Air flow and Pressure Ratio Calcs
Turbo Mini Forums

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Ahhhhh that's better, got my fix.

n = Cp/Cv which is about 1.4 for air.

The temperature will rise through the compressor and then drop through the intercooler. If it doesn't then you have done something wrong.

Now where is that dark room for a lay down?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,

Going back through your maths and my calculations it would appear that the compressor efficentcy has no effect on the power the engine make or the compressor output figures. This doesn't sound right to me.

Well, it does in my calcs, but not by a lot if you have set a high intercooler efficiency.

With a high intercooler efficiency, the extra heat created by the compressor inefficiency is largely removed, so that the engine inlet temperature does not rise significantly and therby drop the power.

I think that if the intercooler has a lot more work to do, it will not be so efficient.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thinking about this a bit more.

The effect of a poor compressor efficiency, not only impacts on the intercooler efficiency, but also the engine volumetric efficiency.

If you think about it, the lower compressor efficiency that puts more heat into the air, also puts greater demands on the turbine. The wastegate has to close a bit to force more gas through the turbine to provide the exra power. This in turn increases the back pressure on the engine and reduces VE.

So you really need to adjust all the efficiencies if you want to identify the impact of a poor compressor selection.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Totally agree with you able compressor efficiently, just couldn't see were you used it in your calculations, however I was being blind, having re-read the attached for the hundredth time I spotted it.

It people want to have a play I've converted the attached pdf into an excel spreadsheet.

You missed something again

Remember that the TT2 runs a GT1752.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

What have I missed this time?

I fully appreciate that the TT2 runs a GT17 but with a Compressor Pressure Ratio of 1.895 and a Compressor Air Flow of 10.9 I make you seriously left of the surge line.

I'm being not to like this maths business.

Rob,

What are you calling the surge line?

10.9 and 1.895 sits between the surge line and the best efficiency line.

You have missed from the calcs that the air flow after intercooling is 12.6 lb/min.

I intend to increase the revs on my engine and get nearer to the high efficiency island.

Edited by Paul S on 4th Mar, 2010.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I've been very stupid and got the surge line and the best efficiency line muddled up, I feel like a proper Muppet.

Out of interest what do you reckon the pressure drop is for each bend in the IC pipes? About the same as the pressure drop across the IC? or does the IC pressure drop take into account the loss due to the plumbing?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."