What is the difference between a Si and DX head besides the cam? I'm doing a mpfi swap on my DX now, and I need a new timing belt soon, so I thought I'd change out the DX cam for an Si one while everything is apart. But do I need the Si head too, or can I just swap in the cam? TIA

 

just swap the cam, I know of no other difference...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Outsane &raquo;</TD></TR><TR><TD CLASS="quote">just swap the cam, I know of no other difference...

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

sounds right, do you need to change the cam gear too or are they the same?

 

Differences -
Cam
Better Casting from factory, i.e. flows a smidgen better stock
.....
...
That's it.

The cam gears are the same.

 

cam gears the same in function...
I think the SI may have different marks on it.. but not positive

 

they is no differents. i swap my dx head for a si and it works fine

 

pm9 vs pm3 head casting. the 1.5's have flat top pistons, the 1.6's have dish pistons, but yet they have the same compression. that tells me the 1.6 head has a slightly smaller combustion chamber volume, that is unless of course the piston to deck height is different, but im almost certain they both are at 0

 

according to my '89 brochure, hf and dx have 9.2:1 while si has 9.1:1. just swap over the camshaft, though.

 

Just torque down the head bolts another revolution and gain higher compression!..


(I hope you know I am joking)

 

i belive the valve springs are a little stiffer from what i heard

 

Deck height is different on the si. I think the heads are the same.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekoms31 &raquo;</TD></TR><TR><TD CLASS="quote">they is no differents. i swap my dx head for a si and it works fine</TD></TR></TABLE>

We have a winner.<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91civicDXdude &raquo;</TD></TR><TR><TD CLASS="quote">pm9 vs pm3 head casting. the 1.5's have flat top pistons, the 1.6's have dish pistons, but yet they have the same compression. that tells me the 1.6 head has a slightly smaller combustion chamber volume, that is unless of course the piston to deck height is different, but im almost certain they both are at 0</TD></TR></TABLE>

The piston to deck height maybe different, remember, the rods are a different length and the wrist pin location is changed.<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bagpipe goatee &raquo;</TD></TR><TR><TD CLASS="quote">according to my '89 brochure, hf and dx have 9.2:1 while si has 9.1:1. just swap over the camshaft, though.</TD></TR></TABLE> <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Outsane &raquo;</TD></TR><TR><TD CLASS="quote">Just torque down the head bolts another revolution and gain higher compression!..


(I hope you know I am joking)</TD></TR></TABLE> I did that ten times, I run with mad compression now <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Civic138 &raquo;</TD></TR><TR><TD CLASS="quote">i belive the valve springs are a little stiffer from what i heard</TD></TR></TABLE> The valve springs became the same part number after 1995, so they now have equal stiffness if you purchase them new from the dealer.

 

How much HP will be gained by swapping in the Si cam?

 

droppoin knowledge on fools!..

nice work

 

i was waiting for someone to clear up that the heads are the exact same thing. swap the cam and be done

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crex23 &raquo;</TD></TR><TR><TD CLASS="quote">How much HP will be gained by swapping in the Si cam?</TD></TR></TABLE>
20 horses to the wheels.

 

Ok, There's no differences between a Si or Dx C/H. The C/H CC's, Intake & Exhaust Valve Diameter are the same. Basically the D16A6, D15B1, D15B2 and D15B7 shares the same C/H. The reason why Dx & Hf has 9.2:1 C/R it's cause' either both has thinner head gasket or the pistons are a little bit domed than the Si. There's no way that you could gained 20 hp with a simple camshaft swap. Need more than that... You could used the same cam gear. If you want to raised the c/r just a little bit, used a 92-95 Civic Si C/H gasket & take a layer off.
It`s the same thing with D16Y5 & D16Y8 C/H and D16Y7 & D16Z6 C/H.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Magic Wheels &raquo;</TD></TR><TR><TD CLASS="quote">Ok, There's no differences between a Si or Dx C/H. The C/H CC's, Intake & Exhaust Valve Diameter are the same. Basically the D16A6, D15B1, D15B2 and D15B7 shares the same C/H. The reason why Dx & Hf has 9.2:1 C/R it's cause' either both has thinner head gasket or the pistons are a little bit domed than the Si. There's no way that you could gained 20 hp with a simple camshaft swap. Need more than that... You could used the same cam gear. If you want to raised the c/r just a little bit, used a 92-95 Civic Si C/H gasket & take a layer off.
It`s the same thing with D16Y5 & D16Y8 C/H and D16Y7 & D16Z6 C/H.</TD></TR></TABLE>

there is some difference in the d15 and d16a6 heads or else they would use the same casting.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91civicDXdude &raquo;</TD></TR><TR><TD CLASS="quote">
there is some difference in the d15 and d16a6 heads or else they would use the same casting.</TD></TR></TABLE>

Believe or not... I checked 3 C/H that i have. One of them from a 89 Civic Si & the other from a 90 Civic Si that i pulled out my self, the 3rd one it's from a 1.5 engine, and all of them are PM3. The question is: Why Honda put PM3 & PM9 C/H in D16 & D15 engines? A mean, from factory... Wierd...


Modified by Magic Wheels at 12:22 AM 5/14/2005