I'm not sure what you're comparing. Having the inlets above the intercooler is about the best place for intake air, there's debate about needing the upper duct though. Sean has some datalogs, the stock intercooler overheats BAD very quickly and the upper duct may not be real important - I'm shocked if that's true. Once the intercooler heat soaks temps rise quick so I'm going for bigger with pipes above it in the cooler air for intake. I'd be interested in knowing how Markski fits it too. Methanol will certainly bring temps down no matter what but distribution would concern me as would fitting a tank with plumbing.

 

the way the intakes are fitted over the i/c is to cut thru the upper ductwork for the aluminum or flexible tubing and run above the i/c. i ran mine behind the upper ductwork so no obstruction of the i/c. the debate will rage on for decades and though i rarely agree with marks he is correct in saying meth is not needed for any of these types of installs. its not even needed for the factory setup.

as far as i/c are concerned there arent many who mod the car beyond a tune and exhaust without upgrading the i/c. using stock for anything above a tune is counterproductive so meth on factory i/c are irrelevant

 

I don't claim to be an expert on this stuff, but I do have some data on my own personal experience. I'm just an enthusiast looking for the best solution, and hopefully my dicking around with this stuff can help someone else make an educated decision on what they want to do with their car. I'm not trying to sell anyone anything, just here to help!

That being said ; there is no perfect solution for this. Each of these options come with sacrifices. Throw the filters on the those and you have plenty of airflow, additional spool, but a large rock could come through that filter and cause some damage quick. The filters get dirty quick, but if you want max power (for the track / strip / whatever) this is probably the way to go. If you get stuck in the rain ( a GOOD rain ) be prepared to pull the car over unless you want to chunk a motor.

You can run a flexible intake pipe, which is a little easier to work with, but space becomes an issue, and restriction on the inside of the pipe as well.

You can make / buy / build a hard pipe setup, which has less restriction than flexible intake piping, but is harder to build, harder to fit, and clearance again is an issue (from the tire and the chassis / suspension over large bumps).

For the other enthusiasts here, my personal situation is wanting a car with great power / torque and to keep the block together. Some tuners say 600tq is the limit, some say 650, some say 700tq...then of course what dyno are we talking. While power IS important to me, keeping the motor together is more important. I really didn't want to run the filters on the turbos because of a close friend losing a motor to a torrential down pour, but we don't mod these cars for our health, we want the power we paid for, so thats important as well.


Here's option 1 : Filters on the turbos. Quick spoolup, sounds awesome, gotta be careful about rain and rocks, most people run pre-filters. Car felt the fastest like this. note how filthy the turbo is, and I probably drove only a few hundred miles like this.




Next option, move the filter up and above the intercooler. Do you just tuck it in the little cavity behind the intercooler ducting knowing that it probably doesn't get fresh air, or do you modify the ducting to allow air to hit the intercooler?

cavity :




modified intercooler duct:



*image courtesy of vivid tuning


Realize if you cut a hole to the intercooler duct that air will take the least path of resistance and not go through the intercooler unless you block it off (what Markski does with his intercoolers).





so if you DON'T do this...air isn't going to go through the intercooler, it's just going to go around.

Once you decide on that, you need to decide what you're going to run. Flexible intake ducting or fab something up from aluminum? Aluminum dissipates heat really well and is stronger than the flex stuff BUT harder to fit, and build. Here was my setups that I tested :







aluminum 2.5" piping :








the hard part about THIS setup is that unless you have to worry about A. the piping hitting the tire and B. the pipe hitting the chassis / intercooler bracket. I tried to remove as little as possible on my first mock-up...which is where the car currently stands now. The intercooler bracket is the only thing that's been modified. I've put 200 miles on this setup and haven't hit it once on the wheel tire (while driving extremely aggressive), but am running an aggressive offset on my rear wheels. In fact, switching from a 315 / 25 to a 305/30 now causes tire rubbing on the fender liner on larger bumps. I will also say that when I hit a large bump i can hear the aluminum intake hit the chassis (not a great sound).

I originally tried running the flex piping lower, but had issue with the tire rubbing the tubing under hard cornering :





when I added the clamp and routed the tubing higher i had no issues with the tire rubbing even under hard cornering :




so what about numbers? WELL. the car was tuned with the filters on the turbos, and then I tested the flex tubing, then the aluminum intakes, and then was re-touched up since the air flow was modified.

Here is a speed over time graph I made from 3 logs comparing filters on turbos, to flex tubing, to hard tubing.



Now don't jump to conclusions too fast, because the added air restriction actually lowered the boost a little bit. Could we have raised the boost to compensate? Sure. But it wouldn't help with spool time.




So what am i going to do? Probably keep the aluminum fender intakes and find a way to make sure they never rub or clunk. The question is, can the chassis be modified a pinch (cut out / punched in) so the pipe can sit 1/2" closer into the car so help with the clearance.

Hopefully this will help some of you that were in the same predicament I was in looking for options.

 

^ dan i had a thought and may try to build some tubing that runs back up alongside the transmission in the same path as the factory setup coming from the top of the motor but from underneath just high enough to get out of the path of hard rain. maybe try some nascar oval or square tubing to make the bends. if theres room to bring it down then theres room to snake it up.
i want to run them off the turbos but the rain scares the crap out of me. in TN we get serious downpours and i can't drop an engine and recover from the cost. something in-between factory and off the turbos for the street and then off the turbos at the track is in my head

 

I guess it's depends on how you drive the car. Do you drive it for fun when you have nothing to do and there's no chance of rain? (this is how i mainly drive the car but i'd be lying if i said I didn't drive it to work on nice days).

Or... do you more 'daily drive' the car regardless of weather? I have other cars to drive in the rain. and the snow. and the cloudy dates. and the pollen days. the 996 is for the perfect days.

 

truck is my daily but its not uncommon to leave in the morning for cruise and get caught in a rainstorm that lasts for hrs. off the turbos is my choice for now but i worry about it.

 

Ive run both filter on the turbo and soon to be above the intercooler. The filter on the turbo gets clogged up VERY easily and quickly I am sure you did these tests with fresh filters but thats normally not the case on the street and driving the car after a week or so.

I would like to see more back to back to back pulls and see certain logs. Because I want to see the type of air temp per say thats being pulled in via the filter location.

 

Now that's some data and seriously appreciated! As an in between of the ribbed and the hard pipe have you considered silicone? The ribbing seriously disrupts the air and I'd expect the silicone to be better and not bang over bumps, it would also flex if struck. Another thought, off the turbo but with a sheet metal guard to prevent direct access to water and dirt? Some folks are running hydrophilic pre-filter socks that seem to work but it makes me nervous too. Very interesting to see the power differences! How about oval aluminum tubing? Not sure proper bends can be found though.

Really appreciate the pictures. I've got a vendor for intercoolers picked out and am pondering removing the upper duct but I can see the concern about air bypass needing to be addressed as Markski has done. I like the idea of putting the stock style DVs down on the ICs too. Lots to ponder and glad to see others digging into this too. I really don't like the convoluted path Porsche built as there's huge room for improvement...

 

i am glad i could reanimate the discussion :-)
the line i posted was a quote from esmotor.
i guess there are different paths for different needs.

 

dkfx great real info post above, thx

My car was set up with the current option 1 with filters off the turbos. As Wealth says the only or main problem here (especially on Long Island roads) is the amount of crap off the roads that gets flung into wheel wells and in around the turbo area.

I think I will change out filters every 6 months or so. I do like the quicker spooling that is very noticeable with the MAFLESS set up and filters on turbos than the stock set up and the nice blow off / whoosh sounds my car makes if I pump the gas and lay off.

The other solutions may be a better DD solution for those of us that can be a bit rough on our cars

 

If I was going to run filters off the turbos, I would run those filter covers like you see on the sand dune cars. They seem to work well.

 

any links? i did see a picture from 356 outlaw f/b page were a german company used a stainless bell and some stainless steel mesh that was extremely fine. looks great for airflow and debris protection but no solution for the water issue in the rain

 

Wow, outstanding thread

 

Outerwears is the term you guys are talking about

 

Is this question a joke/trolling?