Fat 911 T4 Cooling .. datalogger results

[Sandeep]

I've just completed my datalogger and here (http://www.germanlook.com/Transfer%20Folder/DataLog241004.htm) 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 :D 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

[Massive Type IV]

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!

[Sandeep]

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 ! :laugh:

Sandeep

[Massive Type IV]

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..

[Sandeep]

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 (http://www.germanlook.com/Transfer%20Folder/DataLog251004-1.htm).

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

[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.

[Wally]

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? :p

[Wally]

2nd run here (http://www.germanlook.com/Transfer%20Folder/DataLog251004-1.htm).

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

[Massive Type IV]

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?

[Wally]

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! :D
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...

[Sandeep]

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 :laugh: 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 :D

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

[Wally]

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

[zen]

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! :D

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.

[Sandeep]

Thanks for the info Wally, I'll take the measurement this weekend. Just got word that my Hall Effect sensors arrived :clap: , 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

[Bill K.]

Kuhl project. How are you going to aquire oil temp data?

[Sandeep]

I will get the oil temp data by taking the vdo oil temp sender (thermister) in the sump location and remove the thermister and modify it for a thermocouple (thermowell).

I can drive the oil temp gauge with a D/A converter as well as the CHT gauge by modifying my program to feed the signal from the highest cht of the 4 to the cht gauge so it will always read the highest temp from the 4 cht thermocouples.

I'm not worried at all about oil temp right now because my cooler/ducting system never goes over 200F while driving at extended rpms for a long amount of time.

Sandeep

[Bill K.]

I'm interested in datalogging too, so your experience is very helpful.

Why are you converting the thermistor to a thermocouple? Are you using thermocouples for ambient and fan inlet temps too? Why?

The auto max-reading gauge is very kuhl. Will you know what cylinder is being read while driving?

[Sandeep]

I'm converting to a thermocouple for oil temp because the IC's I use to read the TC's have an error of 0.5 F and their output is linear. No need to calculate or extrapolate the temp from graphs that are provided for a particular thermistor, whose output in not linear with temp.

For AAT and FIT, I'm also using IC's with a linear output but the IC tells the temp accurate to 0.5 F, no TC's here and the IC is the size of a pencil eraser ... very small. FIT and AAT won't get above 50 C and the IC's are very accurate in this range.

The auto-max gauge concept is for me to tell if the heads are too hot when I am racing ... I can always tell which cylinder was too hot when I look at the graphs after the run.

I could have used an LCD on the dash to give me the required information, but I like the look of the gauges ... and I don't want my dash to look high-tech ... I want it to look like VW could have built it in '74 :D

Sandeep

[Massive Type IV]

Sandeep,
Head temps are normally not a huge concern in road racing except on the straights.

In the infield you are working in the upper RPM and in a lower gear which removes load from the engine..

Your datalogger will show this very well..

[Bill K.]

Sandeep, are you sticking with a 1 Hz sample rate? How did you decide what was enough but not too much data?

[Chris Percival]

Cool charts.. Whats the 'FIT' measurement?

[Bill K.]

Cool charts.. Whats the 'FIT' measurement?
Fan Inlet Temperature

[Sandeep]

While playing with this datalogger, I've got some cool graphs and I've got the RPM sensor working now. Just have the Rear Wheel Speed sensor to make up to have it fully operational.

I was taking 1 sample per second to see if the programming worked (it did) but have now changed the code to take 1000 samples of each channel per second, taking the average value to get an accurate value to store.

This is limited by the registors in the microcontroller as to how large a value I can get before I divide by 1000. I used 500F as the value to decide this ... hopefully the heads will never reach 500F :laugh:

Sandeep

[Supa Ninja]

Wow :eek: this a awesome thread. Since I'm going to use the FAT setup, already got my fan and ring back from the powdercoater (I told you Zen I'm going to bite off your old setup). All I need is the shroud. I also dig the techno stuff a lot too. The data logger you setup Sandeep sounds very cool. Are you going to write up a tech article on how to make your own?

Nick

[Sandeep]

Sorry, no tech article on this one ... too much time into developing this project .. I've actually put the knowledge I've gained at university to use :laugh:

Some interesting notes on run 2:

1. Highest average head temp on 1-2 is 316F
2. Highest average head temp on 3-4 is 324F
3. Greatest difference between average 1-2 and average 3-4 is average 3-4 runs 37.9F hotter than average 1-2 -> not sure how great of a difference this is ... is it acceptable ?, here is where internal vane design comes in.

1, 2, and 3 are at different times during the run.


4. Highest average head hemp 1-3 (front of engine) is 311F
5. Highest average head temp 2-4 (rear of engine) is 324F
6. Greatest difference between average 1-3 and average 2-4 is average 2-4 runs 13F hotter than average 1-3 -> does not seem to be an issue, is this difference acceptable ?

4, 5, and 6 are at different times during the run.

Keep in mind this is a pretty stock 2.0 GA T4, not a fire breathing 2316.

More data with RPM, RWS to come ! :eek:

Sandeep

[Bill K.]

Great to hear your progress and payback from school. It sounds like your data is worst-case differences over time. I think the instantaneous difference and rate of change is what would affect performance/longevity. Your data doesn't sound bad though. How hard and long were you on it for these runs?

Are you going to sell your system? There is a lot to be learned with real time data and having a cost effective solution would be great.

[zen]

good info. question, since these are averages and you noted side-to-side and front-to-back, is #4 tweaking the averages at all? based on info that has been shared in the past, seems that is a hard one to cool since it sits almost under the fan. what was peak and average of #4 by itself?

also, how would you define the average load you were putting on the engine through the runs? traffic? hills? flat?

any idea how the age/miles on the engine factor into this?

what advance are you running? and what ignition?

[Sandeep]

These are instantaneous values taken per second ... but I agree that the rate of change is what affects performance/longevity. The average values are computed per second so at X seconds, the averages are Y.

The data is already captured to show this ... I will add another chart to show how the temps climb when I'm "ON" it ... would be cool to see how long it takes the cylinders/heads to cool from lets say 350F to 325F or to go from 300F to 350F while driving.

The runs I have posted, I accelerate with foot to the floor, through all gears until I hit 70 mph and then hold 70 till I have to slow for traffic. The RPM and RWS will clearly show this when I install them.

No plans to sell the system ... YET :D

Sandeep

[zen]

play with this too. would have never thought this the case until i saw Jake doing it with my engine on the dyno. when the head's are hot, kill the load on the engine and do some repeated revving (~0-3k RPM) and watch the head temps drop.

[Sandeep]

Time (Sec) CHT #1 F CHT #2 F CHT #3 F CHT #4 F Oil Temp F AAT C FIT C Engine RPM Rear Wheel Speed (kph) Average Temp 1-2 (F) Average Temp 3-4 (F) 34 - 12 (F) Average Temp 1-3 (F) Average Temp 2-4 (F) 24 - 13 (F)

692 276.62 290.40 314.52 324.85 49.23 63.01 42.34 1.10 1.10 283.51 319.68 36.18 295.57 307.63 12.06
912 300.73 286.95 307.63 328.30 66.45 45.78 59.56 1.10 1.10 293.84 317.96 24.12 304.18 307.63 3.45
913 300.73 286.95 307.63 328.30 66.45 45.78 59.56 1.10 1.10 293.84 317.96 24.12 304.18 307.63 3.45
925 311.07 311.07 321.41 324.85 49.23 42.34 52.67 1.10 1.10 311.07 323.13 12.06 316.24 317.96 1.72
926 314.52 311.07 321.41 324.85 52.67 45.78 49.23 1.10 1.10 312.79 323.13 10.34 317.96 317.96 0.00
927 311.07 314.52 321.41 328.30 52.67 45.78 52.67 1.10 1.10 312.79 324.85 12.06 316.24 321.41 5.17
928 314.52 317.96 324.85 324.85 49.23 42.34 49.23 1.10 1.10 316.24 324.85 8.61 319.68 321.41 1.72
929 314.52 311.07 317.96 328.30 52.67 49.23 49.23 1.10 1.10 312.79 323.13 10.34 316.24 319.68 3.45
930 314.52 311.07 314.52 324.85 49.23 45.78 49.23 1.10 1.10 312.79 319.68 6.89 314.52 317.96 3.45
934 304.18 304.18 317.96 324.85 52.67 45.78 52.67 1.10 1.10 304.18 321.41 17.23 311.07 314.52 3.45
938 300.73 283.51 304.18 324.85 49.23 52.67 49.23 1.10 1.10 292.12 314.52 22.39 302.46 304.18 1.72
976 290.40 286.95 321.41 324.85 49.23 63.01 52.67 1.10 1.10 288.68 323.13 34.45 305.90 305.90 0.00
1045 297.29 297.29 324.85 324.85 49.23 83.68 59.56 1.10 1.10 297.29 324.85 27.56 311.07 311.07 0.00


Not sure how this will show up ...

Well that didn't work ...

Anyways, the greatest difference I get between #1 and #4 is 48F, and that is at T= 692s, 1 is 276F and 4 is 324F.

Sandeep

[zen]

good enough to read. obviously #4 is the problem child killing bringing up the averages. i am not sure when an imbalance in temps across the cylinders starts to become an issue. with the limited driving i have done, i usually don't see swings more than 25 degrees left to right. that is even pretty rare, but will see that occasionally. probably a major factor there though is a new engine vs. used as much as anything.

[Sandeep]

The best way to show all the data is to update the link for run 2. I will add more columns and one more chart to show what we have been talking about.

On the new vs used engine ... not sure, but I'm thinking used would have more tolerance (sloppyness) so perhaps it would run cooler ? :shrug: Can't offer any insite into this one ...

Sandeep

[rustbucket]

I'd agree but on no other basis than what you stated.

[Massive Type IV]

Thats about the same types of differences I saw on the dyno..

#4 is ALWAYS worse with ALL 911 set ups!

Told ya so.... LOL

Try changing drive ratios- THATS WHEN IT GETS VERY INTERESTING!

[Wally]

Anyways, the greatest difference I get between #1 and #4 is 48F, and that is at T= 692s, 1 is 276F and 4 is 324F.

Sandeep
Yes, but that is in the 'warm-up' stage as it is the first recorded time (t=692 which is after about 11,5 minutes ?).
After a while, when t=929-930 secs, so at the hottest recorded temps, the temp differences are actually remarkeble small!! Only 7 degrees F, thats about 4 degrees Celcius :eek:
The absolute highest temps (324F) seem still very moderate as well.
Myth busted! ;)

What sort of header do you use? What sort of under cylinder tin do you use?

Thanks,
Walter

[Sandeep]

New columns added for run 2, check it out here (http://www.germanlook.com/Transfer%20Folder/DataLog251004-1.htm). Its true that during the warm up stage the temps are uneven .. but later in the run they seem to stabilize. I'm using stock T4 under cylinder tins and a BAS 21152 header with dynomax super turbo 2 1/4" muffler.

I've got the rpm and rws sensors hooked up and hope to do some hard runs this weekend. There is some snow on the ground now but it is supposed to be gone for the weekend.

Sandeep

[Wally]

Its true that during the warm up stage the temps are uneven ..
Sandeep
and that may even be an engine/tuning issue...who knows?

Thanks for the update and good luck on the run. Keep the car (and youself) in one piece!

Walter

[Massive Type IV]

Very interesting Sandeep....

But its not exactly what I have seen in my testing at all especially with that shroud...

I have never used an engine that small for the testing though, the smallest was 140 BHP.

[Bill K.]

Looks good. You may want to plot the running average of 5 seconds or so to smooth the data. Your resolution of 3.45F is making the data look more noisey than it probably is. I suggest you back off your full scale to 400F to get more res (2.1F, assuming 0-500F full scale). Taking the average of 1000 samples per second is great for reducing noise, but better resolution would help smooth the data. Either way, it's very useful information :agree:

Where do you have the AAT probe mounted? Seems to be picking up some engine heat when you backed off the throttle (t=1700s). Also, looks like there may be some ignition interferance at high revs. Did you route your TC's away from primary wiring? Do you have similar noise with the engine off?

I look forward to seeing more of your progress.

[Sandeep]

Great suggestions folks. I may have to do some minor reprogramming but not a big deal.

Run #2 at t=1471s is when I actually pulled into the drive way and shut the engine off. The FIT increased because the heat from the engine actually finds its way out past the fan :laugh: It decreases again because I started up the engine to adjust the idle and then shut it off again ... cool to see that in the graph though :)

The AAT probe is mounted so it just pokes out past the intake grill on the decklid. I've got lots of wire so I can reposition it but want to keep the wire length short as to not introduce additional noise.

I'll try to get a full run in this afternoon with RPM data :eek:

Sandeep