Engineers: Old vs new engine tech

[Chapap]

I’ve gone down this rabbit hole several times and never found a half way decent article. I’ve probably stumbled upon all-the-way decent articles and just didn’t comprehend what I was reading. I want an explanation between “just because” and doctorate level for why old engines have such pitiful numbers compared to even the most basic modern engines

My 2.3 Lima:
100hp
25mpg max
9.4:1
3.78 x 3.12 = 21% over square

My 1.5 2018 Accord 6mt
192 hp
32-45mpg (I tried hard to get those extremes)
10.5:1
73 x 89.5 = 23% under square

Thesee two engines have two huge differences being the squareness and compression ratio... and vvt, turbo, DI, and aerodynamics. I’m 70% sure the vvt just kicks in during spirited acceleration so can we ignore that? If the accord never sees throttle past 50%, is that like having no turbo at 100% so we can ignore that?

Would it be possible to get these numbers from the Lima and still call it a Lima or would it be a completely new engine?… I mean… gas goes in, smoke come out… how hard can it be?

 

[bobbywalter]

Yeah....

That's a journey to the center of the earth . . Not a rabbit hole..... Alice.

 

[rusty ol ranger]

Horsepower is a product of RPM. Everything nowadays peaks at higher RPMs.

That and more precise ignition and fuel control.

 

[Uncle Gump]

It can be summed up with two words... Volumetric Efficiency

 

[bobbywalter]

Horsepower is a product of RPM. Everything nowadays peaks at higher RPMs.

That and more precise ignition and fuel control.

That explains allot.

Yeah. No.

 

[ericbphoto]

It can be summed up with two words... Volumetric Efficiency

Watch your language, young man. We'll have none of those hoity-toity, hi-falutin cuss words around here.

 

[racsan]

the accord is a front-wheel drive, possibly 4valves per cyl, more air-fuel in/more smoke out. Another thing is the rpm at which each engine is rated, its “”X” horsepower at “Y” rpm. I dont really know for sure but Id bet the accord engine is rated at a higher rpm than the lima. But- you can break timing belts all day with the pinto engine, lose the timing set in a honda and its a boat anchor.

 

[bobbywalter]

You only compare different engines in identical environment to know what the actuals are.

 

[racsan]

So, put a accord engine in a ranger chassis (or a lima 2.3 in accord) & see how they compare. I know theres quite a mpg difference between my commuter car (2.2 hhr ) & my 2.3 ranger, both weigh about the same but many other things are different.

 

[bobbywalter]

Yeah. I do that all the time.

So. Key is using same transmission... everything...just swap engine.

Of course...goes for trans too.

The combination of gearing and transmission can make it perfect....but you need a baseline.

Doing this right now with the Windsor application. And have done it with many powertrains in my situation

 

[Chapap]

Doing this right now with the Windsor application. And have done it with many powertrains in my situation

I didn’t even think about a computer being able to help lol.

Come to think of it, I towed my hobie 16 with the accord once. 800 lbs total trailer weight but huge air resistance. I think I averaged like 50… lowest speed in top gear. My MPG was low/mid 20s if I recall correctly.

Anyone have a dyno run graph for a stock 2.3? The 1.5 accord made over 150 ft-lbs under 2k. Of course it wasn’t happy under 3k and didn’t get into stride until 4k. Redline at 7k.

max hp I guess is a non-comparable… but the accord made 190 ft-lbs.

 

[bobbywalter]

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

 

[85_Ranger4x4]

More of a straight up comparison my old '90 turbo Eclipse was rated 190hp with a 16v 2.0.

5 speed 15yo college kid car, got about 30 MPG

 

[bobbywalter]

Where computers help is in stabilizing power ..

 

[Chapap]

Do number of valves matter for mid hp?… hear me out. If you want to make X amount of power, that would be 1/4 throttle with 2 valves per, and 1/8 throttle with 8 valves per. Or is it an efficiency thing and not at all that straight forward?

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

Has there ever been an engine that didn’t make peak power at high RPM? I’ve never not seen HP climb until it gets close to redline. That’s kinda how the power equation goes