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Haltech Front-Rear EGT imbalance ..Does 6-7% added fuel to rear rotor sound excessive.

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Old 11-21-14, 06:07 PM
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BadAss DoItYourselfer

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Front-Rear EGT imbalance ..Does 6-7% added fuel to rear rotor sound excessive.

Just as the topic states, I have added 6-7% more fuel to the rear rotor to help equalize egts. On average, how much fuel are guys adding to your rearrotor ?
I am running an E8 at ~25psi
Old 11-21-14, 10:03 PM
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Mad Man

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Check the insertion depth of the egts, flip the egts runner 1 to 2/2 to 1, and consider position in manifold if they are different distances/geometry to the egt before you change fuel.
Old 11-21-14, 10:06 PM
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also have your injectors been cleaned/flowed recently?
Old 11-22-14, 07:11 AM
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Have not flowed injectors. It is a fact that most rotarys run hotter on the R rotor and most people do add extra fuel to that rotor. I am trying to an idea on average how much fuel others are adding.
Old 11-22-14, 08:20 AM
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I never had a problem on my car with rear egts being higher. I had also heard that as being a fact as well. I actually made quite a few changes over the years to double check and never had any issues with uneven temperatures (assuming rew usdm lim). Also small differences in sensors, insertion depth and position make a major difference in temperature. All I was getting at was make sure your measurements are correct or check your other inputs that may be causing inaccuracy in your measurements. 6 to 7 % is a lot of fuel to just add and I would verify your injectors are flowing correctly first.

One item that might have helped me though was I was always feeding rear rotor first fuel wise. Might have been extra pressure there but I had never setup pressure transducers in different spots on the rail to verify
Old 11-22-14, 08:30 AM
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Same here with the drag car I work on. Stock FD intake manifold. HBP. Runs within 50* front and rear. Figure that's within the noise potential of the system, so I leave it.
Old 11-22-14, 08:38 AM
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Glad you saw the same thing Chris. Always scared to post things like this that go against forum "truths".
Old 11-28-14, 06:25 AM
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^ Data is Data, almost all of these "truths" are never backed up with data. Discussions like this are what the forum is for
Old 11-28-14, 07:01 AM
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I exchanged the positions of the probes on the manifold to see if the difference lie with the egt apparatus. Got the same results.

With 6% fuel added to the rear seecondary injector, the temps now run within 50F of each other and thats acceptable I suppose. But I think 6% is a lot of fuel just to equalize egt's.
Old 11-28-14, 07:55 AM
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Don't forget that the depth of the probe in the runner has a lot to do with temp readings. You need to make certain both probes are inserted the same depth in the runner. Data is only as good as the means with which you gather it. If the data sucks, the results will suck.
Old 11-28-14, 10:04 AM
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Last time I checked the debth into the runner is the same between probes. I will re-check to make sure there are exact.
Old 12-01-14, 05:12 PM
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Need to also double check the depth on my Probes.

BTW Chris the 60" EGT Probes that I got from you work perfectly, thanks again for all your help.
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