 12:27 PM   #559
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Charley, Ive read all the propaganda about silica, and, your statements about rubber hardness impacting traction and mileage are generally true. I can tell you that my experience was HORRIBLE snow and ice traction. My new M/Ts (made by Cooper) supposedly are high silica. I can tell you they SUCK in water. Much worse than my old ones.
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Unread 08-27-2013, 01:16 PM   #560
Charley3
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Charley, Ive read all the propaganda about silica, and, your statements about rubber hardness impacting traction and mileage are generally true. I can tell you that my experience was HORRIBLE snow and ice traction. My new M/Ts (made by Cooper) supposedly are high silica. I can tell you they SUCK in water. Much worse than my old ones.
Huh. I don't know then.

The Cooper AT3 seems to be a winner though. I wonder what makes it different.

I guess there's still no substitute for sipes.
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Unread 08-27-2013, 04:13 PM   #561
Newtons3
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Absolutely no substitution for sipes.
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Unread 08-27-2013, 04:43 PM   #562
JSahara00
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I'm going to order a sipping tool to cut my mud terrains and see how they are in snow. I was also considering the at3s after a lot of good reviews and cheaper than the duratracs.
I bought a set of used tires that where sipped and they were amazing in all conditions but did not seem to wear well but of course that could have been my fault with not paying attention to pressures.
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00 TJ, OME shocks, all currie control arm, OME steering damper, Brown dog MML, VIAIR OBA with 2 quick disconnects at the doors, jks quick discos, Kolak exhaust, 30 spline D30 w/ ARB and 4:56, 8.8 w/ super 88 and ARB, home made F/R bumpers and tire carrier,OME zj front springs and OME Lj rear springs, CB w/ firestick, DIY highline fenders/hood, 35 pro comp mud terrains, cragar soft 8s .. .

95 XJ 4.0 4x4 Auto, V8 ZJ steering linkage
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Unread 08-27-2013, 05:52 PM   #563
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Any info on brand of gas as it relates to mpg? I've never done enough monitoring to tell much, and usually just get shell or chevron. The few tanks of off brand or big box store gas I've gotten have given me worse mileage than the "good" name brands but what about between the "good" brands? I'd imagine its about the same. Anyone know for sure?
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Unread 08-27-2013, 09:21 PM   #564
Charley3
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I bought a set of used tires that where sipped and they were amazing in all conditions but did not seem to wear well but of course that could have been my fault with not paying attention to pressures.
All the info I've ever seen about sipes on tires used on road says they help the tread last longer by keeping it cooler on hot days.

The only time I've heard of sipes reducing tread life is when the tires are used a lot on rock roads with big sharp rocks (from egg to base ball size jagged rocks), or rock crawling.

So if your siped tires didn't last long (and you're not a rock crawler), then it probably wasn't the sipes fault.
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Unread 08-27-2013, 09:26 PM   #565
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Ive never found any evidence for or against that. What I have found is a trend toward better economy from busier stations with -fresher- fuel (higher turnover rate).
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Unread 08-27-2013, 09:28 PM   #566
JSahara00
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Originally Posted by Charley3 View Post

All the info I've ever seen about sipes on tires used on road says they help the tread last longer by keeping it cooler on hot days.

The only time I've heard of sipes reducing tread life is when the tires are used a lot on rock roads with big sharp rocks (from egg to base ball size jagged rocks), or rock crawling.

So if your siped tires didn't last long (and you're not a rock crawler), then it probably wasn't the sipes fault.
Yeah I'm not surprised that it's probably my lack of attention. It had constant fluctuations in psi from a leaky stem.
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00 TJ, OME shocks, all currie control arm, OME steering damper, Brown dog MML, VIAIR OBA with 2 quick disconnects at the doors, jks quick discos, Kolak exhaust, 30 spline D30 w/ ARB and 4:56, 8.8 w/ super 88 and ARB, home made F/R bumpers and tire carrier,OME zj front springs and OME Lj rear springs, CB w/ firestick, DIY highline fenders/hood, 35 pro comp mud terrains, cragar soft 8s .. .

95 XJ 4.0 4x4 Auto, V8 ZJ steering linkage
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Unread 08-27-2013, 09:33 PM   #567
Charley3
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Originally Posted by JSahara00 View Post
I'm going to order a sipping tool to cut my mud terrains and see how they are in snow.
Many tire stores have a siping machine and will do it for you for $15 a tire.

For max durability, only sipe center tread blocks.

For max traction sipe center treads and inner half of outer treads. This is still reasonably durable.

Never sipe the outer half of the outer tread blocks (tires would chunk excessively).

To say that another way: Never sipe closer than 1" to outer edge of outer treads. I'd feel safer staying 2" in from outer edge of outer treads.

Edited in Later: Factory molded sipes are the most durable. Tire store automated machine cut sipes are second most durable. Do it yourself with a hand siper tool is least durable. That is according to my local tire store's advice. It makes sense to me (for technical reasons that I don't have the energy to type here).
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Unread 08-27-2013, 09:36 PM   #568
Charley3
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Ive never found any evidence for or against that. What I have found is a trend toward better economy from busier stations with -fresher- fuel (higher turnover rate).
Uh oh. I go to a station that is never busy. Seems like I'm their only customer. I've never seen another car there.
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Unread 08-27-2013, 09:48 PM   #569
Newtons3
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Quote:
Originally Posted by Charley3 View Post
Many tire stores have a siping machine and will do it for you for $15 a tire.

For max durability, only sipe center tread blocks.

For max traction sipe center treads and inner half of outer treads. This is still reasonably durable.

Never sipe the outer half of the outer tread blocks (tires would chunk excessively).
You are mostly right. I just don't like the results that I've seen from the tire stores. This is one area where I do have an awful lot of experience, but in a different application. I like to sipe the treads myself. On newer tires, about 3mm deep. Depending on the tread pattern, I've been known to go all the way to the sidewall. It may (probably will) increase the rate of damage in heavy rock, but otherwise, you should be fine. The colder the weather and the shorter the trips, the more siping you need. Hotter weather and longer trips need less siping. This is where a durometer and an IR gun come in handy.

BTW- My hand siper is a $400 tool, not a cold knife that I've seen some people selling. It's probably nicer than what some of the tire stores are using.
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Unread 08-27-2013, 09:55 PM   #570
Charley3
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My preferred way to get sipes is buy a tire with plenty of factory molded sipes. It's easier, and molded sipes are (allegedly) the most durable type of sipes.

(But if a tire lacks sipes, I'm in favor of having tire store add cut sipes)
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