Actual valvespring tests today, except for the Maxima spring. I will go back later and get that exact data to make the comparison more accurate.



Yes I too thought my test data was wrong and the guage was innacurate (this time). Then after I compared the revup spring data to the ESM specs It became clear that my data concurs with the ESMs.

I will go back later and do another real mic. of a 2k2 Maxima spring, which posted currently is the ESM spec. But two years ago when I mic'd some on this same guage they were correct. At that time I also mic'ed 48 VQ30 springs for Mardigrasmax and they were at or slightly above ESM specs. And according to the ESM the VQ30 and early VQ35 springs were the same.

So now we know that newer 350Z valvesprings are weaker than the old ones. I'll start sifting through the ESM data now to determine when this change occured and on what vehicles.


However the retainers are a little different story. The revup retainer is still made of an Al. alloy but it seems to be a few grams heavier than the older ones. The only visible difference is from the top veiw where you can clearly see the new retainers have a little extra meat around the keeper area.




As for the BMW S52 springs, those can't be used because they're the wrong shape. I just wanted to compare them.

 

It appears (per ESMs) that the spring specs got a little softer each time the engines got more powerful. The 2004 model year Maxima and Z have softer valvespring specs than the ones before them.

So far the highest rated OE valvespring is on the original VQ30, but I don't think there is a real difference between those and the DE-K springs.

 

You are referring to the valve springs that they recommend you upgrade when you want to rev high in the RPM band with a VQ35?

 

Ah cool I was wondering if you'd had a chance to do this today Matt (well yesterday now as I post this.. haha)

Thanks for the info. So the Nismo's are about 10-15 lbs stronger on average it seems. Will file this for future reference.

 

I can send you a 2005 VQ valve spring or two if they'll be returned in a timely manner.

 

There is no way I can promise a time frame since my access to the spring tester is limited. That spring will probably be the weakest one of the bunch anyway.

 

Nice info, wish I'd tested my valvesprings before I installed them.

 

I would guess that the springs got softer because the valve train got lighter, perhaps?

 

I haven't found any evidence to suggest the 2005 valvetrain is any lighter than the 2002 valvetrain, but that is certainly possible.

 

Well I suppose stiffer than necessary springs technically do hurt performance...

 

Bump. For the search impaired.

 

So which one of these valvesprings do you have?

 

I still have the stock springs and cams. But since the question was on everyones mind, or so it appeared to be, I decided to do the research myself and display the facts.

 

Cool. Thanks for the quick response.

 

Darnit Matt I came in here thinking maybe you'd actually spec'd some F's now...

lol. j/k.

 

I will let you know when I finally get my hands on the Ferrea samples.

 

Please do, thank you.

 

Not sure what Ferrea springs cost, but BC Dual springs $309.60

http://www.briancrower.com/makes/nissan/vq35de.shtml
http://www.briancrower.com/dl/06pricelist.pdf

Ti Retainers $240.60
Dual spring/Ti retainer/seat kit $593.90
Stage 2/3 cams $857.15
4.15L Stroker Kit $4785.75

 

Time to take out a HELOC.

 

Bumping this thread because I've been getting questions about how JWT springs fare against the HR's, and SR20DEN's original graphs didn't include JWT (IIRC).

SO, the following graph shows the picture. Credit to SR20DEN for the original VQ35HR curve, and the JWT data is from their website and assumes they are a linear spring. If they aren't, the JWT curve is invalid.

 

so the Hr's double shimmed is the way to go from what i see?