Anyone running 3" up pipe and 4" intake pipe?

[Scott89TTA]

Anyone running 3" up pipe and 4" intake pipe and if so how does it fit? I have a 3" up pipe with 3" intake pipe and it is very tight around the intake pipe both above and below in the up pipe area. I'm going MAF less and want to run a 4" intake pipe with my new build but am concerned about the fit.

 

[TT/Ameasap]

I have the same set up as you and wanted to do the same thing until I needed to buy an angle boss and plenum spacer not including the new filter and the actual pipe itself....All together costing way to much. Some have fabbed pipes around the angle boss, but still need a spacer.
I was around 350-400 and fab time.

 

[Scott89TTA]

I don't mind the angle boss...I don't think I can use a plenum spacer since my 3"up pipe already touches my hood liner.

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[jpwalt1987]

I have a PTE front mount with 3 inch pipes and a BorgWarner turbo with a 4 inch inlet. I use a 45* silicone hose on the turbo to a 45* mandrel bent 4 inch pipe. It clears the iac with no problems at all.

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[TT/Ameasap]

I have a PTE front mount with 3 inch pipes and a BorgWarner turbo with a 4 inch inlet. I use a 45* silicone hose on the turbo to a 45* mandrel bent 4 inch pipe. It clears the iac with no problems at all.

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Post a pic.

 

[jpwalt1987]

Here are a few pics.

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[jarredsoon]

With an angled boss I ran a 3" up pipe and 4" maf pipe from rjc racing it all fit no problem. I posted pics on tta.com somewhere. I even had the temp gauge in the up pipe clear.

 

[turbows6]

I could be sadly mistaken, but I question whether a 3" up pipe offers any improvement on these cars, especially with an alcohol kit. My thinking is that 1, it's overkill. 2, it slows the velocity through the pipe and won't atomize the alcohol kit as well.

On the other hand, I'd probably still run a 3" up-pipe if that's what the intercooler had on the outlet side.

 

[TT/Ameasap]

You are correct that you loose velocity. You can also loose velocity by putting a bigger intercooler on too. The sum of the cross sectional area of the IC tubes need to be less than the cross section of the outlet of the turbo to increase velocity. If the cross sectional area is greater in the IC vs turbo, the velocity will decrease. This is an application of Bernoulli's equation.
As for alky atomizing less, I believe this has more to do with the choice size, position and design of the nozzle itself.

 

[turbows6]

Yeah the air probably loses velocity going through the intercooler core, but the alcohol nozzles are located after the intercooler. The air speeds back up when it leaves the IC core (sort of like putting your thumb on the end of a water hose and spraying water) When you figure the cross sectional area of a 3" pipe is 43% larger than a 2 1/2" pipe you will have a corresponding decrease in airspeed going through the piping. The slower the air moves through the pipe, the less efficient the alcohol will vaporize. (Think of how your old carbureted hot-rods needed extra engine speed when it was cold outside)

Like I said, I doubt that it's really a problem because even with a 3" pipe there is plenty of airflow moving through under full throttle, but I'd have my doubts about any benefit of running a 3" up-pipe *with a slic*. (Now if you start talking about using a front-mount with several feet of piping after the IC, the 3" pipe may be an improvement because airflow restriction becomes a factor)

 

[TT/Ameasap]

Its funny because I thought of all this before I purchased my 3'' pipe. I said screw it and decided to see how it reacted. I am more worried about the latent heat vaporization due to E85 and the alky.