100 bhp per litre

[lesz42]

sorry if this is a bit vague, the traditional idea that 100 bhp per litre is point where reliability is reduced, and say an f1 car makes 750 odd bhp in 2.5 litres, means that the engine is pretty stressed

so if a engine in a Mitsubishi Lancer Evolution 8 MR FQ, has say, 800 bhp, from 2.4 litres, is the evo engine, if used hard, just as stressed and prone to fail?



sorry if none of this makes sense!

[Carlos]

Welcome to the Forum lesz42. IMO The '100BHP per Liter ' rule of thumb is probably outdated, it was a standard opinion in the of the 1960's and engine development has advanced so much over the years with fuel injection, variable valve timing and a lot of other improvements. I think there are stock factory motors that match 100BHP/L today.

[Belatti]

Well, this engine (now also in the Passat) features 120+ HP/liter, and its not mounted in an expansive 150.000USD+ supercar.

170 hp 1.4 TSI
Announced at the 2005 Frankfurt Auto Show to be used in the Golf GT, The 1.4l Twincharger is a TSI engine with a turbocharger and a supercharger in combination. Its downsizing leads to economy, with 14% more power than the 2.0 FSI but consuming 5% less fuel. The mechanical compressor operates at low engine speeds below 2400 rpm to increase low-end power, the turbocharger engages at middle revs, a clutch disengage the supercharger which will then be bypassed once the turbocharger reaches sufficient speed to provide boost above 3500 rpm.
Configuration
1390 cm³ straight-4
Head: four-valve, 10:1 compression ratio
Block: grey cast iron, bore * stroke ratio 76.5 * 75.6 mm, 120 bar peak pressures
Fuel: FSI direct petrol injection up to 150 bar, high-pressure injection multiple-hole valve with six fuel outlet elements, injector on the intake side between the intake port and cylinder head seal level
Aspiration: mechanical belt driven Roots compressor operated by a magnetic clutch integrated in a module inside the water pump, internal step-down ratio on the input end of the synchronisation gear pair and exhaust turbocharger connected in series, administrated by a control flap, intercooler, 2.5 bar pressure at 1500 rpm.

Output
125 kW (170 HP) at 6000 rpm, 240 N·m (MEP 21.7 bar) from 1750 to 4500 rpm , 200 N·m from 1250 to 6000 rpm, 7000 rpm max in the Golf GT.

Like Carlos said, it was a standard opinion in the 1960's. And maybe still is in the U.S. where big unstressed engines are common. Please I don´t want this thread into an international politics one, just saying that there are two different concepts for designing an engine, lets say:
1) 5L V8 200HP unstressed engines can last 1.200.000 Kilometers, while
2) 2L 4-in line turbocharged 200HP stressed engine can last 600.000 Km.

We would have to see if the fuel that no.2 engine saves can be compared to the fuel you need to power the plant and logistics to remanufacture it (BIG supply chain)
This diferent design concepts are maybe cause U.S. has very big distances to travel compared to Europe or Japan.

[Jersey Tom]

Using 100hp/L as a rule of thumb for how stressed the engine is.. is a poor metric.

You can have a 50hp/L engine that blows up after 10 miles. You could have a 150hp/L engine that lasts for years. Everything is a little more loaded, more heat to dissipate, etc, but if you design it right..

[Flummo]

How about comparing apples with apples? A naturally aspirated engine can not be fairly compared to a forced induction engine, not for hp/l related to life anyway.

100hp/l still is a high figure for N/A car engines designed for everyday use. On the other hand, for a turbo engine it really isn't anything to get excited about today, quite the opposite - today we have come to expect higher numbers. And for modified road cars... Well, any old 2.3l Volvo 740/940 turbo can have 300 quite reliable horsepower out of its outdated 1970's 8 valve 4 cylinder engine, or 500+ hp (still without any reliability related internal modifications) if the owner accepts the risk of stuff breaking sometimes. Replace a few weak parts and the stoneage engine is good for even more power and will still last for a long time.

The N/A versions of these engines are also popular for tuning here, but in those cases 100hp/l really is a good measure for how stressed they are. A 3.05l rallycross engine costing around 10000€ would give you about 300hp, some claiming slightly more and others slightly less. And that engine really needs maintainance if you don't want it to blow up very soon...

Okay, so those engines aren't modern by any standards, but I happened to know a bit about them. The same applies to the modern 4 valve per cylinder engines available in new cars today, they are to diffrent to be compared directly.

[donskar]

Welcome, lesz42.

100 hp per liter is no longer a big deal. Honda gets 197 out of 2000 cc.

Remember, today even some boring econo boxes have features like FI, VVT, multi-track intake and exhaust systems, direct injection, etc.

Maybe a more important metric would be the combination of HP and torque produced, as well as the engine speeds at which HP and torque are produced. The power/torque "under the curve" might be the most important metric. Meaning: my Nissan at 4,000 rpm puts out more HP and torque than a Honda at that speed. The Honda produces more HP and torque, but at much higher speeds, so is not as quick at ordinary "daily driver" speeds. Back in the day, we would say the Honda was more "cammy."

Bottom line: an engine that produces 150-200 hp from 3,000 - 7,000 rpm is probably a better proposition than one that produces 225 from 6,500 to 8,500!

[Top fuel dragsters get 8,000 hp from 8 liters.]

NOTE: I'm using Nissan and Honda as generic place holders representing "torquey" versus "peaky" engines. I'm not attacking any brand! IMHO, Honda and BMW produce the best IC engines in the world.

[donskar]

flummo, you're right: 100 hp/liter is very good, but Honda NA 2 liter engines are right at 100 hp/liter, and are rliable (and economical). Nissan's old SR20VE (also called NEO) 2 liter 4 cyl was rated at just under 200. And that was dead stock, cast iron header, etc.

100 hp/liter is a figure to be proud of, but it's no longer the Holy Grail.

And to give Detroit's cast iron monsters their due, larger engines, no matter what their level of technical sophistication, suffer from one inescapable barrier to power - friction. Their metric - 1 hp per cubic inch - makes sense when you consider the technical and CULTURAL mileau that gave them birth. Technical: push rods and overhead valves, carburetors, single coil and distributor ignition. Cultural: bigger is better, chrome is god, and CHEAP GASOLINE.

[Flummo]

Agree completely! Just adding numbers: The 2.0 Honda S2000 has 240hp, i.e. 120hp/l and as far as I know the record for N/A road cars.

If you like amazing numbers from the past, how about the Honda RC116 from 1966? 2 cylinder 4 valve per cylinder race motorcycle producing 16hp somewhere above 20000rpm... Edit: Forgot to write that it is a 50cc engine.

[Carlos]

Flummo didn't mention the Honda RC116 twin made 16HP from a mere 50cc. donskar's noted the importance of the relationship between torque/RPM/HP which is a real world measurement of practical performance, that's very important. The Honda doesn't do well by that metric, but what a marvelous motor, Honda also made a 125cc motor which shared many parts. A 5 cylinder 125cc; I once saw a picure of 2 pistons in the center of a mechanics hand Welcome to the forum Flummo

[Belatti]

How about comparing apples with apples? A naturally aspirated engine can not be fairly compared to a forced induction engine, not for hp/l related to life anyway.

That VW 1.4L T engine was the first that crossed my mind, but you are right with what you say.
Would boost pressure be a good factor to compare NA with Turbocharged engines?

...Top fuel dragsters get 8,000 hp from 8 liters...

Qualy F1 engines from the 80´s had the same HP/Liter rate. Flummo, I know they were turbocharged, but those engines lasted 30 minutes, while top fuel lasts 30 seconds or less

[rodders47]

back in the late 60's when I was motor racing, to get 100BHP/Litre in a race car was not that hard, but to get reliability, well that was very difficult.

My normal Road car, as most others of that era produced about 34 BHP/L for a 4 cylinder.

In the early 70's I bought a Ford Falcon GTHO phase 3, as raced at bathurst. In standard trim it produced I think from memory, 350 hp from a 351 cu inch ford block (I think 5 litre capacity). This was good for a sustained top speed of 150 MPH, but at a running cost of 11 miles to the gallon. (can't convert those figures to todays Litres/Kms)

Today I drive a Honda Jazz to work. has a 1.3 litre engine, max torque at 2400 rpm, cruises comfortably at 100 kph up hill down dale and returns 4.9l/100 kms.

Times have sure changed

[Saribro]

a running cost of 11 miles to the gallon. (can't convert those figures to todays Litres/Kms)

If my calculations are correct: 34 liters/100km.
:)

[EDIT]Google prooves I can't:
http://www.google.com/search?client=ope ... per+100+km

[EDIT2]Realised I calced liters/100miles :).

[Ciro Pabón]

From memory, a turbocharged 1.500 cc F1 engine produced 1400 hp, around 980 hp/liter. That's not easy to achieve, let me tell you. Same goes for 8000 hp for 8 liter dragsters, around 1.000 hp/liter.

Legendary production cars, from memory (after googling for the car, of course!) aspirated:

125 hp/liter, Alfa Romeo 33 Stradale. 250 hp from a V8 2 liter engine. Most expensive car in 1968. Beautiful.



123 hp/liter, Nissan Pulsar VZ-R. 197 hp from a 4 in-line 1.6 liter engine (wow!). This car is perfect for drag race betting, nobody will believe the speed if they don't know the car. I have a friend that made a small fortune with it. He got me once, against a factory GTO. What an engine is the SR16VE by Nissan.



Legendary production cars, again from memory, forced induction:

200 hp/liter, Mitsubishi EVO FQ400, of course, 400 hp from a 2 liter engine. I've seen this thing to outrun a Ferrari Modena.



Now, do not forget rotary engines, pleeze, which develop an incredible hp from small capacity:

189 hp/liter, Mazda RX-8 Renesis, aspirated 1.3 liters engine, rated at 247 hp! What can I say.



212 hp/liter, Mazda RX-7 REW, forced 1.3 liters engine, rated at 276 hp. Another wow.



In conventional piston engines the problem you have is that of torque/rpm combination. When it is large, the loads on the rods are large, thus the loads on the crankshaft bearings are large at high rpm. Not a good recipe if you intend to keep the car for a while. I wouldn't change an american hemi V8 for anything in the world, as duration goes. My car is over 40 years, I've repaired the engine twice.

[flynfrog]

pssshshtttt car engines



all of these engines are .5L all NA

[Scotracer]

Hehe, one of my race bikes makes 38BHP (at 10,000rpm) from 0.125L...304BHP/litre