D16Y7 or D16Y8 Turboing...?

[chase13]

I currently have a d16y7 sitting in my engine bay. My brother suggested that i swap to the y8 head, and then port and polish it. I was just curious as to which engine set up is better for turboing? sohc or sohc w/vtec?

[00CivicVTEC]

Find out what compression ratio the Y8 head will bump up your compression to. You might want to get a thicker head gasket to lower the compression so you can boost a little more. Here is what I DO know:

D16Y7 has a 9.4:1 CR and a 34.6cc combustion chamber and 106hp

D16Y8 has a 9.6:1 CR and a 32.8cc combustion chamber and 127hp

There is a "factory-quoted" 21hp difference between the two motors...because of the VTEC...VTEC is good, I wouldn't have a Honda without it

You WANT VTEC, and the Y8 head is a good choice because it has the largest ports of any D16 head, and don't even bother with the head work...

If you want you can smoothen the exhaust ports up a little without actually porting it, to decrease carbon buildup. If you polish the intake ports too much than the fuel will end up settling out and not atomizing well (leading to very inefficient combustion).

[themi6group]

along with the d16y8 head, you'll need the new ecu because of the vtec solenoid, fuel requirements, etc.

[azian21485]

i thought that it doesn't matter if u hav vtec or not when turboing cus the turbo just overlaps it or sumtin like dat?

[00CivicVTEC]

Yeah, you'll need a VTEC ECU and wire in the extra wire to activate VTEC, or you will need a V-AFC.

You also need a D16Y8 head gasket and timing belt.

VTEC is very good, especially with turbo...it lets the engine breathe much better at the top end, when the turbo needs it...but it may move the "optimal" VTEC engagement point depending on your setup, which can be tuned on the dyno.

Whoever told you VTEC isn't good or is not needed if you have a turbo is full of it :

[redfox]

Originally posted by azian21485
i thought that it doesn't matter if u hav vtec or not when turboing cus the turbo just overlaps it or sumtin like dat?

At VTEC engagement, the intake valve and exhauast valve openning interval has greater overlap to help expell used gas and at the same time suck in fresh air. So yes, there is an overlap. That overlap is still very short, which is necessary but cause a bit of boost loss.

However, VTEC is still good because of the high cam profiles as described in previous post. One NONO is to get aftermarket CAMs that increases overlapping to aid NA applications. By increasing the overlap, your precious boost is lost. YOu could however, get a TURBO specific CAM which minimizes overlapping to retain most of the boost. Then again, more used gas will not leave the cylinders because of this and your O2 percentage goes down, hence loosing power. Stock CAMs are by far the best of both words.

I'm tired, what I said may be confusing. Anyway, for the enhanced flow characteristics and better cooling, you want a VTEC engine.

[00CivicVTEC]

Exactly, and there is exactly where DOHC'ers have us SOHC guys beat...they can adjust their valve overlap.

[themi6group]

true dat fellas