Putting in Work Ian. This is great stuff!

 

Curious to see what we learn about the VS855 once you test since they're all over the place. And to think that I tossed out a set of NA8 Valve springs...

 

Darn, it looks like this comes about just as I'm getting ready to build my motor.

 

I found this spring on Summit, not sure if it helps

https://www.summitracing.com/parts/slp-vs-651/

Edit: after further research it seems the seat pressure of this spring is less than that of stock

 

I just ordered a set of springs from them. I am heading over Friday morning to meet the guys at their shop and pick up the order.

 

What do you guys think about the options from Brian Crower?

 

I bought 16 of them last week from this eBay page:

https://www.ebay.com/itm/Valve-sprin...1a35%7Ciid%3A1

When I messaged the seller to make sure he had them in stock he told me has 100+ of them. This was the only place I could find them as of 7/5/19, free 2-day shipping to 48 states.

 

Brian Crower sells quality components. I have his forged rods in my motor. Haven't tried his springs yet.

 

https://www.dropbox.com/s/p4ovihvg5a...Rev2.xlsx?dl=0

Big shout out to Schroedinger for sending Qty 6. of his uber rare VS-855 springs.

Got the average of the 6 units added to my Rev 2 spread sheet. By far the strongest of all the springs.

 

That’s great. I halfway expected them to be the same as the OE NA8 springs.

So no concerns about coil bind height either?

 

Not on a stock VVT intake cam with 9.4mm lift. Not the ideal 0.065-0.070" bind clearance to minimize spring harmonics but on par with the OEM VVT Exhaust spring clearance.

 

I wonder how the light doubles and heavy doubles compare.

 

Would it be a reasonable idea to use the stronger spring on the intake and the factory spring on the exhaust?

We aren't trying to seal against incoming boost pressure on the exhaust side, and the internal pressure will work to seal the exhaust valves on compression and ignition strokes.

Perhaps the extra stresses aren't worth worrying about, but there's a reason Mazda saw fit to do so on the VVT head.



Thank you for all this work @ian99rt , it fills in a lot of blanks in my limited knowledge.

 

.....

 

I can't speak for everyone, but I see valve springs more as precautionary over rev protection then bleeding edge performance.

 

There's an increased pressure on the exhaust side on a turbo car as well. For my Rotrex build though, I will be doing something similar; using the OEM VVT intake springs on the exhaust, while using Volvo ones on the intake, in an attempt to not increase parasitic losses if there's no need to (most probably by a negligible amount, but makes me feel better)

 

Valve spring pressure will not contribute to "parasitic loss" in a way which will cost you power. Equal and opposite reactions are taking place. For every valve working against spring pressure to open, one is working with spring pressure to close. Furthermore I have NEVER seen an engine (bossted or NA) make less power with stiffer springs(sure it would happen at ridiculous seat pressure...but in 20+ years of experience, I've never seen it happen), quite the opposite has happened. Controlling valve movement is paramount to making valves live, guides live and making the most power you can. As long as your lifter surface area, valve keepers and retainers can withstand the pressure (and ours can hold well over 100lbs of seat pressure and more than 300 over the nose) there is absolutely no downside (other than cost) to running the stiffest springs you can afford.

Springs are also a wear item. Like any other spring, they will lose pressure with use and the alloy used in the cheap Volvo springs will lose pressure at a more rapid rate than even the stock Miata parts.

I ran these springs for half a season in a Autocross motor, killed a set of valves and tested about 15% lower on the seat when they were puled out of the motor.

With Valve springs being such a highly important component for reliability and power, I would be using the absolute highest quality and highest pressure springs I could afford.

 

necro bumppp

Thanks for all the info and research @ian99rt. Would be interesting to see the products supertech makes on the bench too. (There is another thread floating around measuring ST singles and heavy doubles, but different equipment and measuring method)

After reading all the research, it seems that a potential combo for a BP6D head with stock cams would to the keep the .020 shims and simply swap the springs out to NA8 valve springs. Coil bind clearance is acceptable, and you simply just get better seat and open pressures. (~25%)

Has anyone tried this? I don't see why it wouldn't work though after reading spring spec sheets.

This could work for many people who are running lower boost or just want some over rev protection with their NA motor. Yes corner/cost cutting and valvetrain should never go together, but let people make that decision on their own with some good info.

 

I'm running NA8 springs in my VVT bottom end/BP4W head N/A build with stock MSM cams.
I have my redline set to 7400 with the knowledge that a bad enough misshift at redline is probably going to mess some stuff up.

 

Also here is that other thread I found with some good data: https://www.miataturbo.net/engine-performance-56/mazda-bp-valve-spring-info-70450

Neat. Did you decide to do that due to the data in this thread?

In all my research and calculations, it really seems to be a good bang for the buck if you're not looking to rev out much, and it's been sitting in front of us for a while. That's assuming that I'm not totally missing something...which is very possible.

With the supertech stuff, if you look at their specs they really don't make sense. Their claimed spring rate for each offering doesn't line up with the other specs they list (seat pressure and open pressure) and what people have measured themselves. If you calculate it out (assuming the force is totally linear, but that assumption is close enough for most things). So who truly knows what is right besides the pros who simply found out when they float/bust stuff.

The VS-949 ones from rock auto are out of the question due to the coil bind clearance being too close for our cam. VS-855 is unicorn dust now. (Found out today the manufacturer is not making them at all as previously mentioned)

It's just the choice now of ST singles or go with the OEM NA8 valve springs for a stock redline/7400 RPM build with a BP6D intake cam. Obviously the NA8 springs work, but do yall think they really are helping much? On paper they seem like they would, and be a worthy upgrade/money shift protection if you're not going all out with ST.