more fuel = less egt's
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Joined: Aug 2005
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From: Airdrie, Alberta
Let me clarify what I was trying to say!
First I upgraded from the hy9 to a hx35/12, then to a PDRhx40/16 then to a phatshaft then the twins.
Injectors went from rv275's to DD2's with the second and 3rd turbo's.
Then I went to Mach 2's (105hp) with the pfatshaft and twins.
Best mileage recorded was with the 3rd tubo and DD2's. i saw 22-23 highway at 72mph.
I was told the phatshaft was a towing able turbo. Bullhocky!!!
Oh, I forgot I had a comp box first the the TST powermax came to me about the time of the phatshaft. tst makes a very reliable box! I went thru 4 0r 5 compboxes.
With the Pdr40 i could tow if I kept rpm up above 2300 or so.
Phatshaft always layed down at most any rpm when I leveled the speed off.
I run daily with the TST off, turn it on to play. EGT's always cool--under 1000 preturbo, and ussually 650-700 at 60mph.
I can tow this way with EGT's under 1100.
Turn box on and run with both turbos spooled.
This truck clicked off 100+ mph with the PDR40 and DD2's in the quarter!!! Of course with heavy smoke. The Mach 2's run better with less smoke.
So, anyone running 200 hp injectors and NO BOX with a modified turbo is something I can believe, if the EGT's are watched and RPM kept up.
First I upgraded from the hy9 to a hx35/12, then to a PDRhx40/16 then to a phatshaft then the twins.
Injectors went from rv275's to DD2's with the second and 3rd turbo's.
Then I went to Mach 2's (105hp) with the pfatshaft and twins.
Best mileage recorded was with the 3rd tubo and DD2's. i saw 22-23 highway at 72mph.
I was told the phatshaft was a towing able turbo. Bullhocky!!!
Oh, I forgot I had a comp box first the the TST powermax came to me about the time of the phatshaft. tst makes a very reliable box! I went thru 4 0r 5 compboxes.
With the Pdr40 i could tow if I kept rpm up above 2300 or so.
Phatshaft always layed down at most any rpm when I leveled the speed off.
I run daily with the TST off, turn it on to play. EGT's always cool--under 1000 preturbo, and ussually 650-700 at 60mph.
I can tow this way with EGT's under 1100.
Turn box on and run with both turbos spooled.
This truck clicked off 100+ mph with the PDR40 and DD2's in the quarter!!! Of course with heavy smoke. The Mach 2's run better with less smoke.
So, anyone running 200 hp injectors and NO BOX with a modified turbo is something I can believe, if the EGT's are watched and RPM kept up.
IIRC, he usually ran on Kill. 550hp was what he usually towed at, according to his posts. He's a good guy, I have no reason to doubt.
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Joined: Jul 2006
Posts: 698
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From: Nixa, Missouri
Back to the posted question about fueling to increase boost. Yes more fuel will cause the turbo to light faster but you have to look at the exit side and where you are reading your EGT's. The CR's turbo with the 9cm housing is small and doesn't expell the gases well thus holding the heat and causing your egt to go up. The more heat that bottle necks, will back up to the head and then to the pistions. So since fuel equal heat and you add more fuel to the back up you will add more heat. Yes it will put a little more air into the piston sooner to work with the fuel but that will also create more pressure which makes more heat. Now there is a flip side the extra fuel can have "some" cooling effect on the pistons but (overfueled P-Pumps as an example) but that doesn't help your head and valves.
The turbo is capable of 500 hp but way out of its efficiency range and going to be run hot all the way around.
The turbo is capable of 500 hp but way out of its efficiency range and going to be run hot all the way around.
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Joined: Jul 2006
Posts: 152
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From: payson,Utah
Point well taken. I just wanted to through the thought out there. I like my turbo overall but it may not be the best for towing. I was just talking to Jacob over at Diesel Auto power about injectors. He suggested I try his intake ram air plate. This basically replaces our stock intake plate. I have read some good reviews. One guy over on the cummins forum has video. It will give you faster spool up, lower egts and cleans up your smoke.
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Joined: Jun 2008
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Fueling is required to make boost, and boost drops egt's. But only if done so without matched increase in fueling. Turbo's are mapped to make the compressor keep up with the exhaust. If you fuel more on high egt's, the egt's will just climb.
To get the egts under control, you need to have more air delivery or less exhaust restriction (more likely the former) *without* more fueling such as addressing a boost or preturbo exhaust leak.
I have heard that the small wastegate port on that turbo can be opened up for better flow so it doesn't back up pressure in the exhaust, but don't know much about that.
There are actually many different variables that affect the turbo map. The boost you develop is a function of engine displacement (rpm x cylinder volume) and the compounding effect of boost driven by this displacement and the expansion of gasses from combustion. This is why higher rpm gets the egt's under control where delivering more fueling at lower rpm just makes them soar.
To get the egts under control, you need to have more air delivery or less exhaust restriction (more likely the former) *without* more fueling such as addressing a boost or preturbo exhaust leak.
I have heard that the small wastegate port on that turbo can be opened up for better flow so it doesn't back up pressure in the exhaust, but don't know much about that.
There are actually many different variables that affect the turbo map. The boost you develop is a function of engine displacement (rpm x cylinder volume) and the compounding effect of boost driven by this displacement and the expansion of gasses from combustion. This is why higher rpm gets the egt's under control where delivering more fueling at lower rpm just makes them soar.
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