3" HKS filter into 3" flexible tubing right into the turbo inlet.
Custom core support between frame rails, incoporates modified stock snub mount with poly bushing, brackets that IC mounts too. Entire assebmly including IC is more or less bolt on with factory mounting points. Some trimming of upper core sheetmetal required to clear top of IC and IC outlet, as well as factory hood latches have been removed and replaced with hood pins. The IC is a tight fit against the hood, and a tight fit all around as you can guess. This is one of the biggest intercoolers I've ever seen mounted in an Audi and rivals the size of the Audi TransAm race IC. Standing back and seeing it mounted brings a great feeling of satisfaction becuase it seemed so unlikely a core of this size would fit. I searched for a while for a core of these dimensions, thanks to Matt Kramer for helping source it for me, and saving me the difference between an Spearco core costing close to $800.
Silicone hump hose to throttle body.
Forge bypass valve, currently running in "blow off" mode
Well, so much for that restrictive airflow meter, now all that is in front of the turbo is a huge cone filter. Then compressed air goes through one 45 and one 90-degree bend into the intercooler, out of the intercooler into a more or less straight 3" elbow right into a huge VW VR6 throttle body. The lower crossover pipe starts as a 2" and flares to 2.5" mandrel tubing. I chose 2.5" because I did not want to oversize and increase pressure drop. Corkey Bell says "Resist the temptation to use larger diameter tubes than necessary, as little drag is created in smooth tubes with gentle bends. Larger tubes will only add to the volume of the IC system, and that is not a good thing to do" - 2.5" will be good for over 500hp. Though it may seem like an IC this large would cause more lag or slow response, I have not noticed any significant difference. I'll be dynoing the car soon to see what the gains are with this new piece in there.
I spent a lot of time on the IC, its not my goal to upgrade it anytime soon, so I wanted to fit the biggest reasonable core I could in there. Luckily the core came with nice endtanks, I just had to seal them up and put the inlet/outlet on it and a mounting system. I found a nice cast tight radius 90 degree bend on ebay to use for the inlet, I ported and hotted out the inside of it to ensure max flow through it, and that got welded on the drivers side of the core. For the outlet things were a bit trickier. The outlet had to move out 5" and up 6" in the confies of a tight area. After messing around with a 3" 90 bend for a couple hours I had just the right solution and a smooth transition right into the TB. From the outlet you can see right into the core, flow should be really well. I estimate that the turbo charge coming out of the IC will be basically ambient even under the most grueling conditions. In the future I may modify the bumper to allow more airflow through it, but at this point I don't know if its necessary.
When you look in front of a stock Audi 80 there doesn't seem much room, so how was I able to fit an IC similar in size to a 3" cross-section of your average refridgerator? Couple things, the most critical being rebuilding the front core support that bolts between the frame rails. Creating a new cross member out of strong steel pieces not only opened up about 4" between the core support and the bumper, it also streghtened the front end chassis. Another modification was creating more room where the alternator was concerned, I modified the upper tension bracket by cutting it and rebuilding it to route to the back side of the alternator, this opened up about 1" in front that would have otherwise hit the IC. I also trimmed about 3/8" off the pulley stud. A shorter alt. belt moved the alternator closer to the motor and opened up more room for the intercooler inlet. Both front tow hooks have been removed to make more room also. Granted, I don't know how this setup will hold in a 5mph hit, I'm hoping I dont find out.
One of the biggest challenges in doing EFI on a KH/MC turbo car is clearing the throttle cam from hitting the fuel rail. The throttle body angles downward sharply and there really in no room to fit a fuel rail. One solution Nate Stuart presented was to move the throttle cam to the other side, which is feasible. Since I wanted to maximize flow, I figured that I could fit the bigger VR6 TB and solve the clearance issued too. Though the 65mm VR6 TB is "only" 5mm bigger, about an 18% increase, it can be bored to 70mm if insane flow is required- they are also very cheap, I got mine free. Misc Silicone hose makes the connections, straight 2.5" for the lower cross pipe and a 3" hump hose from the IC outlet. Fitting the VR6 throttle body required extensive modification to the intake manifold, the original throttle body flange was cut off and a 1" thick piece of billet Aluminum, made to match the VR6 TB, was welded into place. After welding and building up material around the flange, I ground down the entire weld and sand blasted the area to duplicate the factory finish of the manifold. I call it a "South African" manifold, where a lot of odd Audi parts come from! I also had the manifold ceramic coated on the bottom where it is exposed to the exhaust manifold, and the whole thing was coated in a heat rejecting coating to pull heat out of the manifold. Check out Microcoat for more info.
Because I was willing to sacrifice functionality for smooth airflow, the right side hoodlatch had to go. Audi Sport style hood pins went in...oh well, so much for stealth! I also heavily modified the upper core support, I basically cut off all the metal that was in the way and welded reinforcements through it to re-strengthen it. For the throttle cable, I ended up using the stock sheath but cut the cable and slid it out and slid in an MC cable. The point of this was that a longer cable was needed to reach around the IM to the new location of the TB. I reattached the cable to the pedal, works very well. I also modified a VR6 accelerator cable mount to fit the manifold.
I recently added the intercooler water spray system, I did it in anticipation of the August Buttonwillow Drag races which usually feature 110F. ambient temps, and I figured I needed all the help I could get. (Figures measured with original Stage 1 intercooler) Not sure how marked the hp improvement is, but to test it, I ran the spray for 10 seconds while cruising at 70mph, no boost - intake air temps dropped 7 degrees C., so there does appear to be an intake air temp drop, but how it calculates into hp is still unknown. I'm also planning on experimenting with a water injection setup too at higher boost levels. I built the rail out of 3/4" PVC, the water misters are from Home Depot for very fine cooling mist applications. Consequently, it is very easy on water, a full bottle of water lasted a whole track weekend recently.