Valve spring drought
#84
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
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
Last edited by dsamani; 06-21-2019 at 01:57 AM.
#85
mkturbo.com
iTrader: (24)
Join Date: May 2006
Location: Charleston SC
Posts: 15,176
Total Cats: 1,680
In stock. just talked to them. actually have an invoice ready.
5.50$ each. = 88$ a set.
8$ shipping.
Valve spring B18/B20/B30E/F
email John@vp-autoparts.com
phone 8437600170
stateside address. 3225 Fortune Drive STE #B North Charleston SC 29418
Order yourself some. and Cat me up.
have a great day.
5.50$ each. = 88$ a set.
8$ shipping.
Valve spring B18/B20/B30E/F
email John@vp-autoparts.com
phone 8437600170
stateside address. 3225 Fortune Drive STE #B North Charleston SC 29418
Order yourself some. and Cat me up.
have a great day.
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.
#87
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.
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.
#89
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.
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.
#93
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.
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.
#96
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.
#97
Senior Member
iTrader: (1)
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,234
Total Cats: 283
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.
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.
#98
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.
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.
#100
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.
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.