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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Monday, August 22, 2016 5:29 AM
I am curious, why were Nissan stretch bolts used instead of ARP studs? Cost? Simplicity? Timing?
Dan DeRosia
Dan DeRosialink
Monday, August 22, 2016 9:06 AM
Seeing the GTI-R bearings and the similar things that rotaries do on some models makes me scratch my head a bit. I wonder if it's more about timing oil flow than anything, because if you look at the area the oil has to flow out through (clearance of the bearing and all) and look at the area of even just the stock hole it goes in through, the stock feed hole really should be no restriction whatsoever. I mean, I don't think it hurts either, but...

(I say this as someone who worked in the R&D lab of a bearing company, albeit for larger applications than passenger car engines)
Mike Kojima
Mike Kojimalink
Monday, August 22, 2016 9:34 AM
The stock bolts are fine even for moderate power levels.
Mike Kojima
Mike Kojimalink
Monday, August 22, 2016 9:36 AM
If you look at the GTI-R oiling there is a lot more dwell time to transfer oil. For moderate power levels, the stock oiling is ok. I would have done the GTI-R block grooving myself but this was a quick and dirty rebuild. The engine's bottom end was and has been doing fine and can only be better now.
Chris "Shaggy" Allenlink
Monday, August 22, 2016 10:16 AM
Mike & Martin You guys should let me show you how to build your own ECUs and do your own Tuning ! :)
Monday, August 22, 2016 12:04 PM
@ Chris: If you're serious I know that you know Mike and Martin somewhat from your SR days and it could make for fun articles... colin at motoiq.com
Monday, August 22, 2016 7:25 PM
^^^ I definitely agree I would love a informative write up on tuning and putting together a ecu such as megasquirt etc. Would be very beneficial!
Chris "Shaggy" Allenlink
Tuesday, August 23, 2016 11:13 AM
I would love too... I'm not much of a writer but I have known Mike 20+ Years now and Martin almost as long ... I would do anything for this guys ... I am always an open door to help when and where I can ..
Saturday, August 27, 2016 6:56 PM
Mike, this article is perfect as I'm about to begin the process of rebuilding my 66K mile SR20de from my '92 (I'm the original owner) the engine suffered rod knock at a track day at the '09 convention. Yes, it's been that long.
I would like to know your thoughts on Oil Pumps? Is there an upgrade available that flows more? Is it even needed? In my case is may be...
Mike Kojima
Mike Kojimalink
Saturday, August 27, 2016 9:42 PM
The VE oil pump has a lot more flow. With a history of rod bearing failure, you might want to consider grooving the main saddles in addition to running the GTI-R bearing set.
Monday, August 29, 2016 12:46 PM
The best part was when we first confirmed it was the HG: I was cranking the motor (which still felt strong even with the Autometer temp gauge pegged past 260*) and Martin said he heard water splashing. Huh. Odd. I'm sitting in the car and Martin's looking all over for the leak with nothing apparent.

That's when I notice the small river coming out from under the car through the open driver's door. The water splashing was water running out of the exhaust at an alarming rate. Ye Olde SR20 was the world's most awkward water pump!

Too bad we couldn't resurrect that motor. She was a trooper!
Tuesday, March 21, 2017 7:04 AM
As for any rocker armed SR20... why did you skip the important bit? Valve clearance.. yes, it has hydraulic lifters, yes, the shims are interchangeable and should be set correctly using the proper tool. A lot of people don't and guess why the thing has a bad reputation...
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