How Hard Is An Engine Working?

[JiN_MaN]

Assume you have 2 IDENTICAL motors with all supporting mods (FMIC, Exhaust, Fuel Pump)

Motor 1 makes 200rwkw @ 16psi, It makes it power by upping the boost.

Motor 2 makes 200rwkw @ 12psi, It makes it power by having adjustable cam gears and cams.

Now these motor are exerting the same amount of force, in this case 200rwkw, but is one motor doing it easier than the other?

I guess what im asking is, is there different ways to make the same power but one way is easier on the motor?

[tridentt150v]

Efficiency is the key, if the motor as a whole is optimised for efficiency then more energy is converted to power instead of emissions and heat. To use your two examples you would have to ask which one is operating more efficiently, which one is using more fuel, generating more heat or creating more emissions etc

Your first example could be the best alternative for that type of motor, it could run cooler, be more fuel efficient and have lower emissions along with a longer engine life.

[paulr33]

the more boost, the more you ring the engines neck basically

the higher the boost you cram in, is the higher there is a restriction across the in vs out

you are always better off with less boost in any situation

a knock sensor is a good indication of how hard an engine is working

keep adding timing till it knocks, then back out 2 deg - done

[rob82]

the more boost, the more you ring the engines neck basically

the higher the boost you cram in, is the higher there is a restriction across the in vs out

you are always better off with less boost in any situation

a knock sensor is a good indication of how hard an engine is working

keep adding timing till it knocks, then back out 2 deg - done

I've seen engines lose torque/power by using that approach - usually large duration camshafts and unreactive chamber shapes cause this.

And generally less boost in spark ignitions engines is better but I have seen cases that are contrary to this as well. Diesel engines are quite the opposite though - the more boost the better. Its really a case of giving the engine what it likes.

[cankas]

In this statement is just so many variables that u cant say

Whats the static compression ratio?

Peak power is a very small part, what about how the engine delivers its power and torque from idle?

But for the sake of this exercise id go with motor 1, reason being option 2 has a smaller time to burn fuel due to wider cam duration and u probably will have the same amount of air getting into the engine

(option 1 less time more boost, option 2 more time less boost) but because the burn time is less u will have to run leaner to get more out of the fuel increasing the heat in the engine raising the risk of predetination breaking a ring land.

My thoughts anyway.

[cankas]

And generally less boost in spark ignitions engines is better but I have seen cases that are contrary to this as well. Diesel engines are quite the opposite though - the more boost the better. Its really a case of giving the engine what it likes.

Boost is only a measurement of the charged air

20psi into an engine with a 11.5 comp ratio = dangerous

20psi into an engine with a 7.5 comp ratio = safe

[Adriano]

But ive seen 16 psi with 7.6:1 comp crack ringlands. I think we are getting away from the topic

[joeyjoejoejuniorshabadoo]

my cats name is mittens

[zebra]

my cats name is mittens

ROFL!

Imo, Both engines are working just as hard being that there making the same Power figures, But it depends if you have to rev the cammed engine harder due to larger cams, but the engine with cams is the more efficent air pump (e.g sucks and blows easier) But the cylinder pressures whould be ablout the same, Remember boost is just manifold pressure not so much cylinder pressures.

Andrew

[Beer Baron]

there is no real difference. boost is a measure of restriction in the intake. it's a pressure reading, not a flow reading. so it's possible both cars are injesting the same amount of air (almost certainly if they are identical and making the same power). so perhaps changing cam timing has reduced a restriction which allows the car to flow the same amount of air but at a lower pressure. anyway, it's kind of pointless comparison. I'd run the 16psi AND the cam adjustment and make 220kw instead.

[Guilt-Toy]

a torque read out is a good indication of how hard an engine is working

keep adding timing till it stops making more torque, then back out 2 deg - done

Your right on the money there mate

[djr81]

my cats name is mittens

That is an amazing coincidence. I once had a friend with a dog called Rufus.

To go off topic - the measure of how hard an engine is working is BMEP - its brake mean effective pressure. Go look that up on Wikipedia. How the air gets to the engine is largely irrelevent.