does anybody know if VQ30 heads will bolt up and work on our engine?

 

They will bolt to the block, oil and water passages are all good. But the intake ports on VQ30 are a different shape than VQ35. You can port match them but it takes allot of hogging. The CAM reference sender is also different, I'm not sure if the sensors signals function the same. And you lose the variable cam control. VQ35 heads have lighter valve train because their lifters do not have shims, they are manufactured in different heights. VQ35s also have light weight AL retainers. Valve clearance is questionable with stock VQ35 pistons,

 

so.... i guess thats a no?

thanks MGM, i had stumbled upon a set of ported/polished heads for sale real cheap, i just figured id ask.

 

its a defiante yes they work...but they are not an install it and forget it setup...compression will increase and you'll need some form of ecu control to make the best use of them, plus you will lose the variable cam timing

 

For purley selfish reasons... Are you 100% on the valve clearance?

 

Have I tried it myself? Nope...not worth the trouble IMHO. But these are the very same heads that NISMO sells (they offer 2 versions), and there is no piston change needed at all

 

So would a torque plate made for the VQ30 work as well on the VQ35 when boring our sleeves?

 

so the real question is, should i pay 400$ for some VQ30 heads already ported/polished, to install when i get my pistons/rods installed? what would this do if i had 9.0 pistons?

 

It would increase your compression ratio to around 10.0. I wouldn't hassle around with it because basically you would be doing the same thing by just getting stock comp. ratio pistons and good rods. You will gain more hp with 9 to 1 comp. and more boost. Unless you wanted to get 8.5 pistons and then these heads to get around 9.3 comp. Still seems like a lot of hassle for something no one is positive about (cam timing etc.) I think you would be better off spending $400 worth of port work on your vq35 heads. Or cams.

Does anyone offer titanium valves for stock (non-nismo) vq35 heads?

 

whenever the maxima forums come back up I'll dig up some info on titanium valves from another Nissan motor that supposedly fit with slight modification

 

Very good question....maybe. As long as the cylinders are the same diameter, and the studd holes are in the same spot...I dont see why not?

It's a really good question, becuase as the group begins buliding up their motors, most machine shops will likely have a VQ30 torque plate, over a Vq35....

Adam? What do you think?

 

The cylinders are not the same diameter....95.5mm vs. 93mm.

Also, per a SAE tech document and the FSMs, the VQ35 heads are far superior. Just a few things are:

1)Higher intake port angle.
2)1mm larger intake valves.
3)Long reach spark plug with better coolant flow to prevent detonation.
4)Variable timing.
5)Exhaust port shape to prevent detonation.

Plus, how would you get around the VTC ECU faults?

 

If the cylinders arent the same diameter, then how is it possible to install the 300zx heads on the 350z? Given the different cylinder diamters, it seems impossible..unless I am missing something.

 

300Z is a VG30....

The VQ30 Maxima heads or Nismo VQ30 heads will bolt on supposedly, since the combustion chambers of the heads apparently are similar in shape. I'd bet that Nismo just opens up the VQ30 heads to match the VQ35 cylinder bore.

 

One more negative for FI guys would be the raised compression ratio from the smaller ~43cc VQ30 combustion chambers.

You'd end up with ~11.4:1 CR(ballpark with a few ASSumptions).

 

The VQ30 heads bump the VQ35 compression to 12:1 with stock pistons...I have no way to know what it will be with 9:1 pistons - I would check with your machinist.

Not sure on the torque plate..I'd have to do some checking

 

A 3,5L block w/8.5:1 pistons for a normal VQ35, but VQ30 heads is going to give me 9.4:1. Should work great!