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Discussion Starter #1
Last night I finished up installing the header bungs, thermocouples and plugs in the unused bungs.
I made my own bungs from .650 OD hot rolled mild steel with a 1/4 inch NPT thread.
The thermocouple probes are this size and I will be running 2 per side with 1/4 inch NPT dry seals in the other 2 unused bungs. After testing 2 cylinders at a time I will move the probes to the other 2 cylinders and try to get a feeling for which are my problem cylinders.
I welded the bungs unto the headers before drilling the holes through the header tubing. That way I could be sure everything lines up perfectly.
I also finished taping the NPT thread on the bungs after they were welded on and drilled so I could custom tap each hole so when the dry seal plug was screwed in it would be flat with the inside of the tube to cut turbulence down when no thermcouple is installed.
This is the Omega meter I bought along with 2 of the stainless probes and a sample of the yellow K type plug plugged into one of the ports on the meter.
This meter handles 2 probes at a time, has an alarm if you choose to set a maximum temperature. It records the highest temp reached and at the same time shows an output for 2 thermocouples so I can read on the fly

I welded in 4 bungs like this. This shows the 2 center ones

This is how the probe looks installed. It is a nice stainless unit with a relief spring on the wire and a stainless shield over the leadins

This is how the dry seal looks from the inside when the bung is plugged.
They have been taped so the dry seals are flush with the inside when lightly tightened and also flush on the outside so I can tell when the dry seal is down far enough


What do I hope to achieve??
I want to know the running temperature of my exhuast. It will tell me if I am going to lean, If I am running too hot for good gasket , valve and head life, If my blower is too small and blower temperatures too high.
I will buy another gage, another 2 probes for the drivers side.
I am looking for temperatures in the 1320-1350 range.
Want to avoid temperatures in the 1420-1450 range.
And really watch for spikes in the 1600 range which tells me I am detonating.
While I run 8-1 compression once the blower is done adding it's boost I am in the 14.5 range and that can be a problem with pump gas.
I don't know how any of this will work, if it will show what I want but if I can learn something more about how my engine works, what it wants I can go from there.
I learned alot with the LM-1 wide band oxygen sensor and this will just add to that knowledge.
redvetracr is the only one hear I believe who would know if I am thinking straight about these tempertures since he has one in his race car and would know.
Love to hear what you think???
 

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Discussion Starter #2
Forgot. I think but am not sure but I believe on detonation exhuast temperatures can get to 1600F.. Not positive about this but think this happens? The meter has an alarm I can set for any temperture. I want to set it for say 1500F and if I suddenly spike at over this the alarm should go off warning me I have detonated with the extreme temperature spike and hopefully warn me enough to let off before damaging anything.
I recently gave a rundown on detonation, what it means and why but if anyone wants the short version just ask??
 

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Great write up I think there are a lot of use out here with questions as how to get good info out EGT. I run a blower on a carburated 383 sbc. I have F/A meter but when your WOT kind of hard to take to many notes. I think a glance at a temp gauge would be more usefull if it will tell you any thing. and really don't want to spend a lot of money on a data logger for a summer toy.
 

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Discussion Starter #4
Great write up I think there are a lot of use out here with questions as how to get good info out EGT. I run a blower on a carburated 383 sbc. I have F/A meter but when your WOT kind of hard to take to many notes. I think a glance at a temp gauge would be more usefull if it will tell you any thing. and really don't want to spend a lot of money on a data logger for a summer toy.
If you have the narrow band F/A ratio gage I feel you are not really doing anything. I have one also in my car, the narrow and now the wide as well and the narrow is really useless. It is a simple switch that just toggles on either side of 14.7
The wide band is the only way to go.
This EGT will help me pinpoint which cylinders are my hot ones, which one might be running leaner then the rest and spike tempertures.
You should avoid the 1400 range and above and no A/F meter is going to warn me if I get into this range.
It also records peak tempertures so I can just ask for a readout of my maximum temperatures reached during a run.
I can also replay with jetting to see what it does to peak temperatures.
I run quick change jetting bowls on all 4 bowls so changing a set of jets takes minutes without touching any gaskets.
Each jet have a small cover plug, much like the fuel bowl plugs on your carb. I remove this brass plug, reach inside with the proper supplied screw driver, unscrew the jet, and reinstall the next size with the same screwdriver.
Install the brass plug and I am done. A quick simple method for daily jetting changes and yes I ofter rejetted daily or at least every time I took the car out.
I went from 82's down to 72's on my 850 and my A/F ratios improved with every change. This is on a pair of 850 double pumpers.
 

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I also finished taping the NPT thread on the bungs after they were welded on and drilled so I could custom tap each hole so when the dry seal plug was screwed in it would be flat with the inside of the tube to cut turbulence down when no thermcouple is installed.





This is how the dry seal looks from the inside when the bung is plugged.
They have been taped so the dry seals are flush with the inside when lightly tightened and also flush on the outside so I can tell when the dry seal is down far enough



Love to hear what you think???

Nice Norval, I was wondering how you were going to keep from introducing turbulence in the exhaust headers. :thumbsup:
 

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Discussion Starter #6
Nice Norval, I was wondering how you were going to keep from introducing turbulence in the exhaust headers. :thumbsup:
Are we talking about turbulence from that plug?? The uneven surface between the tube and dry seal?? I feel it is minimal and there is nothing more I can do about it. I made an effort to keep the dry seal as close to the surface as possible to cut down on turbulence but other then that I am afraid I have to live with the slight upset of the exhaust flow.
 

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Are we talking about turbulence from that plug?? The uneven surface between the tube and dry seal?? I feel it is minimal and there is nothing more I can do about it. I made an effort to keep the dry seal as close to the surface as possible to cut down on turbulence but other then that I am afraid I have to live with the slight upset of the exhaust flow.
Yes, When you started this topic, I was thinking about how to avoid effecting exhaust flow after you were all done and operational. i.e. plugged. Looks like you did a nice job addressing that.

Bullshark
 

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I have a wideband, it keeps me from running to lean with the blower. I eleminated the top of one piston before I put that in...
 

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Forgot. I think but am not sure but I believe on detonation exhuast temperatures can get to 1600F.. Not positive about this but think this happens? The meter has an alarm I can set for any temperture. I want to set it for say 1500F and if I suddenly spike at over this the alarm should go off warning me I have detonated with the extreme temperature spike and hopefully warn me enough to let off before damaging anything.
I recently gave a rundown on detonation, what it means and why but if anyone wants the short version just ask??
Is there anyway you could incorporate an inexpensive knock sensor calibrated to your engine that would light a display? That might help you pinpoint the detonation exhaust temp??????

Bullshark
 

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Discussion Starter #10
I have a wideband, it keeps me from running to lean with the blower. I eleminated the top of one piston before I put that in...
It is still hard with the wide band to know if you run into detonation. You idle at about 13.8 -14 and that holds for cruising in the 60 mph range. You drop to 12.5 maybe on the secondaries and hopefully this keeps you out of detonation. You could run as rich as 10-1 on full power for an extra margin of safety.
I tuned with the wide band . Now I want to see what the exhaust temperatures are looking like.
Detonation burns the tops of piston. A normal even lean firing won't do it.
At normal running temperatures a thin layer of gas lays on the surface of the piston, gas doesn't burn, the vapors do. This thin layer doesn't burn because the piston dome, relatively cool helps prevent this.
Normal exhaust gases are about 1300 degrees , aluminum melts at 1200 degrees so this thin layer on the surface of the relatively cool piston, a piston in the center is in the 500-550 range. This cool pistons helps prevent this thin layer of gas from burning thus protecting itself with this thermal barrier.
If you run into detonation and gas temperatures can spike in the 1600 range this thin thermal barrier of unburnt gas is blown off and the pistons sees the full effect of this 1600 gas and it begins to pit, gets that sandblasted look, that clean fresh look and soon is destroyed.
I am looking for this spike . See if it exists and no wide band can tell me if I am running into this.
Also since you are blown your intake temperatures are up. This affects exhuast gas output temperature. Yes you ratio might be right but at the same time the temps could be in the 1400 range and this will destroy the exhuast valves and the gaskets.
I just want to know if I am safe, if my tune is safe and if I am running into detonation. This should help understand how the motor is running
 

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Discussion Starter #11
Is there anyway you could incorporate an inexpensive knock sensor calibrated to your engine that would light a display? That might help you pinpoint the detonation exhaust temp??????

Bullshark
A knock sensor would be nice. I just haven't gotten there yet.
I have all the good parts, best of just about everything but I need to make them work together to get the most out of them.
I am trying to get the best tune possible. I have leaned the motor way out with the wide band and it has never run better. I will be running this weekend with the EGT and it will be interesting to see what the temperatures look like and if I run into any spikes.
 

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I'm still thinking out loud........ will the thermal couples have a fast enough response time to pick-up the detonation EG temp spike??? :crazy:

Bullshark
 

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A knock sensor would be nice. I just haven't gotten there yet.
I have all the good parts, best of just about everything but I need to make them work together to get the most out of them.
I am trying to get the best tune possible. I have leaned the motor way out with the wide band and it has never run better. I will be running this weekend with the EGT and it will be interesting to see what the temperatures look like and if I run into any spikes.

do a search on the "other" forum, I posted on how to build a cheap & easy kock circuit out of either an ODBI system ESC or from an ODBII weatherpack ECM calpack.
 

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Forgot. I think but am not sure but I believe on detonation exhuast temperatures can get to 1600F.. Not positive about this but think this happens? The meter has an alarm I can set for any temperture. I want to set it for say 1500F and if I suddenly spike at over this the alarm should go off warning me I have detonated with the extreme temperature spike and hopefully warn me enough to let off before damaging anything.
I recently gave a rundown on detonation, what it means and why but if anyone wants the short version just ask??
the temp you see depends on how far the probe is down stream of the exhaust port. i believe the standard distance is 1.5" from the head
 

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Discussion Starter #16
the temp you see depends on how far the probe is down stream of the exhaust port. i believe the standard distance is 1.5" from the head
I didn't know about this standard distance of 1.5 inches. I have read about distance from the piston and wanted to make it as short as possible but again I could be wrong. My probe is probably about 1 inch outside the head.
 

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Discussion Starter #18
do a search on the "other" forum, I posted on how to build a cheap & easy kock circuit out of either an ODBI system ESC or from an ODBII weatherpack ECM calpack.
I went to corvette forum, I assume that is the other forum and did a search under your name. No luck.
I would like to see that post here.
 

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I'm still thinking out loud........ will the thermal couples have a fast enough response time to pick-up the detonation EG temp spike??? :crazy:

Bullshark
Thats what I was going to ask and you beat me to it, How fast are the probes/Meter?
 

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I went to corvette forum, I assume that is the other forum and did a search under your name. No luck.
I would like to see that post here.

Search the archives for knock circuit, it should pop up.
 
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