Mazda BP Valve spring Info
 

Mazda Valve springs

I took some time and checked out some valve springs for the Mazda 1.8 BP engine.

For a base line I checked the SBI catalog.
SBI replacement valve spring
Part # 160-1250
46 lbs @ 1.600
1.831 free length

AERA, Automotive Engine Rebuilders Association
States the spring installed height is 1.555
The spring pressure is 50-57 lbs closed
OnDemand5 lists the spec as
39.5mm/1.550 installed @ 19.9kg/43.87lbs

I started off by checking 8 valve springs from 2 different heads.
All testing was done using a installed height of 1.555/39.5mm
https://www.miataturbo.net/attachmen...ine=1358219468
I found they fell in the range of 37-40lbs
When the factory .020 spring seat was used they came up to 40-43 lbs.
So close enough to be put back into use for a stock rebuild.

Next up are SuperTech,(ST) and Brian Crowder (BC)
https://www.miataturbo.net/attachmen...ine=1358219468

I know the ST is widely used on this fourm.
I started with the ST Dual springs, that are advertised to be 74lbs @ 33.75mm/1.329
https://www.miataturbo.net/attachmen...ine=1358219468
The ST is a bit light, when the math is done, Keep in mind ST supplies a .250 thick spring seat.
So 1.555 - .250 = 1.305 So .025 shorter installed height
So I tested, I found the springs will install 90lbs @ 1.555
This is a bit off still, due to the inner spring not being fully compressed from the Ti retainer not being installed.
Now I pulled the inner spring, so it would be a ST Single spring
https://www.miataturbo.net/attachmen...ine=1358219468
On the ST Singles, ST advertised 56lbs @ 34.2mm/1.345
But here again, with the thick seats, the installed height is shorter by .040
When I pulled the single spring with the thick spring seat, I measured 70lbs

At this time, I have not checked the ST Ti retainers against a stock retainer to see if they step up or not.

Now on to the Brian Crower valve springs.
These install 80lbs @ 1.420
If the same .250 thick ST spring seat is used, the seat pressure is a whopping 110 lbs
https://www.miataturbo.net/attachmen...ine=1358219468
That is a bit high, so I need to drop some seat pressure.
Now with two .060 thick shims, .120 total
https://www.miataturbo.net/attachmen...ine=1358219468
I get 80lbs on the valve seat.
I like this for a boosted application.
The math works out better also
1.555 - .120 = 1.435
If I add a .015 thick shim, I will have 84lbs on the seat.

Since these are a cost effective spring, that does not require a custom spring seat and will work with the stock retainer, I can see this set up going into use on a wide range of builds.

Neat!

What's the difference in price? I've not heard of BC, and I think the bias tword SuperTech around here comes from brand recognition more than anything else.

One question and a couple of notes.

So you're basically doubling the seat pressure from stock?

You can look it up in your books, but I had heard that the earlier Miata engines, maybe 1.8 94-97 had slightly stiffer valve springs. I had also heard that volvo b20 engine valve springs were used as a hi-po upgrade.

I use a ton of the BC springs on the 4g heads I build. So I was talking to them one day and wanted to find a budget spring of sorts for the Mazda, so I gave them the spring specs from a used BP spring, and found these.

No as far as price, the ST single kit w/Ti retainers and thick spring seats is around the $325 range, The BC springs with commonly found spring shims along with using the factory used steel retainers will go about $125

I still need to check how the shims and springs fit on the head casting, from all I have checked to this point, it looks to be a solid set up.

Getting close to double the stock seat pressure, of 43-44lbs

Keep in mind that when the engine is boosted, the valve spring is given a second job, the spring now has to keep the valve closed against boost pressure.

Figure that there is 1 sq/in of area on the back side of the intake valve, now add 20psi of boost, you loose 20lbs of spring pressure just keeping the valve closed.


Ill check my books and look into the springs you mention.

Slmhofy

Checking my SBI catalog, the springs 160-1250 are for the 1990-1997

As far as the Volvo B20 spring, SBI does not have a listing for springs, it could be beacuse they are an older engine, B20B and B20E were made from 1969-1978 and is an OHV

Roger that. I was just trying to throw out some information as it seems like you love knowing everything there is to know about what you're working on.

Do you have a part number for the BC springs?

This is a very informative thread. A+

The question I always wanted to know is how do you calculate the desired seat pressure for valvetrain weight, camshaft specs, and rpm range?

Don't you want to have just the right amount of spring compression for your application? I have seen too many motors with springs way too big for a particular application, throwing horsepower away.

Another question, can't too much seat pressure put unnecessary strain on the camshaft causing accelerated wear to the lobes? At what point is too much seat pressure undesirable?

I'm wondering the same thing as the 2 posts above:
whats the perfect balance for your average boost setting (10-15) and/or a bit higher (20+)

Something tells me that you don't want to go too stiff, or you'll be putting excessive wear/tear on your valvetrain and/or throwing away power.

Some completely un-educated guessing here: if a stock motor operates at 1 bar and you're running 15+ psi (2 bar) then the double spring rates shouldn't be too bad? Probably doesn't work that way, just guessing

True, the more info I have, the better understanding of what I am working on.
Thats what brought me to this foum in the first place.

"Now you know, and knowing is half the battle!"
I would say I watched GI Joe a bit often growing up ;)



Not at this time, this is a set up that I am working on with BC.

Honestly, I tend to be a tad heavy with spring pressures.

The springs first job is to keep the valve in contact with the cam, nasty things happen when it fails at that job.

Ramp rates and cam lift, have to be taken into account, along with boost pressure.

Also you have to allow for wear on the spring, after a season of track use,or a year or two of "fun" street use, the seat pressure will be a bit lower than new spring.

I do not know a fourmula for figuring spring pressures, it boils down to the head builders experiances.

But you are correct, they can get too heavy and cost HP, or be too light and cost HP and/or damage.

Can I ask a stupid question?

How did we get along before BogusSVO showed up here and starting posting Awesome

???

...

???

Please let me know ASAP when I can buy these BC springs for $125ish, I'll take a set!

18psi...A stock engine is NA, so it operates in a vacuume, springtions do not have to be as much as a Turbo engine.

When you add boost, the spring now has to hold the valve closed against the boost pressure.

With a stock 1.8 intake valve, there is appox 1 sq/in.

So the first thing you do is subtract boost pressure from spring seat pressure.

So with 18psi of boost, and 70lbs on the seat ( ST single if dropped in) leaves 52lbs of spring pressure to keep control of valve motion with the cam.

Factory spring is 43, so you have 9lbs more than stock.

Efini, Once I am happy with the set up, and get back with BC on them. I will let you know.

Curses! A potential value option starts to form just after I had my 99 head redone with SuperTech

Interestingly, I never though to account for boost pressure trying to keep the valves open. I always wondered about others having issues with valve float, when I was running the same valvetrain at a higher rpm. Them being turboed and mine N/A.

Ok. I have been using the Sealed Power ZVS855's. They are about $61 from Summit Racing. At 1.56" installed height they have roughly 66lbs seat pressure and work with the stock retainers and keepers. Just interested if these are a better option.

When is there less pressure inside the cylinder than there is in the intake manifold and you want the valve to be shut? During compression, power, and exhaust strokes there should be more pressure in the cylinder, right? During intake, the valve is open. Or is it just for the brief transition periods around overlap/etc?

--Ian

Exactly what I was going to ask next.

I'm guessing he's talking about the split second transition

So what you're saying is... backpressure from the exhaust manifold or intake manifold can apply pressure pushing the valve in, while at the same time having it beat on my the CAMs causing it to float and turn effectively into a torch, burning the exhaust valves, yes?

In theory, assuming a very low friction environment (which the cam/spring area should be, since it's bathed in oil), shouldn't the hp loss be negligible between light and heavy springs?

Sure it's harder to open a valve with a heavier spring costing hp, but the spring rebounds after opening with more force as well. It'd like comparing the overall work lifting a 10lbs weight 5 feet then letting it drop, vs lifting a 100lbs weight 5 feet then letting it drop (say you're running a turbine or something). In the end the total amount of energy gained/lost from the system in a frictionless environment should be 0 in both cases.

I'm sure there's some additional frictional losses compared to stock, but I bet it's not enough to worry about when debating installing better springs.

I will look into these springs, what life span have you been getting out of these springs?


The main point will be when the intake valve has reached full lift and is now closing, the spring has to pull the valve closed, through the mass of air flowing into the cylinder, also the intake valve must remain closed during the power stroke and not "blow" open. Now if the intake "blows" open on the exhaust stroke, the exhaust gases will diluite the next intake charge.

Valve float happens when the valve "ramps" of the nose of the cam and slams back onto the back ramp of the cam.

A burnt valve can happen for a few reasons, one of the main ones is not enough contact between the valve face and the valve seat. Not enough heat is transfered from the valve and it burns.

Another common one is the valve or seat distort in shape causing a small opening between the two, then you get the torch effect.

In case of the BP, it will make more friction due to the design of the valve train, sliding the cam lobe over the bucket.

But it is a common design, Mazda, Nissian, Toyota, Ford and Jaguar all have heads that use it.

Common sense, logic and experiance all come into play, Instead of finding a spring that installs at 80lbs, I could find one that installs at 150lbs.

But there is no need for a 150lbs set up,at this time, I have not heard anyone here running 50+ psi of boost and spinning 12,000 RPM

Hoping to do some headwork in March/April. Any thing more to say on alternative springs from Crower and Sealed Power? I'd love to get a decent set of slightly stiffer springs for under $175.

I bought a set from Summit and compared them to the stock 2001 springs. They seem to be similar height and diameter, the material is considerably thicker and they felt much stiffer than stock ones. I had my engine machinist to check the stiffness on his load cell unit with dial gauge height measurement. The load cell was calibrated before testing to his calibration spring.

From Summit info:
Universal:Yes

Installed Height (in):1.570 in.

Seat Pressure at Installed Height (lbs):66 lbs.

Open Height (in):1.180 in.

Open Pressure (lbs):175 lbs.

What was measured:
At installed height of 1.550", the seat pressure was 84 lbs.
At 0.350 compression from installed height (1.200") the seat pressure was 180 lbs

The original stock spring was measured to have seat pressure of 46 lbs at 1.550 height and 118 lbs at compressed 0.350.

The stock valve spring has yellow paint mark on it.

Right now I am waiting to confirm the installed valve height for +1 Supertech valves and then deciding which springs to use.

Anyone run the Eibach singles? $180 from Summit. They claim 66 lbs @ 39 mm / 200 lbs @ 27 mm. Lift 12 mm / Bind 24.2 mm. Looks like a middle option in price and pressure from OEM. Would like to hear some comments.

http://performance-suspension.eibach...vs-catalog.pdf

So if a spring uses a thicker shim seat (read ST) does that mean spring pressure at full lift is higher than one with a thinner shim (assuming same installed pressure)?

No, the difference between seat pressure and full lift pressure depends on spring k-value, which is used for determining "stiffness" of spring.
As long as the spring operates within I design operating lengths the spring force is linear depending on the distance it travels. Google hookes law.

To keep the valvespring in this operating mode the length should be kept such that there is no binding of coils at full lift and installed height being longer than free height of the spring. Having couple of mm safety in these lengths would be advisable.

Bump from the dead, thought I'd add my findings here:

@ 1.181″ 165lbs
@ 1.200″ 180lbs

Coil bind at 26mm.

I actually ended up returning my set of Sealed Power VS-855 to Summit Racing. I noticed that the surface finish of these valves are very coarse and rough, there is definitely a case of "you get what you pay for here".

https://www.miataturbo.net/attachmen...ine=1385708228

https://www.miataturbo.net/attachmen...ine=1385708228

You can definitely see the coarse grain structure here:

https://www.miataturbo.net/attachmen...ine=1385708228

Not all spring steel is the same, I ended up using a set of Mazdaspeed duals even though there is an exponential cost difference.

I didn't see this really addressed here, so I'll take a swing at it.

I prefer simple calcs, and you can look at this very simply from a NA vs boosted situation. It's harder to consider changes in rpm, but that can be done as well, but there are velocity/acceleration/mass considerations to make.

Anyway, if you know your valve head area, you can simply consider this a pressure force calculation.

Assuming vacuum as an NA was 15 inHg (7.4 psi vac) and then you go turbo and boost to 15 psig. For sake of argument, lets assume the valve head area is 1 sq in (I don't know the valve size, forgive me, I'm new to miatas).

The calc would be this simple: (7.4+15) * 1 = 22.4 lbs

So in this case, to balance everything out, all else being equal, you'd want to add 20-25 lbs to your spring load.

This of course is ignoring all sorts of other potential effects and impacts, and over simplifying. But it beats guessing.

This would be for the intake side. You'd also want to consider that exhaust pressure between the head and turbine could be double that of the intake manifold pressure. In really small turbos, it could be triple.

An interesting article I stumbled across tonight: Beehive Springs Sound Great, But Will They Work For You? - EngineLabs

Although the article really is discussing the benefits of using a beehive design spring, I think there is some information to take away.

One being that seat pressure is being minimized as much as possible with a beehive spring, lowering the amount of stress that the valvetrain sees. The shape of the beehive spring is supposed to help with valve acceleration compared to a conventional style spring based on the shape of the coils near the top.

This could be related to the discussion of single spring vs. dual springs in our Miata heads, with the common dual setup offered by Supertech. I read a lot of discussion on the easy choice being the Supertech duals, but no real math behind it; just the fact that it worked well for the last guy therefore was good stuff.

Resonance in the valvetrain is also briefly discussed. They make a mention of the ovate wire used for spring steel material to counteract the resonance encountered with high rpm frequencies. What was more interesting though was that they mention choosing an installed height as close to coilbind as possible. I think general rule of thumb for installed height is determining the amount of lift, give or take a few mm so long as the spring does not bind at this height installed. This means that a shorter spring which has been shimmed to the appropriate height can resonate less than one which has not been installed close to coilbind.

+1 here on the zvs855 from summit. revving to 9000 and after two years of drag racing everything still going strong....

Can you install stiffer valve springs on the 94-97 HLA heads? I have things torn apart and it wouldn't be that much more work to get in there and upgrade the springs.

Any update on these BC springs?
Seems like summit is not selling zvs855 anymore, are there any good alternative?

Good read.

I was wondering if the Eibach EVS Valve Spring Set with 75lbs was over kill with dual springs and Titanium retainers?

Even though the supertech is what is highly recommended on this site for rebuilds and they are significantly cheaper from my search 55 dollar difference.

I will be using a fluctuating psi for different purpose in the boost application for street, autocross, and track. I am going to use upwards of 8 to 12 for autocross and +20psi track.

zvs855. 32psi 9000rpm last year for a full drg season no problems at all

What car are you referring to? I'd like to check it out if you've got anything on written about it on here.

I've had the BC springs on my head for just about a year and a half. They've ran great so far. 270WHP street car forged pistons/rods and buzzing it to 7500.

I haven't spoke to Bogus for a long time though, so I don't know the status on the springs. And I don't know the part number.

What is the difference between zvs855 and vs855?
Where would I be able buy these springs?

sorry. nothing here about the car. it was in a protege 97

i scrapped the car this summer
was tired of broking the transmission

car was trapping around 135-140 mph

Holy crap!

Not sure of the difference if there is one. And not sure where to buy. I think I got mine from Summit a few months ago.

I have an extra set if anyone wants. New, uninstalled and unused.

ZVS855 v. VS855
 

Back from the dead. I'm wondering if the big difference between Summit's ZVS855 and VS855 is the part number.

VS855 is a Volvo valve spring made by Federal Mogul. Made in USA. I've seen them panned here simply because they're so cheap--a whole engine for $60.

Update--if they're Sealed Power from Summit, then it's probably the same thing. The unique UPC code is 724956648306


Additional Details

Free Height (In): 1.810 Inch
Free Height (mm): 45.974mm
Type: Single
Minimum Closed Height (In): 1.570 Inch
Minimum Closed Height (mm): 39.878mm
Minimum Closed Pressure (psi): 66 psi
Maximum Outside Diameter (In): 1.056 Inch
Minimum Inside Diameter (In): 0.708 Inch
Minimum Inside Diameter (mm): 17.983mm
Maximum Outside Diameter (mm): 26.822mm
Minimum Open Height (In): 1.180 Inch
Minimum Open Height (mm): 29.972mm
Minimum Open Pressure (psi): 175 psi
Solid Height (In): 1.120 Inch
Solid Height (mm): 28.448mm
Total Coils: 7
Wire Diameter (In): 0.164 Inch
Wire Diameter (mm): 4.166mm

O'Reilly sells them for $3.69 each.

Props to Dale for this thread! It helped me solve an issue I was having from not enough spring pressure.

Hello. On the BP6D cylinder head, is there a difference between the stock exhaust valve springs and the intake valve springs?

I have been searching for a while but couldn't find out.

This is what I was searching for I guess. Found it on this thread. :)

That's the intake side. On the exhaust side, pressures might be twice that (according to the internet).

A while back, I found that above 5500 rpm, the pressure at my turbine inlet was pushing open the wastegate valve and preventing me from maintaining my target boost, even with all the air bled off. It got worse the higher my RPM climbed.

It would not surprise me to find that I was getting 30+ psi of pressure between the exhaust valves and the turbine inlet at 18 psi of boost, especially at higher RPM.

Even with the double heavies, 30 psi of pre-turbo exhaust pressure would take you back down to nearly stock valve seat pressures.

Of course, me being a log manifold kind of guy, that might be contributing to the exhaust pressure.

edit- I went with supertech double heavies on my rebuild, should have dyno results in a few months

I wish bogusSVO was still around. His shit was so informative.

35 psi gauge is what I measured in the exhaust manifold at 18 psi of boost.

The thing about valve springs I don't get, though, is that that when the valve is closing that pressure is on both sides of it, so it really shouldn't make any different to valve float.

--Ian

Two things:

1) The exhaust runners aren't isolated from one another in most turbo manifolds. Each exhaust stroke is forcing out gas that pushes the turbine blades but it also pushes against the wastegate valve and the other cylinder's exhaust valves. I suspect that more log-like manifolds are worse in this regard. By how much? No idea. The size of turbine you run probably also has an effect in terms of how much boost/rpm gives how much back pressure.

2) During the exhaust stroke, I would imagine that it's pretty even, but what about when the piston hits TDC, just as the intake valve is opening and the exhaust valve is about to close? I would imagine that cylinder chamber would be at its lowest right about then. And I think there's a decent chance at higher rpm/boost levels that the pressure on the backside of that valve should be pretty high.

What are you using for valve spring compressors? For a number of other platforms there is a slick tool that bolts to the cam cap and allows springs to be changed with the head on.

Refference:

1
Valve Spring Compressor

2
Honda B18C B16A H22A VTEC valve spring compressor tool

Consensus:

KD Tools Gearwrench Valve Service Kit
https://www.amazon.com/dp/B004ZG5LGI..._o6RGwb4ZEVJ6W

It is possible to determine the spring rate without compressing the spring. Here is a page with a calculator.

https://www.thespringstore.com/sprin...alculator.html

In search of a viable VS855 replacement spring which shares the similar qualities, specifically fitting under the stock retainers & in a similar cost range.

I backordered these a few months back however Jeg's has pushed the date back each month - I reached out to Federal Mogul (Sealed Power) who said that the p/n is not discontinued but there is no ETA available due to no source. Their customer service experience was great for what it's worth, almost makes me not feel as bad that I'm back on the hunt for an affordable valve spring that fits under stock steel retainers (not a fan on Ti much)

Other than the OEM Volvo ones which turn out to be ~$250us, what are the other choices? The BC's at the start of this thread looks promising but there isn't a p/n available and I don't see them listed anywhere from Brian Crower dealers. Where are you hiding affordable single valve spring upgrade?

I've been through the same situation with Jegs for 3 months, it was exasperating. finally I bought the springs that I describe in my previous post and I have already installed them in my head.
You have to look for springs for volvo engine type B18 and B20, the OEM part number is 418737.
The Sealed Power VS855 It is an interchange spare part, there are several manufacturers as ITM, Perfect Circle, Sealed Power...
VS855 Interchange Part Number: 418737, 212-1241, VS437, VS1065, W11454. These are the same springs.
Here is a link where you can buy them:
https://www.ebay.com/p/Engine-Valve-...0L-L6/79503613

Thank you for your research elpazos! So funny enough, Skandix has them for around $100usd, not sure what shipping is...but looking at the same part from US dealers comes out to around $250usd LOL

I'll post my findings if I come up with anything significant in terms of pricing.

*Edit - I just emailed their support to ask for an adjusted shipping rate. Its somewhat of a flat rate at 55 EUR which is more than half the cost of the parts - hoping they can adjust. I also found that they have an eBay Store, Skandix USA - however this part number is not available from their items listed. Also emailed the eBay USA side to see if I could order direct from there. This is the route I'm gong to go, just need to figure out a more realistic shipping cost.

***Edit 2 - The Germany/Sweden side will not budge on shipping. The USA eBay side does not stock the part or have plans of getting it. Shipping is flat rate to USA up to a certain weight, turns out to be $62.38 at this time of posting with the current exchange rate. The valve springs turn out to be $126.13 That makes the grand total $188.52 for those in the USA. I may have another update however, with another option. Doing the research now.

Dang .. I just placed my Jegs order for these springs 2 weeks ago and it was supposed to ship today .. I see that the item page the date keep getting pushed back but I was hoping it was for new orders and MINE would be shipped on the correct date. Judging from your comments here I'm thinking I should just cancel my order.

Depends how fast you need them. My head just came back from machine shop from surfacing so I need a spring solution now. I'm talking to BC right now.