POWER / heat generation and cooling

[madmike]

I like sharks.....

[Pappu1]

to be honest, i dont think a higher power output produces that much of an increase in heat the turbo sees (talking up pipe gas temo as keeping to the theme of things)

it maybe marginally higher like 5-10% max

cos otherwise if the temprature increase was that much then the higher numer kw cars wud have some astonomical temp number

for the most part if the turbo is in its efficiency range and there is similar afr and tune the 200kw and 290kw cars - both the exhaust temp at up pipe be abt the same if not slightly higher only

my old v7 wrx (nz new) had a EGT sensor from stock and iirc the egt temp was abt 5 percent higher for abt a 30kw gain (approx 20%) based on dyno number (yes same place before and after)

[pl0x]

I can see Turtles side of thinking in:

its been drummed in that you rise psi on smaller turbo creates more heat/air temp, but that may only be for intake side? (or more so)

but makes sense that more power/fuel being burnt = more heat...

[Swindog]

Sort of. There comes a point when your turbo runs out of puff and stops producing power but creates heat.

[vorigan]

800-850 deg c is where power is best made depending on intake temps

[Koom]

 funkytown']

Wheres Koom when you need him.???

I was out tending to a couple of fine ales. Should be doing the same now but I've found the flu and it's rapidly degrading into the manflu. I may only have hours left to live.......

I think a few of you have gotten lost between straight temperature level, and the heat energy/potential/capacity of the system (I can't think of what to call it right now, its pretty much the heat energy). Cause as Vorigan said;

[quote name='vorigan said:

800-850 deg c is where power is best made depending on intake temps

there is an optimum temperature range that you can tune to. It probably correlates loosely to the AFR's but I don't really know.

Thinking back to a 290kw engine melting stuff more than a 200kw engine (I've seen plenty of 200kw engines melt lots of stuff like manifolds, turbos, exhausts in general etc etc). If you think about the mass flowrate of "air" going in through the intake, combusting, and going out the exhaust. If we make the assumption that the efficiency is roughly the same at various power levels.

mass flowrate is how many kgs of air per minute are going through the engine. Also the volume flowrate is the number of litres per minute etc etc] - And no, those aren't the SI units.

I'm going to call one kg of air a "unit" to make the sentences make sense.

So if the efficiency is the same, but the flowrate is increased (cause to make more power, you must flow more "air"), and if each kg of air flowing out of the combustion chamber is at 850 deg C, then each unit of 850 deg C air will transfer a certain amount of heat from itself into it's surroundings (i.e. the exhaust pipe).

So there is basically more units of air at a higher power level, with similar temperature in each unit, travelling through, so overall more heat energy can be transferred to the exhaust (or whatever you're talking about in the first place cause I don't know where this conversation came from). So although it may seem like stuff is getting "hotter" it is probably just reaching the peak temperature and staying there for longer.

Otherwise, if the jump from 200kw to 290kw made that big of a jump in temperature, a 1000kw drag car would have exhaust temps that would melt the sun.

[B4 2000]

it's like having a heater in a room, once the walls reach it's optimal heat loss, the room temperature will rise till it's equal to the heat temperature emitted by the heater itself. Then the room temperature will be constant as well as the heat loss from the walls.

But when you have a bigger heater, you'll reach that constant temperature faster but will still the same constant temperature as the the smaller heater.

on a car.

small heater = small turbo

Bigger heater = Bigger turbo

walls = headers, up-pipe and hot side

[edit: after reading Steve's post below]

As a general rule, leaner AFR = less fuel = hotter air out; richer AFR = more fuel = colder air out

i hope my logic is easy to be understood

[vorigan]

It would fun teaching all what happens on the dyno just to show what really goes on and i don't mean how to make power but show the strange things that happen and afr don't mean crap at times as it doesn't reflect other things.

Eg: you can have a rich afr and still have high exhaust temps and the other way around, not enough timing generates high temps as much as too much blah blah blah blah.

The calculator doesn't decide what you get the motor does, if it was a science why doesn't every tuner get the same results?

Ive had many different engines over the years producing very strange outcomes that no one could explain logic just doesn't happen.

Translating all that try explaing to the owner why his catalog weapon doesn't work as good as his budget mates setup does ???

By far the hardest thing i could ever be asked to do is teach someone how to tune along with turbo selections i even give myself a headache with the crap in my head.