im lookin to make my intake tube bigger , I was just wondering whats the best thing to use and does anyone have any good pictures...

 

bigger? the stock one is quite big. search for CAI prelude intake. a 92-94 (i think thats the year) prelude intake can be made to fit qutie easily. do that, heat wrap it, make a box around the filter, and your set!

 

I have a s4 TII, 720 secondarys,rtek 1.7,ported wg,3" turbo back exhaust,sbc-id boost controller,safc, few other mods . From whhat ive read theres a big diffrence in a bigger itnake tube . . . How do I go about making one etc. and was wodnering if anyone had any pictures.

 

Go to the plumbing store and buy an assortment of ABS pipe. Get 3" to fit the filter, a few 45 degree bends and then a 3" to 2.5" coupler to connect to the turbo and a 3" coupler to mount to the AFM. Mock it all up in the car before gluing, making sure to keep the AFM level.

 

The tube is already bigger than the AFM, but if you want to make a bigger one go for it. Also, post the results afterwards.

 

Auto Zone sells a $10.00-$12.00 mock-up kit.

 

ABS starts to bend around 200F and melts at 220F, so ABS is probably best for mockup only.

PS: aren't those popup movie ads annoying?

 

You got spyware, buddy. Download adaware (www.lavasoft.de) or spybot: search and destroy and run them on your comp. Both have a free version, but you might have to look a bit to find it.

 

Try mousing over the word "car" in Aaron's post above! Thanks for the link though, I'm pretty sure I'm clean.

 

I can tell you from my fluid dynamics classes (fluid = gas or liquid, not just liquid) and from my job involving both water and air piping that a bigger pipe will not make any significant difference. If the intake pipe were 50' long it would help, but it isn't. Worry about the AFM, etc. Each of those counts as several yards of pipe.

There is exactly X HP of losses in the stock intake. Your "gains" cannot exceed X no matter how unrestrictive you make the intake. Only higher airflow will increase X. There is only A/B/C/etc. HP of losses in each part of the intake (A + B + C + etc. = X; I am simplifying things a bit, since there is some interaction between A & B, B&C, etc., but this is approximately true). Your "gain" for each segment cannot exceed A/B/C/etc. So you can't "gain" any real HP from upsizing the pipe because there is hardly anything lost in the pipe. Your HP "gains" come from recovering what's lost in the stock intake. You can't create more HP out of nothing with an intake.

 

...and increasing the cross section decreases velocity. I'm not sure how turbos would respond, but in N/As, many shorten the intake length to increase throttle response - there's less air mass to speed up and slow down.

I took a fluid dynamics course way back when, but I dropped it after the first midterm - that was my first and last ME course! In my defense it was upper division.

 

Oh, the forum advertising, gotcha. I thought you meant true popups.

 

ABS is fine. Many people make TIDs out of ABS (including me) and have never had an issue.

 

I also did it for a while, and it worked fine..

 

Well, I can't argue with experience - I was just going off a datasheet for ABS bending and melting points. Here's a more detailed one that lists the temps recommended for the injection molding machine (400 - 500F) and maximum service temp in air (140 - 223F). I would still be inclined to use it for mockup only, but if it works, it works!

 

I am not advocating its use, but it WILL work..

 

They recommend no higher than 140-223F because ABS gradually gets softer past 140. You could probably go much hotter if it's not under pressure. Your intake air probably won't get that hot anyway. Ditto on what J-Rat said.

 

So basically its not worth doing this mod...What about a cai on a turbo?

 

Should be worth it. - cheap and significant gains. Though in theory a ginormous intercooler could replace a cai, since temps after the intercooler are all that matter.

Universal gas law:
PV = nRT: Pressure * Volume = (amount of air) * (constant) * Temperature

More air = more power. So there are two ways to increase air:
1. Increase pressure.
2. Decrease temperature.

It gives about 5-6HP on on N/A. You'd have to ask around to see what people get with a cai in a turbo, since I don't feel like doing the math and it depends on your intercooler. If it weren't for the intercooler, it would be a flat ~4% increase to your existing horsepower.

 

In theory and in practice the colder the air is when it enters the intake, the colder it is when it enters the intake, no matter what happens along the way. No matter how good an intercooler is, a proper CAI will lower the intale air temp further still.

As for the TID, it's absolutely worth upgrading. Again, experience has provided overwhelming proof of that. The stock TID is very restrictive because of it's two very tight bends, and the bottom bend causes poor turbo entry conditions that reduce compressor efficiency.

Here's mine. https://www.rx7club.com/showthread.p...27#post4702327