EGT question for school project.
Hi all,
I am a student in engineering and as part of senior design project I need to know some information for my project model. Pretty much what it comes down to is I need to know the difference in temperature of exhaust gas before and after the turbo. Let's assume we are talking about cruising speed of 60 in overdrive in standard conditions (approximately 70 F), what ever that rpm may respond to. I know, it changes based on turbo and from truck to truck, but I just need a decent estimation to see if the project idea is worthwhile. So if some of you run gages pre-turbo, please let me know what kind of temperatures you are seeing. Same for post turbo. Also, do you guys happen to know if you would see similar temperatures in spark ignition engines? The help is really appreciated. Thank you! |
When I moved mine from down pipe to manifold with no other changes to the engine I saw a 250 to 300*. So for an example at 55 post turbo I would sit about 400* and pre turbo 750*. I give the range because it was different between hard accel and regular crusing. But that should get you in the ball park, good luck on senior project.
And gas engines......? don't have a pyro on my lawnmower. |
Awesome! That's what I expected, and agrees from what others have told me as well.
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Originally Posted by RussianVolk
(Post 2888058)
Hi all,
I am a student in engineering and as part of senior design project I need to know some information for my project model. Pretty much what it comes down to is I need to know the difference in temperature of exhaust gas before and after the turbo. Let's assume we are talking about cruising speed of 60 in overdrive in standard conditions (approximately 70 F), what ever that rpm may respond to. I know, it changes based on turbo and from truck to truck, but I just need a decent estimation to see if the project idea is worthwhile. So if some of you run gages pre-turbo, please let me know what kind of temperatures you are seeing. Same for post turbo. Also, do you guys happen to know if you would see similar temperatures in spark ignition engines? The help is really appreciated. Thank you! AFAIK, gas engines run cooler than diesels, so the temps should be lower. I'd think gasoline would expand in a slightly different way so maybe the temperature range would be different too. I don't know beans about gasoline engines though, so maybe it's just the same. [duhhh] Come to think of it, I don't really know beans about diesels either. [dummy] Don't listen to me, wait until someone who actually knows what they're talking about gives you an answer. [laugh] |
Originally Posted by RussianVolk
(Post 2888058)
Hi all,
I am a student in engineering and as part of senior design project I need to know some information for my project model. Pretty much what it comes down to is I need to know the difference in temperature of exhaust gas before and after the turbo. Let's assume we are talking about cruising speed of 60 in overdrive in standard conditions (approximately 70 F), what ever that rpm may respond to. I know, it changes based on turbo and from truck to truck, but I just need a decent estimation to see if the project idea is worthwhile. So if some of you run gages pre-turbo, please let me know what kind of temperatures you are seeing. Same for post turbo. Also, do you guys happen to know if you would see similar temperatures in spark ignition engines? The help is really appreciated. Thank you! cheers, Douglas When I was in school, Senior Project was funded. If you're close, I'll let you instrument my 1990 and we can take measurements. |
I'm pretty sure gas engines run considerably higher EGTs than a diesel. I think that's why there are more issues in getting a variable geometry turbo to work on a gas engine.
As for pre/post turbo EGTs, it'll depend on the work output from the compressor. Ignoring losses from drag on the shaft from the journal bearings, the work into the turbine = work out of the compressor, which depends on mass flow rate and the boost output from the compressor (and compressor efficiency). From reading around here, I've seen people claim anywhere from 250°F to 500°F. |
Originally Posted by Douglas2
(Post 2888323)
The gearing will change your operating conditions pretty radically. An early G56 with a 4.10:1 rear axle is going to be spinning its engine faster at 60 than any other trans, let alone a truck that has 3.07:1 gears. Of course, the 3.54:1 is somewhere in the middle...:) Also, a truck with a 21cm housing turning its engine slowly will have significantly lower boost pressure than one with a 12cm housing turning just a bit faster. This will change what sorts of EGT to expect, yes?
cheers, Douglas When I was in school, Senior Project was funded. If you're close, I'll let you instrument my 1990 and we can take measurements. Sorry for lengthy post, I dont know if you needed to know all that, but it is nice that here are still people out there that are willing to help [guitar]. I am a student at Purdue (Indiana), and we don't get any funding as far as I know, unless you are working with a company. |
Originally Posted by gman07
(Post 2888419)
I'm pretty sure gas engines run considerably higher EGTs than a diesel. I think that's why there are more issues in getting a variable geometry turbo to work on a gas engine.
As for pre/post turbo EGTs, it'll depend on the work output from the compressor. Ignoring losses from drag on the shaft from the journal bearings, the work into the turbine = work out of the compressor, which depends on mass flow rate and the boost output from the compressor (and compressor efficiency). From reading around here, I've seen people claim anywhere from 250°F to 500°F. Again everyone's input is appreciated. |
hey-Hey!!!,
Let me suggest getting your hands on a turbomachinery textbook. If Purdue is half as good as PennState you should have *NO* issues borrowing one from the Proff...:) It is even more fun to do it at work...you get the problem and have to solve it completely( after deciding just exactly what needs solving ), and depending on the question it can get head-throbbing complex. Let's see, pressure in, temp in, pressure out, temp out and flow rate will tell you *editable* near everything you wish to know about power. cheers, Douglas |
I know this is a little off topic but why do 18 wheelers have the pyro probe post turbo. With an engine that expensive wouldn't you want the most accurate egt reading?
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Will be watching this thread closely, another engineering student(North Dakota State Unversity) Go Bison!
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Originally Posted by Purplezr2
(Post 2888537)
Will be watching this thread closely, another engineering student(North Dakota State Unversity) Go Bison!
cheers, Douglas MS ME |
Originally Posted by d22019
(Post 2888517)
I know this is a little off topic but why do 18 wheelers have the pyro probe post turbo. With an engine that expensive wouldn't you want the most accurate egt reading?
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That makes sense I never thought of that. Thanks:cool:
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