Thread: Engine chip upgrade and/or intercooler upgrade

More air + same amount of fuel = cooler

Originally Posted by Tombie

More air + same amount of fuel = cooler

Really? But that still contradicts the theory of an EGR which works on - Less air @ same amount of fuel = cooler

Originally Posted by Beery

Really? But that still contradicts the theory of an EGR which works on - Less air @ same amount of fuel = cooler

The specific heat ratio of CO2 and water is higher than Oxygen so it absorbs more heat from the process. Exhaust gas is essential these elements.

And yes to diesel AFR, a Petrol engine is the opposite where more fuel = less heat.

Originally Posted by Beery

Im a bit confused here.
On one hand an EGR valve mixes oxygen depleted exhaust gas with fresh air to reduce the O2 available for combustion therefore REDUCING combustion temps and the formation of nitrogen oxides.
On the other hand, a larger intercooler feeds a cooler, more O2 rich air charge to the cylinders...apparently also REDUCING combustion temps!

I'm missing something here...

Tom

In a diesel at idle, there is far more air than needed so the charge is still pretty high, a diesel can run up to ~50% Exhaust gas

Originally Posted by Tombie

The specific heat ratio of CO2 and water is higher than Oxygen so it absorbs more heat from the process. Exhaust gas is essential these elements.

And yes to diesel AFR, a Petrol engine is the opposite where more fuel = less heat.

Ahhhhh ok, that sort of makes sense.
So the CO2 actually absorbs heat from combustion to lower peak temps regarding EGR?

I also didnt realise AFR has any effect on diesel combustion temps. Unlike petrols where the evaporation of a spirit has a cooling effect.

All a bit technical sorry. I'd just want some pretty well founded and qualified advice before spending big $$$ on an intercooler to lower EGT's.

Cheers
Tom

That's cool Tom.

So with a diesel, if you want more power you can just pump in more diesel the mixture doesn't burnt properly but a diesel will keep taking, EGTs will keep rising and eventually the engine will melt down.

With the IC the charge from the turbo is hot (compress and it will heat up) - reducing O2 density - cooling it down increases it's density and O2 charge providing more oxygen in a cooler parcel to feed with the fuel...

Originally Posted by Tombie

That's cool Tom.

So with a diesel, if you want more power you can just pump in more diesel the mixture doesn't burnt properly but a diesel will keep taking, EGTs will keep rising and eventually the engine will melt down.

With the IC the charge from the turbo is hot (compress and it will heat up) - reducing O2 density - cooling it down increases it's density and O2 charge providing more oxygen in a cooler parcel to feed with the fuel...

Thanks Tombie

So, more complete combustion = lower peak temp.

If I disable the EGR valve then, do EGT's rise? Seeing there function is to reduce peak temps..

EGRs primary function is NOx control, and works at idle / very low throttle (fuel) openings.

EGTs really are influenced by throttle/load which is when the EGR is at 0%.