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Exhaust Temperatures


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Guys

 

Messing about in the garage this afternoon, trying to keep out of the sun, and playing with some toys, I happened on my laser thermometer!!

 

Out of sheer interest I took temperatures on the six exhaust header pipes. Equal small distance to each and at similar small distance along the pipe from the head.

 

The two outside were cooler, about 150 deg (no surprise in that). No's 2,4 & 5 similar at around 170 deg but no 3 consistently at around 200 deg.

 

So my question to the cognoscenti is 1) why could that be and 2) is it a problem and how might I address it if it is?

 

As ever, thanks in advance for your thoughts.

 

Regards

 

Tim

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Hi Tim,

the surface colour and texture of the reading surface can affect the readings quite a bit.

Also the cheaper instruments will give varying readings for the same conditions.

 

Ideally a matte black surface would be nice.

 

So, the temps out of each exhaust may be trending as you have noted but not necessarily with the temps you have got.

 

Roger

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Tim

 

It might be worth looking at the colour of the plug in number 3, compared to the others. If it is whiter it will be running leaner and hotter. If yours is injection, it may be worth a check of the injector. On the other hand it could just be how the design of the manifold handles heat dissipation from each cylinder not forgetting that number 3 is towards the centre. May also be just a case of finding some other toy to play with!

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Hi Tim,

 

I'd be surprised if that large a discrepancy is down to operator or instrument error, and the surface texture is likely to be pretty similar between manifold pipes.

 

Lean mixture seems far more likely to me, insufficient fuel injected or perhaps more likely an air leak ?

 

Cheers

 

Alec

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This is an interesting thread !

 

What revs was the engine running at for the test, if idle then perhaps unbalanced throttles or other air leak?

 

steve

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