Hey guys,

I have been thinking about purchasing a shortblock and building, but i recently had a thought of just buying a pair of heads and going the NA route and not touching the block right now. People who say it's not worth it please hold the comment back.

Anyways i was thinking of having them ported, get a valve job, mill them .20 off for maybe a point up compression, Tomei 268's, and upgraded valvetrain. I will also be planning on using some type of standalone as well with basic bolt ons. Especially the Xerd longtube header also looks like a tasty choice for the NA route. Tell me what you guys think??

 

Be very careful when milling these heads for increased compression. The VTC is very sensitive to changes in deck height and chain alignment.

 

the stock heads are very good actually...

best thing you can do is leave them alone...

dont waiste your time with those 46cc heads... in order to get them to work you will have to modify them in a way to make less power then what you have now...

the real power is in tuning... if you are dead set on goin NA look for a new engine mangement system...

 

Why is it good to leave them alone? Work like this can always help in terms of power.

Can somebody also explain VTC in detail and how milling the head would affect this?

 

What do you think of piggyback? Good results? Or by engine management you mean standalone only?

 

I was also think guys what if i minimize the size of the combustion chambers on the heads instead of milling or going with flat top valves? Would this be a better option?

 

I guess if I had a choice I would go with the Nismo Stage 1 or 2 Head, which will eliminate the porting, with a titanium valve train & springs, and Tomei cams (although I'm not sure if they work on those heads)...then again after parts & labor you will probably pay pretty close to what an APS ST costs and only get 30-40% (give or take a few %) hp of what the ST can put down....but hey I would do it too!!

It would be a very aggressive set up that will scream at higher rpms, especially with those 268's. Also, if at some point you were to get a Nismo Competition crank and a forged bottom end you could feasibly get to 8500rpms on the VQ35...but you would have a high rev competition engine under your hood, which would probably suck for everyday driving.

I have the Unichip P&P ECU and have no complaints, but I have no clue as to how it would work with new heads. With it you would want to have a certified tuner near you as well and there aren't many around yet. I've also read some good things about the Motec M600 ECU, which had great gains on an NA engine...here is a thread on it:

https://my350z.com/forum/engine-and-drivetrain/127997-world-first-motec-plug-and-play-on-350z.html

 

The Nismo heads are race heads so you will need race fuel to run them otherwise you will have to detune your car. That is why Jason@Performance was saying don't go with them because you will not see gains worthwhile for street use. If you are looking for track use only then I would get these with the Nismo Stage 2 cams which I believe are 284/268 duration. That should get the NA power everyone here is looking for but its too bad those parts are basically non streetable.

 

race fuel or not...

In order to get the NISMO 46cc heads to work you need to modify them even to work with the VK45 valves...

After the modification is done, they end up being about the same compression as the stock heads with Titanium valves...

So its not really worth it...

There are other heads that have yet to be relased off the super tiku motor which can use the stock valves and yeild a higher compression...

until those are available the 46cc arent really worth it...

 

Thats just crazy. I wonder which valves they used to get the higher compression or where they custom made valves?

 

My plan isn't to get the Nismo heads anyways, so lets just stay on the topic on modifying the stock heads.

I don't want to touch the bottom end either. I want to touch +300whp. I know tuning is crucial, but for now i am buying stock heads and modying them first.

Jason, what do you think of my opinion on raising compression on the stock heads by means of flat top valves or make the combustion chambers smaller? I'm looking around a 11.3:1 compression on stock bottom end. The S1 kit looks tempting as well and seems like it can run reliably and smooth on the street. I'm also looking at a port job.

How would this affect VTC as well?

 

I just checked out the Motc site

http://www.motec.com.au/m400m600.htm

Sounds good to me but I'm sure what it does better than the stock one does.