I was wondering about how much boost the stock bottom end could take. My guess is that it should be able to reliably handle 6-10 psi without any major faults.

After all the SR20 could handle 18 psi on the stock internals and that engine is out of production in the US. I don't know much about the VQ internals though. Does it have beefy rods, and can the pistons take abuse. Nissan should've anticipated that people will boost this engine, I wondering how overbuilt it is.

 

My expirience is with the VQ30 of the Maxima, which is very similar. It can take around 8-10 psi without problems. 6-7 is normal, anything over 8-10 would require and intercooler/aftercooler. I have seen a S/C maxima go as high as 12 psi, and a Turbo go to about 10-11 psi (although there are only a couple T/C max's out there).

I can't say that the Z is any better or worse as far as the way it is built, the configuration is identical, but as far as materials and design I do not know (ie con rods, crank, pistons, valves sp/ret). The CR is a little higher on the Z too....

 

Yeah the Z internals should be similar to the Max since its just a bored out version of the VQ30. 12psi would be nice but I think with the Z's higher CR maybe it shouldn't push 10. Even 6psi would be really awsome in the Z.

So are you going to sell the Max and get that Stillen SC?

 

How much PSI? That depends on how big the turbo is.

 

One maxima owner has a 95 maxima and he was planing to pull the motor out and replace it with a built one. So he decided to see how much boost it could handel. After a littel while of running 18 PSI the motor finaly died. I know 11.5 PSI neted 370 FWHP on a 95-96 maxima too.


BTW JWT is suppose to be releasing cams, valves and valve springs for our VQ35's Suposedly any day they will be ready.

 

Thanks for the info guys.

 

Me too. Is this true?

 

Well, my engine seems perfectly fine after a pretty bad misshift on my part... I say this engine is pretty tough

 

Yes its true. It states in the book "Story of the new Z" that several internal engine components are forged. The one that I can remember off hand are the pistons.

 

i dont want to start one of these arguments on this board, but i will simply say that PSI is PSI... does not matter the turbo size (i assume you mean compressor turbine size/clip angle).

PSI is a measurement of pressure....

a "bigger" turbo can generate pressure easier than a smaller turbo, but the engine cannot tell the difference...

a bigger turbo can also make more pressure than a smaller turbo... but this is a moot point since wastegates are designed to open at a certain PSI, and stop the compressor from accelerating... its just a matter of how fast it spools up.

in other words a 16G or an 18G can both generate 14PSI, and there is no difference to the engine... only difference is the 16G is spinning faster. now there is a point where the 16G cannot generate enough boost comparable to the 18G, without overheating the air due to the friction of the turbine spinning at crazy rpms. this is when you would upgrade to a bigger turbo..

get it..?

m

 

HELL ya ,, chaulk that up as intelligent reply # 3 on this forum..
thankyou!
and from what i know thats completely accurate info

however, what about boost spikes?

 

spike or creeping?

boost spike is when the wastegate doesnt open quick enough.. like after a shift. best way to combat it is with a really nice EBC (electronic boost controller)

boost creep is when the wastegate cannot let enough exhaust out to stop the compressor wheel from spinning. this mostly happens at high rpms.. when air intake/outlet is the highest! the best way to combat it is by porting out the wastegate outlet.

m

 

ya or upgrading the wastegate.. i knw of both i just wanted to make sure someone who knew more about that made the post than me so i didnt fuq somethin up tryin to explain it

 

I would like to know this too??? I just purchased a VQ35DE for my 98 Maxima. I run a V1S blower at 13.5psi on my VQ30DE. I would love for the 35 to have forged internals.

 

Mis Shifts almost always lead to bent valves, not blown engines. But hey strong valves are important too..

 

If this engine has forged pistons and rods then 8-9psi daily and 12psi at the track with race gas shouldn't be a problem, as long as everything is tuned. My Prelude Vtec H22a has weak piston rings and with great tuning I've been boosting 7psi daily for almost a year and my compression is still perfect in every cylinder.

 

Michael,

I believe Phat's point was that if you were running a bigger turbo, you would want to run a lower psi, due to the larger volume of air flowed at the same psi by the larger turbo.

But, I could be wrong...

JD

 

BUwuahaha.. matthel

sheeze

you know. he got 1.7bar on his built VQ!!!!

i'm sure this VQ35 has probably the same amounts of tolerance as the older one.

i'm running 9.5 on my Maxima.

Ethan: how much PSI are you gonna run on your 2k2?

 

I am going to start off with a none intercooled setup. I am hopeing to squeeze 8 PSI out of it like that. Once a good aftermarket clutch comes out I may get a intercooler and bump things up a little higher