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Old 03-23-2015, 12:17 PM   #1
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Default What valve springs for n/a motor?

What valve springs do i want for an n/a BP4W that might see 8000rpms on occasion? Any other supporting parts considered a "must have?" Strictly speaking valvetrain in this case.
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Old 03-23-2015, 12:24 PM   #2
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What valve springs do i want for an n/a BP4W that might see 8000rpms on occasion? Any other supporting parts considered a "must have?" Strictly speaking valvetrain in this case.
949 said they put the super tech light doubles in all their motors, both FI and NA. So that's probably a safe choice.
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Old 03-23-2015, 12:30 PM   #3
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I'm running the Supertech light doubles on my track car on Emilio's recommendation. They work fine and give some peace of mind. The thinking was that weak springs might have been the culprit with the valve troubles I was having (turned out to be bad machining).

I think I'm down on power since installing the springs though. Back when I had the OEM's, my VD pulls showed ~145HP. After installing the springs, they showed ~135HP. I recently confirmed the 135HP reading on a Dynoject (for a NASA dyno reclass). Does it make sense that stiffer springs would cost a bit of high-RPM power? I dunno.
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Old 03-23-2015, 12:30 PM   #4
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Derp i had seen that for boosted applications, must have missed the n/a portion. Sorry about that.

We can consider this thread over, i suspect.
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Old 03-23-2015, 12:58 PM   #5
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I'm running the Supertech light doubles on my track car on Emilio's recommendation. They work fine and give some peace of mind. The thinking was that weak springs might have been the culprit with the valve troubles I was having (turned out to be bad machining).

I think I'm down on power since installing the springs though. Back when I had the OEM's, my VD pulls showed ~145HP. After installing the springs, they showed ~135HP. I recently confirmed the 135HP reading on a Dynoject (for a NASA dyno reclass). Does it make sense that stiffer springs would cost a bit of high-RPM power? I dunno.
excessive spring rate will rob you of some horsepower. As with everything it's a game of compromise. 10 HP difference seems a bit much tho.
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Old 03-23-2015, 04:27 PM   #6
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Any other supporting parts considered a "must have?"
If you're going to 8K, you need this tach.
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Old 03-23-2015, 05:57 PM   #7
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Duude!! I wish mine had ALLOFIT in the pinkline area. I can't even hit my pinkline area because I setup my tach needle wrong.
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