4" intake on 3rd gen 3sgte, disscussion topic! GIVE YOUR 2 CENTS! Options

[presure2]

hey guys, as you know, jim now has the 3rd gen 3s in his car, and after doing some research around various boards, he decided he wanted to try a 4" intake.

now, before you all go nuts, the guys down @ hux racing in florida claim HUGE gains with a 4" over a 3" intake, and have posted some results.

here are a couple "copy paste" deals from mr2.com:

We always figured my street car made at least 280 rwhp. Until we dynoed it on our new Dynojet. The only mods are: our air intake mod 4", Blitz SBC boost controller, our 3" single tip exhaust, & boost cut defeated.

328 rwhp & 316 rwt

This is on a maxed out ct20b, stock ecu, stock injectors, genIII fuel pump, & stock intercooler. This was attained using 100 octane.

heres the dyno sheet:

The GenIII swaps we do I always push them to use our air intake mod since we have seen consistent results using that combo (4" K& N air filter, 4" inlet tube, custom coolant relocator hose).

so, with that in mind, (and the fact that hux racing wants 400$ for somthing they wont even show you a picture of) we decided to give it a shot.

since the inlet of the '20b is only 2.75" (yes, i know its a mm mesurement, but for all intents we all use a 2.75" reducer anyway..lol) we had to find a way to reduce the 4" pipe down to that.

since we couldnt find anyone who makes a 4" to 2.75" reducer, and the fact that i thought it would be kinda flimsy, if we could find one, i headed over to burns stainless to see what they had.

they carry 2 diffrent styles of "trumpets" (reducers) a longer style, and a shorter. so we got the 4" to 3" trumpet, and because of the limited room we have to work with, we chose the shorter style.
heres a pic of what it looks like, with the coke can for size reference.




once i got that in, and the coupler to mate the pipe to the turbo, i went out to the garage, and cut the pipe to set it up:



thats the basic idea, i just need to weld a couple bungs for the IAC and catch can, and weld it up.

im hoping we can get back to back dynos at some point real soon with a 3" intake vs this one, the only thing i need is a 4" k&n, or a 3" ebay special so the tests will be the same with no variables.
if everything shakes down right, we could do this on both dustin, and jims cars, to get more results on diffrent cars, to see what kinda results we can truly get.


discuss!!

[lagos]

Jim, the theory that a vortex will create more power is the same theory behind those Tornado gizmos they sell.
The truth is, that your turbo is already creating a vortex when it spins and sucks in air from the intake. However, the output of that velocity is limited by the size of the turbos 2in outlet. So in essence, how ever free flowing the intake is, it will always be choked by that 2in outlet on the turbo. Its the same as having a huge jug of water. The jug might be very wide in diameter, but the water will only flow out as fast as its restricted opening will allow.

I think the reason why their car made more power on the dyno, is because for whatever reason (maybe the intake did play a role in this) the car was able to hit more boost on the dyno then most ct20bs can. I guess the best way to know for sure is to wait for your dyno results.

I'm looking forward to physics class next semester. Its fascinating how all of this stuff really functions.








This post has been edited by lagos: Dec 1, 2008 - 11:39 PM

[_Jim_]

Jim, the theory that a vortex will create more power is the same theory behind those Tornado gizmos they sell.

This is different. The compressor housing is CREATING a vortex due to spinning at speeds above 100,000 rpms, where as those tornado gizmos just alter the air coming into the intake to "spiral" the incoming air at very slow rates. It just alters the air flow direction more than anything.

The truth is, that your turbo is already creating a vortex when it spins and sucks in air from the intake.

Agreed. But an opening under vortex conditions can flow much greater than the same opening not under vortex conditions.

However, the output of that velocity is limited by the size of the turbos 2in outlet. So in essence, how ever free flowing the intake is, it will always be choked by that 2in outlet on the turbo. Its the same as having a huge jug of water. The jug might be very wide in diameter, but the water will only flow out as fast as its restricted opening will allow.

Not true, because the 2" outlet of the turbo on the compressor side is under pressure. Take that jug (coke bottle) and time how long it takes to drain out when you turn it outside down. Now, take that same jug and time how long it takes to drain out when you turn it upside down and apply pressure (squeez) the bottle. The opening diameter of the bottle didnt change, nor did the amount of water inside the bottle. The only difference was the pressure added to the bottle which allowed it to drain faster.

I think the reason why their car made more power on the dyno, is because for whatever reason (maybe the intake did play a role in this) the car was able to hit more boost on the dyno then most ct20bs can. I guess the best way to know for sure is to wait for your dyno results.

I'm looking forward to physics class next semester. Its fascinating how all of this stuff really functions.

I agree that the higher boost DEFINITELY played a role in those numbers. But I also believe that the intake played a role in this. Yes, the best way to tell for sure would be wait for the dyno results in 2 weeks, but its nice to get opinions and ideas about why or why not a 4" intake may make power.