As some of you may know MBT (mean best torque) is produce at 15 degrees after top dead center, so my question is: in order to achieve MBT where should the spark start at idle? How many degrees after or before TDC? I hope i'm making my self clear. Thanks.

 

Unless I'm mistaken... MBT is dependant on cylinder size, fuel mixture, piston speed, spark plug location, and a few hundred other things.
putting a certain 15* value on it requires more of an explination than what you have given.

 

Ok, stock B series and like I said IDLE, I think that tells you about piston speed. Thanks.

 

honda uses 16* for a reason.

BTW, it's before top dead center.

 

Thank you.

 

did that answer your question, sorry I'm not trying to be an a-hole with the comments above.
Simply confused by your question.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h_turbo &raquo;</TD></TR><TR><TD CLASS="quote">As some of you may know MBT (mean best torque) is produce at 15 degrees after top dead center, so my question is: in order to achieve MBT where should the spark start at idle? How many degrees after or before TDC? I hope i'm making my self clear. Thanks.</TD></TR></TABLE>

I think you mean MBT is achieved when peak cylinder pressure occurs 15 degrees ATDC and you are asking how advanced the spark needs to be to achieve this at idle. ????

Why do you care what it is at idle? Do you drive your car there? The timing required to achieve MBT is going to be different depending on engine and it's design factors.

 

Yes, that answered my question.

 

Ok, did I said I'm driving my car at idle?? Of course not!!! My question is already answered.