Engineers: Old vs new engine tech

[RonD]

Older Gasoline engines ran/run at about 25% efficiency, than means if gas is $3/gallon $0.75 is used to push you down the road, and $2.25 is used to HEAT coolant and air around the engine, sucks don't it, lol

2.3l Lima is 1974 technology, 1970 actually, when it was being designed
It did use an overhead cam which is better for efficiency, no pushrods, and power
OHC also allowed for higher RPMs
But still only had 2 valves per cylinder

When "they" started doing 3 and 4 valves per cylinder and dual overhead cams "we" got better efficiency AND better power
Current engines are 30-35% efficient, still not great but better

VVT(variable valve timing) takes advantage of how valve timing works at lower RPM and higher RPM, best valve timing is different for low RPMs and high RPMs
Without VVT you are locked in at the best valve timing for engine's use, so its a "one size fits all" setup

Higher compression is a double edge sword
The tighter you wind "the rubber band" the more energy is released when you let it unwind
But in the case of compression, OCTANE can be an issue, 87 octane(regular gas) will self-ignite(ping/knock) above 9.5:1 ratios
But EGR systems and Knock Sensors can allow higher a compression engine to run 87 octane, with a loss of some power with changes in spark advance


Diesel engines started at about 30% efficient and are now at 40+% efficiency
Electric motors in vehicles are 85% efficient, but you still need to factor in how the electricity was generated


Torque gets you up to speed
Horse power holds you at that speed
Give me torque any day over horse power, lol

 

[Chapap]

Torque gets you up to speed
Horse power holds you at that speed
Give me torque any day over horse power, lol

Careful now… I’m all for changing subjects, but this is already a wormy can and I don’t want to watch the world burn just yet.

 

[bobbywalter]

I liked the analogy ..

Hp is how fast you hit the wall.

Tq is how far it moves.

 

[bobbywalter]

Direct injection is the key with camshaft variation


Glad they found it.

Love the Ecoboost ...

LOW RPM POWER. 3.5 LITERS

ITS INSANE

 

[Chapap]

Direct injection is the key with camshaft variation


Glad they found it.

Love the Ecoboost ...

LOW RPM POWER. 3.5 LITERS

ITS INSANE

I rented a Harley once. Don’t know the numbers… but I was about to stall the engine from going to slow in 1st. almost fell of the back when I bumped the throttle UNDER idle.

 

[rusty ol ranger]

I will say this.

Hp and tq are not just peaks ...

Useable power is just that. And you gear accordingly.


But like rusty says many newer engines make their peak power at higher rpms....or overall...

Compared to what?

Wtf does that mean?


If you actually think it's a product of rpm....then...well . Yeah

Compared to the older engines. Back in the 70s you had 400+ CI's making 160hp. But usually torque in the mid 300's, peaking below 2500rpm.

Thats how they could put a 169hp 400 in a 5200lb lincoln with a 2.73 rear end and a 3 speed automatic and still have it be able to get moving. Take that 190hp 4 corolla or whatever 4 cylinder and bolt it in that lincoln its gonna puke.

Horsepower sells cars but torque wins races.

 

[scotts90ranger]

horsepower is a simple equation: HP=torque*rpm/5252

At 5252rpm torque in pound feet is equal to horsepower, plain and simple, above that rpm it takes less torque to add on more HP...

Drivetrain efficiency and aerodynamics play a big role, front wheel drives are more efficient because the drivetrain doesn't have to turn any corners, corners lose efficiency , that and less rotating mass and less parts to make it happen...

I'm going to skip a bunch of stuff and just make some general points... An engine is an air pump, the easier it is to get air in and exhaust out and you are going to have more power, more power if it isn't used can lead to better fuel efficiency. Back in the day with early fuel injection the fueling was more consistent than carburetors in some instances (not all, I don't hate carbs, just would rather not have them in a car I have...) all throughout the usability range of the vehicle, fuel injection will self adjust if you start at sea level and drive up a road to 10k feet above sea level while you are driving, can't do that with a carb and expect it to drive the same throughout... Without great control and little processing power the engines went out of closed loop fuel control (looking at the oxygen sensor) early which means they ran rich to try to keep the catalyst and exhaust temperatures to a safe level, but that uses more fuel...

Back in the day, transmissions didn't have many gears, so a flat low rpm torque curve drove better. A low rpm camshaft will peter out quick and power drops off below that magic number of 5252rpm normally so power numbers are pretty low... That's the route Ford took in the '80's and '90's, the 4.0L OHV has a 4600rpm rev limit if I remember right, 2.3L is at 6000rpm, the 5.0L in my Explorers are 5000rpm. Modern engines with a high rpm torque curve and a bunch of gears in the transmission will wind up to 5500rpm before shifting then only drop maybe 1000rpm between shifts staying in the power band, then once you're done accelerating will drop into a lower rpm point at a low to medium load on the engine balancing things out...

Variable cam timing is an odd thing, at work we have engines with it but GM leaves it full advance then the cam phaser retards the cam timing, I haven't played with it much...

It all boils down to the whole drivetrain efficiency and how good of an air pump the engine is, combine some stuff, hold your left leg at 13 degrees and it will sometimes work out

 

[bobbywalter]

Compared to the older engines. Back in the 70s you had 400+ CI's making 160hp. But usually torque in the mid 300's, peaking below 2500rpm.

Thats how they could put a 169hp 400 in a 5200lb lincoln with a 2.73 rear end and a 3 speed automatic and still have it be able to get moving. Take that 190hp 4 corolla or whatever 4 cylinder and bolt it in that lincoln its gonna puke.

Horsepower sells cars but torque wins races.

No ..torque does not win races...unless they are trains

Even then....depends.


Everybody knows 460 cubes...especially in big block architecture usually will have good low end.

The questions raised in the op...

350 ft lb at 2500.... is typical of a 460...at the crank ...and 175 is hp. Which is awesome.

The 3.5eb has that at the wheel...
Which is ridiculously awesome.


It's embarrassing.

 

[bobbywalter]

So ...for engines that don't reach over 2k rpm...

horsepower is a simple equation: HP=torque*rpm/5252

At 5252rpm torque in pound feet is equal to horsepower, plain and simple, above that rpm it takes less torque to add on more HP...

Drivetrain efficiency and aerodynamics play a big role, front wheel drives are more efficient because the drivetrain doesn't have to turn any corners, corners lose efficiency , that and less rotating mass and less parts to make it happen...

I'm going to skip a bunch of stuff and just make some general points... An engine is an air pump, the easier it is to get air in and exhaust out and you are going to have more power, more power if it isn't used can lead to better fuel efficiency. Back in the day with early fuel injection the fueling was more consistent than carburetors in some instances (not all, I don't hate carbs, just would rather not have them in a car I have...) all throughout the usability range of the vehicle, fuel injection will self adjust if you start at sea level and drive up a road to 10k feet above sea level while you are driving, can't do that with a carb and expect it to drive the same throughout... Without great control and little processing power the engines went out of closed loop fuel control (looking at the oxygen sensor) early which means they ran rich to try to keep the catalyst and exhaust temperatures to a safe level, but that uses more fuel...

Back in the day, transmissions didn't have many gears, so a flat low rpm torque curve drove better. A low rpm camshaft will peter out quick and power drops off below that magic number of 5252rpm normally so power numbers are pretty low... That's the route Ford took in the '80's and '90's, the 4.0L OHV has a 4600rpm rev limit if I remember right, 2.3L is at 6000rpm, the 5.0L in my Explorers are 5000rpm. Modern engines with a high rpm torque curve and a bunch of gears in the transmission will wind up to 5500rpm before shifting then only drop maybe 1000rpm between shifts staying in the power band, then once you're done accelerating will drop into a lower rpm point at a low to medium load on the engine balancing things out...

Variable cam timing is an odd thing, at work we have engines with it but GM leaves it full advance then the cam phaser retards the cam timing, I haven't played with it much...

It all boils down to the whole drivetrain efficiency and how good of an air pump the engine is, combine some stuff, hold your left leg at 13 degrees and it will sometimes work out

That equation is an equation ..
Journey to the center of the earth.

Engines that only make 2200 rpm don't give a fawk about that equation.


Engine as an air pump. Why yes it is.

And is exactly the question

How can....and let's stay n/a...a 1.5 liter pump more air then a 2 liter at 5250 rpm

 

[Chapap]

So here’s what I’m putting together. I’m guessing that the Lima era designers thought like I’m thinking. Air in and out. To get better, you need million dollar computers and salaries to tweak contours to near microscopic accuracy. I’d bet engineers know the exact path of air flow eddys n such inside the cylinder and manifold for every rpm. I’ve seen plenty of animations bragging about that.

And I figure hp and tq is not an either/or thing. Generally Hp is how fast you can go, tq is how easily. Low tq, high hp is fast but not pleasant cause you gotta rev… crotch rocket. High tq even with low hp makes for a more pleasant use of power…doesn’t seem like the engine is working cause it doesn’t have to rev.

the old steam cars had 1000 tq from 0-500 rpm. Similar acceleration to modern econo boxes, but bet it feels effortless in comparison

 

[bobbywalter]

A 2.0 liter Ecoboost is an econobox engine.


Low rpm torque for effortless movement was the whole point of the damn critter.

If air actually pumped equals power....

At 5250.....why does it pump more air then any 50 oz imbalance regular firing order modern stock 302?

Why does it make more power at any point on the rpm scale?

If air pumping equals power.


You asked what changed from Lima to Mazda L...that makes the engine twice it's size look like a gas gobbling bitch ....

 

[scotts90ranger]

Theoretically it can't, but in practice if the 2L has bad flow in the intake manifold causing a restriction (measured at the back side of the intake valve, not in the manifold) then it is being a more efficient air pump...

HP sells stuff, no one cares about torque (I'm not talking me here...), I know it's just an equation, I don't give a rats monkey... I tune engines to what they can do while meeting the emissions limits I'm given with the components I have available... right now at work I'm playing with a 9.1L 9.2:1 compression ratio tall deck big block chevy based engine with an 8.1L camshaft that's making like 460hp at 4400rpm which is around 550lbft torque with marine catalysts and 5psi back pressure... uncork it a bit with higher flowing exhaust and it gets over 600lbft torque, peak torque is around 4000rpm but is still around 550lbft at 3000rpm...

If I cared about horsepower or the real world I wouldn't have a 7.3L powerstroke or have a Lima powered daily driver , my boat has a 351W with a 4 barrel, the only gauge that works is the coolant temperature, I don't know what it does for rpm or anything which is fine for me, it does what I want it to...

Why there's a billion engines out there I have no idea other than everyone has a brilliant idea that might work or not... some of them do, some don't

 

[bobbywalter]

Torque sells trucks.
When driven miserly without load...

4 digit torque and 22mpg in a 8500 pound truck happens...6.7l

My 6600 pound truck only makes 22 mpg.......570 ft pound 3.5l

 

[scotts90ranger]

Part of what you just mentioned is the parasitic loss of more reciprocating components...

At work we make a compressor engine that is an 8L V8 that half the engine is a compressor driven by the other half with nothing connected to the back... someone involved with the project talked to someone at CARB and apparently they didn't think it was an engine since nothing was driven by the flywheel, hence it didn't need to be certified... so there's that, things are being controlled by brilliant people...

torque sells trucks, but only like 5% of the population actually understands anything...

 

[Chapap]

something else I find curious and seemingly consistent. The worse the power per cubic inch ratio is, the better the exhaust note. An old 351 with a hole in the muffler makes a lovely racket. Even my Lima with an exhaust leak somewhere isn’t entirely unpleasant. 10 times better than any modern 4 banger. Modern v8s just don’t sound nice without a moderately tuned exhaust