Cooling period for a 993TT
07-23-2002, 07:59 PM
#16
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[quote]Originally posted by Rocket:
<strong>Mark.....I am, of course, referring to the EGT not the temperature of the metal. Perhaps it is an assumption to assume that the turbo parts would raise proportionally to these kind of temperatures, but it isn't going to be far off. Afterall it isn't unheard off to melt turbos.
I take it that your Centigrade is the same one over here i.e 1000C=1820 F.
I used a Mitsubishi Lancer EVO VI as a track car with an EGT gauge (mounted about 3 inches after the turbo), which saw temperatures of about 950 C all day. I ran the car for 12 months and 20,000 miles at this state of tune with no detrimental effects to the engine or turbo.The EGT was primarily used to tune the engine timing, fueling and boost as the narrow band Lambda sensor (oxygen sensor) became inaccurate above about 600C.
This picture (right gauge) shows EGT after just three blasts through the gears and EGT is straight up to 700 degrees C. Left gauge is boost (1.4 bar = approx 20 psi) middle lights top Lambda, bottom white lights Knock (pink/ping) lights.
Rocket</strong><hr></blockquote>
I clearly understood you were talking about EGT. EGT, however, will be very close to the temperature of the metal over which it is passing and your claim of ~2000 deg C (which is a bit over 3600 deg F) would melt the heads and exhaust pipes, not to mention what that would quickly do to the turbo. Even your 950 C is well beyond anything I have seen listed as a safe operating temperature for a turbo, though I admit the info I can find is rather limited. What I can find is that turbo diesels are supposed to remain under 1350 deg F to avoid turbo damage (pre turbo temp) and that Top Fuel Dragsters run ~900 Deg C exhaust temp and are known to pretty much melt the pistons and exhaust valves every few runs.
But, like I said, I can not find a great deal of data on what constitutes a safe temp for turbos. I can add that the kind of in-car gauge you refer to has lots of opportunity for large errors. Thermocouples improperly installed (extra, uncompensated junctions) or not properly calibrated or used outside the appropriate temp range, can produce HUGE errors, as can thermistors and other instruments.
I just can't believe that you can run 2000 Deg C EGT without immediate damage and that even the 950 C sustained temps seem suspect to me. On the other hand, your 700 C is very credible - that matches with everything I can find as an appropriate temp for hard use.
<strong>Mark.....I am, of course, referring to the EGT not the temperature of the metal. Perhaps it is an assumption to assume that the turbo parts would raise proportionally to these kind of temperatures, but it isn't going to be far off. Afterall it isn't unheard off to melt turbos.
I take it that your Centigrade is the same one over here i.e 1000C=1820 F.
I used a Mitsubishi Lancer EVO VI as a track car with an EGT gauge (mounted about 3 inches after the turbo), which saw temperatures of about 950 C all day. I ran the car for 12 months and 20,000 miles at this state of tune with no detrimental effects to the engine or turbo.The EGT was primarily used to tune the engine timing, fueling and boost as the narrow band Lambda sensor (oxygen sensor) became inaccurate above about 600C.
This picture (right gauge) shows EGT after just three blasts through the gears and EGT is straight up to 700 degrees C. Left gauge is boost (1.4 bar = approx 20 psi) middle lights top Lambda, bottom white lights Knock (pink/ping) lights.
Rocket</strong><hr></blockquote>
I clearly understood you were talking about EGT. EGT, however, will be very close to the temperature of the metal over which it is passing and your claim of ~2000 deg C (which is a bit over 3600 deg F) would melt the heads and exhaust pipes, not to mention what that would quickly do to the turbo. Even your 950 C is well beyond anything I have seen listed as a safe operating temperature for a turbo, though I admit the info I can find is rather limited. What I can find is that turbo diesels are supposed to remain under 1350 deg F to avoid turbo damage (pre turbo temp) and that Top Fuel Dragsters run ~900 Deg C exhaust temp and are known to pretty much melt the pistons and exhaust valves every few runs.
But, like I said, I can not find a great deal of data on what constitutes a safe temp for turbos. I can add that the kind of in-car gauge you refer to has lots of opportunity for large errors. Thermocouples improperly installed (extra, uncompensated junctions) or not properly calibrated or used outside the appropriate temp range, can produce HUGE errors, as can thermistors and other instruments.
I just can't believe that you can run 2000 Deg C EGT without immediate damage and that even the 950 C sustained temps seem suspect to me. On the other hand, your 700 C is very credible - that matches with everything I can find as an appropriate temp for hard use.
07-23-2002, 08:53 PM
#17
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Mark......you are challenging some of the most respected views in the business. My brother who is a chief engineering at Rolls Royce Aero Engines knows a thing or two about combustion, and I have had three turbo cars the latter of which was tuned by probably the most experienced and widely respected engine mapper in the northern hemisphere- Bob Rawle of <a href="http://www.brdevelopments.com" target="_blank">BR Developments</a>
I am stating practical experience and fact, whilst you are seemingly just hypothesizing based on a limited knowledge. It is inappropriate for you to marginalise my opinions without having the appropriate factual arguments to counteract my observations.
Rocket
I am stating practical experience and fact, whilst you are seemingly just hypothesizing based on a limited knowledge. It is inappropriate for you to marginalise my opinions without having the appropriate factual arguments to counteract my observations.
Rocket
07-23-2002, 09:21 PM
#18
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[quote]Originally posted by Rocket:
<strong>Mark......you are challenging some of the most respected views in the business. My brother who is a chief engineering at Rolls Royce Aero Engines knows a thing or two about combustion, and I have had three turbo cars the latter of which was tuned by probably the most experienced and widely respected engine mapper in the northern hemisphere- Bob Rawle of <a href="http://www.brdevelopments.com" target="_blank">BR Developments</a>
I am stating practical experience and fact, whilst you are seemingly just hypothesizing based on a limited knowledge. It is inappropriate for you to marginalise my opinions without having the appropriate factual arguments to counteract my observations.
Rocket</strong><hr></blockquote>
Respected views? I can't really find where you present those. If your opinions are based on such expertise, I am more than anxious to hear it.
Your Brother is not the one who posted, but I would be very interested in what he has to say, especially about 2000 Deg C EGT.
I don't get the connection between owning 3 cars and possesing certain expertise.
You then admit what I am marginalizing is your opinions (not facts, opinions).
I stated my case AND admitted it is weak. Some, but not all, of your statements seemed like BS to me and I question them. How about presenting some facts in place of your opinion and you will sway my opinion. I am giving you the opportunity to present facts and you seem to be avoiding that opportunity. Present facts with appropriate backup and I'll listen, otherwise we can stop the BS.
<strong>Mark......you are challenging some of the most respected views in the business. My brother who is a chief engineering at Rolls Royce Aero Engines knows a thing or two about combustion, and I have had three turbo cars the latter of which was tuned by probably the most experienced and widely respected engine mapper in the northern hemisphere- Bob Rawle of <a href="http://www.brdevelopments.com" target="_blank">BR Developments</a>
I am stating practical experience and fact, whilst you are seemingly just hypothesizing based on a limited knowledge. It is inappropriate for you to marginalise my opinions without having the appropriate factual arguments to counteract my observations.
Rocket</strong><hr></blockquote>
Respected views? I can't really find where you present those. If your opinions are based on such expertise, I am more than anxious to hear it.
Your Brother is not the one who posted, but I would be very interested in what he has to say, especially about 2000 Deg C EGT.
I don't get the connection between owning 3 cars and possesing certain expertise.
You then admit what I am marginalizing is your opinions (not facts, opinions).
I stated my case AND admitted it is weak. Some, but not all, of your statements seemed like BS to me and I question them. How about presenting some facts in place of your opinion and you will sway my opinion. I am giving you the opportunity to present facts and you seem to be avoiding that opportunity. Present facts with appropriate backup and I'll listen, otherwise we can stop the BS.
07-23-2002, 11:48 PM
#19
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Something to consider......Exit gas temperature does not necessarily mean that the metal temperature is reaching that level. Exhaust gas flow through the turbo and heat rejection through the lubrication system will remove heat and tend to keep the metal below its melting point. Its a combination of convective and conductive heat transfer mechanisms. If gas flow and lubricant flow are shut down abruptly, the metal temperature will approach the temperature of the "atmosphere" surrounding it.
Taking a few moments for cooldown as a normal practice helped me reach 180000 miles on my original turbo without a hint of a problem. The next owner burned it up in a few thousand miles. With a conservative approach, these wonderful engines will last a very long time.
Regards,
Fred <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
Taking a few moments for cooldown as a normal practice helped me reach 180000 miles on my original turbo without a hint of a problem. The next owner burned it up in a few thousand miles. With a conservative approach, these wonderful engines will last a very long time.
Regards,
Fred <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
07-24-2002, 07:42 AM
#20
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Mark D wrote:
I clearly understood you were talking about EGT. EGT, however, will be very close to the temperature of the metal over which it is passing and your claim of ~2000 deg C (which is a bit over 3600 deg F) would melt the heads and exhaust pipes,
Err... Have a look at this - the exhaust pipes are close to melting so how hot will those heads be ?
<a href="http://www.rs-tuning.de/presse/sportauto/sa0497/sa0497.htm" target="_blank">http://www.rs-tuning.de/presse/sportauto/sa0497/sa0497.htm</a>
I clearly understood you were talking about EGT. EGT, however, will be very close to the temperature of the metal over which it is passing and your claim of ~2000 deg C (which is a bit over 3600 deg F) would melt the heads and exhaust pipes,
Err... Have a look at this - the exhaust pipes are close to melting so how hot will those heads be ?
<a href="http://www.rs-tuning.de/presse/sportauto/sa0497/sa0497.htm" target="_blank">http://www.rs-tuning.de/presse/sportauto/sa0497/sa0497.htm</a>
07-24-2002, 01:21 PM
#21
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Mark.....I find it a bit rich that you regard my posts as "BS" when firstly you know nothing of the subject yourself, and secondly you don't know me personally from Adam.
I am not going to post further on this subject as my views reflect my own personal experience tuning turbo cars, but if you researched the topic further you would find correct. I think really old son, its is you who has earn himself the monica "BS"er, not me
For your assistance have a look at these posts:
<a href="http://bbs.22b.com/ubb/Forum8/HTML/000004-2.html" target="_blank">http://bbs.22b.com/ubb/Forum8/HTML/000004-2.html</a>
<a href="http://bbs.22b.com/ubb/Forum7/HTML/000106.html" target="_blank">http://bbs.22b.com/ubb/Forum7/HTML/000106.html</a>
Rocket
I am not going to post further on this subject as my views reflect my own personal experience tuning turbo cars, but if you researched the topic further you would find correct. I think really old son, its is you who has earn himself the monica "BS"er, not me
For your assistance have a look at these posts:
<a href="http://bbs.22b.com/ubb/Forum8/HTML/000004-2.html" target="_blank">http://bbs.22b.com/ubb/Forum8/HTML/000004-2.html</a>
<a href="http://bbs.22b.com/ubb/Forum7/HTML/000106.html" target="_blank">http://bbs.22b.com/ubb/Forum7/HTML/000106.html</a>
Rocket
07-24-2002, 02:12 PM
#22
King of Cool
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I think Fred's correct.
Even if the exhaust gas temperature is what it is, exhaust pipe itself won't be the same.
Without knowing much about turbos, think about it:
i.e. exhaust pipe; inside gas temp. is 1000 C, outside air temp. is 20 C, so... is the pipe temp. 1000 C? No. Is it 20 C? No, it's something in between.
Even if the exhaust gas temperature is what it is, exhaust pipe itself won't be the same.
Without knowing much about turbos, think about it:
i.e. exhaust pipe; inside gas temp. is 1000 C, outside air temp. is 20 C, so... is the pipe temp. 1000 C? No. Is it 20 C? No, it's something in between.
