Hey Guys

Just finished workign on this, and thought I'd share with you.

As you know, all but the APS TT/ST systems come with intake filter positions right behind and jsut outside the radiator, which is of course less than optimal given the temps that can develop not only under the hood but behind the rad in particular.

Well i sourced what i think is the right material ducting, that is suitable for the purpose of moving the intakes down into wheel wells. It polypropeline/rubber, withstands about 28" of vacuum (far more than I will encounter), temperatures in the 275 degree range, with a pretty smooth internal construction (in fact, McMaster listes this duct as a high-flow duct).


Here are some pictures:

Before:



Here you can see the original intake positions. Also note that this setup necessitates a new coolant overflow reservoir, which in this case is placed on top of the fan shrowd.

After (and during):








The new stock coolant reservoir placement is jsut a very nice bonus. I also made some air scoop cutouts (no pics, sorry - difficult to visualize without) on the bottom of the front fender liner, the part that covers the bottom of teh weheel well, the new intake location. These should aid the cooler air coming in.

Before the conversion, the best differential intake temperature (measured pre-throttle body) was 9.5 deg C (about 16 deg F), i.e. that many degrees over ambient, and this is at highway cruise. On the streets with stop and go driving, that number was always in the 15-30 degree range. Now, the highway cruise differential is 5 degC (about 9 degF), and around 10-20 degC in city driving. So, this mod definitely worked as far as intake temps are concerned. The only concern of mine is whether the bends introduce any type of resonance effect that would reduce the flow. Any engineers (Clint, Tony, etc.) please comment on this, thanks in advance.

Cheers..

 

Awww, a work of art under that hood....TT mmmmmmmmmmmm

 

Looks good to me, i'm just an electronics engineer though. I don't see any drastic bends, so no turbulence to the airflow would seem to be introduced. The curvature of the bends looks smooth. Maybe the left side might introduce a little turbulence, seems to be more bends on that side (can't quite tell though). Just my opinions...

No concern of sucking up any water? I'm sure you thought of that already though.

 

They all look like smooth, large radius bends. I don't think there will be any significant resonances or delta P in the bends. The 1/4 wave resonance frequency will be a little lower simply because the tubes are longer but thats about it.

How does the car perform now that it is drawing in cool air?

 

Thanks for your comment. As far as water is concerned, yes, it's definitely a concern, but only when the filter is submerged. I do not think that it will be an issue with stray water droplets, etc. during a rain storm, especially as the entire mixture is compressed, heated , then cooled by the intercooler (with lots of barriers that will privide further surface area for diffusign any large droplets), followed of course by the combustion chamber... In other words, I don't think it's an issue, as whatever goes in during a rain storm will be far less than water injection would introduce. That's not to say that it doesn;t warrant extreme care...but that's a compromise i was willign to make.

You are right, there are actually two bends on the left, each smaller in magnitude than the one greater one on the right; but nothig reotely extreme... i was careful.

Tony, thanks for your comment. I am either going to have to call you for further explanation of the terms or look up some of these terms. But yes, the improvement in power is noticeable the most at 90+ afternoon temps we are seeing, when my car would simply stop pulling (relative of course) with the 'old' setup.

THanks for the comments, keep 'em coming

 

BTW.. guys

Note this picture:


Do you see that poorly made pre-IC y-piece that joins the two charge pipes (can't seen here, maybe the very edges) into one for entry into the intercooler? It obviously has very poor flow characteristics, as it goes from two 1.75" pipes, into a single 2" (haven't measured it), only later to expand into the ~3" pipe size right before the FMIC.

Anyone know a fabricator that can fab up a new better one, or to modif this one to have a smooth 2x 1.75" transition to a single ~3" without dipping down to a ~2" diamter first? (stupid isn's it? )

I am CONVINCED, Tony, that this is at least part of the reason the car does not make more power at the higher boost levels as seen during the dyno day.

 

Gurgen
What diameters does the tube come in ? Im using a 4in brake duct tube off the T-trim blower and run it down into the passenger wheel . It makes a real hard bend down , But Im able to use a much larger air filter . Yours would flow better than brake duct . Does it bend easy ? hold its diameter on hard bends ?

 

HEy boog..

HEre is all the data.... mcmaster is awesoem that way..that should be your stop for all this stuff...the specify everything from bending radius to vacuum and temperature rating to flexibility to material.....

HEre is the info on that hose.



Otherwise you can go to Mcmaster.com, choose the "Duct Hose" section right on the front page (it's there), and just go through them..that's what I did.

 

thanks Gurgen

 

Once again... Excellent research and great application Gurgen! The advantages of cooler air from the intake filter to the intake valves are well known.

 

I'm sure we could find a way to improve it with diffusers and proper merge collectors. I would need to see it first but it does sound like there is lots of room for improvement.

 

Thanks Tony, so am I jsut driving to your place next week?

 

BTW... Where are you measuring boost? Directly at the compressor outlet and before all the pressure drop mechanisms? Or at the plenum...after all the tubing, collectors, IC and other pressure drop contributors?

 

For the piping ordeal....check into a VW aircooled "Stinger" pipe. It's the single straight pipe that sticks out the back for an exhaust. Looks like a long cone......large size outlet is about 3" and it tapers down to something pretty small like 1.5 inches. They only cost about $15. Cut and weld it to make the transistion a bit smoother.

sean

 

At the plenum. It would be nice to measure them before the IC as well... jsut need to source cheap pressure transducers (MAPs). When I get my second AuxBox, I will just use it's MAP sensor for thsoe measurements. What are you thinking?