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'91 CRX Hf
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Discussion Starter #1
I have searched and have read tons of threads about Y7 and A6 heads but have found little real data (no flowbench head flow numbers or dyno tests).

I am building a mild n/a d16a6 and would like to be in the 120-130whp range. I have considered using a Y7 head (that I have on hand). The Y7 head offers slightly larger valves, a compression boost, and improved combustion chamber.

As I see it, the stock d16y7 made similar hp/tq numbers to the d16a6, while being hampered by lousy intake and exhaust manifolds, a very modest cam and weak valvesprings. An A6 shortblock, Y7 head (port matched to Z6 IM), Z6intake, Delta reground cam, Y8 valvesprings, and an aftermarket header should make a decent little non-vtec street mill.

Any thoughts/experience/data?
 

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i say build what you got

the stock a6/b2/b7 head outflows a stock y7 but you wont be losing much and you already have the y7 head. focus on a good valve job and maybe just some very light port work in the bowls...deshrouding and backcut the valves. mill for a decent compression jump then follow the rest of your plans and your goals should be met with a solid tune.

+1 for nonvtec ;)
 

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Pew Pew!
EJ6
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If you want to stay none vtec and yet want a better flowing head...Have you thought about using a z6 head with y7 valve train?

Im in the works of doing that myself ;)
 

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^^^^i know its been done before but thats a good idea sammo, id love to see a detailed, quality nonvtec build like that

personally i think the y7 head kind of gets shelled on here a little bit...
its got nice straight port passages and with some very light clean work and deshrouding it can flow a good amount of air. that and its combustion chamber is nearly if not completely identical to the z6's.

i think someday it will replace the a6 head as the nonvtec head of choice.
 

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'91 CRX Hf
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Discussion Starter #5
I have both heads. The a6 head is currently on the engine I'll be rebuilding. It seems that the y7 engines make a bit more mid-range torque than the a6. I'd like to preserve that while gaining a little on the top end. Think that's possible?
 

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its tough to get the best of both worlds...
quality head work (performance porting on here) and obviously the proper camshaft choice will go the furthest toward achieving that...well that and a great tuner
 

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92 civic cx hatch
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Y7 all day I rock one in my hatch granted its boosted but makes great take off torque and mid range power but all motor with some compression and a little port massaging its gonna get down
 

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EJ6
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^^^^i know its been done before but thats a good idea sammo, id love to see a detailed, quality nonvtec build like that

personally i think the y7 head kind of gets shelled on here a little bit...
its got nice straight port passages and with some very light clean work and deshrouding it can flow a good amount of air. that and its combustion chamber is nearly if not completely identical to the z6's.

i think someday it will replace the a6 head as the nonvtec head of choice.
Word.

Look into this thread by Ben.
http://www.d-series.org/forums/showcase/144588-naturally-aspirated-fun.html
 

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'91 CRX Hf
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Discussion Starter #10
...Have you thought about using a z6 head with y7 valve train? ...
I'm intrigued by a non-vtec z6 or y8 (with a y7 valvetrain) but it seems like most of the build threads using these combos are stillborn. And I have yet to see any dyno results (or even examples that have seen a few thousand miles or road use).

I've always been shocked that there has never been flowbench testing done on the a6/z6/y6/y8 heads (at least that I have been able to locate).
 

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Out of all the nonvtec heads, the y7 flows the best stock. Well other then the a1, but you can use that one so y7 stock flows the best.
 

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EJ6
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^^^^^^^^^
Edit: OOO snap, I thought I doubled posted because of the avatar. LMAO.

Very true but since ive already gone this far into my build with that set up...I'll have to finish and if you are still within the gray areas and if by that time im done. I'll share my results.
 

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Meat Popsicle
91 CRX Si
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Only think I like about the Y7 head is that the roof of the port blends into the valve guide...unlike the A6 where the guides just stick out.

A6




I've seen flow data for both A6 and Y7. Y7 does outflow the A6 but not by much.

Flow data for my A6 head. Stock is on left (durrrr)

 

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90 CRX
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Either way get the A6 cam and whatever cam gear for the head combo you run. That stock A6 cam can get you some numbers and is the most aggressive stock non VTech cam. Good luck.
 

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'91 CRX Hf
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Discussion Starter #17
I've seen flow data for both A6 and Y7. Y7 does outflow the A6 but not by much.
I suspect that my y7 head is in better condition. I may just choose whichever head is in the best condition.

Regardless the build will remain OBD0 (using either my PM6 or PG7 ecu - until I get it tuned) and use a z6 IM, DC Sports header, Delta regrind, higher compression (milled head and y8 HG if I use the a6 head).
 

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88 ED6
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Only think I like about the Y7 head is that the roof of the port blends into the valve guide...unlike the A6 where the guides just stick out.
That's actually the result of a very low port roof. The Y7 head will be good for a "street" build(the port design helps mid-range immensely) but if you were to go all-out, I'd say the PM3 heads would be a better option.
 
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