My car does backfire about every 10th run @ WOT. Is it possible that the gap
from the spark plugs is too much?

swissturbo

 

What's your setup and plug gap?

 

gap is about 0.85 mm.
drag3 ,stock internals, compression 8.5-1(with gasket),msd 6a,5th injector from porsche turbo with the MF2 controlled,t3/t4.im bosting 12 psi.
the curious is that it only every 10 th fullboost run happend.

swissturbo

 

you can try a .030" gap, which is between .75mm and .8mm, see if that helps

 

o.k thanx i will try this
but why is a smaller gap better for ignition?
do you guys all lower the original gap of the plug ?

swissturbo

 

Smaller-than-stock gap is better for boost, since larger gaps may tend to blow out(the boost pressure extinguishes the spark before it ignites the mixture) under boost.