ENGINE SWAP -or- SELL! the final say for the most efficient square body motor!

[fussfeld]

i request a continuance on this discussion at least until the weekend. i'll have more time to discuss then.

In the meantime, i got a high of 19.49 mpg with a 4.3 and i'm averaging 17.5
http://forum.73-87chevytrucks.com/smforum/index.php?topic=33619.0

 

[foamypirate]

I mean seriously, come on. A vortex "ls" swap is ALREADY more tired and played out than black wheels. People spend THOUSANDS swapping in a $200 or $300 motor only to have it blow up and NOBODY ever questions why you can pick them up for next to nothing and junkyards are full of them? It's only 10 years old!
Really NOBODY EVER says "hay wait a minute, I can make double this power for half as much if I spent it in my original motor!"

?

It's just me I guess. Enjoy your LEDs and 40 series trail grapples. I hope those blue lights help you see the curb really good because if you hit one, you're really screwed! Have you even paid for those wheels yet?
Just like lowridin on 13s back in the day except we weren't POSERS.
It's ALLL hype , like obamacare. Trendy, fake ******** with zero sex appeal. I could not care less!

Like watching some dudes in this MSB fix up a truck , it's great to watch and then?
The dreaded LS swap. Aww ****! Just when it was gettin good.
Never mind !

I think that is the newest best way to ruin a truck and destroy value.
I guess MAYBE if they were as great as everyone seems to think they are, I'd feel differently. BUT I wouldn't.

Fabbed up motor mounts I guess, hadn't really considered that but how bad could it be?
http://www.hotrodders.com/forum/l67...uestions-229504.html#/topics/229504?_k=3wuipu

I've got a good line on F-body parts, all I'd have to do is ask.

Well, and pay... but I bet it's CHEAP.

You really need to stay away from the cheap crack...
This rant has no connection to reality.

 

[fussfeld]

i'm sorry i just don't have time to really get into it on this subject. However, i did re-read your original post and it appears you have 4X4? (which is a problem as far as mpg....) AND you already have a 4.3 v-6 ----and you're getting 12-14 mpg.

i will hopefully have more time to discuss in depth this weekend.

 

[silverscottsk10]

Sent from my iPhone using Tapatalk

 

[fussfeld]

Ok, i finally got more time to discuss this interesting topic. Hopefully it's not too late, but even if so we can still discuss in general.

i had a few questions for you:

1) How much driving do you do on a weekly basis? How far is your daily commute?

2) How are you calculating your mpg?

3) How fast do you usually drive and at what rpm is this?


Now a little background on me:
i also have a 4.3. i am also running a TH-350C and 2.56 rear gear, 2WD. i am averaging 17.5 mpg---this is mostly a 75% highway and 25% city/other mix. i do not drive faster than 65 most of the time. 65 mph is about 2100 rpm, 55 is about 1800 rpm. i have gotten highs of 18 and 19mpg with ALL highway driving on long trips. More info can be found at the above link i provided.

Now, you have 4X4, but you also have fuel injection wheareas i'm running a carb and i 'd say you'd have the advantage there---i am not a quadrajet tuning expert. So i'm thinking the major difference between your's and mine's rigs is the 4x4, and is the 4x4 really costing you 3 to 5 mpg compared to me? And again, this is why i want to make sure we are calculating mpg correctly.


Now, let's get into the engines you've brought up which is the meat of the discussion:

1) 5.7 TBI with roller cam: You already have TBI and the 4.3 already has a roller cam. So i do not think this will do any better than the 4.3---- and we are talking 88 more cubic inches!

As a side note of interest to this, both the 350 and 305 that i ran in this truck before the 4.3 averaged about 16 mpg. i was able to get highs of 17.5 ish for all highway long trips. And these both had non-roller cams. And both ran carburetors---the 350 had a quadrajet and the 305 a 2G.

2) 5.3 LS/LS engines in general:
i think this one has potential; i rented a 2002 (or 3, whenever they went to LS?) extended cab 1/2 ton WITH 4X4 and was able to get 19.8 mpg on long highway trips.

However,i think the problem here is that an LS swap will take too long---especially if you need this as a daily driver; The swap is more complicated than you might think in my opinion.

It would be cheaper and easier to buy a truck that already has an LS if you need a truck. This includes the newer 2003 and up trucks.

Keep in mind i am NOT an LS expert and have no experience swapping one over. But i don't think this is a quick and easy swap.

3) The cumminses:
i have no experience of knowledge here so i can't comment.



The 6.2/6.5 diesel:

Here is an engine that i'm pretty sure WILL get well over 20mpg. It's an engine i'm gradually leaning to swap. i'm still not happy even with the 17.5 average of the 4.3 and plus i just like diesel engines.

The problems, in my opinion, here are:
1) Where to get a decent reman or new 6.2/6.5? Sure you can try the junkyard but how do you really know the condition? Do you want to take the chance? You can rebuild a junkyard engine with good results, but what if you don't have the time/experience/interest in doing so?
i think GM sells a new one for $6000+.

2) The swap, while not "difficult," is likely not a "easy bolt-in swap" either: The engine should drop right in---assuming you have the right frame towers (not too difficult to obtain) and should bolt right up to the transmission.

BUT
The 4.3 exhaust will not bolt up, also you need hydroboost, glow plugs, possibly dual batteries (not 100% sure on this) and probably a lot of other junk that i don't know about. This will always take more time and money than you think.

So let's say you do get one for $6000. How much driving do you do? It make take a while for it to pay for itself. It may never pay for itself.

It may be better to stick with the engine you got even if it's thirstier.

We have not discussed aerodynamics yet. But i'd like touch upon that later.

 

[marks86]

First and for most I read the thread and I cant seem to find what rear-end gear you have. That's going to effect this a lot. Lets say you have a 3.08 or a 2.73 which is pretty much the only way your going to get near 20mpg with any of these motor options. Now on the other hand your going to give up a lot of towing power and as long as your ok with this just being your DD and just trying to get the best MPG you can then ok.

1.350- tried and true. reliable tons of aftermarket, but all it is, is a bigger version of the motor you have. So don't plan on getting better mileage with this option or 20mpg. Easiest way for you to make more power and easiest to swap by far.

2.5.3- IMO this is your best option, your going to get around the same mileage as the 350 but engine will be lighter, more reliable and welcome your square to the 21st century.Also check out the 4.8 that's a great little motor

3.6BT Cummins found in the dodge trucks- Your not going to get 20mpg. Bottom line. These engines are heavy but very reliable and make great power. Dodge guys will tell you all the time how great the mileage is towing 20k pounds. its all BS. A 1996 Dodge 12v cummins with 3.42 gears gets around 15 MPG and around 10 towing 10k. Problem is you will start looking at the simple cheap upgrades for it. Once you do them it will just spiral out of control and kiss any kind of fuel mileage goodbye(ask me how I know.)

4.4BT Cummins- great engine its just a 6BT with two cylinders taken off. You will indeed be able to achieve 20MPG or over with these motor and it wont even break a sweat doing it. Only problem I see with it, is its expensive(more expensive than 6BT) and parts are hard to find. With that being said not the best option

5. 6.2 diesel- Great motor but very under powered. I can say this because I DD one for a year. I had 4.56 gears and I could keep up with traffic till about 30MPH then I had to hammer it just to keep up. Didn't like it one bit, also doubt your get 20MPG more realistic is 16-18. Its possible 2wd truck, low(numerical) gears downhill you can achieve over 20 but everyday driving probably not.

6. 6.5 diesel- Made more power than the 6.2 but came with many problems along the way. Not worth the time and money IMO and got around the same mileage maybe a little less than the 6.2

All in all 20MPG is pretty hard to achieve in one of our old squares My personal opinion if I was looking to get the best mileage I can while still being able to retain reliability and made power I would without a doubt go with the 5.3/4.8. there all over the junkyard for dirt cheap.

 

[fussfeld]

That's true---i forgot to mention gear ratio.

 

[kleedus]

I would swap in a 5.3 4l60 and run it. I daily drive a 06 with a 5.3 I am building its replacement now a 84 crew cab lifted with big tires and a vortec 383 I will be lucky to hit 16 mph but I don't care its a square that will be mine and stand apart from the clone drones everyone else is driving now days.
or my other one with almost the same set up but it will have a 2010 6.0

your 4.3 is a horrible engine for a full size 4x4. I bet a 350 would get better economy

you might look at the 4.8 ls they are still around 300 horse stock. more things to consider for economy. what tires you run what gear ratio. transmission plays a big part overdrive is a must.
a tonneu cover will help with aerodynamics

another thing to consider with a diesel swap is the cost of basic maint. oil changes and so on are a lot more expensive.

plus any break downs are lots more expensive than a gas engine

I would not swap a diesel in unless I need it to tow. don't get me wrong they are awesome but not cheap at all
the high cost of running it and higher break down maint. would take forever to recoup

 

[bluex]

I've come to look at this problem this way.

If I'm buying something new or newer that has a payment then fuel mileage is a big concern as part of my budget will be taken up by the payment and higher insurance/registration costs.

If I'm not going to have a payment on it then I have that payment amount I can spend in gas before I need to worry about fuel mileage. Its also cheaper to register and insure something older. Thats just me though, I daily a 99 silverado on 315's (35s) that probably gets about 12.5 mpg. Its paid for so I dont care though, honestly my square probably gets better mileage than it does lmao.

The main problem with trying to justify an engine swap (or a newer vehicle) soley on fuel mileage is the time and miles driven to get a return on that investment. By the time you get the swap amount out of the fuel savings the drivetrain is worn out again and you start all over. Or your stuck with a boring underpowered civic for 10 years because you want something good on gas....

 

[Rusty Nail]

I asked someone with greater knowledge, regarding this subject, because i have a sincere interest. His reply was that the 200hp RWD 3.8 in the Camaro is NOT a series 2 Buick 231, which is what I want. He says it's a Chevrolet engine and a pile of **** in comparison. THEN he raised a good question himself..Why doesn't anyone else use it?
Hmm.
Motor mounts, haha?
I don't know.

Because it's a p.o.s. Lol?
Maybe the 262 is a better plan. But idgaf about that. Totally not cool in contrast even though the "good" CPFI vortex 4300 is rated at the same 200 HP, it's still gay...

I thought people drive squares because they want to. It's made of METAL. It has no computer. You can fix it with a shovel. It has value and style.Class.Flavor.
If you want good gas mileage, invest in disposeable , recycled plastic. I think you're wasting your time.

 

[87scotty]

I asked someone with greater knowledge, regarding this subject, because i have a sincere interest. His reply was that the 200hp RWD 3.8 in the Camaro is NOT a series 2 Buick 231, which is what I want. He says it's a Chevrolet engine and a pile of **** in comparison. THEN he raised a good question himself..Why doesn't anyone else use it?
Hmm.
Motor mounts, haha?
I don't know.

Because it's a p.o.s. Lol?
Maybe the 262 is a better plan. But idgaf about that. Totally not cool in contrast even though the "good" CPFI vortex 4300 is rated at the same 200 HP, it's still gay...

I thought people drive squares because they want to. It's made of METAL. It has no computer. You can fix it with a shovel. It has value and style.Class.Flavor.
If you want good gas mileage, invest in disposeable , recycled plastic. I think you're wasting your time.

Lmao why has noone said lil turbo on her i went from 25mpg in my lil honda to 35 when i boosted it motor dosnt habe to work as hard when ya force the air in just an idea gotta keep your foot out of her though or itll do the opposite

 

[CSFJ]

Lmao why has noone said lil turbo on her i went from 25mpg in my lil honda to 35 when i boosted it motor dosnt habe to work as hard when ya force the air in just an idea gotta keep your foot out of her though or itll do the opposite

Maybe. I get the logic behind the engine not working as hard, but the honda doesn't have a coefficient of drag equal to an average barn. Anytime you pump more air into the engine you have to add more fuel. Any advantage you may see would be negated by the brick like shape of these trucks.

 

[MikeB]

You basically come out even, assuming you can get up to 20 miles per gallon and drive the truck another 100,000 miles. If you can't get the mpg that high, or don't get 100,000 miles, you are money out of pocket on the change.

You beat me to it! And that assumes the conversion goes well, which they rarely do. Is 20 mpg even realistic in a 4x4?

If the current engine runs fine, I'd stick with it and do some fine tuning in the areas of fuel injection and ignition timing. I'd also go with dual exhausts, or at least the most efficient single exhaust I could find.

I'd also learn the various emission control systems inside and out, and make sure all are working properly. Even a cracked vacuum hose can cause a loss of fuel mileage.

 

[johnnieb]

Let's face it, we don't really own these trucks because of their outstanding mileage per gallon, I have an 06 duramax that gets over 20 cruising at 75, " towing is a different story". but to tell you the truth I like driving the 85 around town, Buy a commuter and keep the square.

 

[Overland Suburban]

So this is a bit of an old thread but its been a few years so I thought it might be worth resurrecting and hopefully a few people might have some things to add. I know I do!

First off I'd like to touch on the idea of a 12 valve cummins swaps. The only thing I could find in the thread about this is your going to get 15 mpg. Coming from a family that has worn out well over 20 dodge diesels first gen, second gen, third gens, and working on wearing out a number of 6.7s I can say my two first gen 12 valves with the rotary pump got over 20 all day long at wide open throttle in a 4X4. My brothers 12 valve had a turned up pump with 3200 rpm spring and he averaged over 26 mpg in a 5 speed 4X4 truck. My 2 wheel drive 1990 5 speed truck is bone stock and gets 24mpg on the highway and 21 running around town! 15 mpg out of a 12 valve is one sick peace of ****. I tow a 15,000 lb 5th wheel with my 1990 2 wheel truck and it gets 17 mpg. That's a 900 mile trip pulling from Montana to California. Like I said 15 mpg is one sick son of a bitch! So some folks are going to say the 12 valve swap is going to cost you $15,000 and so on. Nope! Not if your smart. In fact I see one fella on this forum who accomplished his 12 valve swap for just $2500. Look around for a used truck for cheap there out there and more common everyday. Lots of folks seem to worry about a cummins with 300,000 miles. My 12 valve with the highest miles has over 700,000 miles on it and has never been apart. My other truck has over 550,000. So what kind of mileage can you realistically expect. With some mild mods on a 12 valve that's tuned properly 25 mpg is not a great feat to accomplish. I have an uncle who's pulling 32 mpg with his. Hes smarter than his nephews though so it isn't fair. Hes accomplishing 32 with a p7100 pump 12 valve 5 speed 2 wheel drive. His only mods are the max hp fuel plate and I think a 3:07 rear end instead of the 3:54 the 5 speeds came with.

As far as a square body with a 350 I have some personal experience with that with a 74 4x4 step side I used to have. It had a small Holley 4 barrel and the 172 heads on it and with a good tune, the front end properly aligned, and timing advanced a touch it always pulled 17 mpg on the highway.

My cousin used to be the proud owner of a 1997 chevy extended cab 4X4 with the vortec and some kind of aftermarket chip he had put in. We made a trip from Montana to Southern Oregon to fight fire in 2002 and averaged 21 mpg at 75 mph. I remember a good many folks with trucks from that era that were getting 18,19 in 4X4s at interstate highway speeds

I can't count the number of pessimists ive encountered on this sight in reading the last week just checking it out around here. You would think 12 mpg was pure luck and 8 mpg was more like it. That just isn't so....If you want options there are options and if your willing to learn some tuning tricks you might be surprised what you see. If I decide I want to deal with 1200 lbs on my front end I know I can get well over 20 mpg with a 12 valve.

A few years back a good friend built a 1970 GMC 3/4 ton long box with 35s and a 400 with the Edelbrock Performer Cam, intake and Carb with a custom fuel plate with holes drilled in it that he always put below a carb spacer. It added a lot of low end torque atomized the fuel better to about 3800 rpm where lost on top end. Didn't much matter because that truck was a pulling Sumbitch that was getting 17 mpg on the highway with a lift and 35s.

No fuel injection, no roller cams, none of the fancy stuff just a good wrench and a few tricks.

Hell, I'm thinking there has to be someone out there pulling close to 20 mpg in a 4X4 with a properly built 383 with roller Cam and Rockers. Where the hell are you and post how you did it so I don't have to guess when I do my 383 build


Tracy