The intercooler is probably the only win-win mod you can do to a turbocharged vehicle. There are no downsides unlike other mods. For example, a bigger turbo might give you more air flow but at the cost of low-end driveability and response. Or, that lowered suspension might handle great, but you find you can't drive over normal terrain much any longer. The intercooler is different. It only does good.
The key to optimizing the performance of any vehicle is to lower the intake charge as much as possible. Lower intake air temperature is the key to increased performance and reliability from a turbocharged vehicle. And an efficient intercooler will provide consistent intake air cooling even under extended high speed, heavy load and high boost pressure conditions.
Toyota did just about everything right when designing what we refer to as the MkIII Turbo. From it's race-derived double-wishbone suspension to the world's first double-overhead cam 24-valve turbo inline six motor, it broke ground in virtually every area of automotive engineering. Magazines complimented Toyota even on the exhaust system, stating that the stock cat is one of the highest flowing they'd seen. There was one area, however, where the car lacks when you begin to turn up the wick and experience higher boost pleasures... the intercooler.
According to a July 1988 issue of Turbo magazine, "The factory intercooler leaves little to be desired with regards to both pressure drop and cooling effectiveness. When we ran our first dyno tests on the Supra, we thought the restriction at higher boost pressures was actually in the turbo, but in conferencing with Cartech, Spearco and HKS, it was found that the stock intercooler itself was a major contributor to the problem. Testing at Cartech showed the stock intercooler to have a 3 psi pressure drop at 6.8 psi and a whopping 4.3 psi pressure drop at 9 psi. In other words, the turbo had to do the same work and therefore, produce heat as if it was run at 13.3 pounds of boost, while the engine itself was only seeing 9 pounds of boost...." Other testing I've read agrees with this. This is not to say that the stock I/C is totally bad. If you're running stock boost levels and if you plan to race, give the car adequate time to cool prior to a run, it'll be fine. But when you really start to play, the I/C upgrade begins to look like a better idea.
The only intercooler Turbo was able to do an actual before and after test on was the Cartech unit, although all the intercoolers are similar in size and capacity. Turbo measured an 11-horsepower increase at stock boost pressure. Previous testing on the Cartech intercooler showed a 7/10 psi drop at 6.8 psi and a 1.10 psi drop at 14 psi. In addition to actual pressure drop, Cartech testing of the intercooler showed 89% efficiency vs. 68% on the factory unit. Similar testing by Reg Riemer for SONiC concurred by showing approximately 90% efficiency and extremely good flow for the HKS unit as well.
HKS Intercooler Systems are designed for maximum efficiency and minimal pressure loss. Each system includes a high quality aluminum air-to-air heat exchanger, mandrel bent pressure pipes, all required cad-plated mounting brackets and installation hardware, Nomextm fabric reinforced silicone connector hoses and stainless steel clamps. My mind was made up on what I wanted eventually.
I purchased this HKS 7M-GTE Intercooler Kit used from someone who was parting out their car after an accident. I met this person at the Las Vegas SOGI meet and trusted him not to sell me short (so to speak :-). After chatting via email and over the phone we worked out a fair price and he sent me the entire kit and kaboodle.
It was only after I received the kit and went through everything that I found out that I got a small treasure. This kit was the original HKS Intercooler kit and included things you can't get in the new kit today. This kit was originally sold as a part of an overall package supporting the HKS Full Turbo upgrade. The biggest difference is that it includes an extra pipe for the connection to the turbo. On today's kit, that piece remains the same rubber hose. The only downside is that the brackets for this kit are also a little different and unavailable from HKS now. No matter. I had them all and they just needed a little CJ TLC to bring them back to perfection :-).
Because the original owner of his car installed a Kaminari body kit and decided to paint the new bumper with the bumper still attached to the car, there was a fair amount of rather disgusting overspray on a large percentage of the parts. Being fairly anal retentive in such matters, I decided to clean everything with Brillo (aluminum oxide pads) as best as I could and then R&R the entire lot as well as send everything off to my friends at Performance Coatings for some of their usual magic. Ok, so it would take a little more than CJ TLC, but I was up to the challenge...
I had the coaters subcontract out the intercooler core to get it solvent dipped to remove the excess paint (since bead blasting could damage the fins), professionally cleaned inside and out, straighten all the fins, and pressure test it to 40 psi. Then, the coaters applied a thermal dispersant coating which increases heat transfer by another 10-15% or so, seals the aluminum, and generally makes it look excellent. This is the same tough coating used in a number of places inside my engine including the coolant passages to eliminate hotspots. You can see the dramatic results below in this before and after shot:
After just cleaning with Brillo Myself
After Professional Cleaning and Performance Coating
With the core refurbish completed, I could turn my attention to the pipes...
The hardpipe upgrade also had a bunch of paint and overspray on them as you can see in the following before and after pictures. But I fixed that and went my usual one step beyond. All of the pipes were treated to cermachroming which is a process in which the pipes get blasted absolutely clean and smooth and then are sprayed with a ceramic coating. The coating is then polished to high chrome-like luster, but unlike chrome, this stuff has an R-value :-). Able to withstand turbo exhaust temps without bluing (I should know, my heat shields are done with the same stuff), they were a perfect blend of beauty and protection:
After just cleaning with Brillo myself
After Cermachroming (Top)
After Cermachroming (Side)
I even redid the HKS/3000 pipe in my own special way... First, since that particular pipe is a cast piece, I had it polished to give it the same surface finish as the other pipes and to increase flow through it. Then, it was cermachromed like the pipes above and repolished. The final step was to bring back the original red background behind the HKS lettering. That was done using a high-temp high-gloss red after masking everything off. We shot it red and then recured the entire piece. The results were nothing short of spectacular:
After (Wow! :-)
I think I'm getting a little ahead of myself here. Before sending these off to be coated, I went through each pipe with my Dremel and made sure everything was absolutely perfect, smooth and deburred. The welded-in small pipe for the attachment of the stock BOV stuck into the air stream and I completely buzzed that down to perfect smoothness.
Also, a flange had to be welded on in order to mount the Greddy CBV to the new pipes. You can no longer rely on the elbow pipe included in the MA70 BOV kit supplied by Greddy. You thus need to order the Greddy Steel Flange - Type R/S which is Greddy Part No.: 370102. As the part name implies, this will work for either the Type S or Type R valve, since they only differ by their relative spring constants, valving and output port sizes. I located and welded on the flange for the mounting of my the BOV. Then, I used up a bunch of bits by cutting and smoothing the inside of that flange to perfection:
Since the car this came off of had years of built up grease and goo which I couldn't clean off, I decided to replace all the silicone joiner hoses as well as all the miscellaneous hardware pieces (nuts, bolts, etc.). I sent all of the brackets along with the pipes and had them coated for the ultimate in corrosion resistance and protection. All of the joiner hoses were genuine HKS parts, which meant they were expensive :-) but looked and worked beautifully. The clamps were replaced by genuine 303 Stainless versions and the bolts, nuts, and washers were replaced by zinc-plated counterparts. The stage was set and everything was in better-than-new condition.
Since the moving company managed to abrade my front bumper cover while transporting my car across the country (for my new job), they agreed to pay my entire claim to fix it correctly. This was nearly a grand to do right. I decided that while it was removed to be painted, that I would do a few modifications to the airdam "grille" in an effort to bring it up to more modern asthetic standards. I designed a new look on paper and then went to work finding a suitable grille material and working out the engineering required to mount it. The details can be found in my airdam modification page (coming soon), but needless to say, I made sure everything was maximized for flow to the new intercooler in addition to providing protection for its delicate fins.
Installation & Results