My goal is to get 25+ mpg from my 99 XJ with 30 x 9.5 R15 ATs - Page 33 - JeepForum.com
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Building a Bumper?Ruffstuff Axle Simple Swap Kit!~Artec JK 1 TON SWAP~

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Unread 08-20-2013, 06:15 PM   #481
xj2k1
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It was pretty simple. A bit of work though. I mounted the MSD under the rear seat. I cut the harness for the coil pack, and routed wires back to the unit. I then had to route them back to the engine compartment. And re-connect to the coil pack harness. I think I ended up with a bundle of almost 15-20 wires. I then wrapped the bundle with aluminum foil, and wrapped that with 22 guage bare copper wire. Which I then grounded. That acted as a shield to keep the "noise" from the wire bundle from wiping out the recieve on my ham radio. Also had to use two tach modules. And I bought their filter capacitor. About $450 when I was done. I did NOT see any improvement in performance or mileage. I wouldn't recommend it to anyone. The DIS 6 died after about 5-6 years, and MSD wouldn't repair it. I've still got the tach modules and filter cap if you're interested though.

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Unread 08-20-2013, 09:43 PM   #482
Newtons3
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Quote:
Originally Posted by RacerX View Post
Go to craigslist, get a free 55gal drum (or few) fill them in the winter, use them in summer.**

**There are many do's and don'ts e.g. do not fill them up - they need expansion room. you may want to lay them on side so they can be 'stired' (or rolled)......
So....enough 6 month old gasoline to last through the summer stored improperly, not to mention unsafely, in a random used drum? Terrible idea.
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Unread 08-20-2013, 09:48 PM   #483
Newtons3
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Quote:
Originally Posted by Charley3 View Post
Buick 3800 Generation 2.

No ideas what transmission. It's a 4 speed auto with torque lockup.
Great engine. Im assuming normally aspirated?
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Unread 08-20-2013, 09:54 PM   #484
Newtons3
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Quote:
Originally Posted by xj2k1 View Post
It was pretty simple. A bit of work though. I mounted the MSD under the rear seat. I cut the harness for the coil pack, and routed wires back to the unit. I then had to route them back to the engine compartment. And re-connect to the coil pack harness. I think I ended up with a bundle of almost 15-20 wires. I then wrapped the bundle with aluminum foil, and wrapped that with 22 guage bare copper wire. Which I then grounded. That acted as a shield to keep the "noise" from the wire bundle from wiping out the recieve on my ham radio. Also had to use two tach modules. And I bought their filter capacitor. About $450 when I was done. I did NOT see any improvement in performance or mileage. I wouldn't recommend it to anyone. The DIS 6 died after about 5-6 years, and MSD wouldn't repair it. I've still got the tach modules and filter cap if you're interested though.
Thanks. My engine is FAR from stock and Im looking for other results. Im trying to cure one problem that I have now that I created. Im also looking for a solution to a problem Im about to create.
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Unread 08-20-2013, 10:05 PM   #485
Charley3
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Quote:
Originally Posted by Newtons3 View Post
Great engine. Im assuming normally aspirated?
Yes. Naturally aspirated.

I think part of its secret sauce from factory is Buick used same air intake on this V6 and they did on their larger V8. So it breathes really easy on the V6.

The engine is really fine tuned in computer controlls, and the transmission has perfect gearing.

It only has one cat because it's 97 (pre 2001 cars have only 1 cat). This gives it an advantage over newer cars because newer cars have multiple cats.

Also, it has an electric fan stock.

And aerodynamic. Being front wheel drive probably helps because no drive shaft or rear diff catching air.

Also, mine is the Gran Touring edition, which is lowered 1" front and rear compared to the Base model. That helps aerodynamics, and it has a really low rubber wind skirt in front.

Then I lifted rear 1" to give it a 1" rake.

So front very low and has 1" rake.

And the 205F stat.

It gets 34.6 mpg at 70 mph, or 36 mpg at 60 mph, or 25 mpg at 90 mph. Those figures are with Hankook snow tires on it. That's all I have for tires at this time. Some day it'll get touring tires and the gas mileage will improve.

It also has a top speed of 140 mph. I've had it up to 95 mph and it still had lots of acceleration left.

This car is was sold under different name in Europe. It is popular for use on the autobaun because it's cheap to buy (compared to Euro luxury cars) and has economy and performance galore. Add in a few economods and it has even more economy and still retains high performance.
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Unread 08-20-2013, 10:22 PM   #486
Charley3
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Newtons, perhaps you should try the acetone yourself, as a test. Let us know how it goes.

I'm skeptical.
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Unread 08-20-2013, 10:35 PM   #487
Charley3
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Quote:
Originally Posted by xj2k1 View Post
My '01 XJ used to get about 15 3/8 MPG, pretty much all the time. I put in a set of the 4 hole injectors, and my in town mileage went down to about 14. BUT, my hiway mileage went up to about 17-19. I recently re-geared from 3:55's to 3:73's. Which actually seemed to help the hiway mileage even more. I too am running 30x9.50's(Michelin LTX M/S)..
I suspect that your city mileage went down because your foot enjoys the snappier pickup 4 hole injectors give. When you're on highway, you put it in cruise control, right? So on highway the improvex efficiency is improved.

I appreciate the regearing for 30s info. Thanks. I'm interested in 3.73 gears.

Don't give me that buy an economy car crap. That stupid condescending line is already tired and worn out in this thread earlier. I'm already so close to 25 mpg that I've already shown it's possible, and I still have a few more mods to do (including injectors). I guarantee I'll meet, or exceed, 25 mpg (with 30" tires) in the near future.
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Unread 08-21-2013, 08:13 AM   #488
Newtons3
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I intend to do that. I have a tank, fuel lines, injectors etc. and we are testing for negative reactivity on each in various concentrations. Then Im going to burn a couple of tanks to see what results I get. Im also going to test some oxygenates like nitropropane. Im trying to get my test mule ready to go.
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Unread 08-21-2013, 08:23 AM   #489
1997xj
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Did I miss the discussion on free hubs (manual lock)? Thats got to be good for 1-2 mpg
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Unread 08-21-2013, 09:25 AM   #490
Newtons3
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Originally Posted by Charley3 View Post
Newtons, perhaps you should try the acetone yourself, as a test. Let us know how it goes.

I'm skeptical.
In my experience, the hub conversion is worth 1, maybe 2 mpg on a stock Jeep. The benefit is reduced as tire size goes up. About at the 31 inch level the benefit becomes questionable if even measurable.
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Unread 08-21-2013, 10:44 AM   #491
Charley3
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Quote:
Originally Posted by Newtons3 View Post
I intend to do that. I have a tank, fuel lines, injectors etc. and we are testing for negative reactivity on each in various concentrations. Then Im going to burn a couple of tanks to see what results I get. Im also going to test some oxygenates like nitropropane. Im trying to get my test mule ready to go.
I'd be worried about damaging fuel system, but I'm just an enthusiast amateur. So I don'tcknow. You're a pro mechanic and an enthusiast.. So I'll defer to you on that topic.
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Unread 08-21-2013, 11:02 AM   #492
Charley3
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Originally Posted by 1997xj View Post
Did I miss the discussion on free hubs (manual lock)? Thats got to be good for 1-2 mpg
Hubs hasn't been mentioned until now. Good job for introducing a new topic related to gas mileage!

Would that really gain 2 mpg? If so, might be worth it.

However, isn't hub conversion expensive? How much does manual hub conversion cost? Wouldn't that require new wheels?
I'm to handicapped to turn hubs. I'm all busted up from a past car wreck (12 years ago) and an airline accident (20 years ago). My neck was even broken, as well as 3 crushed disks in neck and 1 in back. I struggled to get able to walk again (12 or 13 years ago). Still struggling with old injuries and severe arthritis. To many injuries to many body parts to list here. I'm struggling each day to live independently. I still work part time because I'm a computer programmer. So I work seated at a computer, which is phyically easy and pays well per hour. A normal life is impossible, and pain is constant, but I do the best I can.

My hobbies improve my life (Jeep, hypermiling, my kitten, my nieces and nephews). I used to do all my own wrenching prior to accidents. I still did some wrenching until a couple years ago when I had a heart attack and heart surgery. Since then my cousins and a friend do my wrenching, but I do the research for them and I buy the parts and run the errands for them (on the days I can walk). Arthritis is hell.
So manual hubs aren't an option for me because I couldn't turn them. This is same reason a portable/removeable winch isn't possible for me.

However, you guys should discuss manual hubs. It might be a good option for abled bodied people.
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Unread 08-21-2013, 11:57 AM   #493
1997xj
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Quote:
Originally Posted by Newtons3 View Post
In my experience, the hub conversion is worth 1, maybe 2 mpg on a stock Jeep. The benefit is reduced as tire size goes up. About at the 31 inch level the benefit becomes questionable if even measurable.
I'd think the reduced drive line wear would be a benefit too. Have you seen this to be true too or negligible? There must be a reasonably priced kit for Dana 30s out there. I'm only going to run 335/70s so might help me out a bit if its not too spendy.

Charley3 sorry to hear of your challenges
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Unread 08-21-2013, 12:34 PM   #494
Newtons3
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Its a double edged sword. The locking hubs have many more parts and require much more maintenence. Arguably there would be less wear on the 5 u-johnts involved, but... How often is there a problem with them? I like the idea of the ring and pinion turning to keep everything lubed. With no load, there is minimal wear. The conversions are very expensive and do require new wheels. Most require a bolt pattern change and changing the rear to match. They are expensive enough that payback is improbable.
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Unread 08-21-2013, 12:42 PM   #495
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Quote:
Originally Posted by Charley3 View Post
I'd be worried about damaging fuel system, but I'm just an enthusiast amateur. So I don'tcknow. You're a pro mechanic and an enthusiast.. So I'll defer to you on that topic.
There is much speculation about this issue but little definitive data. Thats why we are testing individual components first. We have them laying around and want to know rather than continue to guess at the anrwers.
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