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Really a question to the guys who have fitted up engine management systems to their CPTR6's

I am keen to try and reset my metering unit with the aid of my Innovate CO meter and lambda sensor in the exhaust.

I know some types of engines have quite a different optimal AFR ratio and run better at, and wondered what sort of figure you have been able to obtain with the TR engine, with perhaps the PI cam?

I know it has to be a bit on the rich side with a MU, but perhaps that is taken care with the ECU when you go to a full engine management system?

So I'm really looking for a good AFR ration that shouldn't cause too much problems running with a CP cam, like burning valves perhaps.

At present I'm getting about 13.4 AFR and dipping a bit into the high 12's AFR, and wondered if I can get it a little bit higher without causing too many other problems.  Any thoughts would be interesting please.

John

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John,

I played around some years ago with an AFR meter and the MU on my TR6.  The numbers you have are not too bad.  The trouble is if you mean out much more you'll get bogging caused by a transient lean spike during snap throttle opening. I tuned until this happened and then richened the mixture a tad until no hesitation was felt and left it at that.  Even then it was leaner than the standard setting.  

Tim

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As long as all cylinders get same AFR you do not need to worry about burned valves.

Before that our engine does not run nicely any more.

As long as you are not Scottish or German Schwäbisch you will recognice it as

really bad running and dislike that. The engine becomes lazy.

 

So under full load you should expect arounf AFR 12.5 - 12.7 for high performance and not burning valves

at part throttle you may go leaner but that will not work easily because the MU has no accell fuel.

Engine will go a bit lean whenever you push the pedal and that must still be a little bit richer than burning limit

of the fuel what is around AFR15.5.

Your personal taste  is how much you are willing to suffer when accelerating. The hickup is not nice.

 

When engine accelerates just from closed throttle the sync of the throttle plates indicates how lean you can go.

Good spindle bearings and nice lincage will allowe you around 13.5.

I would not go lean in that area although just from what the engine needs that would be okay.

It is simply not a nice feeling to drive.

 

So at part throttle AFR 14.7 and at full load 12.7 would be the perfect figures but the PI system limits that

a little bit and you will have to make compromises to meet your individual taste.

 

As long as you do not go lean under load you will not kill an engine.

 

Missing cylinders at any state  of manifold depression is an alarm signal and must be cured.

 

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