School me on the 454...

[ScottyB]

Remember when I said I knew less than someone who knows enough to be dangerous? Here is where I prove it.

I have the goal of turning my '77 stock C-30 into a gas mizer. I understand that the 454 is known as a high torque engine. Keeping in mind that any towing I would do with this I could also do with my 4 cyl Ranger if I needed to, how would you rebuild a 454 to squeeze the milage out of it?

First thing I always hear is to ditch the carb for TBI or MPI. I see the logic there and I am thinking about the Holly Avenger EFI kit. The cam always comes up and I am told to put in a mild or RV cam. I understand what a cam does and how it works, but the magic behind the numbers is more voodoo that stumps me. With the cam, obviously goes the heads. If they don't match than you are just mixing expensive parts for the sake of spending money. Mild cam and matching heads sound like the way to go but I can't explain why in a way that makes me comfortable.

While I have the engine torn down, it is obvious that I would have the block cleaned and machined in prep for a rebuild. The cylinder bore and crank journals can't really be planned in advance as those are dependent on the condition of the block. This brings up a couple questions though that are related. First is pistons, flat, dished or domed? What is the difference? How does this affect Compression Ratio? I understand that the greater the ratio the better economy you will get. Also, at some point you will need to go to a higher grade gas. That is a trade off I am willing to make if the economy would be high enough to justify it.

Ignition, hotter is better as far as I understand. But at what point are you reaching the point of diminishing returns? This is not a race engine that is going to turn 6-8000 RPMs. This is a DD where the idea is to keep RPMs at a sensible level.

The discussion took place earlier about driving the engine at the sweet spot in order to maximize economy. How much of that is just the nature of the platform and how much of it can be altered depending on how you build it? If you could move that sweet spot from (hypothetical numbers here, don't panic) say 2600 down to 2100 that should also drop fuel consumption. Is this something you can engineer or do you have to change platforms (engine size)?

There are some obvious questions. Why do this instead of change engines? Well, I have a couple answers to that. Because I can. Because I feel the engine is the soul of the truck and I don't really want to transplant it. Because this sounds like a great project for my son and I to work on together. Would I consider an engine change? Yes, but it isn't my first choice. My ultimate goal is a fuel efficient truck that can still handle the occasional load. I would like to do that with the existing 454 but if I have to I will go with a 350. I know that the 350 is easier to configure for this but I want to see if we can get there with the 454.

Who'd like to school me first?

 

[kleedus]

swap it for a fuel injected 350 or better a 4.8 or 5.3 ls

454 and fuel mizer are 2 words that do not go together


the cheapest easiest way would be a throttle body fuel injected 350

you can buy 4.8 ls take out engines on ebay complete with the harness and computer for under 2 grand

I am considering the 4.8 swap in my 63 c10 short bed

4.8L

The Vortec 4800 LR4 is a small block V8 truck engine. Displacement is 4.8 L (290 cu in) with a 96.01 mm (3.779") bore and 83 mm (3.268") stroke. It is the smallest of the Generation III Vortec truck engines and was the replacement for the 5.0 L 5000 L30. The Vortec 4800 produces 270 horsepower (200 kW) to 295 horsepower (220 kW) and 285 lbf·ft (386 N·m) to 305 lbf·ft (414 N·m), depending on the model year and application.

5.3 L

The Vortec 5300 is a V8 truck engine. It is a stroked (by 9 mm) version of the Vortec 4800 and replaced the 5700 L31. Power output is 285-315 hp (223-239 kW) and torque is 335 lbf·ft (454 N·m) to 350 lbf·ft (470 N·m). Displacement is 5.3 L (5,328 cc (325.1 cu in)) from 96.01 mm (3.779") bore and 92.00 mm (3.622") stroke. Another engine variant, the L33, shares the same displacement, but has an aluminum block with cast in cylinder liners, much like the LS1. This allowed a 100 lb weight savings over the standard LM7 model. Other differences were a higher lift cam shaft (0.482" v. 0.456" on both intake & exhaust), higher compression ratio (9.9:1 v. 9.49:1), and used cylinder heads originally designed for the LS6. These differences bumped output: GM rated the engine at 315 hp (235 kW) and 338 lbf·ft (458 N·m). This engine was used only in extended cab, short bed, four-wheel drive vehicles in model years (late) 2005 through (early) 2007.

 

[Jims86]

swap it for a fuel injected 350 or better a 4.8 or 5.3 ls

454 and fuel mizer are 2 words that do not go together


the cheapest easiest way would be a throttle body fuel injected 350

you can buy 4.8 ls take out engines on ebay complete with the harness and computer for under 2 grand

I am considering the 4.8 swap in my 63 c10 short bed

4.8L

The Vortec 4800 LR4 is a small block V8 truck engine. Displacement is 4.8 L (290 cu in) with a 96.01 mm (3.779") bore and 83 mm (3.268") stroke. It is the smallest of the Generation III Vortec truck engines and was the replacement for the 5.0 L 5000 L30. The Vortec 4800 produces 270 horsepower (200 kW) to 295 horsepower (220 kW) and 285 lbf·ft (386 N·m) to 305 lbf·ft (414 N·m), depending on the model year and application.

5.3 L

The Vortec 5300 is a V8 truck engine. It is a stroked (by 9 mm) version of the Vortec 4800 and replaced the 5700 L31. Power output is 285-315 hp (223-239 kW) and torque is 335 lbf·ft (454 N·m) to 350 lbf·ft (470 N·m). Displacement is 5.3 L (5,328 cc (325.1 cu in)) from 96.01 mm (3.779") bore and 92.00 mm (3.622") stroke. Another engine variant, the L33, shares the same displacement, but has an aluminum block with cast in cylinder liners, much like the LS1. This allowed a 100 lb weight savings over the standard LM7 model. Other differences were a higher lift cam shaft (0.482" v. 0.456" on both intake & exhaust), higher compression ratio (9.9:1 v. 9.49:1), and used cylinder heads originally designed for the LS6. These differences bumped output: GM rated the engine at 315 hp (235 kW) and 338 lbf·ft (458 N·m). This engine was used only in extended cab, short bed, four-wheel drive vehicles in model years (late) 2005 through (early) 2007.

Correct^^^^^
I get 17 out of my TBI 350, but thats with OD, could probably do better with a finley tuned Holley MPFI Avenger setup. If I were in your boots, I would get an L31 vortec, and top it with the Avenger MPFI.....unless a 5.3 is an option. Both with a 4L80e of course.

 

[kleedus]

I got the l31 vortec stroked to a 383 with the 96 vortec fuel injection system upgraded to the mpfi injectors I am putting in my crew cab

if I had it to do over again with the l31 350 I would still stroke it but I would just get a carbed intake and use the fast fuel injection system. all said and done the fast wouldn't be much more than what I have in the vortec injection modified harness and upgrades for it.

but after doing more research and thinking I think a lightly warmed up 6.0 would work better in my crew

 

[Jims86]

I got the l31 vortec stroked to a 383 with the 96 vortec fuel injection system upgraded to the mpfi injectors I am putting in my crew cab

if I had it to do over again with the l31 350 I would still stroke it but I would just get a carbed intake and use the fast fuel injection system. all said and done the fast wouldn't be much more than what I have in the vortec injection modified harness and upgrades for it.

but after doing more research and thinking I think a lightly warmed up 6.0 would work better in my crew

L31 is best with a dry manifold setup.....any engine is, really.

 

[ScottyB]

Ok, I get that a smaller/different engine would work better for this. That doesn't answer my questions though. I'm trying to understand the theory behind how it all works together. I would like to try this with the 454 but I am not married to the idea. Right now I am still trying to understand the principles that define the whole "the 350 is more fuel efficient than the 454" argument".

Here is why I don't just blindly swallow that. (I'm not saying it isn't true, I need to understand it first.) My background is driving big rigs. The conventional wisdom says that smaller engines get better fuel economy. This is true, but only in so far as the operators are steering wheel holders and not drivers. Most large companies that spec these engines do see a fuel savings, but that is because these engines can't burn as much fuel. The down side is you have the steering wheel holder mashing the throttle the whole time trying to make the truck go faster. A driver will use the power he has when he needs it but manage it when he doesn't. I have seen 600HP trucks pull the same load as 425HP trucks with greater efficiency because the driver of the larger engine manages the power. The idea is that a larger engine that isn't straining is more efficient than a smaller one that is.

My understanding, in the case of my 454 dilemma, is that the larger engine is also turning at higher RPMs in order to hit it's sweet spot. Higher RPMs will almost always lead to lower fuel economy. I'm trying to understand if it is possible to slow the 454 down and keep it functional. I understand it is a function of the power curve, but for me that is largely theory and one I don't understand well.

I hope this explains where I am coming from even if it doesn't make sense that I would try it. Please be patient, I am trying to learn.

 

[Graystone]

A larger engine has more rotating mass which requires more power to keep it running at the same speed as a engine with smaller components.

Big rigs don't really compare as they tow all the time. A smaller motor in that instance would be required to work harder and use more fuel to do the same amount a larger engine would.

The more power the motor makes the easier it ia to maintain a cruising speed. However that is counter acted by how the power is obtained. Basically power to weight internally.

And the heavier the parts the slower the motor will turn them. A small block with lighter components will rev faster then a bb with larger components.

 

[ScottyB]

I didn't mean to imply that big rigs and pickups were the same thing. I used that to explain where my thinking originates.

If I understand what you are saying, the 454 gets it's higher torque, in part, from it's heavier rotating assembly. More mass means more energy required to get it up to speed, but once up it has more momentum to maintain that speed, correct? What if you were to lighten the the rotating assembly? Wouldn't that make it easier to get up to speed? Granted, you would sacrifice the torque you get from that but that was always going to be a trade off in this build.

Does this make sense, in theory? I get that the practicality may not make sense but I need to understand the theory first.

 

[kleedus]

454 cubic inches versus 350 cubic inches

the 454 is bigger it moves more air and fuel

even at idle the 454 burns more fuel than a 350

you are trying to reinvent the wheel here and you are over thinking it

not a lot you can do to the 454 to get better economy stock cam fuel injection overdrive tranny and axle ratio change and keep it tuned up running at its best. its a bigger engine it is going to eat more

 

[Jims86]

Another thing to keep in mind is the advancements made with small blocks, starting with the Gen1 Vortec, which is simply an LT1 combustion chamber, and runners made for a standard small block. Gearing is the big ticket here. I could build a 4.3 v6 powered truck, with a 6 speed or more trans, that would pull the same loads as a 454 with a 3 or 4 speed trans. A big block just drinks more period, even more at idle.
Another thing to consider, is when comparing light truck gas engines with big rig diesels, is that diesels are waaaayyyy more thermally efficient than gassers. Diesels waste a lot less.
I would best a 454 at 12 MPg, with the technology currently available.
If you are dead set on keeping the 454:
Dont go with large port heads, peanut ports are best for low end torque.

Try to go with The MPFI Holley Avenger setup if possible.

the more gears, the better...6l80E comes to mind.

Don't go hog ass wild with exhaust size, 2.5" for duals, 3" for single....as with the heads, its all about keeping flow velocity as high as possible.
Straight through exhaust is best...try to stay away from funky ass wingplate and airfoil gimmick mufflers.

and finally, the skinniest tire, while staying within the load range is best. Stay away from big ass ghetto bling wheels too, all that unsprung weight drinks gas.

 

[Graystone]

Keep in mind the newer 8.1l motor still gets pretty bad gas mileage. Better then the 454 but not great

 

[bucket]

There's really not much that can be done to improve the mpg of a 454, GM already did their best with it. But what can be done is improve the power without hurting the mpg.

 

[GreaseDog]

TBI 454s can get decent fuel economy. I parted one out in 07 that averaged 14 mpg with no trailer. A large part of its life was spent with a bed load of tools, firewood, or some sort of payload. Completely stock internally, long tube Hooker headers, 2 1/2" dual exhaust, K&N intake, 4.10 gears, 245 75 16s (6 of them) and a 4L80E . Just a well maintained, mindfully driven work truck is all it was. I still have the high pressure, small injector setup, which controls the 4L80E that came from that truck, as well as the headers and intake. Planning on installing them in my current K3500 to obtain similar results. Mine will probably actually do better,as it is an extended cab rather than a crew, and I'm converting it to SRW.