I remember reading somewhere that if I put a VX head on a different bottom end (eg LX) that I would get high compression. Did I remember that right? I ask because I want a VX engine and I know where I can piece together the head, LAF and computer, but I don't want to run into compression issues if I put that setup on my LX short block. My car is a 92, not sure what year the head is but its definitely a d15z1 head.

 

your compression would be in the high 12:1 range.
the Z1 head also flows like a partially clogged drain pipe. (designed to aid mpg not power)
it's also not really portable, the coolant passages run very close to the ports to aid in cooling the extra hot conditions created by the lean burn mode.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 &raquo;</TD></TR><TR><TD CLASS="quote">the Z1 head also flows like a partially clogged drain pipe. (designed to aid mpg not power)</TD></TR></TABLE>

I'm assuming that, like MANY people out there, this guy is looking for better mileage in these days of near $4/gallon gas. But yes, using this head on, say, a D15B7 bottom end without also using D15Z1 pistons is going to result in some seriously high compression. My advice would be to be to just do a full D15Z1 swap. This would be a MUCH cheaper way to go than having to deal with compression issues. In fact, you could probably get an engine for a similar price to what you would pay for the head, manifold, etc. Plenty of people out there ditch these engines when swapping, although be prepared to look a little for one. Also, you want to use the CX or VX transmission for best mileage.

 

Yea, thats what I'm looking for is MPG.

Is it just the pistons that are giving it that much compression in this scenario, or is that dependant on stroke also. I ask because I would like to freshen up the bottom end of whatever I get anyway, and found a rebuild kit that includes new pistons for a d15z1. I was thinking that if the crank, block and rods are the same then I could get that rebulid kit and put those pistons on my LX bottom end, combined with the rest of the parts there I would have a fresh v-tec e.. this also depending on the bore being the same. Am I flawed here?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fogged306 &raquo;</TD></TR><TR><TD CLASS="quote">Is it just the pistons that are giving it that much compression in this scenario, or is that dependant on stroke also</TD></TR></TABLE>

Neither, it is the ridiciliously tiny combustion chamber on the d15z1 head that makes it have a high compression with d15b7 flat pistons.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fogged306 &raquo;</TD></TR><TR><TD CLASS="quote">I ask because I would like to freshen up the bottom end of whatever I get anyway, and found a rebuild kit that includes new pistons for a d15z1. I was thinking that if the crank, block and rods are the same then I could get that rebulid kit and put those pistons on my LX bottom end, combined with the rest of the parts there I would have a fresh v-tec e.. this also depending on the bore being the same. Am I flawed here?</TD></TR></TABLE>

The rods in the d15z1 are unique to the vx engine, they are 137mm in length.

bore on all d-series is 75mm.

if you were to get vx rods + pistons + vx head, this would work though if you were using any d15 block whether it's d15b1/d15b2/d15b7/d15b8/jdm p08 d15b (same bare block as d15z1)

 

Just the answers I was looking for, thanks guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bense &raquo;</TD></TR><TR><TD CLASS="quote">if you were to get vx rods + pistons + vx head, this would work though if you were using any d15 block whether it's d15b1/d15b2/d15b7/d15b8/jdm p08 d15b (same bare block as d15z1)</TD></TR></TABLE>

The fact that the VX (and JDM D15B) uses longer rods than, say, the D15B7, suggests that the VX and D15B both have taller blocks than the D15B7. This would also suggest that VX rods are too long for a d15B7 block.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">

The fact that the VX (and JDM D15B) uses longer rods than, say, the D15B7, suggests that the VX and D15B both have taller blocks than the D15B7. This would also suggest that VX rods are too long for a d15B7 block.</TD></TR></TABLE>

no, because the compession height is 27.75mm on the d15z1 and p08 d15b piston

what's the difference between 137 and 134? 3

what's 27.75 + 3?

what's the height of a d15b7 piston?

http://www.knology.net/~jediklc/dcalc.htm

 

In case someone trys to argue about the 30.70mm compression height of the d15b7

remember that the d15b7 piston sits 0.020" in the hole.


0.020" = 0.508mm

ha, d15z1/d15b (p08) deck height is still the same 207.45

http://www.knology.net/~jediklc/dcalc.htm