SR20DEN

iTrader: (7)

It looks like the VQ35HR spring is the way to go. It isn't linear like the Nismo spring so it doesn't have the seat pressure but it does have much higher full lift pressure and it can go all the way to 13mm vs. the Nismo spring at 12mm.

This means that even with 11mm lift cams you can double shim the HR spring to raise the seat pressure and still not get coil bind (for a total of 12mm effective spring lift pressure).



Thank you Nissan!



edit: Those colors I listed with each spring is the paint color mark from Nissan. And IIRC, some VQ30 springs had yellow.


VQ35HR valve spring part# 13203-JK21A

LA02MAX

iTrader: (3)

Excellent information as usual SR20! HR pistons/rings/valvesprings sound like a good, affordable option for those of us with VQ35s!

Nietzsche

iTrader: (7)

Great charts, here's a noob question; if doing cams on a 3.5 would the HR springs be comparable to JWT, Crower etc..? I'm new to engine building and it's specific requirements for higher revving and stability.

SR20DEN

iTrader: (7)

I have seen a few errors in the VQ35HR service manuals, now it would be nice to see someone confirm the 37mm install height for it's valve springs (which is the same as all other VQs).

NmexMAX

iTrader: (22)

MMmk, double shim HR springs to get Nismo equivalent or better seat pressure, and still be able to achieve higher lift w/o coil bind when using ub3r aggressive camoids, and for 3x less price, with more potential than said Nismo pieces, I think.

I think I'm getting better here. I get up to speed in electronics, and now for mechanical

Thanks, once again, SR20DEN =

SR20DEN

iTrader: (7)

Untill I physically have a spring in hand to test i'd rather not speculate.

I did this chart in 1mm increments to make it somewhat easier to compare with other manufacturers listed specs but those advertised numbers still won't tell the whole story. If anyone wants to send me a Ferrea, JWT, Crower or Supertech spring, I'd be most happy to spec it.

SR20DEN

iTrader: (7)

Well the seat shims are 1mm. So if you double shimmed the HR spring just look at the chart +1mm. ex: The seat pressure on that spring would be 43lbs instead of 36lbs. Still not the same as the Nismo but slightly better than stock. There is also a possibility that you could triple shim this spring, since they aren't binded at 13mm lift (but really close).



I also want to add that with the HR springs, you should use the HR retainers. IIRC, they have a little more meat on them.

Ephraim

iTrader: (15)

man, the more time i spend on here learning about nissan engines the less it seems like i will ever switch over to another company.
this is some pretty interesting info.
question though, what is the importance of having higher valve lift? allowing more gases to enter and escape or what?

nismology

iTrader: (8)

Nice comparo.


So we know it can handle lift. But can it handle revs? The valve is at full lift for a small fraction of the time. I think I'd still opt for a spring with more "area under the curve" when dealing with 11mm+ lifts @ > 7500 RPM, for instance. This might be fine for moderately aggressive cams at reasonable revs, though.



Just for reference, from Z350lover's experience the valves floated with the Nismo springs @ 11mm/7500 RPM.

SR20DEN

iTrader: (7)

But do we know that the area under the curve is really that important here? You want the extra pressure at max lift to keep the valve from going past max cam lift from inertia. That spike is nice to keep the bucket planted firmly on the tip of the cam lobe and get it set in motion in the opposite direction to close. Once it is already in motion do you really need a linear force to close it in time?

That extra linear force also robs the engine of useable torque. Which is another reason why I like the idea of this progressive spring.

He was also using the 55* CVTCs and the 272* cams. Both are to be considered reguarding his problem.

But we have the specs of the VQ35HR to look forward to. It does also rev to 7500 and has a 10.5mm cam lift, not far from the 10.82mm R Tune Nismo cams or the 10.9mm JWTs. Granted those have a higher duration.

Theyears02

this spring does have a higher pressure at that amount of lift, although it is just a small bit more it could be the difference between valves floating and not floating. also, like SR noted, the spring is progressive so it robs less power down low but is stronger up top...best of both worlds

eng92

iTrader: (3)

"Area under the curve" only gives you the amount of energy input required to compress a spring. Generally you want the smallest amount to get the job done in order to minimize wear and valvetrain losses.

Peak valve acceleration occurs for only a brief moment as you come off the crest of the cam. You really only need a relatively large force at this point in order to reverse the direction of valve travel. The HR spring seems to fit this bill better than the other springs presented. (for 10+mm lift)

The brute force method of throwing more spring force at it will not necessarily solve potential valve float issues.

Was that due to insufficient spring force or surge?

You need to be careful when mixing and matching valvetrain components from various vendors and motors for high rpm usage. It is pretty easy to throw some high lift/duration cams, high force valve springs and lightweight valves, retainers, etc. together and think you have the ultimate valvetrain. What you do not know is what you have done to the critical frequencies of the system. (ie. spring surge)

nismology

iTrader: (8)

Logic tells me that spring pressure during ramp down is important as well depending on the ramp down rate. Most aftermarket cams have an asymmetrical profile though (as you already know) to keep from shocking the valvetrain too much so maybe reality > my logic.

I used to think the same thing as well. But although a stiffer valve spring resists the opening of a valve on the ramp up side more than before there's a spring somewhere else in the engine closing a valve with the same force. Not completely in phase, but i think the net effect isn't as bad as one would think.

They're actually 276's on the intake side, but ...

Hey, if doubled up HR springs can handle 8k @ 11mm+ lift, i'm sold.

nismology

iTrader: (8)

Understood.

All i'm saying is i don't feel completely comfortable with how quickly pressure drops off. Especially considering i'm gonna need a spring that can handle 8000 revs indefintely @ > 11mm lift. And i'm not exactly thrilled by the prospect of experimentation.

Haven't heard of a supertech or ferrea dual-spring set failing, ever.


No one really knows why EXACTLY why they floated. I don't think he cared to know either. He went with a ferrea dual-spring kit and revs to 8k and beyond with no issues @ 11.3mm lift.

He was/is using nismo spec 1 camshafts, FWIW.

SR20DEN

iTrader: (7)

I wouldn't do that.

Ferrea or Supertech valve/retainer kit.

AnDyMaN

iTrader: (19)

i guess dual springs means simply 2 springs on top of each other?

also, the HR revs to 7,500, so shouldn't the HR valve train theoretically be able to handle the 8k rev and 11+mm duration? i assume that real world usage is different than theoretical usage.

so, to break it down. using the HR valvetrain in a fwd vq35, revving to 7500 shouldn't be an issue right? and with cams like nismo r (10.5 lift, 262 duration), revving to 7500 with that lift definitely shouldn't cause any trouble seeing as the rpms are oem(HR) with just a little more lift than stock HR cams... right?

any info on HR rod bolts? i dunno if they are designed the same, but from what i've read on here, revving to 7500 rpm on vq35 rod bolts = not a good idea..

SR20DEN

iTrader: (7)

I am revving to 7500 now with the stock valve springs and cams. But there is still no guarantee that the HR springs will do the job to 7500 on cams that have 1.32mm more loft and 24* more duration than the VQ35 OE cams.

There is only one way that question can be answered. Someone has to do it.

AnDyMaN

iTrader: (19)

i see, so a real big factor is the cams have more lift and duration that stock cams....

what about the rod bolts? do HR fit on the vq35? or is that a completely diff design?

btw, you have rod bolts at least right?

SR20DEN

iTrader: (7)

I know nothing of the HR rod bolts. And yes I was the first to install the ARPs. That was a great investment IMO.

SR20DEN

iTrader: (7)

Retainers;

So I have to retract my statement about the HR retainers. I haven't seen one and I do not know anything about them. I confused them with the VQ35DE revup retainer which I do have one of.

Maybe I will order a HR retainer now but here are two pictures I just took of the VQ35DE (2002) retainer next to a revup retainer. You can clearly see the difference in extra mass on the tops.

http://www.vq35de.com/Images/valvesp...etainers01.jpg
http://www.vq35de.com/Images/valvesp...etainers02.jpg

And if you ask why would you want to use the factory retainers, the answer is simple. Mass. These are made from an aluminum alloy which has LESS mass than titanium. If you buy titanium retainers they will be stronger but are also likely to weigh MORE than the OE retainers.

steel > titanium > aluminum

DandyMax

iTrader: (7)

Thanks Matt for the info. Just for fun can you add the VQ30 spring to the graph?

Also, did you ever have a chance to mic any of JWT's springs?

SR20DEN

iTrader: (7)

From what I have checked in the past, the VQ30 spring is exactly the same as the early style VQ35 spring.

Everyone needs to be aware that later style VQ35 springs are weaker (A34 etc.) according to those ESMs.

DandyMax

iTrader: (7)

I knew the newer VQ35's are weaker but I seem to remember as per your post back in (~May 06?) the VQ30's were stronger than the early VQ35's?

Then again my memory's bad... I'll look for the thread if I get a chance.

*edit*: found it, they are the same. Guess I just remembered wrong.

Nietzsche

iTrader: (7)

That's not very reassuring How high can a A34 spring go on stock cams without worry. Don't they use the same springs as mrev Z33's?

SR20DEN

iTrader: (7)

Well now I have to take that back. According to the 2006 ESM, it's pretty much the same as the early VQ35s. But it gives a wide tolerance.

The way they spec the springs in the ESMs makes it difficult to compare them.

Nietzsche

iTrader: (7)

On stock internals would revving to 7k be unadvisable?

SR20DEN

iTrader: (7)

[QUOTE=Nietzsche]On stock internals would revving to 7k be unadvisable?[/QUOTE

There are dozens of threads about how high a stock VQ35 can rev.

7k-7200 is fine

AnDyMaN

iTrader: (19)

im a little confused

so by your greater than/lesser than diagram, steel is best, then its titanium, then its aluminum?

but in the paragraph you talk about why the OE retainers(aluminum) are better (because it has less mass).

could you please clarify?

eng92

iTrader: (3)

He was referencing the relative specific weights of the three metals.

Aluminum is about 1/3 the density of steel.
Titanium is about 1/2 the density of steel.

AnDyMaN

iTrader: (19)

got another one for ya. you say you rev to 7500 rpm.. do you hit that daily? like maybe once or twice a day?

i ask because i remember reading that someone's oil pump failed because of the constant high rpm they were seeing (all motor).

will the stock oil pump stand upto 7500 daily? if not, would the 350z oil pump be able to work in a maxima directly?

Nietzsche

iTrader: (7)

You can use the rev-up pump on a Maxima. I'd look into seeing if the HR pump would fit though.

Theyears02

i recall hearing/reading that the HR oil pump is the same pump that was used in the rev-up

SR20DEN

iTrader: (7)

I probably average hitting 7500 a few times a week. I usually don't rev past 7200.

The oil pump failures are on the VQ30, not the VQ35. The VQ35 oil pumps were the same until the revup cam out.

Nietzsche

iTrader: (7)

I looked in the FSM's and the HR pump has a different housing and bolt pattern so that's a no go. There is no distinction between a revup and nonrevup oil pump in 05. Are there any differences?

nismology

iTrader: (8)

They have a different part number. I remember reading on my350 that there was either a 17% or 19% increase in efficiency with the the rev-up pump. Either way, from what i've seen the regular non-revup 350z oil pump (aka maxima/altima/etc. pump) is good for AT LEAST 7500 RPM.

Nietzsche

iTrader: (7)

That's the conclusion I was coming too. Plenty of turbo Z's with standard oil pumps.

Theyears02

but they arent/shouldnt be revving high. its not power thats the problem usually, just high RPM

nismology

iTrader: (8)

Ummmm.... WHAT?

Theyears02

the boosted z's, shouldnt be revving to 7500+. unless i guess they are on low boost. either way, what i was saying is that a better oil pump is more for higher RPM safety than high HP at lower RPM

nismology

iTrader: (8)

True. But from what i've seen on alot of the buildups is that they'll throw in the rev-up oil pump for good measure even if they don't plan or revving past 7500 RPM or so.



But enough of this irrelevant OT mess.