Riddle me this ...

[LordDigi]

On a 4g63, the crank is machined to allow 2 pistons to move in exact sync 1 4 and 2 3. I disassembled my engine tonight and laid everything out on the workbench, it was time for a refresh on it. Looking over everything I noticed this while examining the head ...



Looks normal? Not to me. Here you see Exhaust Valves 2 and 4 open and Intake Valves 3 open. Not sure why I've never noticed this before, but if the pistons 1 4 and 2 3 are in exact sync why wouldn't the Valves be?! I realize the book says the firing order is 1-3-4-2 but I've switched 1 4 and 2 3 so many times with no affect, that I know they are fired, in pair, at exactly the same time.

What em I missing here? Maybe it's too late and I'm just not thinking strait, but I tune this car off of DSMLink V3 and I've never seen a difference switching the firing order around as long as you keep 1 4 and 2 3 together ...

[bryanwheat]

Originally Posted by LordDigi

On a 4g63, the crank is machined to allow 2 pistons to move in exact sync 1 4 and 2 3. I disassembled my engine tonight and laid everything out on the workbench, it was time for a refresh on it. Looking over everything I noticed this while examining the head ...



Looks normal? Not to me. Here you see Exhaust Valves 2 and 4 open and Intake Valves 3 open. Not sure why I've never noticed this before, but if the pistons 1 4 and 2 3 are in exact sync why wouldn't the Valves be?! I realize the book says the firing order is 1-3-4-2 but I've switched 1 4 and 2 3 so many times with no affect, that I know they are fired, in pair, at exactly the same time.

What em I missing here? Maybe it's too late and I'm just not thinking strait, but I tune this car off of DSMLink V3 and I've never seen a difference switching the firing order around as long as you keep 1 4 and 2 3 together ...

It is because one piston is on the compression stroke while the other is on the exhaust stroke. They don't fire at the same time. They fire every other time. The coils fire at the same time, but not the cylinder. http://www.gill.co.uk/products/digit.../6_4stroke.asp

[LordDigi]

I suppose that makes sense, I never really thought about that, in that aspect ... Thank you for turning that light on for me

Although, the link was unnecessary. I am fully aware on how engine works, I just was unclear on how exactly the firing order worked into the mix.

[Rob10_99]

You could change that with a cam profile like the motoGP bikes, that would be sweet. I wonder what that would sound like with a 4g63....