Pyrometer info
12-04-2011, 11:48 AM
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Pyrometer info
I had a member ask me what my experience was with a pyrometer on a gasoline engine. I wasn't sure which section to post this in but I hope this will suffice. Here is my experience with a 0-1600* F autometer pyrometer on a stock 4.8L with a rear mounted intercooled Garrett T-04E on a 5000lbs truck (I'm pretty sure a heavier vehicle will yiled higher EGT's when driving than a lighter one).
On a cold start up, the pyro would start at about 200* and increase to about 750* after about 5 minutes of warm up time. Under light throttle (granny accelerating) the pyro would gradually increase to about 1200*, hover around that point and stay there once a speed of about 60mph was reached.
With the engine warm and making a hard pull @ WOT, the pyro reading would increase at an average rate of about 50* per second. Peak temperature will dramatically depend on the duration of a WOT or full boost pull(full boost at less that WOT) The highest I ever saw the needle read was right below 1600*. That was also boosting up a hill during a hot summer day.
Shutting down. I idle through the parking lot and park the truck. Immediatley after the column went into park, the pyro would read about 900*. I'd let the truck idle down for about 30 seconds and the pyro would settle around 750*.
Now the effects of methanol. I'll make this one short. I started out with 6psi and no methanol. Then I almost doubled the boost (turned it up to 11.5psi) and added the methanol system during the same garage session. The result......My EGT's were actually slightly cooler with 11.5psi and methanol then 6psi without methanol.
This is just my experience with a pyrometer and the cooling effects methanol has on EGT's. Every setup will vary some but at the very least, this will give some baseline information on pyrometer use with a boosted gasoline engine - methanol or not.
On a cold start up, the pyro would start at about 200* and increase to about 750* after about 5 minutes of warm up time. Under light throttle (granny accelerating) the pyro would gradually increase to about 1200*, hover around that point and stay there once a speed of about 60mph was reached.
With the engine warm and making a hard pull @ WOT, the pyro reading would increase at an average rate of about 50* per second. Peak temperature will dramatically depend on the duration of a WOT or full boost pull(full boost at less that WOT) The highest I ever saw the needle read was right below 1600*. That was also boosting up a hill during a hot summer day.
Shutting down. I idle through the parking lot and park the truck. Immediatley after the column went into park, the pyro would read about 900*. I'd let the truck idle down for about 30 seconds and the pyro would settle around 750*.
Now the effects of methanol. I'll make this one short. I started out with 6psi and no methanol. Then I almost doubled the boost (turned it up to 11.5psi) and added the methanol system during the same garage session. The result......My EGT's were actually slightly cooler with 11.5psi and methanol then 6psi without methanol.
This is just my experience with a pyrometer and the cooling effects methanol has on EGT's. Every setup will vary some but at the very least, this will give some baseline information on pyrometer use with a boosted gasoline engine - methanol or not.
Last edited by kalikid06; 12-04-2011 at 02:49 PM.
12-04-2011, 12:32 PM
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Just as important as the temperature is where you have your thermocouple at. IMO it should be installed directly into one of the exhaust manifold primaries just like the diesels. Some people put them after the turbine on a front mount and that is incorrect IMO.
12-04-2011, 12:51 PM
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Agreed. I mounted the pyrometer probe about 8 inches away from the #7 exhaust port - it was as close to the head as I could get it. I prefer to get the most accurate reading of EGT's exiting the engine, not the turbo
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12-04-2011, 01:23 PM
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Unfortunatly not. I never had the desire, nor the motivation, to install the pyro when I swapped to my new setup. Not to mention, I already have fuel pressure, boost, and wideband AFR on the pillar - didn't want a fourth gauge.
No. However, I did get to about 1598* on one occasion 
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