On 9/28/05, Kelly Troyer <keltro@att.net> wrote:
Ed Anderson has a measurement to check the depth of the combustion depression in the
face of the rotor to determine the compression ratio (the deeper one is turbo).......
How about it Ed, any info on this? Can it be used to tell the 9.4:1 86-88 rotors from the 9.7:1 rotors?
Bottom line check weight first then check the depth of the combustion depression........I have
another way I use to determine what year my rotors are (all my engines are NA 86 to 91).....The
combustion depression in the 86 to 88 is as cast in the rotor (slight grainy surface finish).....The
89-91 depression is machined and has straight machine marks.......
That is really interesting. My old rotors are supposed to be 1991 T2 rotors but they have the cast appearance (However since I got them from Atkins I am not really sure they gave me what they sold me). The rotors that Earnest sent also have a cast appearance. But as I recall, the rotors in the engine I rebuilt had the milling marks... hmmm.. if that is true the balance in my current engine is all SNAFU. Are you sure that system is a valid way to do the measuring?
So I just got back from weighing my rotors - Sure enough, the ones Atkins sold me weighted in at 10.20 and 10.19 making them the 86-88 variety despite the fact that I paid for a '91 engine. Worse, I have no idea what counter-weights he decided to use. If it matched the rotors he sold me then I have been running an unbalanced engine for the last 150 hrs. (that explains part of why the wife won't fly in it)
Does anyone know what the correct weights of the counter weights should be for a given year group? Or perhaps some other way of telling them apart?
BTW Ernest, the rotors you sent also weigh in at 10.18.
Dave Leonard
Check with Ed for his method to determine compression ratio as I do not have it at hand......I
am attaching the rotor weight chart from "Mazdatrix" which will help (note weight does not
include any seals or springs....just the bearing.........Hope this helps........Any more questions
just ask !!
--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2
| Engine |
Year |
Compression |
Weight (Grams) |
Weight (Pounds) |
| 12A |
76-82 |
9.4 |
4603 |
10.15 |
| 12A |
83-85 |
9.4 |
4353 |
9.60 |
| 13B |
74-78 |
9.2 |
5253 |
11.58 |
| 13B |
84-85 |
9.4 |
5253 |
11.58 |
| 13B N/T |
86-88 |
9.4 |
4553 |
10.04 |
| 13B Turbo |
86-88 |
8.5 |
4553 |
10.04 |
|
| 13B N/T |
89-92 |
9.7 |
4328 |
9.54 |
| 13B Turbo |
89-92 |
9.0 |
4328 |
9.54 |
| 13B T/T |
93-95 |
9.0 |
4328 |
9.54 |
NOTE: Weights are approximate, and include rotor bearing, but do not include any seals or springs.