If EGR lowers combustion temperature and lowering combustion termperature increases power, then does EGR increase power?

 

How exactly does an EGR lower combustion temps? Lowering combustion temps does not increase power, perfectly stoichiometric combustion would generate the most power but it results in too high of combustion temps.

I think you are confused.

 

"This system recirculates a small amount of exhaust gas into the intake manifold to reduce the combustion temperature, and reduce NOx emissions." -- 1994 Mazda RX-7 Factory Service Manual, F-125

 

You're close, but not quite there.

The EGR valve does serve to lower combustion chamber temps - at a certain point (like 1700 deg. F) nitrogen and oxygen combine to make NOx, which is a greenhouse gas.

EGR valves inject exhaust gasses back into the chamber. The way it lowers combustion temps is by replacing some of the volume of air and fuel that is to be combusted with a basically inert gas. It's basically like taking 10 sticks of dynamite and replacing 2 of the sticks with sticks of butter - you get less bang, because butter doesn't blow up .

The EGR system was mainly put on the FD to meet federal emission requirements - the Japanese FD's didn't have EGR, nor did the '95s in the US. The system is darn near not functional - the passageway feeding the valve is SO small that it gets blocked with carbon very quickly.

Anyhow, you're not going to gain mad power by removing it - it only functions at cruise/light load, not at full throttle. The only real reason to remove it is just to clean things up a bit and get rid of an unneeded system.

Dale

 

"COOLANT EFFECTS ON PERFORMANCE
Under moderate load conditions, each percent glycol
raises cylinder head temperatures by 1°F. 50% glycol
raises head temperatures by 45°F. This increase in
temperature will raise the octane required for trace
knock levels by typically 3.5 octane numbers. A car
equipped with a knock sensor will retard the timing to
compensate for the increase in octane requirement
by approximately 5°, which will reduce the maximum
brake torque by about 2.1%. Racing vehicles not
equipped with knock sensors can advance timing for
increased torque." -- http://www.redlineoil.com/whitePaper/17.pdf

This leads me to believe that reducing combustion temperature may allow more spark advance for increased power.

 

That's coolant temp, which is fine and dandy - what does that have to do with EGR?

Dale

 

Aren't cylinder head (rotor face) temperature and combustion temperature related?

 

Anyone?

 

Yes, reducing the temps does have an effect on increasing performance. However, that ain't going to happen from removing the EGR. Ceramic coatings of the rotor faces has show a decrease in oil temps (which means a decrease in overall engine temp).