To those of you that have technical knowledge about sohc heads..

im debating on whether use/build a y5 or y8 head for turbo.. which one would yield best performance?

what i know... both heads are vtec but the y5 is a roller rocker desing which i think is a plus compared to the y8. the y5 is a vtec-e but only if the y5 ecu is used, ill be using aem ems so i dont think the -e would play a role here, anyways vtec-e is only under 2800rpm on stock ecu above that everthing is normal operation.


please specify facts, tecnical info on which should be a better setup.

lets see what the outcome is.

 

go y8 head

y5 has roller rockers which mean th cam can be more agressive and you have less problems with valetrain geometry, or so i have been told


Modified by pornstarSR at 3:01 AM 9/5/2003


Modified by pornstarSR at 3:02 AM 9/5/2003

 

Has anyone made any power with a Y5 head? I thought it was like the 92-95 VX P07 ECU... all theoretical potential, nothing to back it up.

 

yes its all very theoretical performance...no one has made power yet

not sure if anyone has really tried, might be a cool project

 

are you sure about the vtec on the exaust part?

what would be the point of increasing the intake flow (vtec) if you cant get it out at the same rate is going in?

i have a 96 hx.. so i coudl use my y5 head but want to explore possibilities and actual specs..

a hybrid... part y8 vtec, part y7 non-vtec.. dam ingeneers...

 

The y8 does not have vtev on the exhaust side! All SOHC's only had vtec on the intake side. The y8 might have a higher compression due the combustion chamber but I believe that the y5 has roller rockers and with those, you could put a serious cam in that car!

 

Yea, it's kind of hard putting exhaust VTEC lobes on a SOHC

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pornstarSR &raquo;</TD></TR><TR><TD CLASS="quote">ok heres a run down...

y5 head is intake vtec only
y8 is intake and exhaust vtec
</TD></TR></TABLE>




No SOHC had/has VTEC on the exahust. Have you actually thought of how it would work since the exahust valves are split on the cam by the intake cams??

The Y8 gives you the ability to use 2 cam profiles for the intake while using only 1 exahust lobe profile, the Y5 only uses 12 lobes with the "other" 4 intake lobes being nearly flat rings wich only barley crack the intake valve open enough to prevent fuel puddling behind it. When VTEC engages on the Y5, the primary lobe is connected to the secondary and they now both open at the rate of the primary lobe. Not exactly how traditional VTEC works.

I can't see how forcing compressed air through only 1 open intak port (pre-VTEC) would be beneficial whatsoever, if anything I'd force the Y5 to be 'in' VTEC the entire time.. but is it worth the effort?

 

thats what i thought about the vtec exaust part.... but he left me thinking hehe...

the desigh on teh y5 is for better gas millage... under 2800rpm it uses only 8 valves (instead of all 16), lean burn, less resstance in valve train and who know what else yields the higher gas millage... i can feel teh diff at arround 3k were there is a mild pull..

i havent found any company that sells cams for the y5, you can have a custommade one but then is $$$

more facts?..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kamaleon &raquo;</TD></TR><TR><TD CLASS="quote">under 2800rpm it uses only 8 valves (instead of all 16), lean burn, less resstance in valve train and who know what else yields the higher gas millage... i can feel teh diff at arround 3k were there is a mild pull..</TD></TR></TABLE>

Actually it's 12v under 2800rpm or whatever, the 4 primary intake always operate, the secondarys are the ones on the smaller lobe that doesn't open much.

 

there u go.. 12v intead of 8v

so does the roller rocker matched with boost present improvements over the y8??

teh 12v - 16v is operated from the ecu right? if this is the case using the aem will make the 16v work at all times.. so the 12v-16v wouldnt be an issue any more..

 

well **** you learn something new everyday...hahah
i had a feeling something didnt feel right when i typed it...

oh well...

i actually went back and researched it a bit yesterday and realized my bumble...

and was coming back today to edit the post...

so yeah oppsss

 

so in theory if you ran a y8 ecu the vtec would work roughly the same as a y8 correct?

 

Yep, and it would ignore the Y5's wierd *** EGR nonsense too.

How close the maps would be to ideal I have no clue, but it would run.

 

no, it would not run with a y8 ecu... y5 comes with L1h1 widewand o2 sensor and y8 is the regular 02 sensor.. diff signal, voltage, etc...

it will run if you use a re-wired regular o2 sensor

still: Head to Head.. (not including ecu's nor sensors) which woudl perform best with FI? using stock cam.

 

well i would have to venture to say EX, more agressive cam profile...

as far as over all the heads are basically the same....as far as overall design...shape and all that jazz..

so it could be said that the y5 and y8 head and even the y7 head could be made to flow equally as well...

as far as best head to start with out of the box, or which is a better platform to start from

Y8 head...you will run into less problems

 

well 02 sensor aside, which yes i know thats an issue with just a basic ecu swap..

if you got an ex wire harness, got some regualr 4 wire 02's, dumped the y5 intake manifold, got a y8 manifold, plugged the ecu in, i could see it working relativly well....

now what will really bake your noodle later on is, will an aftermarket(or even stock) y8 cam fit in the y5 head with the y5 valvetrain and work....cause then you could get a nice aggresive cam profile...with the y5 valvetrain

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pornstarSR &raquo;</TD></TR><TR><TD CLASS="quote">now what will really bake your noodle later on is, will an aftermarket(or even stock) y8 cam fit in the y5 head with the y5 valvetrain and work....cause then you could get a nice aggresive cam profile...with the y5 valvetrain</TD></TR></TABLE>

No. There is no center rocker assembly for the Y8 VTEC lobe on the Y5 valve train. Now will a Y7 fit? Possibly, but you'd ned to ensure the vale train geometry was identical to the Y7 to ensure the cam lobes and rockers were properly aligned.

 

Y5 intake Manifold = Y8 Intake Manifold;

 

Me & BoostedHybrid took My VX head apart, it has roller rockers.

The only possibility is to have custom cam grinds made. We tried swapping A vtec cam in there but it Just will not work. Plus the actual head design is pretty restrictive compared to the Vtec head.

IMO it's just not worth it, I mean are you going to be making 350+ WHP on your D?

just get A Z6 head and put a Y8 manifold on it, thats your best bet with a turbo D.

 

i beleive the y5 head is a bit different from the y8, because of the EGR setup which i beleive is set up attached to the intake manifold

 

Y5 head will def not take a y8 cam. Just tried it not knowing I even had a y5 head. But for the ecu thing I believe they reworked my o2 sensor and my y8 ecu was running the y5 just like a y8. Actually it did run damn good but now I am rebuilding everything for boost. And found out my "y8" isn't even a y8. It's got roller rockers and the cam lobes don't line up at all

 

I have a d16y5 block and i just put a y8 head on it. My ? Is wat would be the best way to go to get more power and to be able to put a turbo on my motor?

 

 

yes I still have the y5 head