IAT Placement With Forced Induction & Alky Injection
IAT Placement With Forced Induction & Alky Injection If alky nozzles are positioned just before the TB on a turbo setup, where would be the best place to position the IAT sensor if you want to manipulate ignition timing based on intake temps when in boost?
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Joined: Sep 2013
Posts: 994
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From: Mechanicsburg, PA
Pre nozzle. Spraying on them will give inaccurate readings. Maybe The Farmer will chime in this thread and post more of the IAT sensor response times he attained data for. Interesting data point for sure.
Ultra-fast responding IAT sensors are definitely the hot new product that nobody asked for lol. Never seen any convincing data to justify their existence.
As for nozzle/IAT sensor placement, I've always welcomed some potential wet-bulb temp discrepancy. Without telling the ECM that there is methanol present, it doesn't know the average fuel quality has improved. So you lose out on extra advance you might run if the methanol injection was fully integrated with the ECM. Next best thing is a slightly undershooting temp reading, keeping your spark a little bit higher. I always place my meth nozzles several feet from the sensor though...essentially as close to the IC output as possible. Works well in all but the most extreme setups.
As for nozzle/IAT sensor placement, I've always welcomed some potential wet-bulb temp discrepancy. Without telling the ECM that there is methanol present, it doesn't know the average fuel quality has improved. So you lose out on extra advance you might run if the methanol injection was fully integrated with the ECM. Next best thing is a slightly undershooting temp reading, keeping your spark a little bit higher. I always place my meth nozzles several feet from the sensor though...essentially as close to the IC output as possible. Works well in all but the most extreme setups.
my meth is plumbed behind the tb blade at the top of the tb , my iat is in a straight piece of pipe 8 inches before the turn to the tb . been this way for 5 yrs and its great . Its not getting wet from meth and its after the intercooler and its before the tb like it should be.
This will prob always be debated, if it works it works. I have been spraying mine pre turbo, prob the sensor does get some wetting, but I guess it's also what the engine is seeing. I dont run an intercooler, so I needed something to cool the intake charge. While not a high HP deal, the plugs look good. On a real hot day, you would prob not get as much cooling, even with an intercooler, as your sucking hotter air into the turbo.
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Can def get away with more lead. I just worry about distribution issues with single point injection. I treat it as extra insurance. Setup the tune so its fine without... then add 7-12gph depending on power being made. I can see a difference in the plug heat reading with my 10gph of 50/50 on around 900-1000 chp. I actually lost MPH going higher than 10gph. I don't alter the tune up. Traps the same with the meth on/off. Just puts up the same # with a cooler CC.
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Verdad Gallardo Interesting to note with my BTR equalizer intake the heat and timing marks on my plugs look way more consistent now. Previously with the ls6 intake number 7 always had more heat in it and was my limiting factor on timing advance.
Probably because of so many GM vehicles having the IAT integrated to the MAF, there is a table to adjust based on ECT vs IAT, since the IAT is so far removed from actual engine temps that affect real manifold air temps. It was pointed out to me quite a while back that this discrepancy could be resolved by running the IAT sensor in the intake manifold, thereby giving actual MAT temps. I plan to experiment with positioning my IAT toward the back of the intake manifold on my next build revision, and see if the IAT vs ECT table can be zeroed out, thus removing one tuning variable. The hope is to get a more "real" value compared to the temps that actually hit the cylinders, vs the wild fluctuations that happen with any pre-intake placement. I have not yet implemented this strategy, so I will have to update when theory and reality collide.
Don’t over think it.
Thousands of people have ran speed density with no maf and sprayed meth pre IAT sensor with no issues. It actually gives you an extra safety opportunity with meth based upon IAT you can pull timing.
My AFR is always correct and I have the old syclone iat not one of the new whiz bang super fast reaction ones. The only time my afr gets off is very long periods of idling it will start to lean out which isn’t an issue at idle and then returns to normal as soon as I start moving again. That’s a fairly normal issue with speed density and has nothing to do with the meth. The ect iat bias can help reduce that as well. This is obviously a gen3 setup.
Ive had much bigger problems with afr when my ect sensor failed lol.
Thousands of people have ran speed density with no maf and sprayed meth pre IAT sensor with no issues. It actually gives you an extra safety opportunity with meth based upon IAT you can pull timing.
My AFR is always correct and I have the old syclone iat not one of the new whiz bang super fast reaction ones. The only time my afr gets off is very long periods of idling it will start to lean out which isn’t an issue at idle and then returns to normal as soon as I start moving again. That’s a fairly normal issue with speed density and has nothing to do with the meth. The ect iat bias can help reduce that as well. This is obviously a gen3 setup.
Ive had much bigger problems with afr when my ect sensor failed lol.
When you have full control of the SD system, you can adjust the temp portion of the program to suit you. My temps varied too widely from staging to shutdown depending on the day. I had my fueling MAT tables zeroed with my EGO correction dialed in. I used the MAT chart to retard timing only at higher inlet temps. Seemed to work well for me on the MS3 platform anyway.
