Project Infiniti G20 Racecar: Even More Power


Removing this hard pipe isn't as simple as blocking off the port on the head and calling it a day.  In addition to the heater and throttle body ports, the hard pipe also happens to house the ECU's coolant temperature sensor, and has a port for the instrument cluster's idiot gauge.  Since this gauge only reads stone cold, reasonable, or replace engine, we would re-tap it for our Autometer sending unit.  The other end of the pipe had a clearance dent for the throttle body, and a nice mounting system to keep it from failing due to vibration, so we decided to retain as much as possible.  Our solution was to simply clamp the end of the steel section coming out of the cylinder head and weld it shut.  On the other side, we cut the offending pipe off of the water pump feed, and clamped and welded it shut near the thermostat housing.  Whenever clamping a pipe shut, make sure to leave enough space to allow the pipe to clamp without pulling out of the ends.  Generally, 2″ is plenty for this.  The remaining nipples were cut to about ½” tall, lightly hammered down until they were flush with the main pipe, and the remaining crack was welded shut.  This solution left much of the OEM mounting bracketry intact, but removed what we didn't need.  To keep the coolant flowing through the pump, we simply removed the thermostat, as it's open for the duration of all but the coldest races. 


Project Infiniti G20 Racecar SR20DE Water Hard Pipe Modified
Our water hard pipe after the offending sections were removed. 


It turns out, turbos are not exempt from the laws of physics, specifically Boyle's Law.  To counter this, we'd need an intercooler.  Our power demands weren't very high, and our airflow through the nose of the car finite, so we decided to use a smallish Forge Motorsports Type 04 intercooler we had lying on the shelf.  This intercooler was of lightweight tube and fin construction, wasn't very tall, and fit perfectly behind our bumper support.  


Project Infiniti G20 Racecar Forge Motorsports Intercooler
Our Forge Motorsports intercooler was mounted directly behind the bumper support to maintain the same amount of airflow over the radiator. 


Why mount it behind the bumper support?  Again, we didn't need a huge amount of airflow to keep the charge air relatively cool, and by mounting it behind the bumper, our radiator was seeing about the same amount of air it had before.  To feed the intercooler fresh air, we simply expanded the license plate frame area of our Euro Primera bumper, and cut some “speed holes” into the bumper support.  We weren't in the habit of bump drafting anyway, so the minor reduction in bumper strength shouldn't be a concern for us.


Our intercooler breathing through “speed holes”.


So far, we've been able to get away with stuff that was either found on a shelf, or in the case of the Earl's plumbing, a necessary extravagance.  That all ended after we noticed the lack of connection between the turbo, intercooler, and throttle body.  Looking at some of the intercooler kits online, none of them seemed to be what we wanted.  Luckily, fabricating your own custom piping isn't very hard, so we turned to Vibrant Performance, and Summit Racing to purchase an assortment of mild-steel U-bends.

To connect our custom intercooler piping together, Turbosmart proved an invaluable resource with their wide assortment of silicone hose couplers and Murray Clamps.  We went with silicone couplers because of their better temperature resistance, flexibility, and durability.  High-grade silicone couplers like those sold by Turbosmart will not deform under racing conditions and pop off, and are much less likely to fail or tear.  


Project Infiniti G20 Racecar Turbosmart Silicone Hose Couplers
Turbosmart silicone hose couplers.


To keep our couplers in place, we used Murray constant tension clamps.  These worm-gear clamps use spring tension to compensate for the effects of thermal cycling, and are extremely easy on the couplers due to their separate inner band.  This inner band has two raised ribs to help sealing, and the edges are chamfered to prevent damage.  No more witness marks on the couplers from the sharp edges of standard worm clamps, and the spring tension design seals better than T-bolt clamps.


turbosmart, Murray Clamps, turbosmart hose clamps
Murray constant tension clamps not only look cool, but also provide better sealing due to the two raised ridges.  The spring tension reduces the likelihood of losing a hose coupling because the clamp can expand and contract.  This spring tension also allows the clamp to be more tolerant of deformed, or out of round, piping.


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