This question has to do with building a motor for a turbo application.

Assume, 84mm sleeved B18C1 motor with B16A head, do you turbo guys open up the combustion chambers on the head to match the bore size?

When using OTS pistons, on the manufacturer website you can find the compression the piston provides with a B16A head.
Opening up the chambers will make the compression lower.

Another question I'm interested in is how do you determine what is the perfect compression for your turbo motors? How does it influence turbo spool?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tommy69 &raquo;</TD></TR><TR><TD CLASS="quote">This question has to do with building a motor for a turbo application.

Assume, 84mm sleeved B18C1 motor with B16A head, do you turbo guys open up the combustion chambers on the head to match the bore size?</TD></TR></TABLE>

I would like to know as well.

I wouldn't even think of doing it without increasing the valve sizes as well, but IDK if it's worth the trouble or not.

Hoping someone will chime in

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tommy69 &raquo;</TD></TR><TR><TD CLASS="quote">This question has to do with building a motor for a turbo application.

Assume, 84mm sleeved B18C1 motor with B16A head, do you turbo guys open up the combustion chambers on the head to match the bore size?

</TD></TR></TABLE>


Keep in mind that the difference is only 1.5mm, or about the width of a pencil tip. Usually people don't mess around with matching the head but I think it still creates a hotspot. I searched around on this issue before and received no real info so I just stayed stock bore

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Another question I'm interested in is how do you determine what is the perfect compression for your turbo motors? How does it influence turbo spool?</TD></TR></TABLE>

Do a search. There are about a dozen lenghty threads where people argue both ways. I would just do what is most common - around 9:1.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EnzoSpeed &raquo;</TD></TR><TR><TD CLASS="quote">Keep in mind that the difference is only 1.5mm, or about the width of a pencil tip. Usually people don't mess around with matching the head but I think it still creates a hotspot. I searched around on this issue before and received no real info so I just stayed stock bore .</TD></TR></TABLE>

Go big or go home

Seems like detonation is a bigger issue when going high compression allmotor, I will try to search around.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EnzoSpeed &raquo;</TD></TR><TR><TD CLASS="quote">Keep in mind that the difference is only 1.5mm</TD></TR></TABLE>

Where did you get 1.5mm from? Hes running 84mm bore and a B16 head which is 81mm.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">Where did you get 1.5mm from? Hes running 84mm bore and a B16 head which is 81mm. </TD></TR></TABLE>

Yup, 3mm diff. It will create nice little ring.

 

3mm = diameter
1.5mm = radius

C'mon guys, remember 9th grade geometry?

The difference will only be 1.5mm.

 

I didn't, and mine worked fine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Quagmire &raquo;</TD></TR><TR><TD CLASS="quote">The difference will only be 1.5mm.</TD></TR></TABLE>

DOH, you're right!

I guess I won't bother, thanks for everyones help.