Bags

iTrader: (3)

Ok, icy and I were disscussing about Turbos in another thread.

It got me to thinking....

At some point you'll reach MAX PSI the stock motor can handle.

But do you work within the compression and keep the PSI low ~12 and do things like head work, mevi, cams

Do you buy things like the J&S and emanage ( just examples ) to push the stock limits?

Or do you error on the side of safety and drop the compression?

Do you get new pistons and rods and push the PSI envolpe?

You'll lose WHP with the lower compression, just up the boost and that will solve that.

But what about the next "weak" link?

what is the common agreement of a WHP limit that our "cars" can handle?

Or is there one?

There aer MANY thoughts like this I think about, but $$$$ is the factor for me and others.

I am just tyring to follow a path of least $$ spent and least mistakes. I have made more than I wanted to so far, but there is a learning curve. ( being hard headed does ot help )

So what are your thoughts?

IceY2K1

iTrader: (3)

My .02.

1)Buy car.
2)Buy turbo.
3)Maximize turbo.
4)Build spare engine with hp/tq goals in mind.
5)Blow current engine increasing HP/TQ...NOT by bad tuning!!!!
6)Drop in spare BUILT engine and repeat steps 2) and 3).
7)Hopefully...satisfied and don't have to repeat 4, 5, 6.

Jeff92se

iTrader: (82)

The amount of HP/torque that can be made is too dependent on tuning to really say. Say you could keep the perfect a/f and timing maps no matter what the fuel/air temp/boost level. Then all you would have to do is just up the boost until something broke. Then measure the hp/torque made.

JeffesonM

iTrader: (5)

Also keep in mind you've got to get all that power to the ground... at some point you'll probably reach the limits of the tranny, axles, etc.

Mishap

Look at it this way...if you're going to push for hp you will need all of those eventually anyway. Just take your time upping the boost and you'll be able to extend the time it takes for you to spend that much money on parts.

At the same time, there's absolutely no reason to completely baby a boosted VQ like it's a grenade w/ the pin missing(different story for us H22A owners w/ over 50% blowing up at 6psi). At $200 a motor, don't sit around putting at 4 psi when the car can reliably hold 9-10 w/ correct fuel. Pushing boost well past 10 just to throw down big numbers for a week then swapping every other week. There's nothing wrong w/ taking time to tune a car for maximum hp per boost level. I'd much rather drive a well tuned 300whp 7psi car than a car that's running 11psi for just a bit more power.

Things like injectors, J&S, E-manage don't go w/ the motor so having them on a built motor just make you that much more prepared for additional power. New pistons or not...user error can destroy those expensive upgrades w/ ease so the electronics are just as necessary w/ low compression parts.

Quicksilver

iTrader: (1)

I definitely agree with the two engine theory.

I also like the idea of the J&S as an added safeguard (but it doesn't replace good tuning).

I also like changing cams, but I know that's not an easy task on this engine. Just make sure not to get one with a ton of overlap if you do decide to get them.

I'm sure the stock internals can handle 9 PSi daily, but you are going to have some accelerated wear with that setup. It just comes with the territory. But, I would venture to say that you should get 50-60K miles with little to no problems once you are properly tuned (injectors, J&S, etc...).

AllGo

iTrader: (1)

One thing to say with regards to baggys question is the fact that a 10:1 stock motor boosted would be a better daily driver and have a better off boost response and gas mileage.

As soon as you start lowering compression with piston/rods/cranks etc. the higher compression's motor and efficiency starts to diminish. I would say with the power available with boost and proper tuning that traction and transmissions are the real limit for the front wheel drive maxima.

With good low mileage precision VQ's available at our disposal then whey spend the $1500+ for custom internals and the $$$ for proper machine work and assembly and lets not forget crazy downtime. Boost and tune the stock VQ and if you are making a reliable 350whp/tq then there are not many cars on the road that have a chance.

Bags

iTrader: (3)

But I want to make at LEAST 425 WHP/TQ

Mishap

IIRC you're gonna need a bigger turbo in there too. If you're running a T3/T4 anything smaller than a 60-1 probably won't get 425whp w/o nitrous.

425whp does not come from stock internals on a Max...at least not for long no matter how good your electronic bandaids are. At that point you're really reaching on every aspect of the motor...reliably getting nearly 3x the factory hp on a car that is N/A normally will not come cheap. Especially one as complicated and intricately engineered as the VQ.

Allgo,
Internals for the VQ generally cost more than $1500 (you might get a set of pistons for that much). Even if they were as widely available as Honda parts you still need 50% more of them. If you want cams...you have to get 4 of them custom made for F/I. Then there's the whole nightmare of trying to get upgraded valvetrain to work together. A solid engine build for a VQ when done costs at least as much as a turbo kit.

Opt for a spare bare block and have it built correctly. Blueprint, deck it, cryo, anything else that will fortify the motor to handle that. Then 425whp starts looking more like a daily driven reality and 500+ on race gas. You're gonna want an increased redline along with a better intake manifold to really make the car efficient for all out hp.

Of course, such an engine coupled w/ a decently lightweight 4th gen you're looking at an 11 second family sedan which is simply sick.

If you do go stock block...I definitely think 350whp is possible and survivable w/ proper tuning running 10-11psi max. Still talking about a 12 second street car w/o an additional huge investment.

Bags

iTrader: (3)

You recall VERY correctly

And that's what I ment by the +425.... on RACE gas

~350ish daily

12- 14 PSI daily with 18-20 PSI on the other sauce

and you nailed it earlier with the electronics... they can do SO much. I have not researched that enough.

Just thinking out loud as per norm..lol

IceY2K1

iTrader: (3)

I agree on the bigger turbo...that's why I said repeat step 2). You can't expect to run the SAME turbo on stock internals AND a built engine. Two different performance envelopes.

hlh0501

iTrader: (1)

I disagree.
With no electronic bandaids I consider my 476whp/505tq 10psi quite safe. Even with a few more psi I am experiencing no probs.

Just as baggs would like to know what a new internalled VQ could hold, I would like to know what WHP a stock VQ can produce. With a decent tune and new turbo setup (SP67...), I think I could produce MUCH higher numbers on stock motor.

Personally I think the VQ is much stronger than it's given credit for.

stephenlc

iTrader: (1)

If you dynoed yet Hal?

They have a 750 hp VQ 350z in japan

hlh0501

iTrader: (1)

I have not dynoed in a while, not since my .68bar pulls
For a while now I've been at .98bar

750hp now we're talking. Do you know what size turbo(s)? Is that hp or whp?

IceY2K1

iTrader: (3)

Hal,

Not to try and discourage you, because I'd like to see that, but the VQ35 has vanadium steel rods and several other strengthened features our VQ30s just don't have.

Prove me wrong though!

hlh0501

iTrader: (1)

and .5 more litres!
yes I know, and yes a 3.5 can make more than a 3.0....

but do we know the max either can support?

IceY2K1

iTrader: (3)

Not *YET*, however "support" might mean different things to me then you.

Mishap

Go read this month's Super Street...has the specs on the Jun/ Options Magazine turbo Carbon fiber Veilside kitted 350Z. The one that was built to run the Silver State Classic but wrecked doing a few miles in at 200mph. It sports a built VQ30DE-T sporting a huge turbo and custom intake manifold...guess the VQ35 isn't that much better for them to build it. IIRC it puts out over 800hp.

As for 476whp stock block...your car is still alone in that range. No one else has replicated those numbers yet so there isn't a huge amount of data on reliability. Could be a reasonable hp level but then again there are a lot more blown motors at lower power levels. Most are user error but there are still some that can only be explained by the stock VQ's weak points.

IceY2K1

iTrader: (3)

I'll have to stop at the store tonight and get that. One of the few times I'd have reason to buy a Stupid Street.

For the Silver State Classic, high speed challenge IIRC, they'd want to go with the VQ30s much slower piston speed. Top speed is all about shorter stroke, gearing, and light weight reciprocating mass NOT strength.

stephenlc

iTrader: (1)

Someone said something on this board about boring out a VQ 3.5 block to 4.0 liters. They said it might go in one of Nissans vechicles. That is what I am talking about, that is a freaking big displacement V6. I am wondering if the VQ block needs to be sleeved to reach 750 hp. Do you think proper tuning, low compression pistons and rods can get the VQ to that point. The only person I would trust to sleeve my block would AEBS, but that is major money right there, at least 1500 dollars.

stephenlc

iTrader: (1)

It seems when people get to that level they crack a piston. Not one person has thrown a rod or damaged the block with that kind of power yet. Nissan says the block is good for 550 crank hp. But people have passed that up and not had a problem.

stephenlc

iTrader: (1)

What are the benifits of a shorter stroke?
Slower piston speed?

The shorter stroke helps you rev at higher rpms, right?


Someone said that the 350z rods are less than 20 dollars a piece at the Nissan dealership. Someone prove me wrong so I can slap that guy silly.

nismology

iTrader: (8)

I'm sure most of the blown F/I motors occured due to detonation, period, not necessarily because of the VQ's "weak links." If more ppl were either willing to run as rich as Hal (10:1 a/f), run 100+ octane race gas exclusively, get a JWT turbo program, or run something like an E-manage we could see more 400 WHP VQ's reliably. And I refuse to believe that Hal's current motor is some "factory freak" motor that is magically able to handle more power than others, especially with how strictly these engines are toleranced from the factory.

Mishap

100+ octane != street car

C16 is $7.50 a gallon and you can't run a cat b/c it's leaded...so you're not exactly a street car. Running ~10:1 kills a good amt of hp so I don't see why not run closer to stoich and lower boost for essentially the same hp w/ careful tuning.

Be realistic here. The e-Manage is still a piggyback...doesn't solve the fact the VQ is still an aluminum block engine w/ high compression pistons. It's essentially a glorified AFC so don't expect it to provide miracles (just better fuel tuning).

Also, last I heard cracking a piston counts as a blown engine. Doesn't matter if the crank lets go, a rod bends, or the block cracks in half. It all means you've got to spend money and buy another motor since fixing it is almost never cost effective. Detonation is something that turbo motors have to be able to handle occasionally.

I'm not saying Hal's car is a factory freak...just saying nobody's repeated those numbers so there's nothing wrong with being cautious about cranking up the boost. Feel free to prove me wrong...bolt up a big turbo and crank the boost controller all the way up. Everyone else turbo @10-11psi hits ~320+ whp w/o serious fuel tuning so it should be comparable to Hal's setup w/o N2O. I think they can see ~350 w/ good tuning. That's still a long way from 476 running @10:1 rich even w/ nitrous.

Don't get me wrong here...I have turbocharged 2 VQ's and they definitely hold up under boost nicely. But also remember the 2 cars that I did are still running original motors. The majority of turbo Maximas in the ATL area have blown a motor for one reason or another so I prefer to be cautious in upping the boost.

dmontzsta

iTrader: (8)

Personally, having a powerful Maxima is nice. But, once you get to around the 400whp mark that is enough for a Maxima, it sort of becomes uncontrollable in corners, you break the tires loose and it is danger with the fwd. If you want something FAST build on a better platform and keep the sleeper Max safe and reliable.

subs1000w

i would also say 400whp is good enough for MOST people but there will be others will will always want more but being in the 11's in a stock looking 4 door sedan is about as sleeper as you get

IceY2K1

iTrader: (3)

Ok...I bought it.

Not sure if it's a misprint or not, but they're running:
JUN cams w/272 duration and 9.8 lift
STOCK valves
JUN valve springs
JUN pistons
JUN cylinder head
Greddy intake
JUN intake manifold
VH45 throttle body(Q45?)
JUN 740cc injectors
JUN headers
JUN titanium exhaust
Greddy T88H turbo and blow-off valve

Now, I don't care why they *SUPPOSEDLY* chose the VQ30 over the VQ35, since the internals are custom, but the fact that they're calling it 3.8L makes me think it's a misprint on the VQ30.

Can you really bore and stroke out a VQ30 to 3.8L?

SOMEBODY needs to find JUNs phone number that speaks Japanese, so we can find out more on the valve springs, cams, cylinder heads, AND 3.8L bore/stroker kit~!!!!!!!!

As for the shorter stroke, yes IIRC. Shorter stroke = slower piston speed, so you can rev higher, which is better for TOP SPEED.

subs1000w

well considering the biggestrocker kit ive seen for a 302 is 347 which would equal 5.0L to 5.7 i seriously doubt they can take a 3.0 to 3.8 but taking a 3.5 to 3.8 im sure is posible

Quicksilver

iTrader: (1)

If you stroke the 3.0L, you get the 3.5L. Bore that, and you can get the 3.8L. That's my guess, but I haven't really thought if it is possible (or played with the numbers).

Quicksilver

iTrader: (1)

I don't think that most 350Z's are described as having a VQ30...

If it were, then they would call it the 300Z and the G30C...

stephenlc

iTrader: (1)

He probally has a VQ30DET in there. Anyone have pictures that they can post?