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  #1  
Old October 25th 2004, 11:24
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Fat 911 T4 Cooling .. datalogger results

I've just completed my datalogger and here are the results of the first run. I was driving quite hard but only for short bursts .. see #2 below.

Time in seconds is on the x-axis, and the sensor data is on the y-axis, logorithmic scale so I can show all data on the same graph.

Some notes:

1. The engine warms up unevenly ... between T=1s and T=310s, difference in 1-2 head and 3-4 head is about 40deg.

2. Once warmed up the temps are pretty even. "Getting on it" was a little difficult because I quickly exceeded the speed limit in my area Need to get on the highway.

3. I have noise in my Ambient Air Temp and Fan Inlet Temp circuit, will need to fix this.

4. No Oil Temp, RPM, and Rear Wheel Speed circuit yet, will get those running in a few weeks ... so its difficult to judge temps without this data ... how fast was I driving, how high was I revving ect..

More data to come !

Sandeep
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  #2  
Old October 25th 2004, 11:40
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Cool! So what do you have for a scale to transfer these to degrees??

About 60 degrees is the norm for what we saw with the fan you have, shroud you have as well as the drive ratio, but our engine was larger displacement- 2270

Great work! when you get that rig all figured out I'll buy one from you!
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Old October 25th 2004, 11:51
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The chart scale is logorithmic on the y-axis ... so between 1 and 10, the divisions are 1,2,3,4,5,6,7,8,9, and 10, between 10 and 100, the divisions are 10, 20, 30, 40, 50, 60, 70, 80, 90 and then 100, from 100 to 1000, the pattern is the same.

When I get the RPM's hooked up, there will be another section, 1000, 2000, 3000, 4000 etc between 1000 and 10,000.

The temps are in F, AAT and FIT in C.

The logger stores data in hexidecimal format (memory savings) and the calcs tab in the spreadsheet makes the conversions through formulas derived from the circuit I designed. I calibrated the system with a pot of boiling water and I'm only off 1.5 F at 212 F (100 C) when the pot is boiling.

I'm off to do another run now !

Sandeep
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Old October 25th 2004, 12:27
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cool....

But you do know that water only bois at 212 when you are at sealevel... You need to do a bit of an equation to figure out your elevation and the differences from sea level..
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Old October 25th 2004, 14:36
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You are right ... Todays pressure is 101.87 KPa and Toronto is at 270m above sea level ... that works out to 210.10 F. Another boiling water test shows the temp on each of the thermocouples at 211.6 F so within about 1.5F. :agree:

I also rerouted my coil spark plug wire and it really helped eliminate most of the noise. 2nd run here.

I won't put up anymore runs until I get the RPM's and RWS sensors hooked up, so I can show the temps at what RPM and RWS.

Sandeep
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Old October 25th 2004, 14:37
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doesn't the mineral content of water also slightly affect the boiling point. I thought only "pure" water boiled at 212 degrees F at sea level.
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Old October 25th 2004, 16:22
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Quote:
Originally Posted by boygenius
doesn't the mineral content of water also slightly affect the boiling point. I thought only "pure" water boiled at 212 degrees F at sea level.
You ARE kidding me, right?
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Old October 25th 2004, 16:28
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Quote:
Originally Posted by Sandeep
2nd run here.

Sandeep
Wow, only maximum 10 degrees Fahrenheit difference and max head temp so far only about 310F ! I am impressed!
To be honest, after all the horror story's of the 911 fan set-ups, I would have expected much higher head temp differences...

Thanks for your effort!

Regards,
Walter
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  #9  
Old October 25th 2004, 19:52
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Also you can note that those temps were above 300 degrees on a bone stock engine (2.0) and I believe that he has stock gearing which is decreasing load on the engine and keeping the cylinders from working as hard.

With a DTM most engines sustain a reading of 275 degrees with a 10 degree variance on all 4 cylinders. Zen's engine won't get any hotter than 275 from the drive that I took in the car up a huge hill.

BTW-The system he is testing gave us the temp readings with the hottest overall temps, Sandeeps test is backing up exactly what I saw when that system was in my car last October for testing..

Sandeep, what drive ratio are you using to test this?
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Old October 26th 2004, 01:51
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Yeah, I also believe a stock (= low) compression ratio will definately help to keep head temps down.
Somehow, I think that the high fan set-up of the FAT shroud might help to get the cooling air easier to the 2 and 4 cylinder; the air doesn't need to make a sharp turn, like with the deeper sitting fan assembly's.
I'am curieus what your take is on this Jake?

Thanks,
Walter

BTW, 275 F up a hill in a high CR 2270 is amazingly low!
BTW II, my stock 1,8 with stock cooling runs 325 F on the right bank and 375 F on the left bank all year...
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Old October 26th 2004, 10:37
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I'm using the pulley that came in the FAT kit, along with the pulley that comes with the 11 blade fan. How do I measure what the pulley diameters are ? I mean .. do I measure the diameter of the surface that the belt actually contacts on both pulleys ? I'm thinking so but just need clarification.

The AAT is also about 10deg C so this might explain the cool temps, just wait till we hit 35C with humidity in the summer Its getting cooler here by the day so the temps might seem fine ... just wish it was still summer ... I got my datalogger project completed about 6 months too soon

I'm using a stock 72 trans right now but am converting to a 914/01 5 speed this winter so the engine/trans combo will be stock for a 914.

I don't have any (big) hills nearby that I can drive hard up, and when I drive hard on the local roads, I reach the speed limit quite quickly.

Sandeep
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Old October 26th 2004, 14:54
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Hi Sandeep,
AFAIK, the pulley diameter is measured on the outside edge, so just the biggest diameter of the wheel.
Mine is 145mm.

In my limited experience since the cyl. head temp measurement device is on, outside temps have hardly any effect on cyl. head temps.
Outside temp (environmental temp) does make a dramatic difference on oil temps, but not to head temps.
Can't logically explain it, but thats it.

Regards,
Walter
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  #13  
Old October 26th 2004, 16:01
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Quote:
Originally Posted by Wally
Yeah, I also believe a stock (= low) compression ratio will definately help to keep head temps down. .......BTW, 275 F up a hill in a high CR 2270 is amazingly low!
yep. as info, my engine is a 2316cc with 9.7:1. that "up hill" was literally about 1 mile or so at 20% grade or so (guestimates here) at around 80-90MPH and high RPM (i'm geared for acceleration). my oil temp gauge was not hooked up though to know what oil temps looked like. based on load hits head temps and RPM hits oil temps, i was VERY pleased with the head temps.

really looking forward to your info Sandeep. especially on head temps on a relatively stock engine with the FAT shroud. although not a favorite for cramming in a bug, it is the easiest (really only) retro fit 911 system out there and probably the most affordable. great way for low budget projects that just have to have the 911 system to get a running stock TIV in their bug.
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  #14  
Old October 26th 2004, 16:11
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Thanks for the info Wally, I'll take the measurement this weekend. Just got word that my Hall Effect sensors arrived , should have the RWS and RPM circuits running on the weekend.

Hopefully I'll have everything ready for the next BoxerAutoGruppe meeting, and I'll take the long way there to get about 50 mins of data. This is a nice trip, about 140kph for about 20 mins on the highway and then some in town driving.

I built this logger for my track days in 2005 so I'll post any data I accumulate before the car hits storage for the winter.

Sandeep
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  #15  
Old October 26th 2004, 19:47
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Kuhl project. How are you going to aquire oil temp data?
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