Ok guys, I've heard a few people doing this. I'm very intrigued by this, becuz the a1 pistons with the y8 combustion chambers makes around 12.8:1 compression, which, when built in with a nice fat cam, could put a crx into the high 13 second range with good driving. But...

Is this a reliable daily drivable set up? Yes, I know that 13:1 compression is a beast. What are ways to keep this tuned so that it won't melt the OEM d16a1 cast pistons with detonation? Anyone have tips or advice on building this type of sohc hybrid? All suggestions welcome!!

 

If you are worried about the high compression, use the d16z6 head instead of the d16y8 head. The compression with the z6 head is about .5:1 less than the y8 head. Also, I work alot with Honda CBR engines and we have run a motorcycle engine with a compression ratio of 13:1 with carbs using 93 octane pump gas and had no problems.

 

What's a D16A1? Is that the civic Si engine?

 

D16A1 is a first generation integra motor. 1.6 DOHC.

 

88-89 Integra motor? How do these yield higher compression, and would they fit the D16Z6? Thanks and sorry for the OT.

 

It is actually 86-89 integra. They are domed pistons which is how they yield higher compression. My understanding is that to put them in a D16A6 you have to bore the block. So I would imagine that it would be the same kind of deal for the Z6.

 

Bore the block huh? Well thanks for the info. I'll definitely start doing some research on that.

 

im currently running d16a1 pistons in my d16z6 longblock. you do not have to overbore the block. i did this swap in my driveway with the engine still in the car. the piston bore matches the block. you need to have a machine shop bridge the valve pockets on either side of the piston so that the vtec valves dont hit the piston top. the valves on the vtec head have diff spacing than the ones on the non-vtec heads. im running about 270 compression across the board. oh btw im using a y8 headgasket - the thinnest sohc headgasket for hondas. i dont know what that computes to in a c/r ... but honestly my car runs FINE on 87 octane. i run it on 87 octane all the time. its been runnin well like that since the summer. i jus went on a 280 mile trip to pick up a b20z2 and i got about 34-35 mpg on a PG7 (88-89) teg ecu. runnin rich. bla. oh well.

 

Have you ran it yet to see how fast you are?

 

what do you mean *bridge* the piston tops? That's really good advice, I've not heard that before. But yea, I now have heard of several people running this 12.5 to 13:1 compression engine setup with no detonation on pump gas. crazy :D

 

bridge or flycut the valve reliefs. They are in the wrong spot to use the A1 pistons under a VTEC head. Failure to do so will = 16 bent valves.

 

i never ran it, actually. it felt really good tho. torquier than my friend's mini-me (d16z6 head on d15b7 block - all stock components). felt much stronger.

 

would they fit in a y8 block

 

This will help you figure out what combination of parts will give you what compression.

http://www.c-speedracing.com/howto/c...c/compcalc.php

Remember, if you end up with some combo that gives you a very high CR you will need some way of tuning the motor. A chipped ECU or at least VAFC.

 

im putting a d16z6 head on a zc block, can i get away with running a thicker head gasket rather than modifing the pistons and by switching heads will i gain or lose horsepower. im doing this to mainly be able to boost the motor.