I used a piston compression tester, I got 115 psi pulses on all faces at 5000 miles. (I got about 100 at 500 miles). Total compression (check valve in) was a tick over 120 on both rotors. I think the piston tester works just fine, I don't understand your low readings.

By chance, did you try dumping oil down the spark plug hole and trying compression test again? (you should gain ~5-10 psi) If you gain a lot more, I guess more break-in is in order.

I premixed for the first 200 miles and then quit mixing after that until 5,000 miles, when I started mixing again.

115 psi pulses? Man I was seeing 55 psi and I heard the average(via rotary ressurection) was 30-35 psi for each consecutive pulse. ?hmm

I am not worried until I hit 1500 miles.

I run about 1/2 oz to a gallon regularly, and have probably done less on the old motor. The housings were still in great shape besides the chipped apex seal bouncing around in the rear rotor. I only run 1oz per gallon during track days or autocross practices.

Well in all fairness, I did take 2 nights to do a 150mi jaunt each night, I went to Daves twice - 600 miles there, and AC over the weekend. 350 miles, so that's about 1250 out of the 2200 right there.......... BUT.... I also had that week long rebuild stretch where she wasn't running at all.... slacker ;)

I've always been told that more premix during the breakin is a good thing. Reason being, you don't want too much dig in, you want the parts to seat, not overheat, not gouge, no be over stressed. After everythings seated and running well and broken in, there is less stress, less pressure points if you will.



Depends on alot of things, personally I wouldn't worry until you start seeing 220+ oil temps and even those are acceptable. Lower would be better but 230 is an eye opener, 240 is like :cuss: The temps you described are just fine. I wouldn't worry at all. When under a more constant load, you should see oil temps 10-20*hotter than coolant. More than that and I would worry about the exchanger. I went a little to big I think, let me rephrase that, I went a little too small but ducted a little too well. I generally see 170* coolatn and 160* oil on the highway. When sitting in traffic in wonderful jersey on the way to AC, coolant hit 186 and oil hit 210. As soon as traffic started moving again it took about 2-3 miles for the oil to get back down to 160's.

35 psi? I have never seen a pulse that low. Ever. (Except on a blown engine, which gives 25-30 with missing pieces of apex seal.) Maybe we do it differently. I simply take the check valve out of the bottom of the gauge and crank the engine with the plugs out of both rotors and the gas floored (about 400 rpm).

I tested a 120,000+ miles turbo II and got 90 psi bounces.

My 160,000 mile '91 has 110 psi bounces.

My 199,000 mile 6-port had 105 psi bounces even after the coolant seals failed.

I don't know if the pulse is actually 115 psi, I watch how high the gauge bounces (there may be overshoot).

The factory tester actually graphs instantaneous pressure on a chart. I have seen several traces and they usually run about 8 bar (120 psi).

The FSM recommends that no pulse be below 80 psi as I recall.

Think about this:

Starting air pressure 14.7 psi
compression ratio 8.2:1
final pressure = (14.7 * 8.2) = 120 psia = 105 psig (assuming constant air temperature, which is clearly not true, so the pressure should be higher). Any air lost past seals comes out of this total.

I can list a video of the gauge bounces if this would help.

What to you do for 35 psi readings?

thats assuming 100% effieciency. I'd be curious what the map readings are when cranking....... lemme go see........ GAWD I LOVE MoTeC

about 98.6 and I live @ sea level. Seans would be much lower. Just being a math geek

Pre-mix is designed to work with internal seals.
I'd question the Idemitsu ratios - maybe for intact OMP's?
Run the usually 100:1 - 150:1 ratios for "normal" driving.
128:1 is perfectly fine.

Also, I wouldn't worry about the compression test numbers.
The more important thing is that they are even.
Numbers will come up.
Different compression gauges will show different numbers.
A sweeping analog needle is something not very accurate in terms of watching for peaks - this is why Mazda used a digital display for their compression tester.


-Ted

Good to know Ted. I will go to 128:1.


As for the comp test: All I do is hold the valve down on the side and observe the pulses. I have heard of some removing the valve to get a more accurate reading. Regardless we will see at 1500 mile OR maybe 2000.

Drove the car up this morning and SINCE I have put the timing back to the factory 5*ATDC my EGT's have gone up some.

My idle is around: Front-1102*F Rear- 1132*F
MY CONCERN is when I am cruising at about 2400rpm @ about 14.6 AFR my front rotor is about 1545-1554*F and my Rear is running very high at 1612-1623*F.....sometimes a 100*F difference.

When my timing was retarded the temps were obvisously lower(850*@ idle and 1350-1400* @ same AFR and 2400rpm).

I have my rear primary injector getting slightly more fuel, lag settings for front pri inj is .03 while rear pri inj is .04. I was advised to run the rear pri inj slighlty richer due to rear rotors being the common one to blow in S4 motors.

Wierd thing is my front seconadary port has a larger runner diameter because the iron was the later s5 port size and BDC ported it like he ported my last 2 irons. He recieved the front iron last due to some shipping mishaps from the orignal iron seller so he had nothing to compare it to since he already sent my other 2 irons to me. You would think it would run leaner and I would have the oppisite EGT problem BUT I know the LIM runners are smaller and would make the difference barely noticable unless the runners were port matched.

This ports size difference between my secondary runners was the REASON I bought my EGT probes because I felt that the daimeter difference(1/8 inch difference on top and bottom of larger port compared to the other ported secondary runner) would still maybe cause some irregular air intake/AFR issues.


I really wish there was some other info out there(beside Ted's) on common EGT ranges for rotaries. I know each engine is different BUT there has to be some common ground....


BTW...Brian, thanks for the advice on the oil temps and DAMN that was some milage in that short time. You had me all down and out on myself. :)

Well drove it back home today and had to adjust my MS of my rear primary injector from .04 to .22 ms
Now my FRONT PRI INJ is set @ .03ms lag and my REAR PRI INJ is set @ .22 ms lag
It made my temps about 20*F apart from eachother on my EGT's.

I wonder if I need to lower my engine timing on the pulley to 0* ATDC since there rotor housings have a different spark plug hole location and my map I am using now was running S4 TII rotor housings and S4 N/A rotors?

Engine just doesn't seem to have as much low end like it did at atmospheric pressure with the retarded timing. :)

man i need to start getting some data logging ability on the MS

I have a Power FC bro. You thinking MS is Mega Squirt? I am talking about milliseconds of injector fire. :)

Good stuff sean!

On the idemitsu pre mix:

Normal ratios for typical TCw-3's are 1oz/gallon. Idemitsu's is 50% less because the "oil is better/designed to operate at that ratio" Thats the summation I got when I asked ID about the reasons behind it.

Its more expensive, but you use less (per gallon) because you need less :)

Depends on the type of oil I guess. I was using QuickSilver Premium Plus 2-cycle and the Idemitsu is actually cheaper as well. Best of both worlds. Then again, the QuickSilver is marine, and anything marine is going to be more $$$$


Nicely done Sean. I had the same issue, about 100* hotter in the rear while underload. I added 2% fuel but haven't been back in to check the results.

ah... nothing like computer mumbo jumbo late at night. its almost as good as coffee in the morning....:)

just wait Kyle.....you will be there soon enough!


Got some tuning done last night and also order one of the FAST ACTING AIT sensors from Dudemannn. Hopefully this new sensor will help in having a more accurate tune. I get a lot of heat saturation when in stop and go and hopefully this keeps things more linear