Valve springs
03-18-2013, 08:35 PM
#1
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Valve springs
I just spent several hours reading all kinds of useles bullsh*t about valve float and nobody addressed the idea of boost in relation to valve springs. I am looking to purchase springs for my head build. Initial plans include a ported head with +1 ST valves. I want to be able to run 30 pounds of boost and up to about 8K. Wondering what valve springs are needed to make sure the valve are doing what the cams want? Thanks!
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03-24-2013, 06:28 PM
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theres not really much options for springs. You can either get the single Super tech spring or the double spring. I don't recall the seat pressure. I know Bogus was working with some Brian crowers to get a combo for a miata, you may want to shoot him a pm.
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03-24-2013, 06:41 PM
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I spoke to him at length recently but he has nothing available yet. Wondering what others who run High boost are using? I know the more boost I run the more seat pressure I need but not sure how much? I don't plan on doing it often at all, but I want to be able to run 30psi.....
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03-24-2013, 08:16 PM
#7
Have you altered the valvtrain in any way?
I would strongly suggest SUB lifters and titanium retainers if you seriously plan to swing the motor that high with that kind of boost.
With that said, your choice of camshaft will be the biggest factor in choosing the right spring rating. Also, everything works together and should be matched accordingly. If you run a very small cam and invest in lighter valvetrain components, you can run less spring. If you do not lighten the valvetrain and or go with much more cam, you will need more spring.
That is about as much help as I can offer you. Your camshaft or valvespring provider will be able to help you get pretty close to the right spring. To find out which valvetrain set up will provide the most reliable power will ultimately be up to you with good old fashioned testing.
I would strongly suggest SUB lifters and titanium retainers if you seriously plan to swing the motor that high with that kind of boost.
With that said, your choice of camshaft will be the biggest factor in choosing the right spring rating. Also, everything works together and should be matched accordingly. If you run a very small cam and invest in lighter valvetrain components, you can run less spring. If you do not lighten the valvetrain and or go with much more cam, you will need more spring.
That is about as much help as I can offer you. Your camshaft or valvespring provider will be able to help you get pretty close to the right spring. To find out which valvetrain set up will provide the most reliable power will ultimately be up to you with good old fashioned testing.
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03-24-2013, 08:32 PM
#9
If you are running stock cams, you will not need to spin the motor that hard. The current valvespring kits like from FM will be more than enough for you.
I do not know which motor you have, but if you have the older hydraulic lifters you should at least move to the later solid lifters. They are lighter, and will extend your rpm range a bit. SUBs are much better however. Lighter valvetrain produces a bit more power, so you get more than just added protection.
I do not know which motor you have, but if you have the older hydraulic lifters you should at least move to the later solid lifters. They are lighter, and will extend your rpm range a bit. SUBs are much better however. Lighter valvetrain produces a bit more power, so you get more than just added protection.
Last edited by miata2fast; 03-26-2013 at 02:21 PM.
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03-24-2013, 08:41 PM
#11
Yes, I saw how much boost you plan on running, 30 lbs. The good valvesprings have much more seat pressure than that over stock.
Also, it is unlikely you will just build a motor and BAM 30 lbs of boost. You will ease into it and see where your weak spots are. Believe me, you will find them.
Also, it is unlikely you will just build a motor and BAM 30 lbs of boost. You will ease into it and see where your weak spots are. Believe me, you will find them.
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03-25-2013, 10:32 AM
#12
Yes, I saw how much boost you plan on running, 30 lbs. The good valvesprings have much more seat pressure than that over stock.
Also, it is unlikely you will just build a motor and BAM 30 lbs of boost. You will ease into it and see where your weak spots are. Believe me, you will find them.
Also, it is unlikely you will just build a motor and BAM 30 lbs of boost. You will ease into it and see where your weak spots are. Believe me, you will find them.
No no I think you got it BAM!
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03-25-2013, 11:59 PM
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Hustler, do me a favor and tell me what you really think!
wtf? why am I an idiot.......I know many reason why I am, but I want to hear why you think so.....99% of the time I plan to be at like 10psi....but want to know my **** will hold together at more.
I have alittle dick and need more PSI!!!!
wtf? why am I an idiot.......I know many reason why I am, but I want to hear why you think so.....99% of the time I plan to be at like 10psi....but want to know my **** will hold together at more.
I have alittle dick and need more PSI!!!!
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03-26-2013, 12:13 AM
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I will prolly only ever run 30 on a dyno after lots of tuning and bugs are worked out. Sav, I hope you know by now that I am trying to not cut any corners. I am trying to build my **** right! Just want to know what it takes to hit 30psi. I believe 99% of the time my car will see 10psi and hope to be north of 250.
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03-26-2013, 02:41 AM
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Why are you so fixated on 30psi? What if the turbo is out of its efficiency range? What if you see no power increase going from 22psi to 24psi?
You can use the concept of BMEP to estimate the boost level required to make a certain amount of horsepower. Soviet made ~315whp on his car at ~18psi. That's a 1.9 liter engine at ~2.2bar of absolute manifold pressure, so assuming he made peak power around 7000rpm, he was making ~56lb.ft/map/L at peak power. Peak torque should be in the 70-72lb.ft/MAP/L range. Even if you try and make 400whp on the 6258, which IMO it won't do, you'll need ~2.8bar of absolute pressure to get there, or ~26psi. Soviet did make 400whp, but he used a 6758 and did it at ~24psi IIRC.
In short, you'll max the turbo's flow capabilities before it produces 30psi of pressure in the intake manifold. Your fixation on "30psi" is unhealthy - focus more on maximizing flow and less on arbitrary boost targets.
You can use the concept of BMEP to estimate the boost level required to make a certain amount of horsepower. Soviet made ~315whp on his car at ~18psi. That's a 1.9 liter engine at ~2.2bar of absolute manifold pressure, so assuming he made peak power around 7000rpm, he was making ~56lb.ft/map/L at peak power. Peak torque should be in the 70-72lb.ft/MAP/L range. Even if you try and make 400whp on the 6258, which IMO it won't do, you'll need ~2.8bar of absolute pressure to get there, or ~26psi. Soviet did make 400whp, but he used a 6758 and did it at ~24psi IIRC.
In short, you'll max the turbo's flow capabilities before it produces 30psi of pressure in the intake manifold. Your fixation on "30psi" is unhealthy - focus more on maximizing flow and less on arbitrary boost targets.
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03-26-2013, 03:01 AM
#20
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Andrew, Thank you for your input. I really value your opinion, you know that. If there is notthing more to be gained then of course I won't do it just to do it. I do want to see what the 6258 is capable of sure! I have no idea what that is, I trust your gut way more than mine on that. I told you, I bet a soda and so I have to make 300whp. My goal when I started was 250-270. I am under the impression to do it right I need valve springs? If I am going to buy them then I want to buy them once. I know I will give a little up in parasitic drag but feel the safety margin of not worrying about the valves floating was worth it?
Since we are comparing to Soviets build, am I wrong to assume I will make more power at a given boost since I will have less restrictions? It is my understanding boost is a measure of flow restriction. iirc Soviet used stock intake, stock head, stock tb? I plan to follow your recipe and use the B18 Blox intake, 68mm TB, ported head with oversized valves. Lets be clear, I claim no first hand knowledge here and going strickle off what I have read and my gut. I have four Miata's and the 6258 may not stay on this head, but I really only want to build this head once.
Thank you for you comments! I have found very little useful information about valve springs.
Since we are comparing to Soviets build, am I wrong to assume I will make more power at a given boost since I will have less restrictions? It is my understanding boost is a measure of flow restriction. iirc Soviet used stock intake, stock head, stock tb? I plan to follow your recipe and use the B18 Blox intake, 68mm TB, ported head with oversized valves. Lets be clear, I claim no first hand knowledge here and going strickle off what I have read and my gut. I have four Miata's and the 6258 may not stay on this head, but I really only want to build this head once.
Thank you for you comments! I have found very little useful information about valve springs.
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