Thread: Isuzu EGT's

Yep, more air=lower EGT's

There is a lot of talk re EGTs and the need for pyros to be installed on turbocharged engines to ensure 'tuning' w.r.t to boost/fuel is within safe working limits of the engine. However, wouldn't an increase in engine load/ EGTs ultimately be reflected (albeit broadly) by the traditional water temperature gauge? (i.e. an increased engine load resulting in increased water temps) or is it a case of too little too late???

Nice gauge set up Brian.

Is the tacho a VDO Product also?

If so a model please

Pete

Originally Posted by 110Landy86

However, wouldn't an increase in engine load/ EGTs ultimately be reflected (albeit broadly) by the traditional water temperature gauge? (i.e. an increased engine load resulting in increased water temps) or is it a case of too little too late???

No, I can get my EGTs up to 350 without a problem on a cold engine. The revised Freelander 2 now incorporates an EGT sensor so the ECU can modify boost and Air/Fuel ratio to develop more power or reduce when needed. With the Isuzu the ECU is simply your right foot, the gear you're in with those inputs based on what the gauge says. The theory is still being used on modern cars just controlled by a computer or they play it safe and tune for safety and remove the inputs. Generally though Isuzu turbo owners like to tinker a bit, hence the gauge.

Originally Posted by 110Landy86

There is a lot of talk re EGTs and the need for pyros to be installed on turbocharged engines to ensure 'tuning' w.r.t to boost/fuel is within safe working limits of the engine. However, wouldn't an increase in engine load/ EGTs ultimately be reflected (albeit broadly) by the traditional water temperature gauge? (i.e. an increased engine load resulting in increased water temps) or is it a case of too little too late???

Short answer.
No.
They are measuring two entirely different things.
I can exceed 720* (pre turbo) easily on a hill without the engine temp going up much at all and that's on a Tdi who's cooling system is marginal at best.

actually yes, you will notice the change in the temperature gauge from higher EGT's however its too little too late when you do. to get the EGTS to sizzle you need to be running high load at low RPMS and depending on the fueling setup mid range boost so that any boost compensator will allow you to have full fuel.

The reason you dont see the cooling system temp gauge move much is to do with heat soak and the basics of thermodynamics while the piston is going down the heat is being extracted by the piston in terms of work and then when the work is done the exhaust valve opens and the hot stuff goes away out the exhaust to power up the turbo and then a load of cool air is shoveled in.

The metal in the engine is acting like a buffer and stopping you from seeing small changes quickly if you push the fuel hard enough you can wind up with the fire in the chamber exceeding the melt point of the metals (the head for a tdi/td5 the pistons for the suzi) used. a similar analogy is holding onto a metal rod that youve poked into the fire if the rod is long enough you dont feel any heat initially as it has to travel up the rod. If the rod is long enough you wont feel the heat because its shedding the heat off to atmosphere faster than its being applied. in both cases you can wind up with one end of the rod red hot and melting while the other end is still cool enough to hold by hand.

550C post turbo may be too hot with 20psi.

The more boost you run, the bigger the temp drop across the turbine becomes. I'd shift the probe.

Not that these engines seem to have any problems running hot for short bursts. I regularly hit 750C and have seen 900C in times of inattention.

Originally Posted by Dougal

550C post turbo may be too hot with 20psi.

The more boost you run, the bigger the temp drop across the turbine becomes. I'd shift the probe.

Not that these engines seem to have any problems running hot for short bursts. I regularly hit 750C and have seen 900C in times of inattention.

G'day Dougal, I know what you are saying but my motor is a 1995 late model with turbo pistons and I am confident that it can handle it for short periods. Although I am curious to know what the difference would be pre to post. Oneday I might shift it to the manifold outlet. With my old engine I could get them up to 650 post with 10psi on a long uphill pull. The temps didn't seem to have any ill effects on it.