Light or Heavy Double Supertech Valve Springs
#1
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Light or Heavy Double Supertech Valve Springs
I have spent the last day searching threads to get a better idea if I need the Light or Heavy Double Supertech valve springs for my ~300hp 8000rpm VVT motor build. Stock valves, lifters and stock VVT cams. 95% street use with 1-2 track days a year (optimistic). The best info seems to be in Emelio's sticky stating "For any engine expected to see 8000 rpm whether intentionally or not, we recommend a heavier spring like the Supertech "light double" spring kit. Above 8000 sustained, the "heavy double"."
Since I am not planning on revving the engine over 8000rpm with stock cams and lifters, it sounds like I would be OK with light double springs. It sounds like heavy doubles would add more margin for an accidental downshift, but what is the real down side of the stiffer springs. I know there is the additional frictional load of the stiffer springs, but what does that mean in real world applications? If we are talking about a slight hit in MPGs then I wouldn't care, but I would not want valves, seats or cams to wear significantly faster due to stiffer springs. Long story short, why not just go with the heavy doubles?
I feel like this answer used to exist in a nice clean thread, but had no luck finding it!
Since I am not planning on revving the engine over 8000rpm with stock cams and lifters, it sounds like I would be OK with light double springs. It sounds like heavy doubles would add more margin for an accidental downshift, but what is the real down side of the stiffer springs. I know there is the additional frictional load of the stiffer springs, but what does that mean in real world applications? If we are talking about a slight hit in MPGs then I wouldn't care, but I would not want valves, seats or cams to wear significantly faster due to stiffer springs. Long story short, why not just go with the heavy doubles?
I feel like this answer used to exist in a nice clean thread, but had no luck finding it!
#2
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It's on our product page. View it in desktop mode. https://supermiata.com/supertech-val...-miata-BP.aspx
Copied here:
Three kit options depending on usage. The below are estimates only and will vary greatly depending on valve weight, cam lift, and other variables.
Single spring - seat pressure 56lbs @ 34.2mm
Sustained revs to 7400rpm, mechanical over rev to 7800. N/A only
Light double spring - seat pressure 63lbs @ 34.2mm
Sustained revs to 7800rpm, mechanical over rev to 8200. < 8psi boost
Heavy double spring - seat pressure 74lbs @ 34.2mm
Sustained revs to 8500pm, mechanical over rev to 9000. > 8psi boost
Copied here:
Three kit options depending on usage. The below are estimates only and will vary greatly depending on valve weight, cam lift, and other variables.
Single spring - seat pressure 56lbs @ 34.2mm
Sustained revs to 7400rpm, mechanical over rev to 7800. N/A only
Light double spring - seat pressure 63lbs @ 34.2mm
Sustained revs to 7800rpm, mechanical over rev to 8200. < 8psi boost
Heavy double spring - seat pressure 74lbs @ 34.2mm
Sustained revs to 8500pm, mechanical over rev to 9000. > 8psi boost
#9
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It's on our product page. View it in desktop mode. https://supermiata.com/supertech-val...-miata-BP.aspx
Copied here:
Three kit options depending on usage. The below are estimates only and will vary greatly depending on valve weight, cam lift, and other variables.
Single spring - seat pressure 56lbs @ 34.2mm
Sustained revs to 7400rpm, mechanical over rev to 7800. N/A only
Light double spring - seat pressure 63lbs @ 34.2mm
Sustained revs to 7800rpm, mechanical over rev to 8200. < 8psi boost
Heavy double spring - seat pressure 74lbs @ 34.2mm
Sustained revs to 8500pm, mechanical over rev to 9000. > 8psi boost
Copied here:
Three kit options depending on usage. The below are estimates only and will vary greatly depending on valve weight, cam lift, and other variables.
Single spring - seat pressure 56lbs @ 34.2mm
Sustained revs to 7400rpm, mechanical over rev to 7800. N/A only
Light double spring - seat pressure 63lbs @ 34.2mm
Sustained revs to 7800rpm, mechanical over rev to 8200. < 8psi boost
Heavy double spring - seat pressure 74lbs @ 34.2mm
Sustained revs to 8500pm, mechanical over rev to 9000. > 8psi boost
Turbofan, is there any real measurable downside to running the 11lb stiffer Heavy Double springs? It would seem that it is a relatively small increase in seat pressure compared to the light doubles.
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Yes, that's right. Many people get away with running normal valve springs but, say an NB1 running those boost levels may be floating valves occasionally without even realizing it. Worth the security in our opinion.
#11
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You cannot buy a valve spring for a Miata that has "too much" seat pressure.
I have NEVER seen a boosted Miata make less power with stiffer springs...actually quite the opposite. Every time we went up in seat pressure, we made more power and the valves lived longer.
So my advice (which is backed by a ton of experience with this specific application) there is ZERO downside (other than cost) to running the stiffest, highest quality springs you can afford. There is actually quite a bit of upside to running a stiffer spring.
I have NEVER seen a boosted Miata make less power with stiffer springs...actually quite the opposite. Every time we went up in seat pressure, we made more power and the valves lived longer.
So my advice (which is backed by a ton of experience with this specific application) there is ZERO downside (other than cost) to running the stiffest, highest quality springs you can afford. There is actually quite a bit of upside to running a stiffer spring.
Last edited by TNTUBA; 01-30-2020 at 07:44 PM.
#12
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You guys had me wondering if I need to ad shim under buckets, but after pricing them I do not think I can justify the >$500 increased cost.
#17
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With a ported head, ST single springs, S2 throttle body, flat top, Tomei cams, and RB header, I set rev limit at 7800RPM IIRC for safety, but power was flat lined around 7600. Stock cams give up the ghost around 6600, another 400-500rpm is just used to put the next gear in the power band.
#18
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This is of interest to me. I have stock ‘99 with TD04. On track, I run 7.5 psi @ 7000 soft red line. On street, up to 16psi.
This sounds like I should be replacing my valve springs if I want my head to last. Am I understanding correctly?
I suppose I could check to see if my clearances are tightening up.
Also, anyone besides Guido’s shop have experience with Comp Cam springs?
DNM
This sounds like I should be replacing my valve springs if I want my head to last. Am I understanding correctly?
I suppose I could check to see if my clearances are tightening up.
Also, anyone besides Guido’s shop have experience with Comp Cam springs?
DNM
#19
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Nobody on this forum has access to the equipment required to measure the power difference between the light double and heavy double valve spring. Get the heavy double.
If you cannot justify the $500 for SUB lifters, I would strongly advise that you reconsider your plans to exceed ~7400rpm.
If you cannot justify the $500 for SUB lifters, I would strongly advise that you reconsider your plans to exceed ~7400rpm.