JClaw

iTrader: (17)

I know we've already determined that the 11.5:1 compression that VQ30 heads give on a VQ35 block is offset by the better flow and superior coolant chambers/knock supression of the VQ35 heads.

But if you were to do headwork on either heads, what would be more efficient/cost effective?

1) Get material added to the VQ35 heads to obtain the desired 11.5:1 compression.

2) Use the existing 11.5:1 compression provided by the VQ30 heads and get a shop to do some work on them to get them to flow better than VQ35 heads.

Cams would be part of the equation either way.

And what about the coolant chambers/knock surpression part? Anything can be done about that?

d00df00d

iTrader: (4)

Free bump for a freakin' great question.

JClaw

iTrader: (17)

And I really wonder how much a shop would charge to add material to the VQ35 combustion chamber to bring it up to 11.5:1.

Kevlo911

iTrader: (36)

Headwork done on the 30 heads yeilds close to nothing from what I have read. Not much room to do stuff.

speed racer

iTrader: (10)

is there an old thread to back up that statement. Its always been hearsay.

Kevlo911

iTrader: (36)

I dont want to search but from what I have seen, the heads are already pretty smooth and the ports really dont have any more room for bigger valves. What else do you want to do?

speed racer

iTrader: (10)

I read this a while ago and I found this to be interesting even though it doesn't pertain to our motors.
http://www.sa-motorsports.com/diyport.shtm

I think head work is essential in the overall efficiency of the motor. Taking money out of the picture, if you want to build an engine that will squeeze every last bit of volumetric efficiency than head work is needed.

Kevlo911

iTrader: (36)

When I looked at our heads, I didnt see anything restrictive so I don't know what could be done. But I am not a head expert by any means. Maybe others can chime in with more information. Did you try to search?

speed racer

iTrader: (10)

nahh I haven't searched.

jmeister

iTrader: (12)

If money is no object... http://www.cosworth.com/uploads/1147892186.pdf

speed racer

iTrader: (10)

if they can do that on a vq35, than I can't see why they can't do it for the vq30.

Nismo3112

iTrader: (12)

What about decking the 3.5 heads?

absoundlab

If money isn't an issue. Cosworth $4289.00


--------------------------------------------------------------------------------
Description
Cosworth VQ35 CNC ported cylinder heads feature dyno tested and flow bench proven ports, engineered for maximum real world power. Each new cylinder head is ported on a 5 axis machine to ensure consistency and perfect port shape every time. Additionally, larger intake (+1mm) and exhaust valves (+1mm) are utilized to help increase flow. Cosworth CNC ported Big Valve cylinder heads come complete with a performance valve job, hi rev (max 10,500rpm) valve springs with titanium retainers and are ready to install. Perfect for big turbo applications or strong normally aspirated engines. Nissan VQ35 heads are priced for the pair. A flow chart for the head is available by downloading the technical document on the left.


Specification

CNC Ported/machine finished ports - New OE Castings

Hand blended finish work

Intake 19% Increased Flow (max)

Exhaust 22% Increased Flow (max)

4-angle Inlet Valve job

3-angle & radiused Exhaust Valve job

Valves are lapped

Back-Cut Inlet Valves

Heads are Ultra Sonic cleaned prior to assembly

Heads are Serialized and sport a machined Cosworth logo

+1mm Stainless Steel Intake Valves (1800 degrees max.)

+1mm Inconel Exhaust Valves (2400 degrees max.)

Performance Valve Springs

Titanium Retainers

Hardened Steel Spring Platforms

Knife Edge port divider

japmaxSE

iTrader: (7)

Isn't adding material to up the combustion chambers considered one of the most expensive ways to increase compression. Also your average machine shop won't have the expertise to accomplish this flawlessly.

Hmmm I'm not sure if JE or Wiseco makes domed pistons for the VQ without having to modify the heads/valves.


Anyways getting the 3.0 heads reworked IMO would be very expensive but less prone to complications vs getting the 3.5 heads to be bumped up a whole 1.2 .
Also isn't 10.3 to 11.5 quite a feat to accomplish to begin with?

Since your question comes down to money I think it's a no brainier if you keep 3.5 heads and discard trying to bump the compression up. With the same money you would have to invest in the heads on the 3.0 the 3.5 heads would and should out perform the reworked 3.0 heads in every way.

japmaxSE

iTrader: (7)

Yep and that's just about how much money your going to have to invest on the 3.0 heads. Plus you prob have to add another $1.5k on cams and you still won't get the flow numbers that the Cosworth provides.

nismology

iTrader: (8)

Oversized valves on an n/a 3.5 is overkill regardless of how much HP you're pushing. I'd stick the nismo heads on a 3.5 before i bought those.

jmeister

iTrader: (12)

But I bet it'd be a sweet NA setup on the 4.3 kit. Those Cosworth heads are reliably capable of a 10.5k redline

nismology

iTrader: (8)

Doesn't matter if you're not making power that high.

liqidvenom

iTrader: (6)

i didnt know you have more insight on this then cosworth....

jmeister

iTrader: (12)

Well until someone develops an intake mani that will feed these heads enough N/A air...
ITBs anyone? Seeing as money is no object in this thread

nismology

iTrader: (8)

Who said these heads were designed with n/a applications in mind in the first place? If you've read on my350z.com, oversize valves are only an advantage when running tons of boost on a VQ35. And I never said headwork was useless. I stated that oversize valves were overkill. That's not the bottle-neck by any stretch of the imagination.

liqidvenom

iTrader: (6)

i love you nismology.....lets be friends

nismology

iTrader: (8)

Hush....keep that to yourself. Some people might actually think that we don't hate each other...

speed racer

iTrader: (10)

So, for simplicity. At what horsepower does the internals become a bottleneck for additional power? And I would think that even on a N/A setup, head work will make the engine more responsive and possible be more friendly in the higher rpm band.

nismology

iTrader: (8)

As far as i'm concerned, people need to be trying to catch up to SR20DEN with stock internals other than ARP rod bolts before thinking about headwork and oversize valves. Yes i know he doesn't hold the n/a record anymore, but that's way beside my point. Maximize what you DO have before moving on to bigger things. I'm not a fan of the idea of just throwing tons of money at a car and expecting magical results just because of what something "should" do on paper.

Hoooper

to answer this question, you could deck the heads for a much lower price than having your 3.0 rebuilt, it would get you to the needed compression and better heads to go with it, even if you needed to get a different size timing chain it would probly be cheaper. (different size cause timing gears closer to the crank

nismology

iTrader: (8)

Now where in the world are you gonna find that? You'd also need different cam gears. Nevermind the other fitment issues that it would cause...(inner timing cover, lower intake manifold).

Hoooper

custom mang, and you wouldnt need any of that other stuff, the amount you would need to deck the head in order to get that compression change is very small. really, youd wouldnt need a different length chain even, im just saying if.

liqidvenom

iTrader: (6)

i think peopel should be striving to surpass even the most powerful vq on this board n/a...i really am shocked we dont have a 300whp vq so far. we need to really embrase(sp) higher revs, head work, custom im and serious tuning to get us over that hump.

many other cars from hondas to vipers make use of head work in some form to get the last bit of ommph out of their power plants and i think we should do that and then more. granted the costs are high....but thats because we havent found ways to put that tech in the hands of more vq drivers.

nismology

iTrader: (8)

I completely agree. But people should know that simply bolting on a head of this caliber won't guarantee amazing gains. My point is that people should worry about optimizing what they have FIRST (like SR20DEN and DandyMax have done) before concerning themselves with expensive, damn near full race heads. There are a handful of other more cost-effective mods they could do first. I mean let's think about it...how many 3.5 swappers have even used an EU to "tune" their setups as much as possible? Not many...
I'm not against head work, i just don't think oversize valves are where we'll find hidden power per what i've seen over on my350z.com. Maybe somebody will prove me wrong. My personal opinion is that you'd have to rev higher than the bottom end could handle (> 8000 RPM) before you saw a gain over the stock heads or even ported stock heads. It would be the very last internal modification on my list behind forged rods and pistons, the Cosworth IM that's coming out soon, super aggressive sticks, nismo VTC sprockets, EU, V-Manage to control said nismo VTC's, balanced and blueprinted bottom end, rev-up oil pump, etc.

nismology

iTrader: (8)

A custom timing chain? Mmmkay...



And what about the potential fitment issues with the inner timing chain cover and lower intake manifold? Not to mention it's effect on the cam timing. You honestly telling me that this method would be easier than domed pistons?

Alex_V

So whats the best way to upgrade a VQ30 then? Custom high compression pistons and some cams?

I really wish I had the money to do a temporary Na build up. Start with some mild porting cams and the highest comp pistons I could order.....Toss that in the mix with some super short ITBs, and some lighter/stronger rods and ARP studs and let the red line set its self.... ooh man that would be sick in an S13.

Liquidvenom- do you mean a ~250+WHP/~300BHP VQ30? Ive heard of a couple 300WHP VQ35's on my350z.

~Alex

liqidvenom

iTrader: (6)

that is tru...but i think that either we go high revs and go nuts, or try to raise compression and then keep our timid 7,500 rev limit people tend to sit around. good fuel and tunning will also be very important to get anywhere near the goals we should be setting for ourselves when it comes to putting down serious power

liqidvenom

iTrader: (6)

better yet....we need someone to build the bottom end, do head work, and all bolt on etc mods and tune a vq 3.0 to at least high 8k maybe even 9k and strap it to a dyno so we can have an idea of what we can make with a fully built motor. it wont be cheap....but one of u rich ****** need to make it happen

nismology

iTrader: (8)

I've always wanted to see a fully built n/a 3.0. Even with the stock bottom end a 3.0 could handle 8k+ revs with just a better oil pump and upgraded valve springs. It's damn strong... Making power up there would be the fun and interesting part...

Hoooper

i would never say that, its always easier to do that. the added weight of the piston wouldnt really be good for high revs but im sure most wouldnt notice a difference. as long as domed pistons are built right, ie no sharp edges, then of course it would work well and be easier.

liqidvenom

iTrader: (6)

i say the same thing to maxima friends around me and all i get is " but whats the point man...we already make more power then hondas"


maybe if this new engineering job pays me nicely and i can put together some cash i might try to build me a car to the specs that i would want it to be at and i'm sure its gonna be a high reving screamer

speed racer

iTrader: (10)

There's a lot to say about going all out N/A style. For one, I don't think anyone has dropped in some 3.5 cams into a 3.0 with the 00VI. What type of gains will this achieve.
Nismology: I understand where you are coming from about work with what you have. People haven't really even considered stand alone's yet. The potential is out there to do many things which hasn't been unveiled.