Bench Racer, on 26 May 2015 - 04:42 AM, said:
We know NA engine temp is higher at the rear of the engine from history reading and the re-plumb kits available.
Do you by chance have an aftermarket temp gauge between thermostat and radiator? If so what are the temp diff?
Does anyone know the wide open throttle temp difference between the front and rear of the engine?
I have a sensor in the outlet of the radiator, and a couple of sensors in the back of the head. I've got a springfield dyno radiator, and generally see about 20-25 degF deltaT across the radiator. Spot check of a race last fall with 100degF ambient showed 200degF at the back of the head and 178degF exiting the radiator.
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I think Jeff's data in comment #13 above is pretty reasonable. I just completed an evaluation on a 99 NB with AIM K-type thermocouples mounted in the thermostat outlet housing and in the rear of the head in the 1/8 NPT plug in the rear of the head at the temp sensor/heater hose cover. I ran an ICE BATH/BOILING water calibration check on both thermocouples going into the AIM logger to verfy system accuracy. The car had a Springfield Dyno radiator, 160 degree T-stat and a heater hose looped to by-pass the heater core. Coolant was distilled water and Redline Water Wetter at recommended mix.
The bottom line is that there was about a 11 degree higher temp at the rear of the head as compared to the water coming from the outlet back to the radiator. This was true for both Max and Avg temp data throughout the laps. Ambient temp was around 80 degrees. Please see data summary table below.
On a side note I typically use a dyno ramp rate such that the length of time for the pull is close to the same time it takes our car to accelerate in 4th gear on a level straightaway. That would be about 125 rpm per second or 20 sec pull from 4500 to 7000 rpm. This minimizes the affect of mass acceleration and has the engine systems operating in the same dynamic rates as when on the track.
Date : 5-24-15 Loc : INDE Motorsports Ranch (Az) Car: 1999 NB #145 with 160 Deg Stat w/Sprgfld Dyno Rad using AIM K-type TC probes, Bypassed Htr. Core Driver: Steve Powers
Lap Time Distance GPS Speed Eng RPM Gear # A/F -avg Exh Temp #4 Coolant Temp_Rear Coolant Temp_Outlet Fuel Temp 2 Rail Logger Tmp Rear coolant +/- Front Outlet
# Min:Sec Feet Avg Max Avg Max Avg Lambda Max Avg Max Avg Max Avg Avg Avg Max
lap 2 01.54.122 11640 69.5 98.4 5419 6579 3 0.98 1171 173 180 163 172 102 94 10 8
lap 3 01.53.682 11598 69.6 96.7 5363 7117 3 0.98 1181 179 185 168 174 108 94 11 11
lap 4 01.56.127 11648 68.3 95.6 5228 6576 3 0.99 1189 184 195 173 186 111 94 11 9
lap 5 01.55.651 11598 68.5 95.9 5238 6466 3 1.01 1185 189 195 179 186 114 94 10 9
lap 6 01.53.407 11622 69.8 98.5 5375 6560 3 0.97 1192 190 195 178 183 115 94 12 12
lap 7 01.54.228 11641 69.5 96.9 5324 6518 3 0.98 1193 190 196 179 184 116 94 11 12
lap 8 01.53.799 11609 69.6 97.6 5339 6479 3 0.98 1202 192 198 181 186 117 95 11 12
Overall Avg-> 185.3 192.0 174.4 181.6 10.9 10.4