FuzzyLog1c

iTrader: (4)

Hey, just wanted to throw up a couple of pictures of my new custom intake built using silicon HPS tubing (please note: there are two nearly identical HPS websites...when I called, they said to use this one) and anodized red Mike Norris catch can. When all was said and done, my total came out to roughly $350, which included:

• 1 foot straight tube - 4.0" (102mm ID, 112mm OD) @ $61.24
• 90 degree elbow 4.0" (102mm ID, 112mm OD) @ $84.24
• Longer straight coupler - 4.5" (114mm ID, 124m OD) @ $18.50

I also bought four t-bolt clamps @ $6 apiece: two 4.5" clamps for the coupler, plus two smaller 4.0" clamps for the ends of the intake tube.

For the Mike Norris catch can, I wound up needing to buy and epoxy a -6AN 90 degree elbow into a hole I drilled in the intake tube, and dropped a 3/8" -6AN nipple on the top of the catch can to mate with the PCV line. Please note that this is not a perfectly optimal build, for a couple of reasons:

1. You're going to have about 6" of tube left over. The 90 degree bend has enormous (5"+) legs that need to be trimmed to fit. Ordinarily, this wouldn't be a problem, but when you just dropped $200+ on a couple of feet of tube, you'll probably look at your left overs and sigh.
2. The MAF is significantly smaller than the 4.0" tube. In order to get it to work, you'll need to take one of the pieces of 4.0" tubing that you cut off, cut a slice in it, and adhere it to the MAF flange with double-sided 3M tape. Otherwise, you'll get leakage. I suppose you could use a reducer, but I plan on moving up to a 102mm MAF soon with velocity stack and larger Amsoil air filter.
3. The 4.5" coupler is slightly too large. As you can see by the ID and OD of the tubing, HPS doesn't actually sell something that "just works." The 4.25" coupler is 2mm too narrow, which you might be able to squeeze on, but I worried about pinching the inner walls of the tubing and creating turbulent airflow. I solved the problem with the 4.5" coupler by wrapping the outside of each 4.0" section with 6-8 layers of electrical tape and verified that it was sealed by plugging up one section and blowing for all I was worth. Almost pooped myself.
4. The stock PCV line is 1/4" ID and won't fit over the 3/8" nipple. Fortunately, the Mike Norris catch can comes with a 3/8" line that's almost twice as long as it needs to be. Therefore, you can cut the line to fit and have plenty left over to replace your old 1/4" PCV line. You might ask: if you replaced the 1/4" line with a 3/8" line, don't you have a vacuum leak? The answer is no: the 1/4" line is a flexible POS that someone stretched quite a bit to get over the valve cover nipple. The 3/8" line seals nearly as tightly, despite being bigger, because it's incredibly thick and stiff and doesn't give.
5. If you have the Lingenfelter airbox, you'll need to remove the last vestiges of the stock airbox bracket (located along the side wall of the bay). Fortunately, it's an easy job: there are two plastic pop rivets similar to the ones all over the rest of the car, and then it's just a tight friction fit that you'll have to muscle to get out of there. Once you do that, you've got plenty of room for the stock S&B filter included with the Lingenfelter kit, or you could choose to go even bigger.

DACTARI

iTrader: (1)

Great write-up. Just wondering, do you really need the coupler? Is the silicone elbow not flexible enough to allow you to push the tube in there directly, the way this fellow did with his 3" tubing (fitting into 3" side of 4 to 3" reducing elbow)?

FuzzyLog1c

iTrader: (4)

The coupler is necessary to connect the elbow to the straight piece if they're the same size.

The difference in the example you provided is that guy is using a larger elbow and hump coupler to connect to a smaller straight tube (probably 3.5"). I wanted to maintain 102mm all the way through the intake tube, so that if I upgrade to a 102mm MAF, I'll be the same diameter the whole way.

By the way, if you don't remove the stock airbox bracket, there's no way that these parts will work, since you won't be able to straighten out the airbox without squashing it a little (as you know from experience, DACTARI).

DACTARI

iTrader: (1)

Oops, that post above should have said 4" to 3.5" reducing elbow.

Lol, please don't revive that CAI fit thread!

kl2onik

iTrader: (3)

I must say this looks interesting and is a very clean install. I am curious to actually see what kind of change you would get in numbers from this setup, lets say over a volant like mine. I would obviously expect some gain due to a larger diameter intake tube but then again it may depend on the car and what you can actually flow with supporting mods...H/C, Fast, blah blah. Either way next time its dyno day would love to know if it made a difference in your numbers...let me rephrase, if the hp difference justifies the price spent on this overpriced silicone tubing. Either way great post.

FuzzyLog1c

iTrader: (4)

You and me both. I made this at the recommendation of my tuner, which came based on my current mods. My primary concern right now is that my filter and MAF may be restrictive. If I ever have an opportunity to dyno the car in its present state, I'll let you know what I get. This definitely should help support a TVS2300 in the future.

By the way, you can buy cheaper 4-ply silicon from other vendors (like siliconintakes.com) and do this thing at maybe half the price.

Larimer

Seems like a bad idea clamping down on just silicone pipes. Any reason you didn't just use a 4" straight pipe instead of the silicone?

FuzzyLog1c

iTrader: (4)

Straight pipe made of what? Silicon tubing isn't as strong as plastic or aluminum, but it's strong enough. Lubelizard did some pressure measurements on a variety of CTS-V intake tubes when he was in for a tune, and found that at 6500 RPM, conditions in the tube were usually 98-99 kPA, which is roughly 14.3 psia (versus sea level 101.6 kPA or 14.73 psia). That's barely anything.

Pressure drop is proportional to flow velocity squared divided by pipe diameter. If you added a TVS2300 and ported heads to my car and made 600 RWHP, I believe you'd need to deliver 50% more air volume per unit time. If I understand my basic principles correctly, this would require double the air velocity in a given intake tube and result in four times (two squared) pressure drop. As a result, efficiency will drop.

This is where having a bigger intake helps: by increasing the inner diameter of the intake from (probably) 75 mm to more than the 90 mm throttle body blade, pressure drop decreases and engine efficiency is closer to nominal.

KamaSutra

What type of intake filter is that?

Larimer

I was thinking metal or composite. Something with strength that doesn't flex like that pipe will when clamped down on.

FuzzyLog1c

iTrader: (4)

I believe your assessment and priorities aren't quite right. Here's why:

1. Silicon is a better material than plastic for intake tubing due to its lower thermal conductivity. Metal (more specifically aluminum), which you're praising for its durability, has the highest thermal conductivity of all three options and needs a significant amount of insulation to function correctly, which is why a show car with a whole bunch of polished aluminum parts in its engine bay, is not a fast car. At least, not after you run it for a little while.

2. You're focusing on the slight bulge in the 4.5" coupler (caused by compression at the clamps because the ID of the coupler is 2mm larger than the OD of the 4.0" tubing), when you should be asking me if a) I have a nice straight, thin, clean interface between the 90 degree piece and the straight tube, and b) if I'm getting a good seal at all four interface points (especially at the MAF and the PCV input).

I'd argue that most of the questions and criticism should be focused on the MAF and throttle body size, since they're making this expensive tube less effective than it could be.