how hot?

[incisor]

How hot should the intake pipe between the turbo and the inlet manifold get when engine is working at 2000 rpm ?

cook your dinner hot ?

[Blknight.aus]

it picks up a heap of latent heat from the turbo and the exhuast manifold...

I wouldnt call it cook your dinner hot... reheat maybe.

if you sit a ham and cheese crisonte just behind it on top of the rocker cover it does an excelent job of just melting it enough.

[justinc]

Dave, (Inc)

Without an intercooler, quite hot indeed. It isn't out of the question to see 55 to 65deg(A cup of coffee temp) from the compressor outlet. Obviously depending on boost presssure/ fuelling etc but you get the idea. This is why anything over 10psi really should be intercooled to enhance efficiency.
You've probably heard this before, but after a hard run up a long hill, I can hold my hand ,just, on the upstream side of the I/C pipe, but into the manifold it is cool to the touch. Fantastic job the I/C does. I have a study background many years ago in thermodynamics, and without trying to quantify it without actual measured figures that I just don't have, the temperature differential across my intercooler is definately showing a marked increase in efficiency=less fuel= more power.



JC

[Bush65]

it picks up a heap of latent heat from the turbo and the exhuast manifold...

I wouldnt call it cook your dinner hot... reheat maybe.

if you sit a ham and cheese crisonte just behind it on top of the rocker cover it does an excelent job of just melting it enough.
I suspect your terminology may be mixed up a little - latent heat is heat associated with a change in state (e.g. solid to/from liquid, or liquid to/from vapour), and there is no change in temperature.

When something is heated/cooled and there is a change in temperature, it is called sensible heat.

[justinc]

I suspect your terminology may be mixed up a little - latent heat is heat associated with a change in state (e.g. solid to/from liquid, or liquid to/from vapour), and there is no change in temperature.

When something is heated/cooled and there is a change in temperature, it is called sensible heat.

John, Very sensible reply.

:D:D:D:D:p:p:p


JC

[isuzurover]

How hot should the intake pipe between the turbo and the inlet manifold get when engine is working at 2000 rpm ?

cook your dinner hot ?

How hot yours gets will depend on ambient temp, how much boost you are running, and how quickly it can be dissipated.

Cook your dinner hot is possible.

[Blknight.aus]

your correct but your wrong.....

the word I ment was conducted.....

how i got that to latent..... urmmm errr.... not enough coffee?


and yes I know the heat it picks up from the exhuast manifold would be radiated heat not conducted but see the line about not enough coffee....

(good catch)

[Bush65]

As Justin said, there are thermodynamic principles involved. But there is inescapable heating from compressor efficiency.

The compressor map for the turbo has a set of curves that plot efficiency for output flow vs pressure. The efficiency plays a considerable part in the amount of heat generated.

If the compressor is operating in an inefficient region it's wheel is spinning (think of wheel spin or torque convertor slip) much faster relative to the air flow created. A large portion of the power from the turbine is converted to heat energy instead of gas flow.

Quite often, when the boost pressure is adjusted up, the compressor becomes less efficient, the heat and boost increase for little improvement in airflow or power (but it improves the bragging factor). A better matched compressor (or modifying the compressor) can allow more power with lower boost pressure, in these cases.

[harry]

How hot should the intake pipe between the turbo and the inlet manifold get when engine is working at 2000 rpm ?

cook your dinner hot ?
yep.
the compressor heats the air as it compresses it, so it will be too hot to touch the pipe, and the radiant heat in the engine bay also heats everything. this heating due to compressing is the reason we have intercoolers, to get more air into the engine, in turn , the more air in , the more fuel we can got in to get more power out.
sorry, didn't mean to give lessons.
it's a land rover, everything under the bonnet is too hot!!!!!!!

[isuzurover]

As Justin said, there are thermodynamic principles involved. But there is inescapable heating from compressor efficiency.

The compressor map for the turbo has a set of curves that plot efficiency for output flow vs pressure. The efficiency plays a considerable part in the amount of heat generated.

If the compressor is operating in an inefficient region it's wheel is spinning (think of wheel spin or torque convertor slip) much faster relative to the air flow created. A large portion of the power from the turbine is converted to heat energy instead of gas flow.

Quite often, when the boost pressure is adjusted up, the compressor becomes less efficient, the heat and boost increase for little improvement in airflow or power (but it improves the bragging factor). A better matched compressor (or modifying the compressor) can allow more power with lower boost pressure, in these cases.

Just so I understand...

this heating you mention due to inefficiency is unrelated to adiabatic heating?

[Dougal]

If you're running 15psi boost, around 105C.
If you're running 20psi boost, around 135C.

[incisor]

so what size intercoolers are people running ?

[weeds]

so what size intercoolers are people running ?

1103.9TDI had a nice water to air intercooler built at a joint in Brendale, well i didn't see the end product but it sounded good and the company seems to know what were on about

[Dougal]

so what size intercoolers are people running ?

Mine is about 100mm thick, by 300mm long by 200mm wide and is air/water. It resides in a box in my garage where it's been for the last two years.

It's on the list and is kind of necessary if you're running the 20psi that I am.

[Bush65]

Just so I understand...

this heating you mention due to inefficiency is unrelated to adiabatic heating?
That is correct, it is addition heat.

The compressor efficiency has to be accounted for.

If the compressor is operating at an efficiency of 75%, then 75% of the mechanical energy from the turbine is being used to compress the air and approx 25% is added to the charge air as heat energy (some of the 25% will be dissipated into the engine bay).

75% is good. When the turbo is not a good match, or the boost is increased such that the compressor operates in a less efficient region it can be ugly.

[Blknight.aus]

inc when I get round to installing the new cooler for big red (next service in 10K Km ish) you can have the old one for the suzi. If you want it.

[harry]

and don't loose track,
if you need to intercool it, you need to supply air flow to the intercooler.
just wacking one in doesn't solve the problem.
think about airflow when driving and puttering and stationary, and do you need to fit cooling fans to cool the inter cooler.
basically, just do what the manufacturer of your desired system did and copy it.

[Dougal]

If you're running 15psi boost, around 105C.
If you're running 20psi boost, around 135C.

To fit in with the recent thermodynamics lessons.
The above temperatures I've quoted are based on a 70% efficient compressor and your air intake being at 20 deg C.

I've measured turbo outlet temps at 105C in a healthy T25 at 15psi and close to 150C in a sick IHI (dust eroded compressor blades).

[isuzurover]

Thanks John and Dougal, I am surprised efficiency makes that much difference, I thought most of the heat was adiabatic and conducted/radiated heat from the housing.

I suppose moving air molecules back and forth rather than sending them where they are wanted creates a lot of heat...