Here's an issue that we never discussed on the FI forums.. Coming from the VW world, I know that lowering compression with a proper sized headgasket with boost is a common way of decreasing the chances of engine failure. So I was wondering why no manufacturer has tried this yet.

Now that we have some of the problems like crank angle sensor addressed, I am getting more and more convinced the stock engine can handle some boost. So I was thinking if someone were to get a turbo kit and address the fueling issue (APS, CJM or AAM), then the CAS issue, we could also try on a set of headgaskets to reduce the compression to 9.5 or maybe even 9. Then boost to 9 or even 10 psi more confidently.

Sure, everyone is after record high whp numbers and some have put down 450+ on stock internals thanks to the stoch high compression but what if you were able to have not 450 but maybe 380-400 much more reliably on a daily driver on 9 or 9.5 to 1 compression.

post away peoples

 

VTC and the cam chains are extremely sensitive to adjustment like shaving heads or adding thicker gaskets. Not a big problem with belts like on the Honda's but yes with the Nissan VTC.

 

Just do the ol skoo method of double gasketing it. I haven't looked at our gaskets, but you might be able to take two apart if they are 3 piece gaskets and then add the middle piece of one to the middle of the other one making it a 4 layer instead of a 3 layer.

 

This is also common on 7M motors. I have stacked HG's on a 3VZ V6 Toyota motor also. It does advance the timing but you can run a bit more boost. Cometic does make MLS HG's for VQ35's. They only list one thickness but they also only list only one on the 7M's but they have atleast 4 different thicknesses. Adding another .010"-.020" wouldn't be too bad.

 

I would also think that with all the picky electronics in the newer engines, such "old school" methods would alarm bunch of sensor and flashing check engine lights everywhere. On the other hand, coming from the german car world, I must say that Japanese make things MUCH easier than Germans so I'm happy with what I have to deal with.

But that VTC argument is obviously very valid, that's something I did not consider when I thought of this.

 

Bringing this back from the dead ... Memed thought of this like a year before me but...

VW VR6s have timing chains and have no issues with this... So I'm wondering, with proper tuning couldn't the problems the chains on the VQ be edited out/avoided?

 

There is someone on the boards running a thicker HG. Can't remember his name though.

 

i was under the impression that gasket thickness can only change compression by a few .1 or a point. not quite the effect u were hoping for.

 

Nope. You can get it down to 9.0 or less just by a HG. Cometic makes some thick ones for the VQ.

 

I wonder if some of the older Turbo'd maximas have any insight on this?

 

this thread really is back from the dead wow

if we could even drop it by .5 points, that is .5 points.. sure, it wouldn't be a replacement for forged internals, just added security for those that prefer to run stock internals with FI

 

To me, it wouldnt be worth the labor to remove 1/2 the motor to be able to run 2-4psi more safely. Id stick with a stock set-up or just build the block. If it was an easy job say like for a Honda Id do it though....

 

Good Point 2-4psi more would be more than enough anyway. Why is it we always want more. Damn human nature!

 

It would be to me. I'd spend an extra few hours of my own FREE time to get a few more psi out of the turbos/turbo safely on a stock motor. It'd definitely save you money over building (and paying for the assembly process of) the motor.

 

The concept is very intriguing. Anyone willing to be a guinea pig?

 

The problem is that it wouldn't be a few hours. Plus it would be very hard with the engine still in the car. You would also need new head bolts. Once you start taking the heads off, you would wonder what you got yourself into. It's not as easy as popping a head off an I4 like a B18. Much more involved.

 

If I buy a Z... (Which is quite possible, put the Z/28 up for sale today) ... I'll likely be the guinea pig myself.

I'd like to try for out of the norm whp with the stock block.

 

For every .010" of added deck height from gasket you get about .25 less, Go to Diamond Racing.net and use their calculater, it will allow you to figure everything exactly if you cc everything accurately.
Stock gasket is a compressed thickness of .024"
piston below deck height .018"
57.5cc combustion chamber
2cc worth of dome on piston
.120" down to top ring

 

All the oil passages for the rear chain housing along with the VTC covers that actually insert into the ends of the VTC gears. Then the intake sets low on the heads, misaligned ports, etc. Quench area is bad. Just the beginning.

Wonderful idea until you read the FSM, then disassemble a full motor.

Automotive design is very good now a days.

 

First time I dissasembled the VQ35 it was an eye opener. That's why cams are so expensive to install on these cars.