I know this topic has been covered plenty of times and I have searched. However, I'm still debating on whether to tap the #3 runner or the downpipe right after the turbo. If I am tuning with a wideband 02 and the probe is either in the dp or runner, couldn't I just use the egt number at whatever air/fuel ratio it is at as a reference? For example, if the engine is tuned at a 12:1 mixture and the egt reflects a certain number whether it be in the dp or runner wouldn't that number be a solid reference of what the egt is? I know the readings will differ from location to location and I also know the number 3 cylinder is prone to running the leanest. But I'm just trying to figure out if gauging an egt number from a wideband reading would be good enough if it is probed in the downpipe.

 

Having the egt 1" from the cylinder head will produce the most optimal readings, on runners #2 or #3. Moving the egt gauge downstream of the manifold will produce lower temperature measurement. Most of the egt's that tuners will reference are from exhaust manifold tapped sources, keeping 900c as the absolute limit. It should be noted that tuners typically dont tune with egt gauges, both fuel and timing have profound effects on egt readings. The tune should be set up with a appropriate fuel mixture, conservative timing and use the average egt reading in higher gears to base what is the limit egt level. The egt gauge should merely be used to monitor temperatures in the higher gears, and nothing more.

 

I tapped mine on the downpipe flage... I just didnt want to drill out the manifold.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 50trim EK &raquo;</TD></TR><TR><TD CLASS="quote">Having the egt 1" from the cylinder head will produce the most optimal readings, on runners #2 or #3. Moving the egt gauge downstream of the manifold will produce lower temperature measurement. Most of the egt's that tuners will reference are from exhaust manifold tapped sources, keeping 900c as the absolute limit. It should be noted that tuners typically dont tune with egt gauges, both fuel and timing have profound effects on egt readings. The tune should be set up with a appropriate fuel mixture, conservative timing and use the average egt reading in higher gears to base what is the limit egt level. The egt gauge should merely be used to monitor temperatures in the higher gears, and nothing more.</TD></TR></TABLE>

I agree, but if your egt's go up in first or second or any gear, it's mostly timing, but yeah i think EGT's speak alot in fifth gear boosting. But bottom line, if your car is tuned there shouldn't be a problem.

 

Tapping the EGT probe into the downpipe result in a much colder reading. Mine came out 300 deg. Celius colder. Basically useless.

 

is there a problem moving it to the downpipe or should you keep it in manifold i dont want to tap my full-race mani
and what is a normal operating temp for a boosted h22

 

I understand that the downpipe will result in a much colder reading. It is not useless if your egt is reflecting a target air/fuel. I know people like to compare apples to apples and the standard is to tap the manifold. To me it makes sense if you are tuning an engine and dial in a safe air/fuel ratio, then take whatever number the egt is giving you, whether it be in the downpipe or manifold, and use that as a reference for the desired air/fuel. Example, tune an engine to 12:1. Tune the ignition timing. Make some full throttle passes. What does the egt say? I'll throw a random number out and say 1200 degrees f. with the probe in the downpipe. Tune the same exact engine at 12:1 with the probe in the manifold. Now your egt says 1500 degrees, Now if you are driving, and the egt climbs above 1200 or 1500 depending on where the probe is, wouldn't that tell you either your not getting enough fuel or the timing is off compared to what it was when you tuned it? Isn't the whole point of an egt to be used a reference to your air/fuel/timing mixture, and not an actual tuning device? All I'm trying to say is whether you tap the manifold or downpipe, egt number should reflect whats going on inside the engine. I think im making this sound more complicated than it really is.

 

hmm you lost me

 

EGTs don't directly correspond to a/f value.

 

you want EGT to be read as acurately as it can get. The most efficient way to read it is to tap it as close to the exhaust port as possible. If it's placed to far, you lose resolution and it may not be trustworthy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 50trim EK &raquo;</TD></TR><TR><TD CLASS="quote">EGTs don't directly correspond to a/f value. </TD></TR></TABLE>

Timing.