Project G20 Race Car: Building a More Bulletproof SR20DE!

Project G20 Race Car: Building a More Bulletproof SR20DE!

by Mike Kojima

The good old stock SR20DE in our Project G20 Racecar has been doing yeoman duty, reliably lasting for the last few years racing in the MotoIQ Pacific Tuner Car Championship and doing many for-fun track days.  The stock SR20DE in our Project G20 Racecar came from a Japanese engine importer and has never been opened up, other than to add big cams back when we used to run the car in N/A trim.  For the past three years the engine has been turbocharged which has greatly increased the strain it’s experienced.

The SR20DE is pretty bulletproof within reason as long as the oil and coolant temperatures are kept in check and the power is kept to a reasonable level.  We were really surprised how the engine with its stock cast pistons has kept on chugging along on boost even under grueling road racing conditions.

However, the inevitable finally happened during one of our MotoIQ Pacific Tuner Car Championship races at Buttonwillow Raceway.  Old reliable finally gave up the ghost via a blown headgasket.  It was pretty apparent what the problem was when water shot out the #3 cylinder after taking the spark plug out and cranking the engine during our on-track diagnosis. Funny side note, car still managed to putt its way up on to the trailer!

During the engine teardown we found a significant and unrepairable amount of detonation damage around all but one of the cylinders. We also found that our JDM engine was of the high-compression variety. Which meant we were boosting a 10:1 high compression engine with stock internals for quite some time, which explains the detonation damage.

Our JDM SR20 has been a trooper and performed well beyond its intended limits, but this will be the end of the road for it as a new head and block will need to be sourced in order to get Project Infiniti G20 back on the tarmac.  We will once again be using an SR20DE block and head, only this time we will build her up for boost and use heavier duty racing parts to further increase reliability.

Since we have a FWD platform we don’t particularly want more power, just greater reliability. We don’t want to spend too much time with a fully anal race engine build and most of all we don’t want to spend too much money.  So it’s all off the shelf parts with good machining and careful assembly, but nothing too trick.

Check out what we did to make our bulletproof engine even more bulletproof without breaking the bank!

The main part of the build is focused on replacing the stock pistons with some Forged JE asymmetrical FSR pistons and K1 Technologies billet steel racing rods.
The JE FSR forged pistons are made from tough 2618 low silicon aluminum alloy. They are CNC machined to tight tolerances.

In the case of our pistons, JE’s latest lightweight strut type FSR blank profiles were used. Since we are cheap and race on crappy pump fuel with a splash of VP C16, we went to a dish top piston to reduce the compression ratio from the stock 10:1 to 8.5:1.

Withe the 8.5:1 compression we can run a little more boost and run more spark timing in the map to lower EGT’s and make everything happier. On this dish top piston, the net shape of the forging is very close to what we want to run so no under crown milling was needed to lighten the piston.

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