: Home-made air intake tube, 3.5" or 4"



Twitch
12-15-07, 05:33 PM
Hey guys,
I did the research, and found the website to get all the hardware.
Just not sure if I should get a 4" tube or a 3.5" tube. I know most guys have the 4", but its very tight. I doubt I'd be loosing anything with the smaller tube, but I kinda like the big-ass aluminum tube in there.
Thanks

Tony

Black Sunshine
12-15-07, 05:40 PM
The bigger the tube, the bigger the man.:yup:

Twitch
12-15-07, 06:00 PM
The bigger the tube, the bigger the man.:yup:

LOL That's a lotta help :thumbsup:

nikon
12-15-07, 06:56 PM
I have the 4"....a couple months ago I took it off to clean my K&N and found that one of the radiator bolts had worn through the tube.....so, my suggestion is to go with the 3.5". I solved my problem by covering the hole then beating the tube in slightly....the only piece I'll suggest is something that will give the tube and the airbox some movement between each other....y'know how the factory tube is rippled?? Find something like that.

Pegasus04
12-15-07, 07:16 PM
I used a 4" tube. I replaced the bolt, closest to the air flow sensor, with one that has a smaller head and I ground down the plastic around it. I haven't had any problems with it. Good luck.

trukk
12-15-07, 09:07 PM
I currently have a 3.5" tube. When I had my stock intake and 78mm TB, I just didn't see how a 4" would easitly fit. Before I kinda figured out how to configure my aftermarked intake tube with the LPE intake, I acually had my MAF wiring harness get partially eaten by the local pulley.

Since I upgraded to a Fast 90/90 combo, I will probably upgrade to a 4" tube. The Fast has a small incline in the TB mounting location, of about 5-10% off perpandicular from the top of the engine, which raises the throttle body a bit, and actually creates a bit more room for the tube.

This is a farily low priority at this point, but one thing I'll probabaly eventually do. Something to think about if you have a FAST intake or plan one in the future.


-Chris

JonCR96Z
12-16-07, 12:19 PM
The TB is 78mm or 3.0709 inches. So the 3.5 is enough to cover that without restriction. Theres not gonna be any difference in the 3.5 to 4 performance wise, just some clearance issues.

Twitch
12-16-07, 05:06 PM
I currently have a 3.5" tube. When I had my stock intake and 78mm TB, I just didn't see how a 4" would easitly fit. Before I kinda figured out how to configure my aftermarked intake tube with the LPE intake, I acually had my MAF wiring harness get partially eaten by the local pulley.

Since I upgraded to a Fast 90/90 combo, I will probably upgrade to a 4" tube. The Fast has a small incline in the TB mounting location, of about 5-10% off perpandicular from the top of the engine, which raises the throttle body a bit, and actually creates a bit more room for the tube.

This is a farily low priority at this point, but one thing I'll probabaly eventually do. Something to think about if you have a FAST intake or plan one in the future.


-Chris

How much is a FAST intake, and what do you get out of it? Not planning on getting hearders, but a mild cam might be something to think about down the road.
So I guess I'll go with the 4" to 3.5" elbow, 3.5" aluminum tube and end piece to the MAF plus 4 clamps. Am I missing anything?
Thanks guys

SkullV
12-16-07, 10:54 PM
How much is a FAST intake, and what do you get out of it? Not planning on getting hearders, but a mild cam might be something to think about down the road.
So I guess I'll go with the 4" to 3.5" elbow, 3.5" aluminum tube and end piece to the MAF plus 4 clamps. Am I missing anything?
Thanks guys

If you do modifications to make the engine breathe in better (intake) you should definitely do equal mods to let it breathe out (exhaust), so go with the headders if you are thinking about the fast intake/throttle body.

trukk
12-17-07, 11:19 AM
How much is a FAST intake, and what do you get out of it? Not planning on getting hearders, but a mild cam might be something to think about down the road.

Lol, FAST 90 is about $750-800. 90 MM TB will run approx $300-500. $50 bucks for some new gaskets. I got mine ported for more flow down the road ($600). Install and tune ($$$). It only really makes sense if you are going all out on a heads/cam NA setup. I lost hp & tq below 5500 rpms (approx 10 each), and then gained over 5500 (approx 10 each). That's with just boltons, no heads or cam yet. It will start to show gains fairly substantial gains with heads & cam.

I'd look at the Katech cam, or the Thunder Racing CheatR cam, if you don;t plan on getting headers. Both would be a good choice. Personally though, I don;t understand getting acam and not getting headers. But it's your car :D



So I guess I'll go with the 4" to 3.5" elbow, 3.5" aluminum tube and end piece to the MAF plus 4 clamps. Am I missing anything?
Thanks guys

Sounds perfect, for what you are planning. I posted in an earlier thread, that I couldn;t believe the difference it made swapping out the factory 'squeeze tube', for a 3.5" straight tube. I think part of it had to do with that being the major restriction, and it allowed my ported TB, and LPE CAI to really work much better.

-Chris

trukk
12-17-07, 11:23 AM
The TB is 78mm or 3.0709 inches. So the 3.5 is enough to cover that without restriction. Theres not gonna be any difference in the 3.5 to 4 performance wise, just some clearance issues.

Agreed. I'm thinking with a 90mm though , it might be something to consider. Then the bottleneck becomes the MAF. So at one point either go MAFless, or wait for the Texas Speed 100mm MAF (:holycrap:) to be released. LOL, I can't stop.

Jon, do you have a 3.5" or a 4" intake tube?

-Chris

StealthV
12-17-07, 01:26 PM
Had about every intake brand and tube on the V including 4", 3.5" and a one-off 3.5 to 4" combo - 3.5" is what I'd do on the V today if I could.

trukk
12-17-07, 02:00 PM
Had about every intake brand and tube on the V including 4", 3.5" and a one-off 3.5 to 4" combo - 3.5" is what I'd do on the V today if I could.

Reasoning?

FWIW, I have an FFV on mine, and it definately works. I was amazereded.

-Chris

Ferny
12-17-07, 02:21 PM
what do you mean by home made intake? like a pipe they would sell at auto zone and then put a k and n filter?? would that give u any HP?

Twitch
12-17-07, 07:19 PM
what do you mean by home made intake? like a pipe they would sell at auto zone and then put a k and n filter?? would that give u any HP?

I have a LPE cold air intake, but it uses the factory intake tube. Guys were finding that it was restrictive, so they went aftermarket. I think Stealth V was the only one that sold them. He doesn't make them anymore so you have to make your own.
You get a little power out of it. Dont think you'll notice it though. It does set you up for future mods, :stirpot: like headers, intake etc.
Looks cool too. :thumbsup:

StealthV
12-17-07, 09:37 PM
Reasoning?

FWIW, I have an FFV on mine, and it definately works. I was amazereded.

-Chris

Um....it fits? :D

Everything else being equal a larger diameter tube means the air is moving slower. Sometimes faster moving air from a smaller tube is a good thing when it comes to throttle response and filling intake manifolds.

JonCR96Z
12-20-07, 05:23 PM
Agreed. I'm thinking with a 90mm though , it might be something to consider. Then the bottleneck becomes the MAF. So at one point either go MAFless, or wait for the Texas Speed 100mm MAF (:holycrap:) to be released. LOL, I can't stop.

Jon, do you have a 3.5" or a 4" intake tube?

-Chris

I have a volant corvette air bridge similar to the one below. That goes from TB to MAF then to a 4inch conical K&N. With some duct work attached around that and sealed up for some ram air. Something that only the king of bolt-on Vs would have. :yup:

http://67.199.19.45/images/product/350221_lg.jpg
http://i98.photobucket.com/albums/l261/JonCR96Z/DSCN0262.jpg

This is what I had previously, with the 90/90. When it dynoed 372/363 with just the 90mm and the EWP. Its 3.5 inch, but I the air box sealed with a 3 inch piece of pipe connecting it to my left brake cooling duct.

http://i98.photobucket.com/albums/l261/JonCR96Z/DSCN4415.jpg

keithsm2
12-26-07, 08:12 PM
how does a dyno take into account RAM air?? Can you simulate that?

JonCR96Z
12-26-07, 09:07 PM
It doesn't. The big fan they put in front of the car may help power, but not enough to notice I'm sure.