i drive a 95 dx hatchback, Looking for 11.3:1 to 11.5:1 CR....92/93 octane is pretty hard to find in my area, so I am going to build a 91 octane z6, What mods will raise, lower, or not affect my cr?

thanks, im a cr noob.

 

im totally lost

 

I'd say your best bet is to get some form of programmable stock-ECU based engine management such as Uberdata or Crome and have it TUNED on the 91 octane gas.

My D16A6 is 11:1CR and it will detonate some even with 93 octane gas in the summer unless I retard the timing a tad at the distributor. My dumbass sister borrowed my car once and put 1/4 tank of regular unleaded and it spark knocked so badly I thought it was going to bust a piston ring land.

My SOHC car is untuned on a 1989 Integra ECU, so what I'm saying is with anything over 11:1CR on less than 93 octane you NEED tuning!

 

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To answer this question.

Pistons are the biggest thing that raise or lower your CR. Also milling the head and block will bump it up a bit.

For raising the compression in a d16z6 you are going to want the SOHC ZC pistons I think. I'm not sure though, you should be able to figure it out by searching.

Good luck. I thought about putting some higher compression pistons in my d16z6 while I was building it... but I chickened out and replaced the pistons with stock compression replacements. I went through two years of expensive gas with my turbo setup and I was ready to drop back down to lower octane gas.

 

Oh damn I totally missed his question about what mods affect compression.

If you want a nice N/A D16Z6 try adding some 1986-1987 Integra pistons and a 1996-2000 Civic EX metal head gasket. Others may say "you can get the 92-95 Civic EX/Si head gasket because it's metal" and that's true too, but the one I'm suggesting is exactly the same, but costs a lot less.

With those mods right there you will be in the 11.5:1CR range - trust me it will pull like a bastard!

Before you think "how the hell do Integra pistons even fit into a D16Z6?" you must first understand that the 1986-1989 Integra had a D-Series engine in it, the D16A1 DOHC non-VTEC engine that is very similiar to the JDM DOHC ZC engine.

The pistons in the D16A1 engine are 100% identical in bore size, wrist pin location, - in other words they fit exactly the same. The key difference is that the dome on top is taller on the D16A1 piston than it is on the D16Z6 piston, in fact the D16Z6 piston is dished.

There are two different types of D16A1 pistons - 86-87 which are what we call "flat top" due to their very slight 1.3cc dome, and then there's the huge-*** domed 88-89 pistons with a +7.2cc dome. You won't want the 88-89 pistons due to your gasoline requirements, and besides they bump the Z6 well up over 12:1CR.

If you are planning to do this for sure then you'll also need to understand that you'll need a lot of other parts to build the engine the right way. A quick list would include:

Pistons with rings and wrist pins
Head gasket
Intake manifold gasket
Timing belt
Waterpump
Cam seal
Crank seal
Rear main seal
Valvecover gasket with spark plug tube seals
Thermostat and gasket
Valvestem seals
Head dowel pins

Those are the essentials, there are more parts such as exhaust manifold gasket, spark plugs, plug wires, distributor cap, rotor button, etc. etc.

It's a lot of work, but it can be rewarding.

 

goodluck on the project. let us know how it goes