Engine Temperatures?
05-28-2008, 05:53 AM
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Vehicle: 1999 Hyundai Tiburon
I have spent last few hours reading a lot of articles on net and did some seraches here on RDT but couldn't find an answer to a rather simple question. What should be normal temperature of a NA engine and forced induction tibs engine? Did anyone take EGT readings on a NA engine? What are your temperatures with turbocharged engines? Which temperatures should be considered normal and which temperatures should be considered as "dangerous".
05-28-2008, 06:36 AM
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Exhaust temperature is what I would like to know. Water and Oil are not sucha a problem since I had those values before going turbo. But never bothered to get Exhaust temperatures. And since EGT rises when the engine is knocking (or knocking possibility is higher when the internal temp is higher) it would be great to know what are some standard values fing02.gif
05-29-2008, 11:35 AM
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Exhaust Gas Temp reading vary A LOT depending on engine load and what the ignition timing is at the time. It also varies according to the placement of the EGT probe. Typically most recommend placement of the probe nearest the cylinder that tends to run leanest. In a normally aspirated car this can be the cylinder at the end of the fuel rail or depending on intake manifold design it will tend to be the cylinder that gets the most air first.
For a normally aspirated car running at stoich (14.7:1) fuel ratio you can see anywhere between 1450-1600 degrees F depending on the spark advance. At Wide Open Throttle on the same car the EGT might drop down into the mid 1300 degrees F due to the richer AFR. A richer air fuel ratio will tend to cool the combustion charger lowering the temp of the exhaust gas. You can also lower the EGT by upping the timing (spark advance). Retarding timing tends to increase the EGT because the spark event happens closer to TDC.
On a normally aspirated car converted to forced induction its VERY important to keep you combustion temps, measured by EGT reading, lower than they would otherwise be just normally aspirated. This mainly holds true under boost because the increased charge pressure will naturally increase the combustion pressure, increasing the exhaust gas temp and the likely hood of detonation and possibly the more harmful pre-ignition. For a boosted normally aspirated engine you want to be in the 1100-1250 EGT range at full boost WOT. Cruising or light load should be in the 1450-1500 degree F for safety's sake. To change the EGT you can typically richen the AFR or increase the timing to a point. If you go too far on the timing you can actually cause pre-igntion. Pre-igntion is anytime the charged air combusts before the spark plug fires. Detonation happens after the plug fires.
For a normally aspirated car running at stoich (14.7:1) fuel ratio you can see anywhere between 1450-1600 degrees F depending on the spark advance. At Wide Open Throttle on the same car the EGT might drop down into the mid 1300 degrees F due to the richer AFR. A richer air fuel ratio will tend to cool the combustion charger lowering the temp of the exhaust gas. You can also lower the EGT by upping the timing (spark advance). Retarding timing tends to increase the EGT because the spark event happens closer to TDC.
On a normally aspirated car converted to forced induction its VERY important to keep you combustion temps, measured by EGT reading, lower than they would otherwise be just normally aspirated. This mainly holds true under boost because the increased charge pressure will naturally increase the combustion pressure, increasing the exhaust gas temp and the likely hood of detonation and possibly the more harmful pre-ignition. For a boosted normally aspirated engine you want to be in the 1100-1250 EGT range at full boost WOT. Cruising or light load should be in the 1450-1500 degree F for safety's sake. To change the EGT you can typically richen the AFR or increase the timing to a point. If you go too far on the timing you can actually cause pre-igntion. Pre-igntion is anytime the charged air combusts before the spark plug fires. Detonation happens after the plug fires.