Options for rebuilding the 360, better mileage?

[stuart]

Although this is basically a reprint of a reply to "Different Engine/Tranny options" I thought I'd post is as a separate topic to hopefully get more replies. Sorry for the repitition.

"...With that said, when having an engine rebuilt what can be done, different cam etc. to inceased mileage. My 88 is a daily driver which when used for work will see a minimum of 60 miles a day and sometimes up to 120. I will tow a utility trailer a couple of times a year."

Stuart

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<LI> 88 Grand Wagoneer 55K mi
<LI> Stock except...
<LI> Kenwood CD and speakers
<LI> Carter 4bbl, Edelbrock intake
<LI> Dupont Cherry Red Pearl paint
<LI> View my baby (http://albums.photopoint.com/j/ViewPhoto?u=1340994&a=10041302&p=33310327)

[pedaler]

Stuart, I have a 1988 GW and a rebuilt long block that cost me about $3,000 including installation. I get 11 MPG in town and maybe 13.5 on the highway. The long block has 6,000 miles on it. I also have Jacobs Ignition on it. If you are concerned about gas mileage you better get a different vehicle.

[trssho]

Stuart,
To be honest, this is the wrong vehicle to try to sqeeze some economy out of. I think the best you could hope for is 15 mpg. Which really isn't bad considering a Durango gets about the same. The best way to eek out some economy is to start with a Jacobs ignition upgrade. Next I would have your carb rebuilt and professionally tuned. An option to that is an aftermarket fuel injection system(which some of the guys here have installed). Lastly, I would install original size tires with a street tread.( keeping them aired up is also helpful)I run mine about 34 psi. My Blk cherry Jeep got 13 mpg on a trip from FL to MI. This was with an Edelbrock 4bbl and a mild cam on a fresh rebuild.
So I suppose that fuel mileage is relative. An Excursion probably onlt gets 10 mpg on the highway, so 13-15 isn't all that bad.
Good luck, Andy
PS. I know of a guy who put in a 304 with roller rockers and managed 20 mpg

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1989 GW Tan w/106K miles
1989 GW Blk Cherry 69k miles

[Brown Bear]

About the best way to get better mileage out of these things is to chop the roof, scoop the hood, round the corners, and try driving downhill most of the time. The aerodynamics of these trucks is really the limiting factor in gas mileage. Somebody on here did a test on the highway: fully loaded, five people and equipment yielded the same mpg as completely empty, same speed/distance, conditions.

Nathaniel

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1984 Grand Wagoneer
bone stock
P235/75 R15 Daytona Stag XT

[stuart]

Thanks all, I understand this brick of a vehicle will never rival a Honda for mileage and the Range Rover I own and used daily gets 13 mpg. I just wondered what if any things could be done to improve the mileage.

After all, while rebuilding if you could eek out another 2-3 mpg wouldn't you do it?

Stuart

[EEVW]

I also get around 12 mpg going 75 mph on the freeway or 35 mph in town...so you can guess I tend to go 45-50 on the main roads. That Edelbrock Performer package is just to tempting.

Does anybody think wind farings/deflectors on the front hood ( like th bug deflector types)and also on the front roof ( like on those new Nissan SUV)would help.

EEVW

[Snakeyes_Tx]

I've got a buddy who works for a Chevrolet dealership and through his million questions a day to the more experienced mechanics there... he had found out that those bug shields decrease gas mileage and puts more strain on the engine with increased drag. I wouldn't bet that anything bolt on to the body could really help...

On the other hand... Homer's "Speed-holes" wont make ya go faster either http://www.ifsja.org/ubb/wink.gif



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Snakeyes_Tx
86 J-20 "The Rusty Dinosaur"

[Narnian]

I do believe you can improve mileage on these beasts, but the changes you would have to make would be drastic.

First, you would need to put in a Port Injected fuel system. TPI is generally 30% more efficient than carbs.

Second, you would want that on a ~300 CID motor, like a 304, or a GM TPI 305. The goal is to reduce the displacement a little.

Third, you would want to trash the drive train in favor of something that supports overdrive, like the drivetrain out of a Tahoe.

I think with those changes you could expect highway mileage around 17 - 21 mpg.

After all you spent on making these changes, it would take you 7.2 years to recover your money through fuel savings! (depending on miles per year)

As per everyone's comments, you are really not getting as bad a mileage as you think. Making changes to the motor during a rebuild won't affect mileage as much as you would hope. You will do far more by improving fuel delivery (Fuel injection) and keeping your tires filled.

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360 w/Holley Fuel Injection, Edelbrock manifold, NP219, 3.31, 33's, no fuzzy dice (yet)
AND an 86 Corvette & 87 GMC Jimmy (Jimmy soon to be for sale)

[Veepster]

another thought would be to do some friction coating when you have the motor apart.....I am in the process of coating the internals for my Veepster motor......I read somewhere a long time ago that something like 50% of the motors HP is lost due to internal friction..........so some coating on the bearings, oil pump, pistons,lifters etc might give a bit of mileage....

having someone else do the coating can get really expensive!!....I am going to do it my self...costs $70 materials....then I need to buy a small sand blast bucket(I already have compressor) and then I need a small airbrush.....pop the parts in the oven and voila!.....I figure i will be in about $200 total, but next time around it will be really cheap, materials only....check out www for more info
http://www.techlinecoatings.com/



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Peace.............BartG

the Green Flash!
360 2v, TH400 QT with low
4" skyjacker Rancho 9000's
33x12.50 BFG KO's 8" American Racing Baja Rims
Thorley headers, 3" exhaust, Dyno Max
Infiniti power leather seats
50%Luxury Car, 50%Tractor
http://www.teamgodspeed.com

[Bryan]

I had a 1985 F250 w/460 ci & auto, I put a bug screen on and lost almost 1 mpg so you dont want to do that. My friend had an early 90's small blazer with a rear wind deflector, he removed it and gained about 1 mpg. Sooooo..... I see that you have a 1988 GW so you probably have that wind deflector thing, maybe try removing it? Has anyone else out there tried this?? Just a thought based on second hand info http://www.ifsja.org/ubb/smile.gif

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1988 GW
30x9.50 TXR's
2.5 inch exh w/hi-flow cat & muffler

[Tom Evans]

Regarding Narnian's ideas on fuel economy:
Your right about how long it would take to recover all those costs unless you were thinking about jumping in for the price of a newer vehicle with PAYMENTS! Ouch. Also you could do them one at a time like - the overdrive is available from Gearvendors(www.gearvendors.com) and will bolt up to a 208 or 205 case. Also heard it is possible to put in a 700R4 with some modifications on those originally equipped with TH400. There are other benefits to O.D. besides gas mileage like longer engine life, less highway noise and vibration etc.
The gearvendor guys are selling these things for newer vehicles that already have O.D. for a double O.D. down around 1.90-1
Somebody do this and tell me how it went.
Tom E.

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[Gregorio]

Well, Stuart, there's mucho good info here but I'd like to add my flatulance and maybe save you some money.

Would you spend $20 to try to increase your mpg by 30% or more? Try a coil for a '79 Ford F-350 with a 460 CID engine. This is the single biggest boost I have had with modifications. And I have spent one heck of a bunch of money on my 87GW "Big Grin".

When I rebuilt the engine I had it line bored, balanced and decked. Those things cost me an extra $200 or so in the rebuild. Whether or not they added to the fuel efficiency I can't say but this is one hell of a smooooooooth running engine and the power is unbelivable.

I added a Howell TBI. Again, I can't say that there was an improvement specificly due the the Howell unit because I had it installed with the installation of the new engine. I do like the Howell because I hate to fool with carbs. I have had no trouble with it.

I added that coil a few months after the other items and my mpg went from 10 to 14 in town and 16 on the hiway.

[scotty]

if it makes anyone feel any better,my 82 j20 is getting about 6 mpg highway.the engine is recently rebuilt and has awsome oil pressure and runs good.its a 360,727,208,3.73 gears with 33" mud kings. it has a cap,and the big highway trips ive made in it have been with 1000+ lbs of junk in the back.its a really cruel joke the jeep gods play on me- the fuel gage is wired backwards(reads "E" when full) and wont move at all for 130 miles,making me think its not doin so bad.when it starts miovin-it drops quick! you can almost watch it move from 3/4 to empty while you drive.

i have not even checked the plugs yet,and the carb may need some help. im sure i can improve it some,not sure what is reasonable to expect from a a big truck with a big carbed v8.id be happier than heck with 13!

[reddog]

While fuel injection and ignition are the 2 areas where you will likely see the most gain (as previously stated - no miracles) the fuel injection is costly and will take a long time to recover the cost. Jacobs/MSD ignitions are certainly less then the injection but still take quite a while to recover the cost. The TFI conversion is cheap especially if you do it via the junkyard route. I saw close to a 2 MPG increase with the TFI change that included new plugs and plug wires.

If you don't ford alot of streams then you might consider using synthetic lube in your axles, xfer case and trans. If you make your Wag swim alot then the constant changing of the fluids is not cost effective. I feel the same about synthectic motor oil - its a good thing but too expensive as I think that you may well never see the gains of motor longevity that it can give you and the mileage increase is offset by the addition cost when you change your oil regularly. But in the other components the fluids are not changed that often and it may well be cost effective.
You may also consider putting lock hubs on the front axle. They are under $100 and may give you 2-3 tenths increase in MPG thus may also be cost effective. Just don't ever put it in 4 wheel drive without the hubs locked - it will be the end of your transfer case. If you let someone else drive it just lock the hubs before they take it - you can drive it with hubs locked all the time - same as stock. JMHO

Kerry

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87 GW - Stock (but it looks like RiverBeast when I'm sleeping)
TFI upgrade
360,727,NP229