Hi, looking for a set of double-heavy (70-85lbs seat pressure or so) or equivelant valve springs and retainers for a 1999 Miata head.

Yes, I know numerous vendors on here sell the Supertech's, but honestly nearly $600 for a set of springs and retainers is just....well, very expensive.

I called PAC racing and they suggested a CatCams spring (PAC-S90015) 'could work' but I haven't confirmed.

I've heard of the Sealed Power V855's, but haven't seen any for sale.

If someone has a used set, or an alternative suggestion I'd appreciate it.

Thanks,

F

 

Volvo springs are what quite a few of us use, but they are singles and not that heavy. I think they are in the 60lb range.

If you want doubles I think the supertech's are about the only answer unless you can filter through PAC or PSI's spring catalog and find a diameter and free length that will work.

 

Yes, Volvo springs are only slightly stronger than stock.

 

PAC "might" have an option, haven't checked PSI but will. The best solution would be some used Supertechs, at least for my budget. But so far, haven't found anyone selling a set.

Thanks for the info, the Volvo's aren't enough seat pressure for what I would like. Definitely want 75 lbs or more.

 

are you trying to spin the motor to 8000+?

Do you have stainless valves?

You may mushroom the factory valves with those kind of seat pressures.

 

Yeah, want the option to spin it above 8k and build in some safety margin with heavier springs. I haven't heard that the factory valves can't handle the higher pressure springs. Anyone have experience with that issue?

I've considered stainless, but decided money would be better spent on other things as this is a turbo application and 1mm larger valves would also need pretty extensive headwork to make them worth it....vs just turning up the boost a bit. That work would allow earlier spool, but I'm going with a GT2560R for now and likely one of the newer EFR 6258 at some point in the future.

 

Anyone know if I can use stock retainers with the Supertech double heavy springs?

Also, PAC, PSI, Crower, Kelford and GSC don't seem to have options.

 

What cams are you going to be running? Stock cams will run out of breath and nose-over basically around the factory redline, even with boost.

FWIW the VS855 part number was the Sealed Power aftermarket number for the OEM volvo spring. The OEM volvo springs seem to still be available from Volvo, part number is 418737, seems they are around $16-19 a piece. But as someone stated, they are hardly any more seat pressure than stock, and reportedly lose seat pressure pretty quickly if you actually spend time beyond ~7000rpm. They are from a pushrod volvo motor from the 60s that probably revved to ~5k max? So while yes they are dimensionally similar and have more seat pressure, they're just not meant for really high cycling rates.

PAC, PSI, etc, might not list a catalog spring for a miata, but I'd bet money they make a spring that would fit. I have PSI's in my k24 that I got from 4Piston racing, but in doing some digging its the outer spring of a dual spring setup PSI makes for some snowmobile motor, just happens to have the right dimensions to work in a K series. So a phone call with some specific dimensions may yield something. However it will not be cheap. my 16 springs for the K cost nearly a grand with retainers.

But back to basics; if you're keeping stock cams there is little point in spinning it that high. Especially when you have the ability to add boost and make the power lower in the RPM range. And keeping RPM lower is hugely beneficial for longevity, even if its not as sexy. Granted miata motors sound pretty terrible at any RPM anyway, but that's another topic lol.

TLDR: Supertechs are the best option for a host of reasons.

EDIT: For a poverty-spec option, NA valve springs are heavier than NB springs, due to similar redlines but the NAs having weightier hydraulic lifters. Somewhere out there are seat pressure specs listed, but NA springs would be very cheap or even free from some folks, and get you a small bump in seat pressure.

 

Interesting, I didn't realize that stock cams are insufficient for power above OEM redline. That pretty much ends the entire conversation as I definitely am not doing cams, valves, valve springs, etc. There would be well over $1.5k in just the head alone...assuming porting, etc. Not worth it, I'm not trying to build a serious race car and am not on a race-team budget. It really is surprising how much some of these parts cost.....oh to be running an LS. I can pull and buy a junkyard LS for less than the cost of Supertech's valve spring kit, but clearly that's talk for another forum.

Thank you for the insight, it has definitely helped me in my particular build.

 

Just found another thread that said these are all the same valve spring. Is this true?

VS855, 418737 (Volvo OEM P/N), 212-1241, VS437, VS1065, W11454. The springs are for B18/B20 Volvo engines.

They are pretty reasonable, apparently fit with OEM retainers and, as Monkeyman noted, have been reported to have slightly more pressure than stock. Better than leaving stock, obviously not better than the various $500+ options....still some extra seat pressure is better than none. Some have said around 65 lbs at stock height.

 

A few things to consider. The weight of the valvetrain components and cam profile are both a factor. Stock cams with an increased valve area and of course a large enough turbo might go to 8krpm. The 1mm oversize valves are to restore the valve installed height after machining the seats. To see an actual benefit from an increase in valve area it will require a 2-3mm increase. Ti retainers, lighter lifters (SUB type) and undercut valves will reduce the mass enough to affect the max RPM. Seat pressure is important, but so is the open pressure. Typically for road racing FI can make enough power below 7500rpm. NA applications are another story and engine speed is paramount.

 

Well sure, LS's are great but you've gotta keep in mind they work well in small, light vehicles straight from the junkyard because they have twice as many cylinders and nearly triple the displacement (assuming we're talking a generic 5.3), so you don't need to modify them to greatly increase the power to weight ratio of the car. Reflect for a moment on the fact that you are looking to double or even triple the output of the Miata BP, so its gonna cost some money; similarly, if you wanted a reliable 900hp out of an LS, you could spend $1500 faster than you can blink (or way more!).

Cylinder heads generally make-or-break engine performance and reliability, hence why they demand the biggest allocation of funds. As mentioned, without doing cams and/or big valves to meaningfully increase the breathing ability of the motor, there isn't a lot of point in spinning beyond about 7000. It just starts to cost exponentially more for every few hundred RPM increase in redline. Cam profiles will work in a pretty similar range whether NA or boosted, you'll just make more power in the same range with boost, but the dynamic efficiency of the cam profiles don't magically move up 1500rpm with forced induction.

I certainly don't want to dampen your enthusiasm, but I learned long ago from the wisdom of these boards that budget dictates power output. If you've got $2000 to spend, 250hp is a realistic, reliable power figure. $6000? Go for the 8000rpm, 400whp beast. Being honest with yourself about your budget is how you figure out where you're gonna land power-wise, and then everyone here can help guide you towards the best recipe to meet those goals.

 

Everybody thinks they can LS swap a Miata for cheap because "junkyard"...

Im going to be in my swap 20k+ dollars, but im doing a "lightly" built motor with about the only trick part being semi-custom forged pistons needed to make the whole destroked setup work. Otherwise its factory LS crank, rods, block, heads, intake manifold, injectors, etc... 1500+ in an ECU. 5k in the rear end fully setup with axle shafts. 5k into the trans and clutch. 10k in the motor with all accessories...

Also kinda like the "just k-swap it crowd" until they realize the 900 dollar motor is the cheapest part of the 12-15k dollar swap LOL.

 

Truth

 

Ah, I hadn't considered shoving an LS into a Miata....but can't imagine it would be a ton of fun as it's got to be a tight fit. I assume there aren't kits therefore a bunch of custom work is needed...thus the costs?

My comment was more geared towards the vast array of parts available for the LS, from many many manufacturers at reasonable rates.

I find it odd that with the huge love for the Miata, and a thriving aftermarket community, that parts availability is really rather limited. Yes, cams, pistons, valves, springs, rods, intakes, TB's, etc. are all available....but not with a ton of choices like other platforms. Honda K's, 2JZ, LS, Ford's 5.0, etc.

Is what it is....and, after a lot of thought, am going to dig into the wallet and buy a set of Supertech springs and retainers....mainly for peace of mind. I just don't want to risk over-revving and dropping a valve on a newly built engine.