8v Xu9ja Std Compression Turbo

[B1ack_Mi16 67]

I´m not shure if that is correct....

 

If the same engine is tested with 2 different turbos, and they both at a given RPM provide the same pressurelevel in the plenum, that would mean that the same volume of media(in this case air) is flowing through the system into the engine.

 

If it´s not like that something is seriously wrong with my knowledge of the affinitylaws and how pumps and fans are working in piping systems, and my knowledge shouldn´t be wrong there cause i work daily with dimensioning stuff like that.

 

But i think i understand what you mean though, although you might have explained it a bit strange.

 

I don´t mean to be offensive or anything like that, just curious about what you meant

 

Well you also have to take into account exhaust manifold pressure, before the turbo-unit, not only inlet-charge pressure.

 

So if the turbo makes a 2bar inlet pressure, and have big exhaust housing giving a back pressure of only 0.4 bar.

Then another turbo might also make 2 bar inlet prssure, but with smaller exhaust housing it will build more back-pressure, for example 1bar.

 

So the first turbo will let the engine empty itself with exhaust much more efficient, hence giving room for more fresh charge into the cylinders than the later one.

 

Logical?

[tom_m 0]

If the same engine is tested with 2 different turbos, and they both at a given RPM provide the same pressurelevel in the plenum, that would mean that the same volume of media(in this case air) is flowing through the system into the engine.

 

in this case density comes into play doesn't it? a more efficient turbo will provide a cooler denser charge so this must count for something.

[snillet 1]

Now i´m a little more enlightened about what´s going on

 

I always like to know what people mean when talking about stuff i´m about to start reasearching, planning a "downsizeing engine" project on ethanol in the future. Meaning high compression low volume with small turbo.

 

Thanks

[cybernck 400 1 Cars]

snillet> afaik, boost level just shows the amount of compression going on, above atmospheric level,

not the actual amount of air per intake volume. like tom_m said, if you use a more efficient turbo or

a better intercooler, keeping the boost level the same (via wastegate, mbc or ebc) you will get denser

air meaning higher actual compression and more power. partially what i was originally trying to explain .

[snillet 1]

snillet> afaik, boost level just shows the amount of compression going on, above atmospheric level,

not the actual amount of air per intake volume. like tom_m said, if you use a more efficient turbo or

a better intercooler, keeping the boost level the same (via wastegate, mbc or ebc) you will get denser

air meaning higher actual compression and more power. partially what i was originally trying to explain .

 

I thought the original explanation was a bit short and didn´t give as muche info about the variables as i would like to hear, now i really get the whole picture of them.

 

Anyone has tips on litterature about turbos and turbocharging ?

[Normski 1]

Cybernck, what your saying is right. A turbo will have a range of boost pressure that it will work in efficiently i.e. not adding too much heat to the inlet charge. At a certain stage that turbo will not be big enough to supply the needs of the engine in terms of air density. Getting more power out of it by raising the boost pressure doesn't work due to the heat that's being added. To get more power a larger turbo would be needed.

High oxygen density is what your after, this is effected by temperature and pressure.

 

Snillet, have a look for 'Forced induction performance tuning' by A. Graham Bell. It's excellent