Boost vs EGT
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Elder User
Joined: Feb 2010
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From: So Cal
Boost vs EGT
Guys,
Quick question on theory...
I keep reading that by getting a bigger turbo (i.e. D66/ H2E) your egt's can drop because it is pushing more air. Questions is, I noticed during my last camping trip towing the trailer that the egt's would climb higher (very fast) when the boost would climb and fall/hover when boost was kept approx 10lbs. As soon as I would get a little more into the throttle the boost immediately jumps to 15lbs plus (depending on how much fuel I want to waste) and egts are immediately ~1200-1300*. So, how would pushing more boost through a system with a bigger turbo, lower egt's if during my last trip egt's would rise with boost?
I already know I need an inter cooler just need to start searching for new spyder pipe and 6.blow cooler...
Thanks,
Quick question on theory...
I keep reading that by getting a bigger turbo (i.e. D66/ H2E) your egt's can drop because it is pushing more air. Questions is, I noticed during my last camping trip towing the trailer that the egt's would climb higher (very fast) when the boost would climb and fall/hover when boost was kept approx 10lbs. As soon as I would get a little more into the throttle the boost immediately jumps to 15lbs plus (depending on how much fuel I want to waste) and egts are immediately ~1200-1300*. So, how would pushing more boost through a system with a bigger turbo, lower egt's if during my last trip egt's would rise with boost?
I already know I need an inter cooler just need to start searching for new spyder pipe and 6.blow cooler...
Thanks,
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
My understanding at this point is that even though your turbo is pushing more air, when you see your boost numbers rise, you're also dumping more fuel. The turbo is driven by exhaust which is made by fuel again, so more fire = more boost. The thing is though that a bigger turbo will make more boost at full fuel than a smaller turbo will with the same amount of fuel. In other words, your stock turbo at WOT would make say, 15 PSI of boost, whereas a larger turbo might make 20 PSI since it is pushing more air.
That's my elementary understanding of the subject.
That's my elementary understanding of the subject.
Postmaster
Joined: Nov 2005
Posts: 3,168
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From: San Ramon Ca.
What RPM range are you in when you hit the high temps? A upgraded turbo is going to increase the amount of air being pushed onto the intake. So in theory (I'm not really up on this so take this with a grain of salt) more air with a higher flow rate in volume and pressure could lower EGTs. But you can only go so far power wise before an IC is needed to protect the system from overheating in any case. Back pressure is your enemy too. An injector upgrade could help in that area also. I can't remember what your running now. LOL I could be full of poop too!
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Elder User
Joined: Feb 2010
Posts: 746
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From: So Cal
Nate/Pete,
Makes sense... I am running 4.10's so RPM's are approx 2500 when in 3rd (OD off). Fuel consumption would be the same no matter what turbo you are running, just the amount of boost applied to the power would be upgraded w / a better turbo.
On this note... What does everyone think of the D66 from Beans? It, from my minimal research on the subject, seems to be a really good "bang for your buck" at just over a grand...
Thanks for the insight.
Makes sense... I am running 4.10's so RPM's are approx 2500 when in 3rd (OD off). Fuel consumption would be the same no matter what turbo you are running, just the amount of boost applied to the power would be upgraded w / a better turbo.
On this note... What does everyone think of the D66 from Beans? It, from my minimal research on the subject, seems to be a really good "bang for your buck" at just over a grand...
Thanks for the insight.
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
Mike, what I have seen with the D66 is a quicker spool and maybe a little less EGT's. I can hit 32 lbs now but its only a little more then the stock turbo. Its a good turbo but its not a cure all, unbeliveable turbo, IMHO. The claim is 30% more air but like talked about above, its hard to explain. More fuel, more EGT's. The more mods that help power need more mods to keep EGT's down. My IC bought it down 200*, my coolingmist water injection brought it down 200* and I think the D66 helped. I can stay in it longer and harder but like everybody, my right foot does what my gauge does. It goes up, my foot comes up and visa vera.
Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
Mike, I'm just talking in averages, not WOT. When I pull that 5er in my signature if you WOT your melt the engine down, LOL. Three or so years ago I put the IC on and I figured by past experience I dropped 150 to 200 degress on average. Last winter I put the coolingmist on and wanted more accurate results. Took the 5er out and south of town hit a hill at 70 and watched rpm's and boost. Turned around and did the same thing. First run I let it stay at 1,400 for a while, not long and this run was with the coolingmist off. On the second run, doing the same thing I was at 1,200 with coolingmist on, I was impressed.
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Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 99
From: Ashland City, TN
Okay. I skipped the other ones.
Bigger turbo = More Volume.
It's not just about how much pressure your pushing, its more about how much volume your moving.
bigger turbo means more volume, which means lower EGT's. Your moving air faster, keeps it cooler.
Bigger turbo = More Volume.
It's not just about how much pressure your pushing, its more about how much volume your moving.
bigger turbo means more volume, which means lower EGT's. Your moving air faster, keeps it cooler.
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Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
That's not entirely true. While a bigger turbo WILL produce more volume, the engine can only hold so much air, so the pressure will rise as the turbo pumps more air (volume). What you will see however with a bigger turbo is that they will not run out of air volume at higher RPM so it will be able to maintain better boost pressure at higher RPM.
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