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the rex is my dd
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Discussion Starter #1
In a last minute consideration, I am seriously contemplating going with a Z6 head rather than my stock rebuilt head on the D16A6. The bottom end is done so my concern is if it will work without problems.
I have 11:1 75.5mm CP pistons with a decked block so I'm afraid the compression ratio will be too high for a reliable daily driver with the Z6 head. Everything I am reading is usually based on high CR stock pistons with the A6/Z6 combination. I have no problem at all running 93 octane fuel which I prefer anyway. If any of you have this setup or something real close I would like to get some impressions of the driveability. I will eventually get a strong tune but this build is taking ALOT more money than I expected and I'm piecing together at this point.

Last thing: Based on a stock Z6/A6 being 9.9:1 and my pistons being 11:1 w/stock head can I safely assume 12:1 compression with a slightly decked block?
 

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based on a a6 running 11:1 my calculations say 11.94 give or take a little

that is with zero shaving of the head and zero decking of the block


I hate dome pistons, they suck
 

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97 honda coupe
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i would suggest staying with your a6 head if you want to keep your compression to managable reliable levels. I ran my z6 with p29 pistons and 13.3:1 compression for over
6 months but since i didnt have a cam or a cam gear i couldnt keep it from detonating because i didnt have a cam and it killed my ring lands in only 6 months of easy driving. it pulled very hard but after 6 months it killed my ring lands.

So, i would suggest staying with the a6 head and getting a cam the first thing you do infact i wouldnt even start the motor without atleast a stage 3 cam.
 

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the rex is my dd
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Discussion Starter #6
Only problem with that is that I can only find 2 companies that even offer regrinds on cams for this head. NO COMPANY makes a NEW cam for this head that I can find. Only hardwelds and they are too expensive. Again we're talking money for a regrind, then new springs/retainers, etc, etc....... I am sure I will be ok for awhile with the stock head until I can put some money together to finish everything off like I WANT it. I think I will stick with the A6 head
 

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Only problem with that is that I can only find 2 companies that even offer regrinds on cams for this head. NO COMPANY makes a NEW cam for this head that I can find. Only hardwelds and they are too expensive. Again we're talking money for a regrind, then new springs/retainers, etc, etc....... I am sure I will be ok for awhile with the stock head until I can put some money together to finish everything off like I WANT it. I think I will stick with the A6 head
Ok now time for pictures.






thats 6 months of easy driving at 13:1 compression TUNED with range 9 plugs 93 octane and stock head/cam. And delta cams located in tacoma washington offers regrinds, exospeed is a good cam as well, i belive it was 240$ last time i checked. If you cant pay then you shouldnt play.
 

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Classic Man
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you want a cam? Colt Cams - custom camshaft grinding

5 year warranty. mind to wild. call up Geoff and tell him what you need.

he ground a cam for my z6 and it breathes like a champ up to 9000rpm.
 

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the rex is my dd
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Discussion Starter #9
Reviving this thread after 5 months and more money spent. I did decide to go with the Z6 head and the higher compression that goes along with it. I found a Z6 head lying in a local shop that amazingly already had a Crower stage 1(63441Z) cam installed. Paid a ridiculously low price(don't even ask). Immediately came home and ordered an OBD0-OBD1 conversion harness, a used VTEC solenoid, and a Phearable socketed P28 ECU. John recommended i upgrade the fuel pump which I was thinking of doing anyway due to age so i threw in a walbro 255 and install kit. Found out on that call that I CANNOT use the A6 distributor so that was a bummer. Dizzy coming soon. I hope, pray, and beg that I can finally get this motor together weekend after next. OH, the local NAPA store has a pretty kickass head guy so I took it to him for a freshening. New seals, regrind the valves, cleaning, etc.

I looked back at cervans posts and realized that those were stock P29 pistons and what looks like stock rods. Of course the ring lands failed after a short time, they were only designed for around 9.5:1 compression. I bought CP forged pistons and Eagle H beams with the best rings you can buy. I may produce failed ring lands also but I was assured that that these pistons, rings, and rods with ARP bolts would take most any compression I throw at it. I also have the ARP head stud kit and Cometic 3 layer headgasket.
 

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Reviving this thread after 5 months and more money spent. I did decide to go with the Z6 head and the higher compression that goes along with it. I found a Z6 head lying in a local shop that amazingly already had a Crower stage 1(63441Z) cam installed. Paid a ridiculously low price(don't even ask). Immediately came home and ordered an OBD0-OBD1 conversion harness, a used VTEC solenoid, and a Phearable socketed P28 ECU. John recommended i upgrade the fuel pump which I was thinking of doing anyway due to age so i threw in a walbro 255 and install kit. Found out on that call that I CANNOT use the A6 distributor so that was a bummer. Dizzy coming soon. I hope, pray, and beg that I can finally get this motor together weekend after next. OH, the local NAPA store has a pretty kickass head guy so I took it to him for a freshening. New seals, regrind the valves, cleaning, etc.

I looked back at cervans posts and realized that those were stock P29 pistons and what looks like stock rods. Of course the ring lands failed after a short time, they were only designed for around 9.5:1 compression. I bought CP forged pistons and Eagle H beams with the best rings you can buy. I may produce failed ring lands also but I was assured that that these pistons, rings, and rods with ARP bolts would take most any compression I throw at it. I also have the ARP head stud kit and Cometic 3 layer headgasket.
Its not the compression your worried about, its the detonation. If your engine could handle 20:1 compression like diesels and not detonate it would probibally last about as long as stock but my main point of showing those pics was to deterr you from using stock pistons if going for a high compression level and how important a good tune and a good cam are.
 

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Discussion Starter #11
I appreciate the warning. I'm going with the 63441Z Crower since it was already in the head and I will more than likely end up doing two chips for the tune. One on 93 octane and one on race gas. I now have come to learn that anything over about 12:1 will actually require DE-tuning to get the timing right so that it does not detonate. I'm not ruling out a meth injection kit but that would come later. That kinda sucks but its the price I pay. This is truly my daily driver so I'm flirting with less reliability running all this compression but I'm chasing an old dream of building an all motor single cammer.
 

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I appreciate the warning. I'm going with the 63441Z Crower since it was already in the head and I will more than likely end up doing two chips for the tune. One on 93 octane and one on race gas. I now have come to learn that anything over about 12:1 will actually require DE-tuning to get the timing right so that it does not detonate. I'm not ruling out a meth injection kit but that would come later. That kinda sucks but its the price I pay. This is truly my daily driver so I'm flirting with less reliability running all this compression but I'm chasing an old dream of building an all motor single cammer.
just remember that your engine is most detonation prone at low rpm's and high loads, like in 5th gear and at 2000 rpm's going half throttle will most definitly make your engine detonate.
 

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Discussion Starter #13
unfortunately it gets extremely hot down here in super south Alabama also which can cause detonation
 

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My last set-up in my A6 was around 11:1 CR and a stg 2 cam. It wasnt tuned but I was running a "chipped" ecu and adjustable fpr. I could hear it pinging under low RPM load if I didnt keep the timing retarded. Tuning is definitly key. I never tried my newer Crane stg 3 cam past 3000rpm and half throttle because I knew what would probably happen. I just decided to tear it all down and start a fresh build. Still haven't gotten around to it...lol
 

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My last set-up in my A6 was around 11:1 CR and a stg 2 cam. It wasnt tuned but I was running a "chipped" ecu and adjustable fpr. I could hear it pinging under low RPM load if I didnt keep the timing retarded. Tuning is definitly key. I never tried my newer Crane stg 3 cam past 3000rpm and half throttle because I knew what would probably happen. I just decided to tear it all down and start a fresh build. Still haven't gotten around to it...lol
if you ever want to sell that crane 16 please let me be the first to know, i bought your 12 and ive been looking for a 16 since i started my build.


to the op the compression ratio for those pistons is normally a calculation with .040 milled off the head, at least i know srp does it this way all there comp ratio's for a a6 are calculated with a .040 head mill so your comp may nor be as high as you think its gonna be if cp does the same thing
 

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Discussion Starter #16
MAN hatchaddict, THAT is some good info to know! I was extremely worried that this new head would come back as already being shaved a little. I will contact CP and see if they account for that also. Last night I was mad at myself for not having the specific specs so I could use the calculator. Speaking of milled heads, do any of you know what the factory height of the Z6 is supposed to be?
 

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Discussion Starter #17
Black91CRXSi I subscribed last week to your thread. Get to work son! hhahhahaha!
 

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Discussion Starter #19
thanks again, I'll let the shop know tomorrow and they will measure it.
 
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