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4.7L vs the bigger egines?

5K views 22 replies 5 participants last post by  SnoylCC5 
#1 ·
Hey guys I tried to find a search bar to ask my question, but couldn't find it...

So hopefully you all don't mind me asking!

Is there a big power difference (that you can notice) between the 5.7 or 5.2 (compared to the 4.7L)? I'd imagine one of the only reasons to go with a 4.7 is to save gas (maybe i'm wrong). Is there really a big difference? Also, is there any problems with the 4.7 model vs the other two? Like different that the others or would one have the same as others?

I'm sure I have more questions for you all. I'm currently looking to buy something within the month, and want to know as much as possible before going into the dealership.

Thanks a lot guys!

Josh
 
#2 ·
4.7 and 5.2 about the same amount of power, but the 4.7 will get you better mileage. BIG power difference between 4.7 or 5.2 and the 5.7. The 4.7 seems to suffer from a sludge problem if not properly maintained, but otherwise seems to be a good engine. One thing I have noticed with that engine family (3.7/4.7) is you have to take great care of your cooling system. From what I have seen everyone who has overheated one has had it fail not too long after, mainly from a valve seat dropping out of the head.
 
#4 ·
From what I have heard, the 4.7 doesn't get all that much better mileage than the 5.7 since it's such a small engine pushing a big truck. 4.7 does the trick for most things, but most people say they'd like to have the 5.7 for the power. You can make a 4.7 almost as good as a stock 3rd gen 5.7, but if you start with the 5.7 you're up over a 100hp from the get go.
 
#6 · (Edited)
If you're talking about new trucks then you're talking about the new 4.7L, just clarifying...

As far as sludge issues, I've seen a lot of this online but never actually seen it. I know a bunch of people that have pre 2008 4.7L's and they don't have sludge issues(they do maintain their vehicles well though). I have never heard of any sludge issues with the 2008+ 4.7L.

As for the overheating I'd agree that's true but if you overheat any iron block aluminum head engine you are going to crack a head or have a head gasket leak, so I wouldn't say that's a "down fall" of the 4.7L.

The 3rd gen hemi has 345hp/375lbft. The 4th gen hemi has 390hp/409lbft

The pre 2008 4.7L had 235hp/295lbft. The 2008+ 4.7L has 310hp/330lbft.

All the engines are good truck engines(ample torque for a half ton truck). If you do heavy towing I'd avoid the older 4.7L. Also, everyone I know with the older 4.7L gets roughly 15-17mpg avg. Everyone I know with the older hemi gets roughly 12-15mpg avg. Depends on configuration and driving obviously.

I have known a few people with the new 4.7L and they all get about 15 city/20 hwy. I get about 16 city/21 hwy with my quad cab, but I have a tuner that adds nearly 70lbft of torque at low to mid rpm.

People with the newer hemi get about 15city/20hwy from who I've talked to and what I've seen. Nearly as good as the new 4.7L.

Without the tuner my truck is "adequate". With the tune my truck feels great, and I'm more than satisfied with the power. It is quick enough, has plenty of grunt, and tows light to medium loads fine. If I were towing 5,000+ lb I'd want a hemi though.

One reason I love my 4.7L is because it does not have MDS, VVT, and Variable Intake Runners or whatever it's called. All this stuff gives the hemi a lot of power and mpg but I would just fear replacement costs when they go bad, as I plan to keep my truck damn near forever.

I'm very happy with my huge truck's mpg, and think it moves out pretty well too. Honestly, the only time I can tell a difference in my truck vs my freind's RT hemi or brother's express hemi is at WOT. Anything under 1/2 throttle and they feel identical. So if you aren't racing or towing heavy you don't need a hemi. I will say though that if I couldn't tune my 4.7L I'd probably want the hemi....and the new trucks can't be tuned, so.....

To put it in perspective with the tuner, the new 4.7L is ~340hp/375lb ft with the tuner, intake, exhaust(easy mods). What's even better is the tuner adds almost 70hp/70lbft MAX gain at lower rpms(not peak hp/torque). So you get more usable power.

Hope this helps.
 
#7 ·
Snrusnak, I don't think I would buy anything newer than a 2008, unless I saw a GREAT deal. I don't do any hauling, except some once in a great while move of furniture. I mainly wanted something with a bit more power than my 99 5.2L, and the most reliable between the 4.7 and the 5.7 (and I think the 5.2), if that makes sense. But from what your saying it sounds like with a little bit of cash I can make a 4.7L fairly quick, with decent gas mileage. Althought a tune, CAI, exhaust, headers, and a little bit more mods, is something I would do to any truck that I get. Just when I think I figured out what i'm going to do, more info gets added! Haha. I appreciate the info.

Thanks,

Josh
 
#8 · (Edited)
i love my 4.7, but i find it a bit gutless at times (especially since coming from a 5.9 in my previous truck), the fuel mileage is fantastic. although, like sean stated, the Hemi gets amazing mileage too with the MDS and VVT. If i had more time to buy a truck when i needed it (mine died and i had to practically buy the first one i found in decent shape) i would never have considered anything but the hemi...

sorry to the OP for this thread jack...but what tuner do you run sean?

Im too am looking to do the exhaust and CAI, so the tuner would be the next logical step. I can't even get the tires to break loose unless its wet out.
 
#9 ·
Nabors,
Honestly if you are looking at 2007 and older 4.7L's, I'd skip and get the hemi. Of course it depends what your use will be but they are not quick trucks. They have torque but most find them lacking in the hp.

primo I have the superchips flashpaq. I know guys that used the diablo on their 2008+ 4.7L then the superchips and said the superchips had way more power. I'd get the tuner before anything else, I get at least ~1mpg better and the power difference really is incredible. Feels like you added a cylinder when tuned.
 
#14 ·
so im just researching your tuner...

here are some silly questions.

does it plug in to the truck and then does the module have to be mounted somewhere?

does the tune come pre programmed??
 
#15 ·
It plugs in to the OBD2 port and you follow instructions on the handheld tuner, then about 15 minutes later you unplug it and store it under the seat. The reason to leave it in the truck is just in case there's an issue and you need to plug it in(say you are on vacation out of state and something happens and you need to tune back to stock to take it to the dealer, etc).
 
#18 ·
excellent...:leghump:

i just found one in canada for 339...good price?? looks like i can get the diablo cheaper, but if you say this is the one, then im with you...

just to recap...so without any other peformance mods, this tuner will chirp the tires?? ive got the 20's...and 3:55's.:4-dontknow:
 
#19 ·
Well my truck (quad cab with 17's and 3.55's) would usually chirp the tires (open differential) when stock. The tuner certainly helps out lol. Most of the torque increase is at low to mid rpms like 2000-4000 rpm so it helps greatly with acceleration, even with moderate driving.

I paid $330 for mine. I bought direct from SC, you can sometimes find them cheaper(or used) but they are local to me so I just figured I'd buy direct.
 
#20 ·
yeah i can gt it local and shipped total price for 339...so i guess its pretty good.

i have the 3.55 Rear Axle Ratio and the Corporate 9.25 LD Rear Axle..with the traction control button..so open diff??
 
#22 ·
yup..no anti spin diff..

but i will say when i got my rear end rebuilt, the dealership put the posi additive in...for some reason...

"hoping they put a posi in":devil:
 
#23 ·
sorry to jump in here, but i have the "old" 4.7 (07 QC) and it is.... slow. :i_rolleyes: It has adequate torque (i pull absolutely nothing and only load my bed down with the occasional fire wood). it will still beat a ford fusion or those types of cars. but put up against cars/trucks that have any balls, i dont stand a chance after 30 mph. however, with the being said i still love my truck. it cost me $3,000 less than any other dodge with a hemi in the year and mileage and it was a good deal. i bought it used. if you dont do much heavy towing or pulling then i would say try the 4.7. you will save some money (unless you can get a good deal on a 5.7). and with a tuner, im buying one soon, it really will do everything i need my truck to do and look damn good while im at it :D
 
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