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If you're stuck with a 5-speed stick, why don't you just pull a T56 6-speed out of a Camaro or Trans Am? If you want you can add a little more gearing to give the car a bit of an umph as well as have the .5 overdrive to keep your rpms down at cruising speeds.

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I've going that route for my car. It's not cheap, even with used stuff. The transmissions aren't the cheapest thing out there. I'll need to hang a hydraulic clutch, the conversion bellhousing is over 500 bucks itself, have to cut the torsion bar crossmember and floor to fit it, in stock form the transmission has no provisions for a mechanical speedo output. Have to fab my own mount, etc. There are a lot of issues to deal with. I bought the trans for 500 bucks, but I'm sure I will have at least 2k into it by the time it's done.

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If you're stuck with a 5-speed stick, why don't you just pull a T56 6-speed out of a Camaro or Trans Am? If you want you can add a little more gearing to give the car a bit of an umph as well as have the .5 overdrive to keep your rpms down at cruising speeds.

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I've going that route for my car. It's not cheap, even with used stuff. The transmissions aren't the cheapest thing out there. I'll need to hang a hydraulic clutch, the conversion bellhousing is over 500 bucks itself, have to cut the torsion bar crossmember and floor to fit it, in stock form the transmission has no provisions for a mechanical speedo output. Have to fab my own mount, etc. There are a lot of issues to deal with. I bought the trans for 500 bucks, but I'm sure I will have at least 2k into it by the time it's done.

A couple other interesting options for transmissions are out there if you pick up a bellhousing from a mid-late 90's v6 dakota with an ax-15 transmission. That bellhousing will fit a 2wd ax-15 transmission from a 90's cherokee you can score one of those transmissions for cheap, and all the needed conversion bits can be had for quite cheap already. Especially cheap because you're building such a mild v8. I have one of these transmissions in 4x4 form in my jeep behind a 5.2 magnum but have yet to run it. Another option is a toyota supra R154 transmission will bolt to that bellhousing as well. One of those could probably be made to work quite well on the cheap also and should be strong enough.

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But that's still $2k cheaper than any Keisler kit out there,

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And as far as I know, no one has officially released a drop in 5-speed transmission. The last I heard, Passon Performance was still waiting for bearing (I think) that were on back order, and even then they're price was around $4k or so.

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Torque.

Torque production is a direct reflection of volumetric efficiency. Volumetric effciency is making the most power for a given fuel consumption.

Then engine combo that makes the most torque over the broadest range will produce the most mileage while being the most fun to drive in the lowest rpm range which will allow it to live the longest life.

Certainly smaller displacments use less fuel than larger discplaments, but I would not build a 273 over a 360 for that single point. Also, there is a sweet spot for piston speeds that can be demonstrated in a pumping efficiencies map. Compression is a big factor as well since the more you squeeze the charge, the more power you get from it, the less displacement you need because you're using the fuel more completely. Combine that with swirl and squish and you can get a lot of thermal efficiencies out of a gas engine.

Back to your personal combo...

I'd go 5.2 or 5.9 if they are readily available. If I had to choose, I'd go 360 first with some high swirl heads and as much compression as you're wlling to live with because it is a large torque engine. 650 AFB carb. These are easy to tune and you can really dial in the cruise and power circuits without a lot of trouble. Parts are readily available across the country. Ignition, maybe a stock dizzy with a a chrome box to reduce failure liability, and a decent coil. Simple, effective. small tube headers with dual exhaust and a manual trans of your choice.

Personal note on ignition-in my drag car I ran a stock system with a Jacobs coil, a Crane system with a stock dizzy, and a comlete MSD Digital 6 system. Between all three there was no appreciable difference in idle quality, e.t., or mph. That tells me there is not a huge gap in ignition capability among the popular options.

Using the above approach, I've been able to get the 440 in my truck regularly run in mid to high teens for mileage with a carb, 3 spd auto, and 4:11 gears while pulling like a diesel and being an overall low maintanence build.

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Torque.

Torque production is a direct reflection of volumetric efficiency. Volumetric effciency is making the most power for a given fuel consumption.

Then engine combo that makes the most torque over the broadest range will produce the most mileage while being the most fun to drive in the lowest rpm range which will allow it to live the longest life.



Certainly smaller displacments use less fuel than larger discplaments, but I would not build a 273 over a 360 for that single point. Also, there is a sweet spot for piston speeds that can be demonstrated in a pumping efficiencies map. Compression is a big factor as well since the more you squeeze the charge, the more power you get from it, the less displacement you need because you're using the fuel more completely. Combine that with swirl and squish and you can get a lot of thermal efficiencies out of a gas engine.

Back to your personal combo...

I'd go 5.2 or 5.9 if they are readily available. If I had to choose, I'd go 360 first with some high swirl heads and as much compression as you're wlling to live with because it is a large torque engine. 650 AFB carb. These are easy to tune and you can really dial in the cruise and power circuits without a lot of trouble. Parts are readily available across the country. Ignition, maybe a stock dizzy with a a chrome box to reduce failure liability, and a decent coil. Simple, effective. small tube headers with dual exhaust and a manual trans of your choice.

Personal note on ignition-in my drag car I ran a stock system with a Jacobs coil, a Crane system with a stock dizzy, and a comlete MSD Digital 6 system. Between all three there was no appreciable difference in idle quality, e.t., or mph. That tells me there is not a huge gap in ignition capability among the popular options.

Using the above approach, I've been able to get the 440 in my truck regularly run in mid to high teens for mileage with a carb, 3 spd auto, and 4:11 gears while pulling like a diesel and being an overall low maintanence build.

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I think for the first iteration, finding a running drop-in 360 Magnum would be perfect. Probably only slightly less MPG than the 318, and a lot more fun. Thats gonna make a helluva lot more power than my stock 70 A66 340 did, and that car was fun (and heavy!).

I've become a big 'less is more' guy, and the idea ov tuning the hell out ov a plebian combo like a 360/5-speed/highway-geared/small carb/small cam light car actually gets me excited. My A66 70 Challenger i had years ago was a damn fun car... and it was bone-stock and heavy, and i never even got close to tuning it (still had stock exhaust even). I could make a 360 Magnum 5-speed 3000lb Challenger fly...

Further down the road... if the plans dont change (or if i dont find a real job) then i could see building a tight-quench ported-head, higher comp 318 Magnum. At that point maybe i'll have the T56 and i can run some actual gear out back. At that point the car will most certainly be even lighter as well... and that means under 3000lbs.

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The way i am with scrounging and money i figure that once i get on it, the T56 route will end up costing me a LOT less than 2K all done... especially now that i'm not building a 500HP engine.

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In their readership survey of Durango owners about a dozen or more years ago,
Popular Mechanics magazine reported that the owners wrote that the 360 apparently got
0.75 MPG less
than the 318

It is so much easier to get MPG increases
with low rolling resistance tires,
And simple aerodynamic improvements
That those two areas should not be overlooked.

Improving innate engine efficiency is hard...
But getting to a better area of the "island" of best efficiency on the BSFC graph
Is mostly about using a numerically lower differential ratio,
And perhaps selecting a camshaft to match the rpm range of whatever diff ratio you go with.

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i like this thread!

ill chime in- i dont think a magnum is a necessity for what you are doing and you will lose manifold heat and could hurt mileage,why bothr the added expense of a magnum manifold?you dont need the extra horsepower for a car you desparately want to drive the wheels off?

heres what i would do:

85 closed chamber roller cam 318
swap in a factory magnum cam
swap meet alum manifold
try lots of carbs to see whats best
headers/big exhaust
elec fan
smallest stock pulleys you can find
stock elec dist recurved
working egr system
working hot air to carb system


lockup 904 tranny built strong
2.76 rear end gears

100 shot N O for spirited driving!

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If you go with a 360 Magnum, be aware that the power steering pump will interfere with the battery tray, unless you get one out of a van. Apparently they mount the pump different in vans. I have a '72 Challenger that has a 360 Magnum/727 in it, and couldn't figure out why the previous people put the battery in the trunk. Then I read a thread about it the power steering issue here, and the dim light bulb came on. Just one more little thing to be aware of.

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my buddy had a 318 dakota with a 4 speed auto with some bolt on stuff-headers,pulleys ,computer,no big deal- IT GOT 12 MPG

he also had a longbed 76 dodge with a 440- IT GOT 12 MPG

i have yet to see a computer setup that does an overwhelmingly better job at mpg than carbs.

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I would not bank on that. Core T56's aren't that cheap, nevermind if they need a rebuild or any fresh parts. A decent clutch plus the hydraulic conversion bits are going to cost at least 500 bucks. Then the t56 to mopar bellhousings are in the 500+ dollar range. Then you need a new driveshaft, blah blah blah it all adds up quick. You may end up at 2k but I know for sure I'm budgeting much higher than that. Better to budget high and come back low than the other way around.

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If you are looking for mileage AND performance when mileage isn't the main goal plus cheap, you better become a Thermoquad guy.

Properly set-up they can't be beat. I have a buddy with a 78 Cordoba with a 360 Mag in it. 4000 lbs 3.21 gear on 275/60/15 rubber. Mild cam maybe a step or two up from a "good" stock 340 cam, headers, M1 dual plane and a finessed TQ. Has run 12.90's on slicks and gets 22 mpg highway.

Kevin

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I have a mechanic friend (a real mechanic, not just a 'parts-installer') thats a Holley guru that would agree with you 100%. I'm still not sold, but i'll concede that if everything is running/tuned perfect, the carb could at least be damn close. There are some pretty damn smart builders/tuners that still dont like EFI... even for MPG.

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My 87 Diplomat was running a 318 with a 600 cfm Edelbrock carb, MP ignition, A833 and 2.94 SG rear. Got 25 mpg highway regularly, on regular.

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Our Main Man "dmerc" has been there and done it.

25 plus mpg out of a small block stroker in a Duster.

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