Thread: Increasing boost to reduce EGTs - 300TDI

Originally Posted by isuzu110

Hi All

I'm still looking at ways to reduce EGTs when on long hill climbs like Cunninghams Gap in SEQ. Yes, I'm aware that dropping back a gear really helps EGTs.

The 300TDI defender has a fatter I/C, EGT gauge and straight through pipe replacing the centre muffler. Fueling on the IP has been upped marginally as per advice on this site.

My current boost maxes out at 15PSI as measured from the back of the input manifold. If I increased boost by say 2psi to 17 PSI, does anyone want to hazzard a guess how many degrees I might wipe off my EGTs when hill climbing ?

Secondly, I assume increasing max boost will not decrease EGTs when cruising on the highway at less that max boost - correct ?

Correct on your last.

Just disconnect your waste gate and observe what happens on full pedal up the gap. That extra heat will spin the turbo faster, you will make more boost and should result in lower EGTs. Can only do this for small increases before your efficiency drops of and you heat the air up coming out of the compressor/turbo.

whats it hitting to start with?

be careful disconnecting the waste gate, you may damage the T piece that feeds the boost compensator If that happens you wont get full fuel as the compensator is not seeing full pressure.

even with the extra 2psi you'll still be able to cook it up to 650+, it just might take a short while longer and you'll be going quicker (or working harder depending on how you've sliced your fueling/use the loud pedal).

Originally Posted by isuzu110

Hi All

I'm still looking at ways to reduce EGTs when on long hill climbs like Cunninghams Gap in SEQ. Yes, I'm aware that dropping back a gear really helps EGTs.

The 300TDI defender has a fatter I/C, EGT gauge and straight through pipe replacing the centre muffler. Fueling on the IP has been upped marginally as per advice on this site.

My current boost maxes out at 15PSI as measured from the back of the input manifold. If I increased boost by say 2psi to 17 PSI, does anyone want to hazzard a guess how many degrees I might wipe off my EGTs when hill climbing ?



Secondly, I assume increasing max boost will not decrease EGTs when cruising on the highway at less that max boost - correct ?

15 psi is what it was designed to do, that's the book max.

more boost means higher inlet temp, so more work for the intercooler to cool, but forward motion and perhaps reduced rpm, if not in a lower gear,
will reduce the effiency of the intercooler, so increasing fuel should cool it a bit as the extra fuel will be wasted because you can't get enough air to it.

turbo charging is there to maximise air in the cylinder, the intercooler cools the air so we get more in, so the more air we can stuff in, the more fuel we can add, the more fuel, the more power.
but if you're crawling up the gap, the intercooler isn't doing its job as if it were on the flat at 100 km's, so less air in, but you have upped the fuel, so black smoke and a cool turbo

Originally Posted by harry

[snip]

turbo charging is there to maximise air in the cylinder, the intercooler cools the air so we get more in, so the more air we can stuff in, the more fuel we can add, the more fuel, the more power.
but if you're crawling up the gap, the intercooler isn't doing its job as if it were on the flat at 100 km's, so less air in, but you have upped the fuel, so black smoke and a cool turbo

No, black smoke = a hot turbo and pistons.
We're talking diesels here Harry

isuzu110, I can't answer how much EGT's will drop with 2 extra psi even though I'm running 16.5-17, but I do know I dropped 23* with stock fueling when I made a 3" exhaust.

EGT's dropped from 623* to just under 600* going over my test hill (not quite as steep or long as Cunninghams Gap but about 150m or so gain in 2.5km)

I can exceed 750* on a hot on that climb so I just moderate the loud pedal to compensate.
On a cool, misty day it may not even exceed 700*.

Gas injection,mines got an extra 40 torques for a 20 degree rise in EGT's. Pat