To say this post is a long time coming is a massive understatement, most readers have probably moved on waiting for this and are probably driving Golf Rs, Audi RS3s or Elgrands and hanging up the modification gloves.
Not long after Part II of Pearl’s build thread I believed i would have sorted out the bottlenecks which hindered the progress to 300kW.
The original goal was to reach a responsive 300kW figure using the stock bottom end without anything blowing to pieces.
Life as it usually happens, got in the way and playing around with VTEC didn’t help either.
In 2016 after all the mods had been said and done, Pearl pumped out a respectable 272kW.
Looking at the dyno figures, it was evident power was dipping after 5000rpm which left us scratching our heads.
The Deatschwerks DW300 fuel pump was swapped out for a Walbro 460 which was hardwired in. A 3.5” dump pipe and larger hot side intercooler piping were also thrown in for good measure.
Back on the rollers, the gain was only 6kW and the power dip was still apparent.
Whilst not a show stopper and not so noticeable on the lower 1.5bar boost setting, knowing performance was not optimal meant it would eventually need fixing.
Even with the suboptimal setup, Pearl was an absolute brute with a huge mid range punch which managed to net a 1:06.6 around Wakefield which is decent for a street car with full trim.
After many discussions, Johnny and I declared that the source of my high end power robbery were the valve springs i.e. valve float (turns out the “recommended” Tomei Type A springs are barely stiffer than stock).
Supertech springs were immediately purchased and then benched for 1.5 years.
Mid way through 2018, it was time to finally entrust a workshop to perform the valve spring install and crack the 300kw with the internally gated GTX2867R 0.64.
New supertech springs installed and timing fixed (as a result of trusting a workshop), it was time to leave the tuna magic to Johnny – trak-life’s ECU whisperer and the only person I’d entrust with tuning the S15.
Good news is the valve float has been banished, VCT remained intact and a rod did not poke through the side of the block.
Bad news (sort of) is 280kW at the treads was the max the setup would take at an almighty 1.8bar and 1150cc injector 100% duty cycle on E85.
Winding up the boost did not yield any higher power and scenes from Fast & Furious 1 flashed before my very own eyes serving as a warning.
A few GTX2867R Gen I users have claimed 300kW using an external gate and/or forged motor so considering the simple bolt on setup Pearl had, 280kW was a good result and satisfying knowing the top end power curve was sorted.
Out on the track, the car sees lower boost and still scares the bejeezus out of me.
Engine wise, that is how far I’ll go for now with the stock bottom end. It’s plenty of power for the street and Wakefield which satisfies my need for speed.
If it does eventuate, Pearl v4.0 will be an absolute monster.
Pearl the S15 Specs
SR20DET Black top with VCT
ARP head studs
Tomei Poncams 256 11.56mm
Garrett GTX2867R Gen I 0.64 with Turbosmart IWG75 actuator
6boost T2 low mount manifold
Custom 3.5” dump pipe to 3” exhaust
HKS relocation + oil cooler
Blitz D-SBC EBC
Z32 5 speed gearbox
AO gearbox adaptor and tailshaft
Unknown 2 way LSD with 3.9 ratio
HKS Hypermax III Coilovers
D2 6 piston 356x32mm Front BBK
D2 4 piston 330×32 Rear BBK (to be installed)
R33 2 piston rears
Intima Type-D v2.0 brake pads
Garage Mak CF bonnet
Origin CF GT wing
AGI Half cage
Bride Zeta Plus FRP seat
Gotta hand it to Nissan engineering, the SR20DET can really perform and last when built, tuned and maintained properly especially considering the engine is almost 20 years old!
Really a testament to the level of engineering you don’t see these days. Long live the SR20DET.
So in conclusion after a few long years, the big question is – was it all worth it? Would I have been content if I’d never embarked down the v3.0 path and stuck to 223kW, stock 6 speed and stock turbo?
It’s a yes and a yes. Was it all worth it – yes. Would I have been content sticking with the old setup – yes.
Now at a point where the car is running optimal safely, the feeling of accomplishment when I gaze upon the old girl is humbling. Sure, the bank account took a hit but you know full well when buying an S15 and pushing some power into it that it’s not going to be cheap (because gearbox goes bang).
I’m not into brute power so the modest 223kW stock turbo setup previously was enough. Applying the skills and knowledge I have today, the car would have hit the 1:07’s around Wakefield.
Sure, power is addictive and everytime the tires light up I let out a goofish snort like a moron but for those who know my driving style – I’m an absolute granny on the street 99% of the time and just enjoy the drive feels.
When I started Pearl Build v3.0 back in 2015 I set a goal, 300kW on stock bottom end with a 28 frame turbo.
Although that was not directly achieved, there is no feeling of failure here.