93egSIboi

ok, i did a search on d16a1 pistons compression ratio in a d16z6 and didn't find any solid answer. Some people said it bumped the cr up to 11.5, some say aroud 12 and some say as high as 13.5. Is there anyone that can give me a solid answer?

civictildeath

it will be 13.6:1 compression ratio

_RevHardD15

is that safe?

civictildeath

i dont know if the valve are gonna smack the pistons but if they clear then he better get one hell of a good head gasket and no plans to do forced induction

unknown0001

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civictildeath &raquo;</TD></TR><TR><TD CLASS="quote">i dont know if the valve are gonna smack the pistons but if they clear then he better get one hell of a good head gasket and no plans to do forced induction</TD></TR></TABLE>

Agreed

93egSIboi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civictildeath &raquo;</TD></TR><TR><TD CLASS="quote">it will be 13.6:1 compression ratio</TD></TR></TABLE>\
thats too much to be street driven, correct? hmm, what about the earlier model pistons from an 86-87 teg combined with a 2-layer head gasket? That should be around 12:1 compression, correct? With 12:1 cr I could still drive without problems on 92 octane?

civictildeath

with the pg6b pistons (86-87 teg) it will be 11.3 i would use OEM headgasket

93egSIboi

i got 11.6:1, http://www.knology.net/~jediklc/D.htm, just wondering if i did something wrong or not.

MrTodd

Everybody here is wrong - the compression ratio with P29/ZC (d16a1) pistons in a full Z6 engine is 12.03:1, using the stock Z6 headgasket.

Remember that although the P29 pistons have a nice peak, the piston to deck height is 0.040" below the deck. Also, the P29's have been proven to have no valve clearance issues in 12.5:1 compression motors with various aftermarket camshafts. All in all, the P29 is the best OEM piston upgrade for any D-series engine.

93egSIboi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrTodd &raquo;</TD></TR><TR><TD CLASS="quote">Everybody here is wrong - the compression ratio with P29/ZC (d16a1) pistons in a full Z6 engine is 12.03:1, using the stock Z6 headgasket.

Remember that although the P29 pistons have a nice peak, the piston to deck height is 0.040" below the deck. </TD></TR></TABLE>

thats what i thought. with the 12.03:1 cr would i still be able to drive it daily using 92 octane and no pinging?

civictildeath

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrTodd &raquo;</TD></TR><TR><TD CLASS="quote">Remember that although the P29 pistons have a nice peak, the piston to deck height is 0.040" below the deck. </TD></TR></TABLE>

ok i did not know that he is right

the pg6b pistons give a 10.5 cr

MrTodd

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93egSIboi &raquo;</TD></TR><TR><TD CLASS="quote">

thats what i thought. with the 12.03:1 cr would i still be able to drive it daily using 92 octane and no pinging?</TD></TR></TABLE>

Yup, street driven D-series engines have been successful with compression ratios up to 12.5:1 with no pinging/knocking issues. Anything higher than that can still be street driven, but you'll need to modify the ECU fuel and ignition maps more aggressively than what a V-AFC can do.

You're on the right track, P29s in a Z6 are a mean combo - the results are definitely worthwile.

We had a huge discussion on this exact topic on the CRX thread a while back. I'll post the link when/if I find it...

civictildeath

whats the bore size in a d16a1?? would the p29 work in a d16y8?? sorry to steal thread

MrTodd

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civictildeath &raquo;</TD></TR><TR><TD CLASS="quote">whats the bore size in a d16a1?? would the p29 work in a d16y8?? sorry to steal thread</TD></TR></TABLE>

Yes, all D16 engines (and d15s for that matter) have the same bore size of 75mm, it's the stroke that varies. P29s work great in a full Y8 engine, but you'll need a thicker than stock headgasket to keep the CR down to a managable rate. The Y8 head has flush quench pads with the deck, making the CR much higher than what a Z6 head would reveal. To be exact, the Y8 with P29s would have at least a 12.6:1 compression ratio. You can get everything to work with that, but it's not gonna be easy.

civictildeath

well the knology site says that a 0.053 thick head gasket would give a 12.5 is that ok for daily driver?? need to change rods or anything else?? i do drive mine like i am racing all the time

MrTodd

A .053 headgasket will bring you down to a 12:1 compression ratio. It'll work for daily driving.

Yes the stock rods are all you need for any N/A application. If you want to do it the right way, do a full rebuild, stress relieve the rods and balance the crank for 8000+ rpms. Rebuild the head with new springs, retainers and a nicer camshaft (Crower Stage 2 has been proven with good results) along with a good valvejob. With that combo, your engine will actually pull like a racecar engine.

93egSIboi

thx for the info thus far . one more question though, im planning on putting a better cam in at the same time i change pistons, do you think the zex quicktime street/strip cam would like the higher compression or do you think i would need to go with something else?

MrTodd

Hey it's no problem, I'm glad that I can actually help in some performance theory. The ZEX cam is an upgrade over the stock Z6 and Y8 camshaft, but after the dyno graphs that I've seen, it doesn't seem like it's worth the money. Personally, I'd invest in the Crower Stage 2.

BTW: If you really want to learn something, read this ENTIRE thread that was originally posted quite a few months ago in the CRX/EF Civic forum. I was planning a nice D-series build back then, but I never got through it because I sold my CRX. I'm always going to regret never finishing the build. Anyway, here's the link: https://honda-tech.com/zero...age=1

93egSIboi

great info . looks like on my way for my d-series buildup. plan is thus far:

p29 pistons
d16y8 intake manifold
upgraded t/b ls or gsr (not sure)
crower stage 2 cam
crower springs and retainers
adjustable cam gear
v-afc
fpr
dc header
short ram or cai
tanabe srm exhaust
high flow cat
and dyno time

let me know what you think of the setup

sleepyEK

that sounds similar to my buildup, although i'm starting with the y7 block, using a pnp'd y8 head w/crower stage 2 cam and valvesprings, and using individual throttle bodies w/ITG filter, 290cc injectors, and straight through 2 1/4" exhaust. oh, can't forget the 4.7:1 final drive in the y4f/k4f tranny.

sheissrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrTodd &raquo;</TD></TR><TR><TD CLASS="quote">A .053 headgasket will bring you down to a 12:1 compression ratio. It'll work for daily driving.

Yes the stock rods are all you need for any N/A application. If you want to do it the right way, do a full rebuild, stress relieve the rods and balance the crank for 8000+ rpms. Rebuild the head with new springs, retainers and a nicer camshaft (Crower Stage 2 has been proven with good results) along with a good valvejob. With that combo, your engine will actually pull like a racecar engine.</TD></TR></TABLE>

But do the p29 pistons weigh the exact same as the y7(don't know the "p" code) pistons? If they aren't exactly the same weight, then the crankshaft will have to have weight added, or taken off. Would you happen to know for a fact? thanks.