I was wondering if anyone has logged or reviewed individual egt temps at idle on a large lopey streetport engine. I have noticed a 150 deg difference at idle, and am not sure if its the porting causing it or the injectors at low openings causing imbalance fuel injection. Thoughts?

 

This is right after the engine warmed up (in the driveway) but before driving. There's about 80 F between front and rear rotor. No A/C or electrical loads on the car. Ignition timing is the basic -5 -20 but with Power FC closed loop idle control to smooth the vaccum reading. Vacuum is about 11.5-12" at this idle speed.

 

I have one where I was experimenting with negative split for low speeds. I am amazed at how smooth it is.
Barry

 

^ uh dude, those "smooth" parts are dead spots in your logs. Notice are the lines are basically flat in certain areas? If you pull open the log with Excel and look at the time signature you'll see what I mean.

I think your test is inconclusive at best. I don't see much of a difference in the basic shape of your yellow and pinkish lines there.

 

arghx,

Not quite right. The straight parts are where the new map is being loaded by the PFC while the engine continues to run, the second short spot is where I pushed UPDATE.

Notice when I loaded the negsplit the pulses slowly move together and get smoother........, then I put the old map back in.

Barry

 

How lopey (is that even a word) is the idle and how large are the ports? Mine definitely sounds almost like a bridge.

 

I guess what I'm trying to get at is that maybe the lopey running at idle is from small differences in ports and maybe not in the injector differences at low openings. Overlap I'm pretty sure has something to do with it as well.

 

There are things that you can do to make it lopey if that is what you want. Too rich a mixture and wrong timing come to mind.

But if you are addressing the inherent problems of the Rotary I think that overlap from our porting “improvements” is a big problem. Exhaust reversion being the biggest.

 

I don't believe the AFR's and timing are the issue on my setup. I think its got to be low injector opening inbalance, or something to do with overlap/porting.

My question would be does that create the differential in EGTs? I would like to see if anyone with a bridgy has dual egt's that could comment about idle.

 

Fritts, my non-bridge ported RE switches from the rear rotor being higher at idle/low speeds to front being higher temp in boost.

Also the injector harness could be reversed depending on how many rewirings you may have done.

Barry

 

I'll have to check that when I get home.... Good thought. As RPM goes up the timing of the injection becomes less import.