Exhaust temperature question

Hello Grumpy or Anyone Who Can Help,

I have an L98 with AFR 180's, Lingenfelter cam (74216), Accel high flow TPI, and ceramic headers. The car is running very smooth with no known issues. However, when working on it the other day I noticed the passenger side headers were much cooler than the drivers side. The ceramic coating is better on the passenger side but I do not think that could cause the difference. The temperatures are posted below and reflect 5 minutes of idling. Like I mentioned, everything is running extremely well. All temperatures were taken with an infared heat gun at the beginning of the tube that connects to the head.

What could cause the temperature difference? What should the header temperature be and is a difference between cylinders a problem?

Cylinder 1: 170 F
Cylinder 2: 63 F
Cylinder 3: 240 F
Cylinder 4: 67 F
Cylinder 5 : 214 F
Cylinder 6: 63F
Cylinder 7: 178 F
Cylinder 8: 63 F

Thanks for your help!!!
 
GIVEN the info you posted,Id strongly suspect that odd number (drivers side) cylinders are running significantly LEANER than the EVEN number or (PASS SIDE CYLINDERS), or the pass side cylinders are not firing ,cylinder temperatures measured with an IR temp gun ,after the car warms should run in the 400F-650F range on most headers once the cars engine fully reaches operational temps at idle. a vacuum leak could cause that, or a bank of injectors not firing,just remember the drivers side runners on the tpi feed the pass head and the pass side runners feed the drivers side head, but the injectors are are the side they supply fuel too..
remember early tpi were batch fire and all the injectors on each bank fire at the same time, your injector pulse duration may need tweaking,each bank of injectors has its own separate fuse so get out the shop manual and locate and check your fuses.
now two other potential reasons are your catalytic converter is partly clogged on one side so test for back pressure if you cant find another reason, or your 02 sensor on one sides defective, I would have suspected one injector bank not firing but you state it runs fine

reading the plugs should give you more info on the burn conditions in each cylinder

I doubt youll see engine block temps exceeding about 350F and keep in mind that coolant rarely exceeds 270F and oil rarely exceeds 300F even in extreme conditions when things are not working as designed BUT exhaust manifold temps commonly exceed 550F-850F and in many cases the exhaust manifolds, or headers are located very close to the heads and block in some header and manifold designs, so reflected heat is significantly higher than you might imagine near the headers, its very common for exhaust gas temps to run close to 650F-670F

http://www.gizmag.com/spray-on-ceramic-coating-dramatically-reduces-external-temperatures/6642/
READ
demonstration of difference in exhaust temperatures with coated headers, can and usually does reduce under hood temps





irtemp.jpg

http://www.professionalequipment.com/ex ... ermometer/


headerclear.jpg


redheaders.jpg


stc1.jpg

stc2.jpg
 
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Thank you Grumpy!

That is why I come on this board because I assumed the cold side was the problem. I truly appreciate your help.

All gaskets are brand new (Fel Pro) but there is always the potential for a vacuum leak. I will check tomorrow.

The plenum was "opened" by a friend of mine but he did significantly better on opening the walls on one side than the other. Could smoother air flow into one side make the difference?

These temperatures were taken at idle. I cannot drive it right now as it is getting painted. Should I let it idle for 15-20 minutes and take new temperature readings?

The entire exhaust is new (Magnaflow), so I cannot imagine there are any issues with it as it only has about 3 hours on it. The O2 sensor is mounted in the driver side header. However, I cannot imagine the car got warm enough to go into closed loop.

Thanks again!!!
 
you state that the engine runs ok ...and that the cars equipped with
"ceramic headers. The car is running very smooth with no known issues."

and that it idles reasonably well, its very unlikely that if one bank of injectors was not firing at all that would be the case, so I had to assume (always a bad idea)that both banks fire, and since you also stated coated headers and only allowing minimal heat up time had elapsed...that was the more reasonable suggestion, and checking the spark plugs will verify that or prove that wrong. the fact that one bank seems to be non-firing as the exhaust temps are not rising is due either to a non-firing bank of injectors or your run time was very short

links to threads that may hold answers you need


/viewtopic.php?f=32&t=1401

/viewtopic.php?f=32&t=168

/viewtopic.php?f=32&t=2697&p=7173&hilit=noid#p7173

/viewtopic.php?f=55&t=1906&p=5032&hilit=noid#p5032

/viewtopic.php?f=44&t=579&p=743&hilit=+infrared+tuning#p743

/viewtopic.php?f=55&t=1241&p=2648&hilit=+testing+injectors#p2648

viewtopic.php?f=55&t=606&p=7969#p7969

/viewtopic.php?f=70&t=751&p=1073&hilit=noid#p1073
 
Well Grumpy, I think you are right once again.

Last night I started the car and it sputtered a little at first but then ran reasonably well. It was vibrating but I could have set a glass of water on the plenum without spills. Anyway, I placed a screwdriver up to the passenger side bank of injectors and not one click! The whole entire bank it not working. However, you would barely be able to tell by listening to the engine and watching it. It does have brand new polyurethane motor mounts, so I guess that can account for the lack of vibration.

What would cause one whole bank of cylinders to not work?
Lastly, how in the heck can the engine run so smooth on only 1 bank of cylinders? I can post a video if you like.

Thanks!
Josh
 
wildjyoung said:
Well Grumpy, I think you are right once again.

Last night I started the car and it sputtered a little at first but then ran reasonably well. It was vibrating but I could have set a glass of water on the plenum without spills. Anyway, I placed a screwdriver up to the passenger side bank of injectors and not one click! The whole entire bank it not working. However, you would barely be able to tell by listening to the engine and watching it. It does have brand new polyurethane motor mounts, so I guess that can account for the lack of vibration.

What would cause one whole bank of cylinders to not work?
Lastly, how in the heck can the engine run so smooth on only 1 bank of cylinders? I can post a video if you like.

Thanks!
Josh

check your fuses as theres a separate fuse for each injector bank, then read thru the sub links in these threads


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Tuning Via EGT vs, Wide Band/ Narrow Band Meters

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 an engine 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 at 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 12.0 and 13.5 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 supposed to be highly accurate and everyone has jumped on the bandwagon with these lately. Unfortunately the naive and impressionable often don't question the accuracy of these devices. We have seen some dyno plots indicating best power was achieved at AFRs of 9.7 to 1 on gasoline. This is PHYSICALLY AND CHEMICALLY IMPOSSIBLE and shows that either the sensor was bad (leaded fuel used possibly) or the meter was not calibrated properly. Again, the wide band sensors have the same limitations as the narrow band- leaded race gas quickly fouls them. We have heard and read many stories now indicating that certain brands of wideband meters differ as much as 2 points AFR in readings between each other. In other words, the accuracy of some of these devices is highly questionable. Extensive testing with laboratory quality instrumentation on aircraft engines universally indicates that best power is NEVER made at AFRs richer than 12 to 1. Airflow and fuel flow rates are independently measured and each cylinder is instrumented with EGT probes.

We recently dynoed a shop road racing Celica on a DynoJet equipped with a wide band meter. The meter was saying that the engine was going super lean (17 to 1) at high rpm so we kept upping the fuel there. The engine lost more and more power as we added fuel. The dyno operator was convinced that the meter was right but logic told us with no serious dip in power on the curve and the fact that the engine was still alive that the meter was not correct. We started leaning the engine down more and the engine started gaining power. Finally, when confronted with this information, the operator checked the water trap for the wide band sensor. Once this was emptied, the AFRs looked reasonable again. We didn't need the wide band to tell us this, only the torque curve from the dyno.

We have heard of several other instances with people using wide bands getting erroneous readings and tuning their SDS based on these readings. Then they phone us saying that the system is crap. Look at the dyno curve, when the engine makes its best power at a given rpm, that's where it likes the AFR irregardless of what other instrumentation is telling you. Remember, a bad sensor whether O2 or EGT equals bad information. When the engine sounds crisp and makes great power, you're there.

I would suggest that mixture meters and EGT gauges 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.
viewtopic.php?f=32&t=1401

viewtopic.php?f=55&t=1241

http://www.summitracing.com/parts/fst-1 ... dia/images
example
http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf

viewtopic.php?f=55&t=6765&p=25598#p25598
 
Grumpy,

The video below is what confused me. This is the engine running with only the driver side bank actually firing. The passenger cylinders are all dead. How could the engine run like this?

 
Ive never seen an engine with 1/2 its cylinders dead run that smoothly, but in theory a batch fire engine has some intake runner reversion that might be just enough at low rpm to give the plenum a cloud of fuel/air mix that might allow that to happen., but like I said Ive yet to see that
 
I am just glad that I am not crazy! I had to take a video because no one believed me that the engine could run smooth with only 1/2 cylinders running.

You saved the day again! I checked the fuse and it was blown. I replaced it and the engine is running beautifully! This issue really had me guessing though.

Thanks again! I truly appreciate your help!!!
 
I,m always glad to help you gentlemen :mrgreen:
Ill go back and add some notes to make it easier for the next person reading thru this to locate a similar problem and correct it.

holleytunekit.jpg



easier to weld thicker bung with base contoured to fit collector
https://www.summitracing.com/search...-type/weld-in-bungs-and-fittings?fr=part-type




HOLLEYS GOT A NEW TOY

Want to closely monitor Air/Fuel ratios on your carbureted or EFI vehicle? Holley has just the product for you. Holley is proud to introduce the Holley Wide Band O2 Controller with gauge.

A wide band oxygen sensor is the ultimate addition to any carbureted or EFI vehicle. It will accurately measure any air/fuel ratio between 10:1 and 18:1. This allows the engine tuner to read the air/fuel ratio in real time for extremely accurate tuning.

The 534–201 kit is intended for the consumer who wants to be able to accurately measure air/fuel ratios so the perfect tune up can be obtained. The 534–201 can also be upgraded later for use with an NTK sensor by simply reconnecting a jumper loop and purchasing the NTK sensor (P/N 534–194).

The Holley Wide Band O2 gauge features a 3–digit numeric display along with a 40 segment bar graph. With the ultra–high intensity light emitting diodes you will be able to see your Air/Fuel ratio even under direct sunlight.

The P/N 534–201 is designed to operate in street or race environments and will withstand heat, dirt, and vibration. The Holley Wide Band O2 gauge will fit in a standard 2–1/16” gauge pod.


Features

Controller Features: Small weather-sealed unit for convenient mounting
Easy Installation
Accurately measures A/F ratio between 10:1 and 18:1
Will accommodate a Bosch or NTK sensor
Includes Bosch LSU4 Sensor
Aides in tuning for maximum power and fuel economy
Gauge Features: Features a 3-digit numeric display and 40 segment multicolor bar graph for a quick read
Ultra-high intensity light emitting diodes for easy viewing even in direct sunlight
Standard 2-1/16” diameter for ease of mounting in a standard gauge pod
Built for race environments to withstand heat, dirt, and vibration
Connects to vehicle light switch to dim the gauge during night time viewing



Technical Information
Instructions for Part# 534-201

Shipping Dimensions
L 7.750 in. x W 5.250 in. x H 3.250 in.
Weight 2.000 lb.
 
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