View Full Version : PYROMETER TEMPS How much is too high?


Warhorse
12-29-2007, 07:48 PM
PYROMETER TEMPS How much is too high?

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Test drove new 408 turbo today, I had several gauges installed and one being a pyrometer.
Motor is still in tuning stages. I do not know what pyro temps are considered normal but while cruising under no load around 2400 2800 rpms, I was seeing approx. 1400 to 1475 degree temps. Sensor was mounted approx. 2 inches from head on No. 7 header.

Applying throttle into boost would decrease temps somewhat but when you return to a no load cruise, temps would immediately rise. Is this normal ? Outside temps today were around 50*

Any knowledgably info would be appreciated.

gametech
12-29-2007, 09:49 PM
A pyrometer is of little use in a gasoline motor. There is a HUGE difference between running Xtemp at cruise and Xtemp at WOT. Think of the difference between a match and a large bonfire. Even at the same temp, one is going to heat up its surroundings a lot more than the other. Diesels need pyrometers because their AF ratio constantly varies, as they have no TB. Gas motors are much better served with a wideband AF gauge.

SS2win
12-29-2007, 11:05 PM
I *think* 1500 - 1550 is where you need to start worrying... would be nice if someone who knows fer sher would discuss.

Shawn @ VA Speed
12-29-2007, 11:07 PM
Egt's are always important.They are just as important on a gas motor as a diesel.They tell you more that air fuel ratio but also things like timing.Those egt's are high for part throttle.I would say the timing is too retarded at cruise.try adding some timing and see what happens.

gametech
12-29-2007, 11:23 PM
Egt's are always important.They are just as important on a gas motor as a diesel.They tell you more that air fuel ratio but also things like timing.Those egt's are high for part throttle.I would say the timing is too retarded at cruise.try adding some timing and see what happens.

While your post IS correct, my point is that a pyrometer is of limited value for a gas engine. If your part throttle timing is too low, your BSFC wil be high, and your plugs will not look right. If your AF is lean, you will have reduced power and/or detonation. Pretty much anything a pyrometer can tell you will be obvious in other ways on a gasoline engine. OTOH, a pyrometer is essential on a diesel.

ssheets
12-30-2007, 12:14 AM
They sure are important on gas turbines:secret2:

gametech
12-30-2007, 12:33 AM
Yes, but gas turbines operate in a similar manner to diesels with regard to AF ratio. They are controlled by fuel input as opposed to air input.

ssheets
12-30-2007, 12:44 AM
Yes, but gas turbines operate in a similar manner to diesels with regard to AF ratio. They are controlled by fuel input as opposed to air input.Yep:D

2002_Z28_Six_Speed
12-30-2007, 02:37 AM
They sure are important on gas turbines:secret2:

Chrysler turbine car...