Hello everyone,

New here. Know the 5.9L magnums are horrible for fuel. Anyone have any ideas or luck getting better with upgrades that arnt super expensive?

I have seen Hughes has that upgraded edelbrock intake but CDN$$ its close to $900 without shipping and gaskets etc

I have seen other intakes that are not the hughes one that are for alot less (on amazon and edelbrocks site etc) and say they bolt to the small block chrysler 5.9 (360ci) block i have, but are they any good?

I have done plugs, need to do wires and would love to do a MSD setup but again $$$$

also any suggestions on replacement "carbs" also?

thanks everyone.

joker

 

The 5.9 is not a real efficient motor, and just changing the intake won't help that. A lot of the carb manifolds are for the LA series engines though, (92 and older for the 5.9) and won't bolt to your magnum. Going to a carb will actually COST you fuel economy, as a carb can never be as efficient as fuel injection.

These days though, there is just not a lot of aftermarket support for these engines any more..... I think fastman still makes a 50mm throttle body, which is good for a bit more power/throttle response, but, won't really help with fuel mileage. (I won't even call it 'economy', as these engines are anything but 'economical'....)

The best way to improve gas mileage would be a lighter foot, (I hear they have them on sale at walmart....) or a custom tune. Can do some amazing things with custom tuning, but, the learning curve is LONG and STEEP.

 

I was going to mention I don't think you can buy an air gap intake anymore, new anyway. I would love to find one for mine. New plugs, maybe 02 sensors and catalytic converter.

Its been a lot of years since i daily drove a 5.9 magnum, but if i recall take anything over 7mpg and be happy.

 

I figured / knew there wasnt much support for it (sadly) anymore or ever. I mean it's really an impractical engine but with all the issues the older hemi (the '02-04 at least) has and the 3.5 V6... it would be nice if there was even a slight hint of more support, but ce le vie...

I was just hoping an aftermarket intake would help solve the plenum issue as well as perhaps give me slightly better gas mileage. Cause I think my plenum is leaking too I think.

Yah I had an '04 magnum with the hemi in it and it was brutal on fuel too but not quite as bad *laughs* love the truck tho...

Also for clarification when I said "carb" i meant intake throttle.

As for plugs and O2 I have done em in last yr. I have some more I gotta do (like pass front wheel bearing, shocks etc) and aluminum rims instead of steelies. But I appreciate the help!

I am getting about 18.9L/100km or 400km to a full tank.
Don't know the conversions. I am not expecting ever to get even 16L/100km but even 18.4L would be great!

thanks again everyone!

Joker

 

The plenum issue was mainly the bolts were simply too long. Pull the intake, change the gasket, use shorter bolts, or trim the existing ones, and the plenum is no longer an issue. I went the aluminum plate route on my 96, and it was still clean six years later when I sold it.

 

18.4l/100km is around or just under 13mpg, so you're doing quite well in my opinion. I'm not sure what hemi issues you are talking about directly. to me the 03-04 hemi was the best of them all (there was no 02 hemi), maybe the eagle head engines are comparable, only because better heads to offset the poor cam n lifter design. The biggest down fall to the hemi or any pentastar motor is do not idle them, and 5w-20 is to light of oil.

My 1500 mega will average 15mpg or closer to the 16l/100km you desire on the highway, 13mpg daily driving and that's rolling around a 5000-6000 truck on 34" tires.

 

really? Hmm.. I may, just i am running 18.9/L - 100km and it's a 4x4 truck I get it. Just hurts at the pump so wanted to try and extend it a day or two. I mostly do city driving unfortunately.

thanks for that advice tho. I will deff check it out. I have done the pcv, plugs, cap and rotor and waterpump and steering rack just before got the truck. Also helped my mechanic replace the trans too.

Just gotta do a few others, wires, belt and tensioner pully.

so I am deff gonna keep it in mind about the plenum and the bolts. As I said before was just hoping someone had luck finding a more efficient intake and throttle body too.

ce le vie as I said. Love the truck, hate the fuel mileage.

thanks again

joker

 

So you think bigger tires help? I am running the 17" and i had a magnum with the 5.7" hemi with 19 or 20" i think (forget the size but they were stock) and i hated movin em! Too damn big.

Thanks for the '02 hemi clarification. I didnt know exactly when they came out. I just remember that magnum ran about 15 or 16L/100k I believe roughly and even tho the magnum engine isn't as efficient I was just hoping to do better then 18.9. Although when I got the truck a year and half ago it was running 19.9 so... there have been improvements lol

My wife has the penastar in her '14 grand caravan and has the oil filter leak that I am gonna take care of in the warmer weather. So thank God it's that and not somethin worse but still... *ugh* lol

As for mine I forgot I also have / gonna do my pass front wheel bearing (non-abs) cause my driverside dropped and I did it a few weeks ago and looked like factory... so gonna just do other too cause don't wanna be driving and have it go.

driver side didn't let go but once I got it home, parked and in the air, the amount of shake of that tire bolts securely to the hub... :🫣🤯😤🤬 scared the 💩 outta me cause I had my wife and kids in it like 20 min before I found that out...

so all in all better fuel economy has to be in the cards somewhere right? Play lie to me and say it is 😆 🤣

thanks for helping me out everyone.

🃏

 

If it has a buncha miles on it, doing the timing chain and gears will likely help you out a bit as well. I was absolutely amazed at how much better mine ran after doing so. (I had a coolant leak from the timing cover, so, I was right there anyway... and swapped 'em out for a good double roller set.)

My 98 has the 8 liter V-10. If I can manage to break 10 mpg, I feel I am doin' good. I think my 96 averaged around 13 or so......

 

Hmm... that's a good call. Wife may not like the price tag *laughs* and understandably. My truck has over 263K on it.

What do you mean by double roller set? I have never done a timing chain / belt etc on any vehicle. I know what they do and all but again never done one.

Thanks again

🃏