[Mpower]

Originally Posted by ananthkamath

What all this means is that having a turbo is effectively free power. Yes, a turbo is the classic advocate of a free lunch!
Ananth

Not quite AK, turbos increase backpressure tremendously which means more negative work during exhuast stroke robbing some IMEP. This means the piston is driving the turbo during the exhuast stroke, just like the crank pulley 'drives' the supercharger. But indeed its lesser than a supercharger because the exhuast gases have plenty of energy due to combustion inefficiency.

[ananthkamath]

Isn't this why purpose-made turbo engines (or aftermarket turbo-specific cams) open their exhaust valves earlier...to compensate for the backpressure and also increase EGT and hence velocity?

[Mpower]

Originally Posted by Mpower

But indeed its lesser than a supercharger because the exhuast gases have plenty of energy due to combustion inefficiency.

First let me correct myself, exh gases have plenty of energy because of the inability of the otto cycle to harness the energy into mechanical work.

I have also seen this cam timing strategy applied in high revving twin cam engines.....opening about 30 deg BBDC. Basically the idea is to use the high Delta P in the cylinder (which you find BBDC) to scavenge the exhuast rather than use pumping work.

High EGT is usually obtained by retarding timing. Commonly used strategy in Euro 4 cars for quick catalyst light off.

[ananthkamath]

Yeah the P-wave is used to scavenge the cylinder and it is not uncommon to find the pumping loss turned into the so-called "pumping gain"....But second order resonances also sometimes have an effect exceeding the primary, though only at very high RPM....the motorcycle engines which use these RPMs are known to be "musical", I'm not talking metaphorically here, but in terms of the range of frequencies harnessed to get a pumping gain...

[navin]

hey guys, my wife has an Opel Sail 1.6. Any simple performance mods you guys can suggest like maybe K&N filters?

I figure if we can up the power to about 100bhp and up the torque by say 4ft-lbs she whould be happy.

[turbo_lover]

a free flow and a k&n should get you near that mark .. Corsa is not a very modd happy car ..

[rkg]

Hi!
in today indian express, bangalore edition there is a news item regarding turbochrging. it seems some one in britain did it. by this method they are able to generate electrical energy. the article is with photo. i could not get the online link to post it

[navin]

Originally Posted by turbo_lover

a free flow and a k&n should get you near that mark .. Corsa is not a very modd happy car ..

thanks. i realise the corsa engine (1.6L atleast) is not a very free revving engine that is why i asked.