I agree on the PITA on maintenance of the 3.6. I am approaching 75k and will be changing plugs soon. I will be checking the rockers as well while that far into it.
Into the weeds engine design for fuel efficiency discussion.
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I agree on the PITA on maintenance of the 3.6. I am approaching 75k and will be changing plugs soon. I will be checking the rockers as well while that far into it.
Dave_J
Well-Known Member
If you could divorce the Body computer from the engine management computer then just use the whole engine wiring harness in a A body.
Way too much work for me.
I agree. Idea that won't happen by my hands. Already a dozen or so projects on the list.
Dave_J
Well-Known Member
Where is the dividing line between total build for max efficiency or just freshen up a good combo and pay a bit more in gas?
Adding a Gear Vendors OD will set you back about $2500. How long will the better gas mileage take to break even of the unit costs and having the driveshaft shortened?
I mean, take my 78 LRT. If I needed it to tow a small trailer a lot then I'd maybe put a complete 2000's two wheel drive Dodge 1500's wiring, 5.9 Magnum engine and A518 trans in it then tweek it with a "HP Tuner".
Adding a Gear Vendors OD will set you back about $2500. How long will the better gas mileage take to break even of the unit costs and having the driveshaft shortened?
I mean, take my 78 LRT. If I needed it to tow a small trailer a lot then I'd maybe put a complete 2000's two wheel drive Dodge 1500's wiring, 5.9 Magnum engine and A518 trans in it then tweek it with a "HP Tuner".
I am usually all about the bucks down approach. In this instance though I am building either a big block or small block stroker. Either will have a 518 behind it. Just looking to get close to the best possible combo. Only see gas getting more expensive over the long haul.
Dave_J
Well-Known Member
Then a used 2000's Dodge 1500 with a 5.9 and A518 would be my choice.
Get a Scat Stroker kit for the 5.9, bore it 0.040 over and have a 410ci. Put a mild fast lift ratio Roller type cam in it and have 425 HP and (A flat curve) over 500 Lb/Ft from 1800 RPM to 5200 RPM. Use the Kegarator manifold with some mods and the engine computer from the truck. Then a HP Turner to tweek the setting.
Blueprint Engines and others have 5.9 stroker short blocks and long blocks, just whip out the VISA and smile.
I bought a ATK 410 Short block 3 years ago for $2500.
Right, and to attain the mpg goal, at some iteration in the design planning the rpm and conditions (parameters) need to be determined.
We know mixture density must increase under high load conditions, and ought to be moderately rich at idle for power.
If the engine is going to be in stop and go traffic alot, then mpg is going be greatly effected by fuel consumption at idle. (Yes a smaller engine will help greatly here)
But as you and others have pointed out, if the engine will be under load for large portions of the operating time, then it needs good part throttle efficiency and ought to be designed so to minimize the time it needs to go to high load enrichment. (A larger engine should help here, depending on gearing available and speeds that this load will typically be pulled).
If going with a larger engine but where time idling is significant, then being able to run very low idle speeds will help economy even though they require richer mixtures.
Interesting discussion.
You also got to factor different engine sizes with similar performance the smaller one needs more rpm and overall gearing probably negating any mpg advantage. Plus why do people generally want diesels most will say torque, but really cause it makes peak power at a very low 2500 rpm which allows you to operate at peak power at normal driving speeds for long periods of time so you can put everything the engines got to tow/work. Most truck gas engines are gonna make peak above 4000 rpm so generally out of range and wouldn't handle being at peak for long periods of time. The only main way to improve NA power idle to 2500 + rpm is displacement bigger the engine will generally have more towing power, above 3000 rpm don't matter much for towing but good for fun even then you probably want to keep peak hp no higher than 4500-5000 rpm. To me that means you either build the biggest you can or the size that will make your desired hp between 4500-5000 and build it the best you can to be good on gas or at least don't do any thing that will kill mpg. It's easier to ruin mpg then gain it, to me it comes down to cam choice for best mileage and head choice for best power, look at LS and Gen 3 Hemi they make power with heads and smallish cams.
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