Lean Rotary

R

rlekun

New member
I noticed some earlier threads relating 12A overheating and a lean condition. Seems like many of us rotor heads are finding hotter than normal running conditions this year. Now for a wild hypothesis: Could this be attributed to our fuel acquisition ports restricting fuel volume? I changed to the carter fuel pump before this season and of course put an in line fuel acquisition set-up in. Pressure gauge looks fine under all RPMs. But of course I have no way of knowing if I'm delivering enough fuel volume. I'm no expert mechanic, so I'm I all wet?

I just had a new motor put in and upgraded to a new radiator...so I want to make sure I've closed off any other threats...
 
If I were having heating/overheating issues & had just put in a NEW motor & raditor I beleive I would also put in EGT gauges. Immediate response for motor temps long before water or oil temps develop.

When racing Karts some people have head temps from a pickup at the spark plug, others have EGT gauges. EGT's report critical temps before you stick a piston in Kart motor turning 16,000 RPM's. (melt the pistion alum over the ring).

Have Fun

David
 
Good point. It is my understanding that we rotary guys are in need of specific EGT guages....

Any input from the rotormeisters out there as tothe right guage, installation location of the pickup and the expected readings? (for the 12A)

Thanks in advance!

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Jake Gulick
ITA 57 RX-7
Northeast Region
[email protected]
 
I use a 2000 degree scale guage from http://www.westach.com/. It is a double guage. Since a rotary will run about 1650-1750 degrees F it is the only guage I have found that will go high enough. I was amazed when the first time I ran the car with the 2000 degree guage it pegged. Can you say "way lean". I still think I'm running a little lean on one rotor but with the dual guage you can, in theory, tune each rotor.

Drive well
 
Interesting that everybody is running hot this year, I've noticed that too.

I have a A/F meter/O2 sensor setup that says I've been running OK (not lean).

Festus (or anybody)- do you have any experience regarding whether A/F gages are incorrect vs. EGT.
 
kart type with readable red digits are Digtron Dual readout EGT meters $300, but im having trouble finding their website
 
RacinRich,

Have never used a A/F gauge. Have thought about it but never have. The temp gauge seems to work fine. For a factory authorized rebuild that is getting close to 6 years old the engine is pretty strong from what my competitors say. Now all I have to do is fix the front end damage that resulted from a shunt at about 110 mph. Tire wall worked real well.

Hey, I spelled "gauge" correctly this time.

Drive well.
 
IMO EGT gauges are more accurate than the common, inexpensive narrow band A/F gauges. As far as the thermocouples ability to take the heat, I read an article in Powerstroke Registry on EGT gauges a while back and it said all theromcouples used for an automotive type application would be the same type (K if I remember right). They tested a bunch of different brands and basically all the variables (response time, accuracy) were in the gauges and not the thermocouple itself. So find a gauge that reads what you need it to read and don't worry about melting the thermocouple.

Chris

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Chris Ludwig
08 ITS RX7 CenDiv
 
I seem to remember Dave Lemon at Mazdatrix saying something about using an EGT to tune engines with, and that it was more accurate than the average narrow band A/F gauge. I bought one of the wide band kits from a supplier in Australia and will build and install it this winter.

At the Ft. Wayne regional, I was looking at 220 - 230 water and 260 - 270 oil. I am going to take the sensors out and check them in a pan of boiling water with the pyrometer.

Chris - Are you coming up for the race in September? I plan to do some additional ducting in the front of the car. Have to get the temps down.

db
 
Hey Dave! Yeah, I'll be there. Have you gotten a second oil cooler in? I think I finally got my temps under control. Come over and take a look at my new setup. Might give you some ideas. I just hope my motor that's buring a quart of oil each session makes it two more weekends!
biggrin.gif
Were you up there last race weekend? I was there helping with an ITB car and it seems like I saw you drive by. Went to look for ya and couldn't find ya.

Chris

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Chris Ludwig
08 ITS RX7 CenDiv
 
I thought my street port was running lean until we put it on the dyno, and got great results on air/fuel. Paul Yaw has at least one article on his website about tuning with an EGT gauge, as well as some other suggestions.
 
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