Big Block -or small block?? 1994 K1500 GMC

[HeavyAsAChevy]

I just saw a video of a k5 blazer(technically a jimmy, but you can picture what I’m talking about) had a 8in lift or something with like 37’s(not exactly sure) but it was a BBC 572 and he got about 16mpg

 

[RichLo]

Yes, you can get 16mpg with a vortec BBC in a half ton truck. I get 13mpg with my 97 ECLB Dually with 4.10's.

BUT honestly, why are you worried about gas mileage in a full size pickup? Aerodynamics will always keep it below 20, just look at new trucks vs GMT400 gas mileage ratings. The new trucks still cant break 20 mpg

Just get a cheap daily driver Chevy Cruze or something that gets 40+ MPG for every day commuting and keep the truck for truck stuff and the vette for fun stuff.

 

[Pinger]

Yeah, but think about that. If it takes "X" power to move "Y" car down the road at "Z" speed, the big block is going to make that power with less throttle opening. Efficiencies come in to play and create differences, but it's definitely not as clear nor simple as the big block is just inhaling more air. Now at full throttle; yes.

Vettepilot

A better way to view that is to consider the larger engine does the same as the smaller engine - but at lower rpm (and therefore with less internal friction).
Less throttle opening (at the same rpm) is where it falls apart due to throttling losses.

 

[0xDEADBEEF]

A better way to view that is to consider the larger engine does the same as the smaller engine - but at lower rpm (and therefore with less internal friction).
Less throttle opening (at the same rpm) is where it falls apart due to throttling losses.

RPM is a function of gearing, but on the subject of internal friction the BBC has bigger parts, which means more internal friction and inertia to overcome.

 

[Schurkey]

There's a thousand factors that influence fuel economy; and operating expense in general. Many of those factors are contradictory, or off-setting.

A larger-CID engine that's NOT using a power-enrichment system to add fuel under load can be more economical than a small-CID engine that has to run extra-rich to haul the barge around.

More intake vacuum means greater pumping losses, reducing fuel economy. But more intake vacuum also means a more-sparce/lower-mass air/fuel charge in the cylinders, potentially increasing fuel economy.

Overall vehicle weight means almost nothing in terms of fuel economy AT STEADY SPEED.

Big blocks are great fun. A "350" or similar--Intercoursible 345, Dodge 360, Ford 352, etc.--needs some help in many cases to achieve adequate power once strangled by well-intentioned but poorly-thought-out emissions/economy regulations and compromised engineering to meet those regulations. It's a genuine shame that Chevy gave-up on the 400 small-block.

CAFE regulations have done more to damage US automakers and US consumer choices than emissions standards. The USA should IMMEDIATELY and ENTIRELY abandon CAFE standards.

 

[0xDEADBEEF]

There's a thousand factors that influence fuel economy; and operating expense in general. Many of those factors are contradictory, or off-setting.

A larger-CID engine that's NOT using a power-enrichment system to add fuel under load can be more economical than a small-CID engine that has to run extra-rich to haul the barge around.

More intake vacuum means greater pumping losses, reducing fuel economy. But more intake vacuum also means a more-sparce/lower-mass air/fuel charge in the cylinders, potentially increasing fuel economy.

Overall vehicle weight means almost nothing in terms of fuel economy AT STEADY SPEED.

Big blocks are great fun. A "350" or similar--Intercoursible 345, Dodge 360, Ford 352, etc.--needs some help in many cases to achieve adequate power once strangled by well-intentioned but poorly-thought-out emissions/economy regulations and compromised engineering to meet those regulations. It's a genuine shame that Chevy gave-up on the 400 small-block.

CAFE regulations have done more to damage US automakers and US consumer choices than emissions standards. The USA should IMMEDIATELY and ENTIRELY abandon CAFE standards.

At a high enough speed, the drag becomes the biggest factor as it is exponential with speed, but mass is a linear factor.

 

[PlayingWithTBI]

E=MC squared

 

[RichLo]

It's a genuine shame that Chevy gave-up on the 400 small-block.

CAFE regulations have done more to damage US automakers and US consumer choices than emissions standards. The USA should IMMEDIATELY and ENTIRELY abandon CAFE standards.

I totally agree with the 400 statement, that engine was the right engine at the wrong time, same with the 400 small block ford.

I think CAFE requirements actually helped automotive engineering to make cars as reliable as they are now. Without that we would probably still be driving carbureted cars with 3-speed transmissions. Just look at small engines in yard equipment, that industry is unregulated and hasn't had any real technological advancements since the 60s or 70s. Why change something that is cheap and easy to manufacture if there isnt any push to change? Snow blowers, push mowers, garden tractors, weed whips, chainsaws, etc are all still 1960s technology, just refined.

HOWEVER with that in mind, 1-ton and higher trucks are exempt from CAFE so auto manufacturers can do whatever they want with those to make as much power as they want. As long as they meet the US emissions standards (every vehicle sold in the US needs to meet those requirements, not just US manufacturers). That is why Big blocks generally used in 1-tons dont have as many power robbing, fuel efficiency increasing restrictions as the small blocks that are commonly used in 3/4 and 1/2 tons. But they still got the modern fuel injection and catalytic converters to meet the emissions restrictions.

Without CAFE, I couldnt have a 40+MPG Chevy Cruze for daily driving and save a ton of money driving a 1hr commute each day. Just saying.

 

[0xDEADBEEF]

My C8 gets 28 mpg and makes 495 HP. This is probably the golden age of the small block V8. It's probably all turbo 6's pretty soon.

 

[Frank Enstein]

You want the BBC for sure.

You can throw away the 87 TPI engine at my house and I will dispose of it properly.

I'm planning a turbo TPI for Frank and Betty because I don't have any 4.8 Vortec engines laying around.

Turbo TPI (with a smarter computer that understands boost) meets my fuel economy goals while having enough power to not have to downshift as often when hauling.