Any modern engines or engine builds for modern results?

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1970boy said:
Would i have to cut my floor up to fit the A518?
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Yeah. You pretty much have to kill/butcher a large chunk of the transmission crossmember/torsion bar crossmember to fit an A518, they're extremely fat in the back and they want to take up a lot of the same space that's used by the torsion bar crossmember
 
1970boy said:
To me that basically means not an engine that would produce results such as 8-12 mpg, i want more efficiency
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That's extremely easy to do with 1960s technology.
 
what are the major advantages to the magnum 5.9 vs the la 360 ? should I go with the engine above and try to build a good combo with it? or would it be more worthwhile to build a 5.9 from the get go?
 
I like LA engines, but Magnums are good too. If going to OEM efi, maybe a nod to the Magnum. LA is a good simple engine.
 
You don't need overdrive but you do need high quality machining all around, a cam around 220° @ .050, and some good tuning prowess. A flat top piston and Magnum type head wouldn't hurt. Headers are mandatory. A tight convertor and numerically low gear (2.76s) will get you there if it's all matched and machined well, and then tuned well.
 
Plus to get a performance and mileage of a modern car you don't need as much power as since our cars are a lot lighter then most of these modern muscle cars. You could get by probably 100hp less. Which will be a much milder engine.
 
Thermoquad is the performance carb for power and mpg. Stock 340 intake or really any manifold with a spacer, but I never really liked spacers.
 
Do magnums get better mileage than the la 360's? head to head are magnums generallt more effiecient?
 
1970boy said:
Do magnums get better mileage than the la 360's? head to head are magnums generallt more effiecient?
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My 5.9 AWD Jeep Grand Cherokee only gets 12.5 - 13.5 mpg intown. It probably gain a few in an A Body so I'd say equal.

The magnum heads flows in between 1.88 and 2.02 heads with there 1.925 valves. There's like a 40 hp jump from roller LA to magnum and since the bottom end is very similar it seems to all come from the heads.
And the magnum long block responds really well to just a cam intake and headers.
It's the only heads I've seen reach 2 hp per cfm with out to much work. One of the reason the magnum supposedly responds better to cam changes is it better CR but haven't seen to many measure it's actually CR. We know LA is terribly inaccurate.
Haven't really seen a similar stock long block LA build to see the difference but stock the Magnum heads seem to have more potential but ported I think you can get more out of LA heads. Since most use aftermarket magnum heads now on a fresh build it don't matter if you start with LA or magnum unless you want factory roller then you need late 360 or magnum.
 
ENGINE
magnum 5.9

HEADS
-magnum engine quest heads
-tight quench .30 bowls opened up
-weisco dished pistons

INTAKES -MAGNUM HEADS DRILLED FOR LA INTAKES
-mopar m1 performance dual plane intake
OR
2176 edelbrock dual plane intake


CAMSHAFT
-Roller cam Compcams #20-000-9 506 lift 216 intake 224 exhaust duration.
OR
-Oregon Cam Grinders regrind214/224 and .512 lift, 110 LSA with thestock hydraulic roller lifters
CARBURATORS?
-Thermoquad 850
OR
-Edelbrock 1406


PROS
-hydrolic roller cam
-generally more efficient than la360
-option for oem efi


TRANSMISSIONS
- Silver Sport Perfect fit 6 speed
OR
-Silver Sport Perfect fit 4 speed auto
OR
-727/904 with gear vendor unit


EXHAUST
-Mopar TTI 2.5 inch dual exhaust system?
-best exhaust system option??


CONVERSION
-disc brakes?
-driveshaft length?
-schumaker creative services conversion mounts for /6 to 360

MISCELLANEOUS
-Aluminum radiator
-compression ratio?
-electric fan
-msd ignition
-msd distributer
-Tall tire 24-26 in
-Best gear ratio option??
-1-5/8 inch headers????Best size in your opinion


-so far have compiled this, any thoughts? , additions?, changes?, sugguestions? It would be greatly apreciated
 
The efficiency Magnums have is mostly in the heads, manifolding, and accessory drives. The roller lifters don't do much because they're heavier and the pushrod angle is worse. So once you take an LA 360 and change to those Magnum-based heads, replace the pistons with modern hypers or forged, stick in a retro hydraulic roller, and run headers - there's no real difference. Price-wise the differences are the cost differential of the lifters and the cam you chose to run, and the valvetrain for the Magnum setup. The last hydraulic roller I did I use stock lifters (roller LA block with LA heads). Much less $$ than any performance name brand version lifter and no performance drop.
The VAST majority of bad gas mileage reports are due to poor tuning ability. Mechanically it's not hard to make them efficient and good power is a side effect of that, but some people just don't have the experience or hands-on tuning talent. It takes very little to get mileage to drop 25-50%. Tire pressure and alignment alone can drop it 15-20% and that's on a modern car with all the electronic controls, OD, and weight savings efforts.
 
The reason you see terrible gas mileage in the Magnum-powered Jeeps is because the drivetrain is very inefficient and they are big, heavy SUVs. The Grand Cherokees that came with Full-Time 4x4 had a viscous coupling between the front and rear driveshafts (kinda like a torque converter), I'm sure you can imagine what having essentially 2 torque converters to push power through does to fuel economy. Those transmissions were never very efficient either, some guys on here with A-518 swaps are getting a few better MPGs but their drop in 1/4-mile times says a lot about power being thrown away. Manual transmissions FTW when it comes to gas mileage.

With regards to weight and especially emissions affecting gas mileage... A modern 5.7 Hemi Challenger weighs a hefty 4200 lbs and typically get low 20's/high teens MPG average with mixed driving. People who have swapped 5.7 Hemis into their classic Mopars that typically weigh at least 500 lbs LESS and don't have to worry about emissions are averaging mid to high 20's, slightly less if they didn't use an O/D trans or tall gears.

Since my 360 broke I'm going to build basically a 318-based version of the same thing and just swap over the stock Magnum heads, Air-Gap manifold, get a good modern street cam in the 220-230* @.050" range, put in some KB hyper flat-tops and top it with a 600 cfm Edelbrock or maybe Street Avenger Holley if I can find one for a good price. This combo is nothing new and is proven to make around 300 HP at the crank if done right (machining, assembly, tuning) and with good gearing 20+ MPG, at least on the highway, should be no sweat.
 
MOPEkidD-3 said:
The reason you see terrible gas mileage in the Magnum-powered Jeeps is because the drivetrain is very inefficient and they are big, heavy SUVs. The Grand Cherokees that came with Full-Time 4x4 had a viscous coupling between the front and rear driveshafts (kinda like a torque converter), I'm sure you can imagine what having essentially 2 torque converters to push power through does to fuel economy. Those transmissions were never very efficient either, some guys on here with A-518 swaps are getting a few better MPGs but their drop in 1/4-mile times says a lot about power being thrown away. Manual transmissions FTW when it comes to gas mileage.

With regards to weight and especially emissions affecting gas mileage... A modern 5.7 Hemi Challenger weighs a hefty 4200 lbs and typically get low 20's/high teens MPG average with mixed driving. People who have swapped 5.7 Hemis into their classic Mopars that typically weigh at least 500 lbs LESS and don't have to worry about emissions are averaging mid to high 20's, slightly less if they didn't use an O/D trans or tall gears.

Since my 360 broke I'm going to build basically a 318-based version of the same thing and just swap over the stock Magnum heads, Air-Gap manifold, get a good modern street cam in the 220-230* @.050" range, put in some KB hyper flat-tops and top it with a 600 cfm Edelbrock or maybe Street Avenger Holley if I can find one for a good price. This combo is nothing new and is proven to make around 300 HP at the crank if done right (machining, assembly, tuning) and with good gearing 20+ MPG, at least on the highway, should be no sweat.
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Thanks for the insight and info i really appreciate it, also where you say "good gearing" and "machining, assembly, tuning, done right" can you give more specifcs on what that would be to give me an idea on what to do for my build i want gearing to have decent get up and go in the city without sacrificing highway mpgs and as far as machining and assembly what should be done? Over bore . 30? Zero deck?
 
1970boy said:
Thanks for the insight and info i really appreciate it, also where you say "good gearing" and "machining, assembly, tuning, done right" can you give more specifcs on what that would be to give me an idea on what to do for my build i want gearing to have decent get up and go in the city without sacrificing highway mpgs and as far as machining and assembly what should be done? Over bore . 30? Zero deck?
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I would first find a competent machine shop (try to get recommendations for your area) and take what you have to them; they will be able to tell you all that it needs. The bores might not need to be increased that much; maybe .020" will be enough to clean it up and there are off-the-shelf pistons in .020, .030, .040, and .060" oversize but you won't know for sure until it is inspected by an expert. I would definitely recommend having it decked to blueprint, in fact square-decking is the way to go but I've heard some shops can't really do that properly so perhaps look into that (ask). Also have the rotating assembly balanced once you find out the bore-over and get the pistons. Lastly make sure the cylinders are honed with a torque plate (mimics the effects of having the heads bolted on which slightly distorts the bores from the clamping force).

Tuning would involve either getting a proper spark-plug reading tool (like a scope that an ear doctor uses) and/or a wideband O2 sensor with air/fuel ratio readout and tuning the ignition timing and A/F ratio to where you have a reasonably lean cruise mixture and plenty of vacuum advance and an advance curve that suits your overall setup (weight, gearing, trans, etc.). For gearing it's generally accepted that 3.23:1 is the best all-around ratio; tire diameter will change that too so depending on that 2.94s or 3.55s could work as well. But then if you run an overdrive transmission you could run shorter gears than that say 3.73-4.10:1...

My '70 Duster currently has 2.94 gears in the rear and I plan to put in a 2600-stall converter I have on the shelf. I will probably swap to 3.55s for better performance but I know my gas mileage will take a dive, which I'm OK with because I'm turning it into more of a weekend fun/track car than a driver which it used to be.
 
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Something else to consider from the efficiency aspect... building an engine with good quench (closed-chamber heads, zero-decked block, flat-top pistons) will allow you to not only run a higher compression ratio but it will make the best power on a leaner air/fuel ratio and it will continue to run smooth at leaner cruising mixtures; as in a quench engine can smoothly run on 17-18:1 A:F but if you try doing that on an original 340 with open-chamber heads it will probably surge and eventually overheat and/or ping. Point being that all saves gas because you're using less fuel to keep the engine turning.
 
I'm putting together a 340 with ported Edelbrock heads, Comp 222/230 .538/.534 lift hydraulic roller cam, drop in lifters, Super Victor EFI intake, FAST 4150 throttle body, & FAST XFI Sportsman EFI, backed with a Tremec 3550 5-speed. It's going into a 72 Duster 340 clone with 3.91 gears! Engine is at the machine shop. Hope to have it ready by summer!!
 
darndart said:
I'm putting together a 340 with ported Edelbrock heads, Comp 222/230 .538/.534 lift hydraulic roller cam, drop in lifters, Super Victor EFI intake, FAST 4150 throttle body, & FAST XFI Sportsman EFI, backed with a Tremec 3550 5-speed. It's going into a 72 Duster 340 clone with 3.91 gears! Engine is at the machine shop. Hope to have it ready by summer!!
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Sounds like its gonna be a sweet build! Is there a lot of fabrication involved in putting the tranny in your a body?? How are you going about doing that?
 
From what I've researched the tunnel will need some work. I've found some pics to kind of go by. It's going to be a process but well worth it!
 
I like Passons Hemi O/D gear set in a A body 4 speed. 18 spline input shaft, .80 O/D using standard A body main shaft, housings, and shifter. It will be good enough for me.
 
darndart said:
I'm putting together a 340 with ported Edelbrock heads, Comp 222/230 .538/.534 lift hydraulic roller cam, drop in lifters, Super Victor EFI intake, FAST 4150 throttle body, & FAST XFI Sportsman EFI, backed with a Tremec 3550 5-speed. It's going into a 72 Duster 340 clone with 3.91 gears! Engine is at the machine shop. Hope to have it ready by summer!!
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Let me know when you're ready to have that Sportsman system tuned.
Rich
 
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