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| mx68u
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| Posted:Nov 9 2002, 12:52 PM |
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hey guys,
im after an egt sensor to whack into my exhaust, better than the jaycar air/fuel kit so im just wondering were i can score one cheapish... i know aircraft use these sensors and understand that they can be applied to our cars coz the heat ranges are roughly the same.. anyone ever enquired about this? |
| Rodhog
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| Posted:Nov 10 2002, 06:50 PM |
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What one do you want Exhaust Gas temperature or exhuast oxygen sensor
Exhuast Temp gauges are avilable and you need a temp guage to fit they are mostly merchanical gauges but you need a nice hole to run the line into the cabin, the bad bit is these can break if bent incorrectly. YOur right aircraft do have them. I had one fitted for a day off a Piper from Tafe it was part of testing we just unbolted my Oxy sensor and replaced it with a sensor, it just shows how hot it is. Nothing special and not important unless you plan of running in a race with 20laps of full booost.
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| mx68u
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| Posted:Nov 10 2002, 07:21 PM |
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EGT
doesnt the temp in exhaust gas indicate rich lean mixtures more accurately
than an oxy sensor... further more doesnt it indicate also how hard the engine is running... apparently having temps of around 900 will indicate you car is running lean and lower temps around 600 indicating rich mixtures.. seems like a good tool to have i was thinking of getting the sensor plumped in when i score a custom manifold  |
| Rodhog
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| Posted:Nov 11 2002, 06:23 PM |
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No not really they can but you have so many ofending factors
they can help but not so much in cars that run methanol and other types of fuel that when run just rich can change engine temp, they do do something. you see you may give it several hit around for 5 mins and it will show about 800degreeC but after long drive off light boost for 1 hour it could show 700Degree C because of heat build up being sustained, it's a lot of math to work out correctly. I have really only seen them used in weekedn race cars when taken to the track to yes watch fuel levels but also to watch for things like turbos getting way to hot after only 30min or work, and as a turbo timer. a good wide band oxy sensor is better for mixtures becuase the difference in temp specialy turbos could be from a hot day with coopling system runing hotter or it may be less because you are running lower boost. As gauge to watch for mixtures a Air/fuel rati o quage works much better.
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| mx68u
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| Posted:Nov 13 2002, 02:17 AM |
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ahhh fair enough rod.. thanks for the input man.... since i already have two jaycar air/fuel kits setup i'll just the buffer that everyone seems to refer too and hook that up... cheaper in any event
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| redneckmx6
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| Posted:Jan 30 2003, 06:43 PM |
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Here is a little reading for EGT's
There seems to be a lot of mystery and misinformation about using exhaust gas temperatures to tune engines. Claims by many EGT gauge manufacturers about it being the best way to tune an engine must be qualified. The BEST way to tune an engine is on the dyno- PERIOD. What EGT is good for is a reference for where the engine made maximum torque at wide open throttle. Once removed from the dyno, a similar air/fuel ratio can be established a later date by dialing in the mixture to achieve the target EGT. It is really the AFR that is important, not the EGT. Most engines will make maximum power at an AFR of between 11.8 and 13 to 1 however, the EGT may vary from 1250F to 1800F and is dependent on many factors.
It should be mentioned that the target EGT is valid only on the same engine configuration as was used on the dyno. If you change the ignition timing, cams, pistons, headers etc., the optimum EGT may also change. Raising the compression ratio with no other changes will drop the EGT at the same AFR. Retarding the ignition timing will generally raise the EGT at the same AFR. One engine might make best power at 1350 degrees while a very similar engine might be happier at 1500. You can't guess at this or you are simply wasting your money on the instrumentation. Wankel engines have higher EGTs than comparable piston engines due to their lower thermal efficiencies. 1800F is not uncommon here.
Some gauge manufacturers say you should tune to achieve maximum or peak EGT for maximum performance. This is incorrect. Peak EGT generally occurs at an AFR of around 14.7- 15.0 to 1 on gasoline. This is far too lean for maximum power and is dangerous under continuous WOT conditions. Many people think that the leaner you go, the higher the EGT gets. This is also incorrect. Peak EGT occurs at stoichiometry- about 15 to 1 for our purposes. If you go richer than 15 to 1, EGT will drop and if you go leaner than 15 to 1 EGT will ALSO drop. It is VERY important to know which side of peak EGT you are on before making adjustments. It is safe to say that peak power will occur at an EGT somewhat colder than peak EGT.
You can sometimes feel a lean of peak condition as the mixture is hard to ignite and power will be down a bit as well. Once the AFR gets close to 17 to 1 at WOT, generally the engine will start to lean misfire. Most tuners always recommend to begin jetting or programming from a known very rich initial setting and carefully leaning until torque falls off slightly, then going back richer to the point of max torque. Note the EGT at this setting. Be aware that altitude, barometric pressure and ambient air temperature may affect this optimal temperature to some degree.
Are EGT gauges better than AFR meters? Conventional narrow band oxygen sensors and digital LED meters are not the best devices to measure AFR in the richer ranges but they certainly warn of a too lean condition immediately and obviously, without translation by the driver and they are affordable. Meters combined with wide band sensors are laboratory quality usually, highly accurate and useful but very expensive and sometimes bulky. EGT gauges have the limitations above and are generally priced between the other two. I would suggest that the two types are complimentary. EGT gauges have the advantage of working long term with leaded fuel which will clog oxygen sensors. EGT gauges are widely used to set mixture on engines used for steady state high power applications where operation has been carefully documented such as in aircraft. The choice would depend on the application. Both are better if you can afford them.
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WARNING: Does not play well with others (it seems others have a problem with losing)
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| QUOTE | posted by 90tx5
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| mx68u
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| Posted:Jan 31 2003, 08:43 AM |
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| QUOTE | | This is also incorrect. Peak EGT occurs at stoichiometry- about 15 to 1 for our purposes. |
brilliant article redneck.. thanks for the input man.. i pressume you copied and pasted that from somewhere considering how bloody well its been written and without one grammatic or spelling error.. seems like a top resource.. is this info based on the f2t? |
| redneckmx6
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| Posted:Feb 3 2003, 06:31 PM |
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EGT will vary alot dpending......
Mine will run 900C because of the timing
and there is no detonation and the af ratio is perfect
so you can't say peak EGT occurs at stoichiometry because at a cruise I run at 600 at A/F is perfect there too
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Yes it's a turbocharged FE3, (soon on the bottle) and NO you can't drive it
WARNING: Does not play well with others (it seems others have a problem with losing)
My Beast
| QUOTE | posted by 90tx5
cheers
you r like the car god on this forum |
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| redneckmx6
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| Posted:Feb 27 2003, 09:06 AM |
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That article I posted on the EGT should be stuck at the top for future/everyone else's reference 
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Yes it's a turbocharged FE3, (soon on the bottle) and NO you can't drive it
WARNING: Does not play well with others (it seems others have a problem with losing)
My Beast
| QUOTE | posted by 90tx5
cheers
you r like the car god on this forum |
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