Why the decrease in engine displacement?
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From: Southern Illinois
Despite all the technology and smaller, more efficient and powerful engines, there is still a spot, engraved in my mind, for now and always will be, that there is simply still "No Replacement For Displacement" 
Fleet Owner
Joined: Sep 2005
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From: Lake Tahoe, Nevada
Originally Posted by Oval_obsessed
It seems to me that the engines cubic inches are getting smaller and smaller as the years come and go. Is it due to trying to improve fuel mileage?
Posting Guru
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From: Destin/Ft. Walton Beach,
the 8.1 496 ci can only be had in the gmc line
Postmaster
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From: IL
Originally Posted by polarbear
With an EPA of 16 city, 26 hwy. 505hp, no gas guzzler tax. Amazing.
Could it be gmc with their deep pockets pulled some strings to get those #'s!?!
I'm also curious to see how durable the motor is and whether it will make it to the six-figures with ease. Chevy big blocks, as I know of em, made great power, just never held together well. Time will tell I guess!
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From: just outside of Phila.
kind of off topic, but kind of related...does anyone have any idea at all of what the efficiency of those Indy engines are? I know they have a bigger bore, but a much smaller stroke. Wouldn't the smaller stroke mean less friction, and in turn, better efficiency than a typical passsenger car engine?
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From: St. Petersburg, FL
Simply put, materials have advanced, manufacturing has advanced, and sophisticated computer engine management has taken over. You can now make as much, if not more power, out of much smaller engines, than their older and larger counterparts.
Stronger, more stable and longer fatigue life materials allow using less of them, less rotating mass results in decreased internal parasitic losses -- couple that with tighter tolerances and tighter fits, it leads to less valve leakage, less blowby, greater compression(hot and cold), which results in reduced wear.
Better mileage is mostly a side-effect (Though it's usually touted as a design feature)
Power out = (Power in) X (Efficiency)
Better efficiency, equates to less power in (meaning the rate of consumption of potential energy stored within hydrocarbon fuels).
Stronger, more stable and longer fatigue life materials allow using less of them, less rotating mass results in decreased internal parasitic losses -- couple that with tighter tolerances and tighter fits, it leads to less valve leakage, less blowby, greater compression(hot and cold), which results in reduced wear.
Better mileage is mostly a side-effect (Though it's usually touted as a design feature)
Power out = (Power in) X (Efficiency)
Better efficiency, equates to less power in (meaning the rate of consumption of potential energy stored within hydrocarbon fuels).
Senior User
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From: St. Petersburg, FL
Originally Posted by jdmorg
kind of off topic, but kind of related...does anyone have any idea at all of what the efficiency of those Indy engines are? I know they have a bigger bore, but a much smaller stroke. Wouldn't the smaller stroke mean less friction, and in turn, better efficiency than a typical passsenger car engine?
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From: Damascus-Boring, Ore
Originally Posted by Fordsflylow
That "reads" as great mileage for that size motor and hp, but is it reality? I know of no one who gets what the EPA has set as mileage claims for a particular vehicle.
Could it be gmc with their deep pockets pulled some strings to get those #'s!?!
I'm also curious to see how durable the motor is and whether it will make it to the six-figures with ease. Chevy big blocks, as I know of em, made great power, just never held together well. Time will tell I guess!
Could it be gmc with their deep pockets pulled some strings to get those #'s!?!
I'm also curious to see how durable the motor is and whether it will make it to the six-figures with ease. Chevy big blocks, as I know of em, made great power, just never held together well. Time will tell I guess!
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
I think most of the Corvette's mileage has to do with the fact that it's a very low, aerodynamic car, not anything too special with the engine. Notice the difference between city and highway mileage. You put that big engine to work, the mileage is going down. What do those things weigh, anyway?
You'll notice I never said there was anything wrong with it! 
Originally Posted by captchas
our ford v10 is 415 ci's at 6.8l. putting out a whole lot of smooth clean burning hp and tire twisting power. so what if it's a 5.4 with two extra pistons it runs powerfull and clean when put along the side of a gas guzzing 8.1 gmc
Post Fiend
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From: Damascus-Boring, Ore
I think TMyers mention his- about 3200 pretty aerodynamic pounds. Way back when, Oldsmobile put a big block in a Cutlass Supreme with really tall gearing and called it a "Turnpike Cruiser." They got astounding Hwy gas mileage- somewhere in the low-mid twenties,
Elder User
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From: Lindsborg, KS
I'm not a fan of these new engines, or new vehicles, I have a 1957 F-250, i'm putting a 302 in it. I'm a fan of carbed engines, and engines that don't require computers to run. I'm in a class of the new generation that there are not many of. I'm going old school all the way. Go ahead and criitcize me, i don't care, i love the old stuff.
Dustin
Dustin
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From: Running Springs CA
I also disagree that displacements have been getting smaller accross the board. It is only in the "small-block" V-8's that has happened. Passenger car fours and V-6's have been generally getting bigger. The Focus has a 2.3 replacing a 2.0. Mustang's 3.8 was replaced by a 4.0 German Ford V-6 that grew from 2.6 to the current size. Import brand sixes have grown from 2.5 to 3.5 over the past few years, and Ford is soon upsizing the Duratec to 3.5.
Jim
Jim
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From: just outside of Phila.
Originally Posted by Baja Daze
Not necessarily. A larger bore has a larger circumference which is directly proportional to the frictional face of each piston. The greatest benefit of short strokers, which allows them to rev to much higher rpms's, is that peak piston velocity is less with a short stroke, for a given rotational speed -- this translates to less acceleration/deceleration of your reciprocating mass.
You're gonna need to dumb that down for me, or I'm just over thinking it. What I was going for is that (and I'm not sure) I thought that Indy car engines were generally smaller, and that they also contained less rotational mass, because of how short the stroke was (I'm not talking about materials here, as it's probably unrealistic to look for F1 quality materials in a Windstar or something), which all lead me to think that the effieciency of an F1 engine was much greater than that of a normal, stock V8, and not just because of the materials used. Do you know what I mean? Is that the case?
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Originally Posted by rusty70f100
If you look at the hp / cubic inch of GM's 8.1L V8, it's really sad.
try to build an engine that will last under heavy load at modest rpms and where you need pulling power from a low rpm level and thats what you end up with. high horsepower comes with high rpm's and it isn't the best combo in a 1 ton truck.
old f600 I had with a 370-2v would be classified as a dog of a motor,maybe 150 hp, but you couldn't kill it and it could run full throttle all day long.
built that way for a reason.
IMHO way too many people just look at numbers and make assumption. its like dyno graphs,just a number on paper.