The effect and consequences of fitting EGT

[Olazz]

Having made all of changes to the truck, it was obvious that the fuelling had to be increased to cope with hauling 4T around the bush. I read on various sites that it would be wise to fit an EGT gauge and meant to do this after fettling with the pump. Anyway I adjusted the fuelling and though no more of it. We have doe about 15,00km with increased fuelling.

Before this latest trip however, I decided to get it done . I have a mad man gauge now fitted mid manifold and pre turbo and the default alarm setting is 720ºc

Having read up quite a bit about this subject (and opinions differ) I left this as the default setting to see what was happening on my particular setup. According to many reports the pre turbo Temp will be between 200º - 300º higher than post turbo, due to turbo spooling and heat absorption.

Opinions also vary on what is an acceptable max for temp in various diesel applications, varying from 700º – 900º. ( all pre turbo temps)

So what’s the point?

• I have had to change my driving style considerably as a result of this extra information.
• Earlier gear changes are not always the best to keep EGT low.
• Dropping to a higher gear reduces EGT by the fact that you are driving slower… if you still keep the pedal floored EGT rockets.
• One can still maintain a set speed even if you back off the throttle slightly, thereby saving fuel too.
• There is a considerable increase in EGT in my vehicle by increasing the speed by as little as 5km when over 100kph; varying between 550 – 650º @ 100 and 690-760º @ 105kph.
• Cruise control is not good for maintaining steady EGT as the sender unit applies FULL throttle to keep speed constant when there is a drop off.

Now the max I purposely pushed to was 890º over a 2 minute period, to allow the cruise to maintain 100kph whilst climbing a steep hill in top.

I would assume that as I drove like this often, pre installation, either:-

1) I have already done huge damage to the motor.
2) These temps are quite safe to operate at.

Will be interesting to hear if anyone who has more experience of this has some advice or comment.

 

[Jon Wildsmith]

I haven't messed with the max fuel screw on mine but it has mods something like the LCOOL boost compensator mod from fiddling with vacuum pipe settings. It goes well so not lacking in fuel but not excessively fueled either so I haven't felt the need to mess with max fuel (yet). Max pre turbo EGT I see is 650c driving up hill full throttle / 12psi boost for long periods in high 30's to low 40's C ambient temps and running pretty heavy. This is with the 3" exhaust and dump pipe which are said to lower EGT.

I haven't seen much information about sensible max EGT's from a reliable source but have 750 in mind for that ...

 

[Olazz]

That's interesting Jon, as I haven't done any mods on my pump other than increasing the fuelling. I'm now wondering if the pump tweaks would give me the same performance as greater fuelling. perhaps a combination of both would allow me to back off the fuelling a little.

I too am running a clean 3" pipe with dump. No cats and small silencer.

The jury is still out whether I keep the gauge alarm set @ 720º or increase it to 800º. It definitely make me drive differently, so maybe not a bad thing to have. It is however just another bit of info that I spend time looking at and worrying about.

 

[Towpack]

I've run mine to 1300F on the gauge (704C) for short periods but I'm not comfortable cruising over 1250 (676). I also have a 3" exhaust but no IC.Pure aluminium melts at 1220F (660). The melt point for the aluminium alloy used in pistons will be higher than this but not much. A figure I've seen mentioned is 1320F (715). You can get EGT's higher than this momentarily without damage as the airflow though the cylinder will mean the piston temp will climb slower then the EGT but you're pushing your luck IMO. Increasing fuel burn will give more power but also more heat. Increasing boost will force more air though the engine and cool the intake charge and hence the EGT but only up to a point, after which you then need to cool the air through an IC to counteract the heating effect of high boost as just compressing the air through the turbo has the effect of heating it. JMO