Hi all,
I have been playing around with this shroud for a few weeks now and along with my datalogger, have what I believe to be an accurate baseline to compare any modifications to my FAT 911 cooling setup. I'm using stock T4 under cylinder tins.
I have tuned my engine the best I can and it seems to be running well. I have quite a few graphs produced by my logger and have noticed some interesting points:
1. With the unmodified shroud and stock 11 blade fan/ alternator ring, as the engine warms up, #1 and #2 warm up slower than #3 and #4. The slope of the graph for these temps over time indicate that #4 warms up twice as fast as #1. (Is #1 receiving twice as much cooling air as #4 ? :shrug: )
2. After a hard run up to 140 kph from a dead stop, and then coming to a dead stop and idling (900 rpm) for 5 minutes ... #1 cools down twice as fast as #4. The cylinders seem to cool down with #1 cooling the fastest, then #2, #3 and then #4. #1 cools at the rate of -0.35F / Sec and #4 at -0.18F / Sec.
3. By taking the fanbelt off and starting the engine and letting it idle, all 4 cylinders warm up at the relatively the same rate ... making sure its not a tuning issue causing the temp imbalance.
4. Driving the car in 5th gear at 115kph (3000 rpm) vs 4th gear at 88kph (3000 rpm) creates temps 25 degF hotter (engine load im thinking)
I'll post some pics of how the 911 alternator ring has 4 built in diverters that seem to direct airflow in this shroud. The airflow of a 911 axial fan spins clockwise and I have a cool picture of an axial fan showing the airflow pattern and air distribution in free air.
My plan of attack is to place diverters on the back of the alternator (alternator cap ) similar to a stock 911-6 setup to start, and working with the alternator ring diverters
So ... does anyone have any suggestions on how to equalize the airflow (swapping to a DTM does not count
) ? I have my own ideas but it would be great to place all of this information in one thread, where everyone could benefit from this information. I'm not looking to market this product, just love the look and sound of this setup and want it to cool more effectively.
Sandeep