660 EGT Questions

[TGP37]

Wondering if anyone has some input regarding acceptable exhaust temps. I read exhaust valves melt at 1,650°F....or maybe that was aluminum.

Basically I'm looking for a solid limit as I gently lean out the AFR in mild boost (5 psi).

The sensor is mounted darn close to cyl 6. And the manifolds are double wrapped. I expect a temp reading very close to actual temps versus a reference temp post turbo.

Now, I read I can get more efficient power by tuning EGT's hot under load....just not TOO hot.

Also, is the EGT a reasonable method of finding true stoich at idle via logging the highest temp? Knowing that the EGT is at it's hottest around 14.7-15.0 AFR.


As some may tell, I am new to EGT's and how to use them.

[ericjon262]

that's an interesting question that I don't have an answer for but would like to hear one.

[95SleeperAcheiva]

Ditto. I helped tune an integra years back with a turbo and an egt. I tried to stay safe and keep temps around 1200, he went for 1400. We never got a chance to track test it, we got done on a friday night and he went and picked up his girl, then was showing off and scattered his gear box all over the road.

[TGP37]

Ditto. I helped tune an integra years back with a turbo and an egt. I tried to stay safe and keep temps around 1200, he went for 1400. We never got a chance to track test it, we got done on a friday night and he went and picked up his girl, then was showing off and scattered his gear box all over the road.

Ahhh, trans died.......what a drag. Looks like 1200°F is a good starting limit to obey until I can get more information. Unfortunately, I don't have a spare motor to test the limit on...lol. I've read 1650°F is an absolute maximum as aluminum gets soft at that temp. But no one wants to flirt with that temp, so it still leaves the question of optimal temps hanging.

Maybe I need a dyno to find the temp of greatest output.

[3400-95-Modified]

Maybe I need a dyno to find the temp of greatest output.

That is the only way you will find out for sure, otherwise everything is speculation and guessing... A dyno is the only way to verify that info and find the fall off point. It may not be great for exact HP numbers but it will give you comparison ability to different combinations.

[TGP37]

That is the only way you will find out for sure, otherwise everything is speculation and guessing... A dyno is the only way to verify that info and find the fall off point. It may not be great for exact HP numbers but it will give you comparison ability to different combinations.

Yeah, I really need a dyno tune. HPTuner is great but I need a dyno to find that sweet spot. Especially since my heads had the exhaust valve slightly deshrouded. Change the heads, change the combustion characteristics.

I still like having en eye on EGT's, especially in boost.

[Joseph Upson]

Wondering if anyone has some input regarding acceptable exhaust temps. I read exhaust valves melt at 1,650°F....or maybe that was aluminum.

Basically I'm looking for a solid limit as I gently lean out the AFR in mild boost (5 psi).

The sensor is mounted darn close to cyl 6. And the manifolds are double wrapped. I expect a temp reading very close to actual temps versus a reference temp post turbo.

Now, I read I can get more efficient power by tuning EGT's hot under load....just not TOO hot.

Also, is the EGT a reasonable method of finding true stoich at idle via logging the highest temp? Knowing that the EGT is at it's hottest around 14.7-15.0 AFR.


As some may tell, I am new to EGT's and how to use them.

Unless you are dealing with some pretty heavy duty parts I recommend you follow your AFR numbers. Although I've read a recommended max AFR under boost of about 13:1 if your parts can handle it, I wouldn't run more than 12.5:1.

I run two EGT sensors one pre and one post turbo with about a 200 deg difference in temp under load and cruise. The pre EGT sensor usually runs no higher than about 1300 deg and even that's rare, but that has a lot to do with how hard I don't run it. For me 1400 deg would be my intended limit.

I aim for a certain AFR range and then watch my EGT gauge. If my O2 sensor is not reading properly I can usually tell by watching the EGT temps which recently indicated a Code59 tune was off despite what the AFR was showing because temps were nearly 200 deg higher than normal under cruise conditions.

[TGP37]

Unless you are dealing with some pretty heavy duty parts I recommend you follow your AFR numbers. Although I've read a recommended max AFR under boost of about 13:1 if your parts can handle it, I wouldn't run more than 12.5:1.

I run two EGT sensors one pre and one post turbo with about a 200 deg difference in temp under load and cruise. The pre EGT sensor usually runs no higher than about 1300 deg and even that's rare, but that has a lot to do with how hard I don't run it. For me 1400 deg would be my intended limit.

I aim for a certain AFR range and then watch my EGT gauge. If my O2 sensor is not reading properly I can usually tell by watching the EGT temps which recently indicated a Code59 tune was off despite what the AFR was showing because temps were nearly 200 deg higher than normal under cruise conditions.

Yeah, I don't think I would have gone higher then 12.0:1 AFR under boost (5-8 psi range). I do plan to put an EGT past the turbo later, it would be interesting data to log and pour over on excel.

How accurate is the EGT when it comes to stoich? I read stoich burns the hottest so tweeking the AFR at idle could lead to confirm/calibrate the WBO2? i.e. if egt is hottest at 14.1 on non-ethanol gas then could it be said the WB is 0.6 off?

One day I plan to build a high boost 660.......learning everything I can.

Thanks

[3400-95-Modified]

Yeah, I don't think I would have gone higher then 12.0:1 AFR under boost (5-8 psi range). I do plan to put an EGT past the turbo later, it would be interesting data to log and pour over on excel.

How accurate is the EGT when it comes to stoich? I read stoich burns the hottest so tweeking the AFR at idle could lead to confirm/calibrate the WBO2? i.e. if egt is hottest at 14.1 on non-ethanol gas then could it be said the WB is 0.6 off?

One day I plan to build a high boost 660.......learning everything I can.

Thanks

I'm sure you can error check one with the other, but who's to say the EGT isn't off... You'd have to calibrate both in a way that you know the current condition, I wouldn't attempt to find error on one using the other since you may be putting that error on the wrong item and or not dividing it up between the two equally.

[TGP37]

I'm sure you can error check one with the other, but who's to say the EGT isn't off... You'd have to calibrate both in a way that you know the current condition, I wouldn't attempt to find error on one using the other since you may be putting that error on the wrong item and or not dividing it up between the two equally.

I agree completely, just wondered how "solid" and EGT is. it appears the type K Thermocouple is accurate within 1.5° in the temp range of operation.

I read how widebands can be off up to 2 AFR points...that is a large deviation. But then the EGT is distance critical, so it seems the ....ahh I see what you are saying, it just hit me. It is the overall reading of all sensors which is the greatest source of accurate understanding.

By viewing spark plugs, wb, egt's I should be able to "find" true stoich and then note the AFR reading. I have relied heavily on my wideband but now I wonder just how accurate it is. One thing is for sure, there is no leak ahead the wideband. I spent time ensuring a solid seal to retain the best AFR reading possible.

Any info on a preferred Wideband Gauge w/ data logging output that is a quality item? I'm using the glowshift wideband, and regret it. Data logging is fine, but the gauge read out is slower then others.

[3400-95-Modified]

I have two PLX devices but they don't come with a native serial port on them. I had to modify mine to allow a DB9 plug on it and use it for logging. I think the larger PLX devices may have a com output but I went with the small SM-AFR Combo with gauge. Even the Plx-m-300te doesn't list it to have a com port. Innovate seems to be a pretty regular type used as well.

[TGP37]

Caution: This file has a flaw, needs to switch the cmd AFR with Wideband for a proper calculation.

[95SleeperAcheiva]

http://dodgeram.org/tech/dsl/FAQ/turbo_faq.htm

I found this. scroll down for the data charts it shows egt temps for safe operation and cool down times.

[TGP37]

http://dodgeram.org/tech/dsl/FAQ/turbo_faq.htm

I found this. scroll down for the data charts it shows egt temps for safe operation and cool down times.

Nice, now I have a target to look out for. Over time I'll get a feel for the temps and post up.

Thanks