EGTīs
EGTīs Iīve been thinking about how high can you go with the EGT on both N/A and FI
I know this is a raw queston(just really brainstorming) but where is the limit of Pump/Race Fuel in that matter,never read or see any info about it?
I know this is a raw queston(just really brainstorming) but where is the limit of Pump/Race Fuel in that matter,never read or see any info about it?
TECH Enthusiast
Joined: Apr 2005
Posts: 540
Likes: 0
Thats a very loaded question
Depends on your application. Catalytic converters typically limit your max EGT in an OEM application. Turbo's can also limit your max EGT.. High temp turbos (1050 deg C) are very expensive.. 950C turbo are much less so.
One major point to adding "fuel enrichment" is to keep the EGT's in line. The more enrichment you add.. the lower your BSFC.. but no racer really cares about that more than power..
Depends on your application. Catalytic converters typically limit your max EGT in an OEM application. Turbo's can also limit your max EGT.. High temp turbos (1050 deg C) are very expensive.. 950C turbo are much less so.
One major point to adding "fuel enrichment" is to keep the EGT's in line. The more enrichment you add.. the lower your BSFC.. but no racer really cares about that more than power..
To answer your question, your EGTs could be high as hell, but the combustion chamber temp could be substantially lower, and that is what the piston is exposed to.
I won't rely on EGT's for general performance tuning unless I'm looking for some specific data. Looking at skin temp differences between the pipes is helpful if you have a hole running differently (lean or rich) but its nothing that you couldn't get from a heat gun, and you don't have 8 wires with probes getting in the way. Currently I have a couple of EGT's plumbed into the chambers and an O2 in each pipe for tuning. If I need EGT's, I have the bungs and can put the probes in if needed
Last edited by TT632; Mar 6, 2008 at 10:40 AM.
6 & 8 Second Club
Joined: Aug 2006
Posts: 2,284
Likes: 0
From: Illinois, RT 66 dragway area
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I use 8 on the fast car. I've been 1490's with no damage. Been higher, for a micro second before probe & piston melted.
Never looked it up, but I was told a piston melts at 1508?? Also, my temps might not be accurate.
My data recorder is 13 years old. Antique compared to the new racepac.
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I use 8 on the fast car. I've been 1490's with no damage. Been higher, for a micro second before probe & piston melted.
Never looked it up, but I was told a piston melts at 1508?? Also, my temps might not be accurate.
My data recorder is 13 years old. Antique compared to the new racepac.
.
Your temps are more accurate than one in the collector,that is most likely accurate reading but depends where you place it on the pipe for accuracy if the other pipes are not shaped the same of comparing them
1500 is at the limit of competition pistons with high grade aluminum mix,is what i have read,iīve seen 800-1200° on most motors but donīt know the internals to verify
1500 is at the limit of competition pistons with high grade aluminum mix,is what i have read,iīve seen 800-1200° on most motors but donīt know the internals to verify
.
I use 8 on the fast car. I've been 1490's with no damage. Been higher, for a micro second before probe & piston melted.
Never looked it up, but I was told a piston melts at 1508?? Also, my temps might not be accurate.
My data recorder is 13 years old. Antique compared to the new racepac.
.
I use 8 on the fast car. I've been 1490's with no damage. Been higher, for a micro second before probe & piston melted.
Never looked it up, but I was told a piston melts at 1508?? Also, my temps might not be accurate.
My data recorder is 13 years old. Antique compared to the new racepac.
.
Your pistons survive these high temperatures because of their mass, heat dispersion through the piston, heat rejection through the cylinder walls and into the oil, and the short length of time they are exposed to these elevated combustion temperatures. This is analogous to hitting your pistons with an oxy- acetylene torch for a few milliseconds. It will take minutes to get a typical sbc piston to get up to melting temperature of aluminum and actually burn through. I’ve Thermocoupled pistons for this condition when testing thermal coatings, and the results were very interesting. The commercially available thermal coatings work very well as long as you’re not detonating, but that is a different topic.
Last edited by TT632; Mar 10, 2008 at 11:37 AM.
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Verdad Gallardo Yes, if you are running rich and have late ignition or early exhaust valve timing you can have low combustion temperatures and have high EGTs from the burn taking place in the exhaust.
Teching In
Joined: Sep 2007
Posts: 28
Likes: 0
Cylinder pressure and optimising the cam for power must not have anything to do with it? Well, every cylinder is timed individually and they are not run rich because that takes more pit stops and is just plain dumb. Do you have another explanation?
TECH Fanatic
Joined: Jun 2002
Posts: 1,979
Likes: 3
From: Upstate NY
I assume any engine run in a 24 hour race not only has to be durable, but it needs the best BSFC it can achieve for the minimum amount of refuelling you mentioned. My rough figuring says a 24 hour race engine fires each cylinder well over 3 million times. It has to be a hoppy (oops, happy) engine to do that and live.
Jon
6 & 8 Second Club
Joined: Aug 2006
Posts: 2,284
Likes: 0
From: Illinois, RT 66 dragway area
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Agree with Tuff. I don't care what the actual number is. It's a tool to use with my record keeping.
If something changes, then we start looking WHY!! But as I said, the probe & piston did melt at 1500+.
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Agree with Tuff. I don't care what the actual number is. It's a tool to use with my record keeping.
If something changes, then we start looking WHY!! But as I said, the probe & piston did melt at 1500+.
.
