i wanna know more bout slant sixes

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m-wellbaum

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well i aint been on here in forever i got a jeep for my first project instead of a duster(dad knew id do donuts either way n he ratherd i do em in the mud lol) and well its awesome but i need better n 13 mpgs i wont be able to drive it thru college i hear a /six is good for 30 mpgs but i worry bout a lack of power i am 17... i would very much like to have me a little pep to it how much could i build it without breakin the bank and loosin gas milage i love dusters i have for a long time i figure i can get one that get good gas milage and keep the jeep for rocks n mud best of both worlds lol
 
I think 30 mpg and donuts are mutually exclusive.
 
C39 said:
I think 30 mpg and donuts are mutually exclusive.
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well I'll have to agree to a point, I'm headed the way of power but I will refuse to let it drop bellow it's current 14/21 MPG, who knows maybe we all will be headed toward the MPG finish line the way things are going.

if MPG is what you want.......really want.... do a search for MPGMIKE at slantsix.org if heard of around 40 MPG out of a /6 just keep in mind that power WILL suffer....most say intolerably
 
I don't know what year your Jeep is, I had a 1980 CJ and have a 2002 TJ (Wrangler) now, they aren't very good on gas because they are very heavy particularly the older ones I think. Full boxed frame, front diff and transfer case adds a lot of weight and they typically have tall gears. The inline 6 they came with makes pretty good torque which you need, I don't know if a /6 would be a great idea. If an engine has to work to hard it won't get good gas mileage anyway.
 
I don't think Jeeps came with a slant 6. They were all AMC derived inline 6. It's either 3.8, 4.0 or 4.2 depending on the year. These were actually good Jeep motors, decent torque but gas mileage wasn't very good. Were you thinking of retrofitting a slant into your Jeep?
 
my jeep has a 4.2 inline six i put it in there but yea i get about 13 mpgs my jeeps a 89 wrangler i love it robs right it makes great torque i think the peak is like 1600 rpms its great for rock crawlin you just gotta gear it i just wont be able to drive it during college itll eat me alive on gas so i figured since im a big fan of dusters maybe id get one with the slant for my everyday driver that gets good gas milage then still have the jeep who knows after college i may put a 5.7 or 6.1 hemi in the duster but for now im mainly explorin my options and i aint gunna rush i got another year till its a big issue n i want to get as good a deal as i can find plus im broke lol so power is probly gunna be an issue hope its got more than a 99 stratus 2.4 liter auto ah well thats not what they are for i guess
 
I had an 89 XJ (Cherokee) with an 8 inch lift, 35's with 4.88 gears, locked front and rear, and my last trip netted me 19 mpg on the freeway. I was running an open element air cleaner, and a free flowing exhaust. I think it had over 168k in mileage when I sold it.

I actually thought my straight 6 was fairly good on gas for what I was asking it to do.

YMMV (Your Mileage May Vary...8)

Thanks,
OldMoparsRule
 
Thrashard340 said:
I don't think Jeeps came with a slant 6. They were all AMC derived inline 6. It's either 3.8, 4.0 or 4.2 depending on the year. These were actually good Jeep motors, decent torque but gas mileage wasn't very good. Were you thinking of retrofitting a slant into your Jeep?
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Actually If you chase that 4.0 to it's original manufactorer you'll find that International was it and yea it was a dam good engine. I'm not sure about the 3.8 or 4.2 tho.

Terry
 
I would love to put a 4.0 in my car. "slant" it for fun. Ive had 2 cherokees and they both got 25 mpg atleast, would love to know what they would get in a car.
 
i havnt actualy heard of the 3.8 was it an amc?the 4.0 has more hp and torque than the 4.2 but it makes the most torque at maybe im wrong but i think its like 2400 to 2600 rpms its also fuel injected the 4.2 had a carb so there is part of the difference in gas milage they both share the same block when my first motor got finished off i seriously considered the 4.0 or a 360 :toothy5: but i got my new 4.2 that had a weber carb and a cam(i dont know what kind) for a hundred bucks i just couldnt let that deal go by so i got the older gas hog lol also i got 2.73s for gears it is what was in it and i just havnt got new ones yet
 
30 mpg is very optimistic. My Dart got around 18 mpg in city driving before the latest round of mods, and it's pretty rare to hear of one going over 25 mpg. Maybe if you went hog wild lightening the car and went for EFI...
 
somthin ive heard of for helpin with gas milage is a hydrogen generator im not exactly sure how it works but i got a buddy buildin a small one its supposed to get 10% better gas milage supposedly there is a more complicated version that gets you 75% better but hes starting small first i may do that to a slant... how much gas milage does a stock 318 or 340 or 360 get if i could get one of those to get 25 mpgs.... power wouldnt be a issue
 
A generator might help if you had the hydrogen generator at home running off household current, compressed the hydrogen, and stored it in cylinders - if you're driving it off the alternator, you'll take at least 4 times as much power from the engine than you'll get back from burning the hydrogen. Also, it takes about 2.2 to 2.5 gallons of water to make enough hydrogen to replace 1 gallon of gas. If you take a look at most of the small hydrogen generators, they're way too tiny to get even a 10% improvement.
 
MadScientistMat said:
30 mpg is very optimistic. My Dart got around 18 mpg in city driving before the latest round of mods, and it's pretty rare to hear of one going over 25 mpg. Maybe if you went hog wild lightening the car and went for EFI...
Click to expand...

Have a good friend who bought a rust-free, bone stock slant 6 Duster out of Fl and brought it to MI (bad mistake) to use as his daily driver. He said in normal everyday driving it would get around 20MPG. Just for giggles and kicks he brought it to the Nationals with a goal to see if he could get some decent mileage out of it on a long trip. By driving a pretty steady 55, he was able to get 27MPG out of it. Again, it was a bone stock 74 Duster with a 904, PS and AC (AC not used on the trip). Within 3 years of using it as a daily driver, it was a rusted out hulk! Gotta love them MI winters!
 
I don't see how a slant-6 couldn't get mileage that high. However, I personally think every good slant-6 should have a turbo. They are practically made for a turbo (lots of space, intake/exhaust manifolds in same place, etc.) and with the right size, could give you a lot more power without sacrificing mileage (of course only if you kept your foot out of it). New multi-spark ignition, good carb, and free-flowing exhaust would also help. BTW there's an article on Allpar.com about turbo'ing a 225 /6 with a junkyard turbo from a 2.2/2.5 4-banger (although personally I think you could get away with using one a teeny bit bigger).
 
Don't think International built engines for AMC. AMC & predecessors have a long history with the L-6. Here's a breakdown on the development of the last 6 cylinder engine family AMC developed.

199
The 199 cubic inch (3.3 L) 199 was produced from 1965 through 1970.

Applications:

Rambler Classic (1965-66, fleet cars only)
Rambler American/AMC Rambler (1965-69)
AMC Hornet (1970)
AMC Gremlin (1970)

[edit] 232
The 232 cubic inch (3.8 L) 232 was produced from 1964 through 1979.

Applications:

Rambler Classic (1964-1966)
Rambler American/AMC Rambler (1964-1969)
Rambler/AMC Marlin (1965-1967)
Rambler/AMC Ambassador (1965-1970)
Rambler/AMC Rebel (1967-70)
AMC Javelin (1968-74)
AMC Hornet (1970-77)
AMC Gremlin (1970-78)
AMC Matador (1971-74)
AMC Pacer (1975-79)
AMC Concord (1978-79)
AMC Spirit (1979)
Jeep CJ (1972-79)
Jeep Cherokee (1974-79)
Jeep Wagoneer (1965-1971)
Jeep J series trucks (1965-1970)
Jeep Commando (1972-1973)
International Harvester Scout (1969-1971)

[edit] 258

Engine bay of a 1980 AMC Spirit AMX with numerous emissions controlsThe 258 cubic inch (4.2 L) "258" in-line six was produced from 1971 until 1990. It featured an undersquare 3.75 inch (95.25 mm) bore and 3.895 inch (98.93 mm) stroke; it was otherwise similar to the 199 and 232. Later 258 models (starting with the 1980 model year for California AMCs, 1981 for California Jeeps and 1982 for all other applications) are equipped with AMC's CEC system.

Applications:

AMC Hornet/Concord/Spirit/Eagle (1971–1988)
AMC AMC Pacer
AMC AMC Matador (1971–1978)
AMC Gremlin and Spirit (1971–1983)
International Harvester Scout (1972-1974)
Jeep CJ (1972–1986)
Jeep Cherokee and Wagoneer (1972–1986)
Jeep J series trucks (1971-1988)
Jeep Wrangler (1987–1990)
Jeep Commando (1972-1973)

[edit] 4.0

Engine bay of a 1993 Jeep Grand Cherokee with 4.0 LThe 242 cubic inch "242 or 4.0 L or 4.0" straight-6 was an evolution of the 258 and 2.5 and appeared in 1987. It had the same 3.875 inch (98.4 mm) bore as the 2.5 with a longer 3.414 inch (86.7 mm) stroke giving it a displacement of 241.573 CID (3,959 cc).[1]

The 4.0 was discontinued at the end of the 2006 model year as the redesigned Jeep Wrangler uses Chrysler's 3.8 L OHV V6.
 
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