Y’all Wanna See Some Porn?

"That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms" (thatbastardkurtis5) 03/23/2020 at 17:01 • Filed to: Slow Racecar, Velocity Stacks

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My velocity stacks showed up today and I don’t really need to say much beside that, do I?

I was worried they would be too big/wrong size because they claim to be for a Weber IDF 48, but they’re perfect for my DHLA 40s. The length I was not worried about, I needed the flare to clear the alternator, and I’ve got another 4-5 inches beyond them to the firewall.

Absolutely zero science went into choosing a length for the stacks. I measured the alternator, decided 6 inches would clear AND look wicked and that was that. I also ordered RamAir filter socks:

But I honestly think it may be illegal for me to actually install them and cover up those stacks. Guess I’ll just take them off when the car is parked.

Anyway. I’m a throttle linkage and clutch away from it being totally finished. Feels weird to almost be done with a project, but I suppose getting it in the car and making it run is another thing entirely. 

OmerCarrothers333 > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms 03/23/2020 at 17:10

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Ngghggggg...

On the real, that is teh hotness.

UserNotFound > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms 03/23/2020 at 17:12

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That motor’s  going to have an exciting torque curve.

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > UserNotFound 03/23/2020 at 17:33

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The only info I could find on stack length vs rpm range was one guy who said shorter stacks were better at high RPM who was flatly contradicted by the very next person to comment. Another person said 6” stacks were good for 2500-7500RPM on VW motors of similar displacement...I also know nothing about the specs of the cam, so the whole thing is just gonna be one big surprise once it runs. 

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > OmerCarrothers333 03/23/2020 at 17:34

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I want to put it in my living room instead of under the hood of my J2000. 

SBA Thanks You For All The Fish > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms 03/23/2020 at 17:39

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At least in Audi land— with their variable geometries they SHORTEN the runner lengths at higher RPMs. It makes a noticeable improvement in high-end performance... because the vacuum pods that control them often fail. Repair those pods? instant power adder!

GM always claimed that the ‘tall’ longer-runner truck intakes were for better cylinder filling and torque at low RPM... basically using the forward inertia of air mass to improve cylinder filling and “mix tumble”, so that checks out too.

Looks like you’ll get some wonderful induction sounds from that!

The Snowman > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms 03/23/2020 at 17:53

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I think the law says you have to run with no filters and then shove stress /tennis balls in them when you park.

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > SBA Thanks You For All The Fish 03/23/2020 at 17:54

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That makes perfect sense. I guess on this one length is just relative until I get it to run...when I actually get the car to the dyno it might not be a bad idea to grab a set of short stacks to compare. If the difference is negligible, stick with the long ones because come on just look at it, haha.

I’m excited to get it running. It’s all  such an unknown, I have no idea what power it’ll make, what rev range it’ll like, even how it’ll sound since I got it in pieces. 

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > The Snowman 03/23/2020 at 17:56

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That sounds right to me. I can’t imagine it’s legal for me to just cover them up. 

UserNotFound > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms 03/23/2020 at 18:15

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The velocity stack promotes a resonant pressure wave between “atmosphere” and the intake valve. The characteristic length determines the resonant frequency. Shorter stacks have higher frequencies, longer stacks have lower frequencies. When the wave frequency coincides with engine RPM, the high pressure part of the pressure wave effectively drives more air in to the cylinder, which increases torque at that RPM.

Longer - lower torque peak
Shorter - higher torque peak

Here’s a good read:

http://www.emeraldm3d.com/articles/emr-adj-length-intake/

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > UserNotFound 03/23/2020 at 18:21

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I really should have asked Oppo instead of Google.