Analyze burn pattern

[BCjohnny]

.......but that Somender Singh guy must be onto something............

[automotive breath]

…I know you believe most improvements come from a more complete burn but I am thinking that this groove may be directing the intake mixture away from the exhaust port during overlap causing the smoother idle. What do you think?

Beth, I believe the altered fluid flow ATDC does have a positive impact on reversion during overlap accounting for some improvements at idle. I intentionally point the groove between the valves to disrupt reversion.

Beth, Can you give your thoughts on the burn pattern and reversion?

[beth]

My experience with burn patterns has been with comp eliminator engines that are apart every 5 or 6 runs and shut off cleanly at the finish line. Even tho the coloring was seldom removed it was never that thick or that dark.

A bracket motor spends at least 5 minutes at idle and no load acceleration for every 10 seconds of maximum power. I'm not sure you can draw conclusions. Rich idle mixtures and accelerator pumps can wash away the thin grey coating accumulated in one pass. What does the coloring inside of the piston look like above the pin?

Idle and low speed along with different fuel additives can cause strange colors in the intake port. Does it wipe off or is it baked on?

[automotive breath]

What does the coloring inside of the piston look like above the pin?
Idle and low speed along with different fuel additives can cause strange colors in the intake port. Does it wipe off or is it baked on?

Your right, an engine that has run for a year can’t be compare to one that has run for five runs. In addition the specs are very different in particular the compression ratio.

I haven’t pulled the pistons.

Normally I see a wet dark intake port on a bracket engine with plenty of overlap. Now I see a very light dry dusty white carbon in the intake port. This is consistant regardless of the fuel in use.