Williampreza's Kamaitachi: NA BRZ The "Easy" Way
 

This is a record of efforts to develop a high revving, well-sorted and comfortable, sports car with good street manners and a surprising turn of speed.

https://i.imgur.com/wJP058u.jpg





Listed are Goals and the plan to achieve them as they stand at the beginning. Some may prove unrealistic or irrelevant. Some may not make any sense to anyone but me. This journal is primarily for my own benefit, but I like talking about cars, so don't hesitate to ask.
Goals:

• Mission: To create a Sports car using minimalist aesthetic modifications, positive functional modifications, and efficiency improvements.
  
  • More power by reducing the amount of work the car, as a system, has to perform.
  • Least added wear
  • Reduced long-run expense
  • Avoid changes that require significant supporting modifications.
  • Any synergistic modifications must be sequentially positive. That is, they must improve the car individually, or occur at the same time.
  • All modifications must fall within the scope of the original design for the car
  • No super/turbocharging
  • Original engine
  • Power through high rpms, maximizing NA efficiency, light weight
    
    
  • Goal is a more enjoyable driving experience
  • Sports car, Not a race car
  • Track days are a way to appreciate what a car CAN do, not to decide what it SHOULD do
  • Aesthetics are a balance
  • Perfection lies in the appropriate combination of imperfections
  • No one else is ever going to “get it” completely. So, make the car mine.
  • Resale value is not a consideration.
  • "Better" is superior to "More"
  • I am part of the equation. Improve the driver to match the car.
    
    
  • Efficient changes
  • No warranty-killers
  • Each modification builds toward final goal, each modification, by itself, results in an improvement in the driving experience.
  • Avoid duplicate modifications (multiple ECU flashes, upgraded components replaced by further upgraded components)
  • Minimalist change; each alteration shall have the minimum scope and magnitude necessary to achieve the goal
  • Minimalist change; each alteration shall fulfill as many functions toward the goal as possible
  • Minimalist change: each alteration shall have no, or negligible, negative effects relative to the goal.
  • Long-term cost reduction comes from careful planning, selection of parts, and implementation of changes, plus efficient disposal of surplus.
  
  
• Methods:
  
• Each part/change must pass three tests:
• Does this part/alteration make it easier for my car to do what it is was designed to do?
• Does this part/alteration reduce or have no effect on the natural rate of wear of the car or its parts?
• Does this part/alteration result in a pure elevation in my aesthetic experience of the car?
• 
  
  
• Powertrain: Naturally aspirated, Street daily driver level modifications.
• First; improve external engine breathing
• Catback and intake (Completed 02/24/18: Corsa Cb exhaust, Perrin inlet tube, K&N filter)
  
• Oil cooler
• Consider upgrading radiator
• (Warranty expires)
• Intake manifold (porting/honing or replace with high flow or ITB’s) and headers simultaneous
• ECU flash†
• E85/Flex Fuel
• Coatings†
• Second; improve internal engine breathing through valvetrain*
• Add lightness- lightweight valves, retainers, springs (avoid increasing spring rate if possible)
• Stage 1 camshaft
• Third; further improve internal airflow with porting/modification of cylinder head only if necessary*
• Fourth; Displacement and compression modifications via full engine build, only if necessary*
• Stand-alone ECU if necessary.*
  
  
• Suspension:
• Stock suspension is already perfect for the way I drive (Oops. Some RS-R Down Lowering springs must have fallen into my car and installed themselves. Accidentally. :shrug: )
• Modifications that allow alignment corrections to correct wear problems
• Camber/crash bolts
• Adjustable control arms only if necessary
• No pillow balls, harsh bushings, except as necessary to prevent damage or excessive wear of other parts
• Aero mods: Balanced front and rear
• Functional front splitter
• Functional rear diffuser (Completed 02/29/19--Verus Engineering Non-aggressive Rear Diffuser)
  
  
• Brakes:
• Dot 4 Brake fluid
• Upgraded brake pads suitable for both spirited street and rare (1-2 per year) track days, installed after stock pads wear out.
• Steel brake lines seem like fun, if not completely practical/functional.
  
  
• Tires:
• Moderate increase in grip relative to stock tires, focused on tire compound changes likely will have try several sets over the years until I settle.
  
  
• Wheels:
• Lightweight, as robust or stronger than stock. Stock diameter is perfect. Possibly keep stock wheels.
• Interior:
• Weight reduction:
  Nope, I can’t think of anything I wouldn’t miss.
• OEM-style center armrest (Completed 02/24/18)
• Stereo system: Keeping stock (Changed the Infotainment system anyway.Completed 01/05/19
  Swapped a JVC sub amp and Alpine DVC 8" subwoofer from another vehicle.
  Added Pioneer AVH1440NEX head unit with Maestro RR for SWC integration. )
• Gauges:
• Add Oil Pressure Gauge (Completed, Moved to vent location in September 2018)
• Seats: If stock seats prove too uncomfortable, may consider upgrading, but I’d rather keep the airbags. Bolsters?
• Window Tint: (Legal max on side windows and rear windshield. Blackout quarter panel windowsCompleted 02/21/18)
• Pedals: Throttle pedal adjustments Ended up going with an aluminum pedal set from FT86Speedfactory. Completed ~09/26/18

*Only used if previous modifications do not achieve power goals
†May accompany other modifications, possibly in multiple iterations

So, I like to read outdated How-To books and, a long time ago, I read in one entitled "How to Drive Sports Cars" --or something like that-- that a sports car should have at least 250 horsepower. That was an enormous leap from the cars I was familiar with as a 10-year old kid in the 1980's, and that number stuck with me, even though later I would learn that 250hp means different things in different situations.

Later, I got enamored with other ratios, power density figures and power to weight ratios like the 10:1 lbs/hp. These are all a bit arbitrary, but then, any number you attach to a concrete phenomenon is bound to be so. Regardless, those two stuck with me, 250 horsepower and 10:1 lbs/hp (which consequently works out to around 280 for my car). Therefore, that became my goal; to achieve between 250 and 280 horsepower in a street-friendly (note I didn't say "streetable" because that can be interpreted more loosely), naturally aspirated engine.

Here's where we're starting. The baseline for power is measured on a chassis dyno. My goals are as they would be measured on an engine dyno, so we will assume (arbitrarily) that the chassis dyno costs about 25 hp or 15%. The difference is negligible considering the relatively low horsepower numbers and the breadth of my target hp range. That means I'm shooting for somewhere between 213 and 238 horsepower on the chassis dyno. Note that I'm not especially concerned about torque numbers, so long as they don't go down.

https://i.imgur.com/q0SBqJb.jpg?1

The first mod:

https://i.imgur.com/ODTFwmR.jpg

I like your "mission statement", so to speak. Will keep an eye on your build

Most people don't think enough about their mods (I've ruined two cars that way). On the other hand, you just might be overthinking. Still, if it results in your perfect car, great.
Only thing additional I can think of is catch can, as a reliability mod.

Fun facts

"Kamaitachi" also can apparently be interpreted as "stance sword", which is not at all what I was going for.

And there's this guy...

http://www.voicesofwrestling.com/wp-...2/93492261.jpg

Pretty color caw as it sits.... good plan too


22R

True. I do enjoy overthinking things. My wife claims
That my “real” hobby is planning my hobbies.

This is me too.

I'm looking forward to this, I really like your view on how your build should be done. I'm curious what you will end up doing with the intake manifold and how it goes.

I ordered some basics last week.

Tint is done. It looks great and I shall not comment on the process as that is documented in mortifying detail elsewhere in these hallowed halls.

En route are a K&N filter specific to the 2017's, an also-2017-specific Perrin inlet pipe (black), a Corsa Sport Catback Exhaust with Stainless tips, and an OEM-looking center armrest because my arm gets tired from waving it about while I rant about things that turn out to be irrelevant.

I picked the Corsa exhaust because, based upon overwhelmingly positive YouTube reviews, it looked to be a quality product and it might sound as close as is reasonable to a Ferrari 308 GTB (do a search and you'll find that discussion.)

Some of the threads regarding the Corsa exhaust plus headers have led me to question my plans about adding headers at all. I'm going to see how I like the whole setup after tuning and E85 (these changes will be a while, since I'm not interested in losing warranty coverage.)

As for the intake ideas, those will happen AWE (after warranty expires) as well, but some possibilities I've been tossing around in my head are:

ExtrudeHone/abrasive flow machining, which polishes the interior of the manifold by pushing a peanut buttery, silly putty type fluid through it. The fluid has an abrasive media mixed in it and that is supposed to do all the work. Ideally, this would smooth airflow through the runners and improve volumetric efficiency throughout the rev range. Less ideally, it might just hog out the inside of the runners, increasing cross-sectional area and improving VE only in the higher RPM's. Since my ultimate goal is an 8000 rpm engine that maintains stock or better torque all the way through, that might still work.

I've only found two places that do this kind of machining. One is is Pennsylvania and the other in California. That's surprising since I live in Oak Ridge, where there's gobs of science happening and people are polishing damn near everything so the neutrons don't get stuck. You'd think it would be easy to locate a local shop that does this.

A similar approach, and one that might actually have a local presence, is Magnetic Abrasive Flow processing. Basically, you fill your workpiece (manifold) with a mixture of abrasive media and ferrous beads, then stick it in a machine that rotates magnets around the whole assembly, vibrating the beads and therefore the abrasive. This sounds promising, but the only applications I've seen are either in university settings, or in machines intended for jewelers. Not on the scale I need.

I am however, eyeing my random orbital sander and wondering how to attach a magnet to it. (and some steel BB's... need a lot of those...). Hold my beer.

Anyway, the intake polishing idea may or may not produce measurable results, but it seems to be relatively affordable, and it fills in an area that is yet unexplored, somewhere between ITB's and custom intakes.

Will report back with photos of the exhaust, etc. as they're installed.

I did a lot of research into headers+corsa volume, even met with a guy locally to see if it's something I'd be able to live with and I have to say, it's not bad at all. The car was fully catless and the noise was livable. I'm just looking to get the headers and leave the front and over pipes alone. This is exactly what mine will sound like actually cause I'm looking to get the Gruppe S header.

www.youtube.com/watch?v=fQ2NO-Z1ai8

Nice choice on the Corsa, it's a quality piece and sounds lovely. Only issue I have is trying to align the tips.

I think the key to keeping the volume down with a catless header will be as @StraightOuttaCanadaEh mentioned, keeping the stock frontpipe.

Maybe there was variation between production batches, but I had no trouble getting the tips even and centered, and usually that's the kind of thing I NEVER get right. So, I imagine the credit goes to Corsa for adjusting their production.

https://i.imgur.com/XXGW4sI.jpg

https://i.imgur.com/q8e9CJh.jpg


Sent from my iPhone using Tapatalk

@Williampreza looks great! Initial thoughts?

And they probably corrected something after I called them multiple times and they tried to make it sound like my fault haha. :bonk:

I haven't done an exhaustive search, but my impression is that the Corsa sounds much better by itself than it does with headers. I couldn't find a UEL pairing that sounded better than a Perrin or MXP after a quick poke around. Interested in what you find here.

I do wonder what an A350 would sound like with the Corsa..

https://youtu.be/fQ2NO-Z1ai8Have you heard this one though? Corsa+Gruppe-S, combo I'll be going for :wub:

[ame="http://youtu.be/fQ2NO-Z1ai8"]http://youtu.be/fQ2NO-Z1ai8[/ame]

That one sounds pretty cool! I'd be interested to hear some in-cabin or drive-by recordings. Not that the camera mics ever do these justice :thumbdown:

Seems a bit more aggressive than the JDL + Perrin I'll likely go for. Any idea of how loud that setup will be?

No idea, sorry. All I know is if you wanna keep the volume relatively simple, leave the oem overpipe and front pipe in place

Well, my wife and I went out last night and nobody complained. That's even after quite a bit of extra driving because our favorite restaurant went out of business (retirement) and we had to drive around deciding on a substitute.
Lower end rpms are completely acceptable. The only notable difference was that, particularly when at intersections in heavy weekend traffic, I kept looking around for the car with the aftermarket exhaust, only to remember that it's me. :party0030:

Wide open is a blast and the overall effect is exactly what I was looking for. Now that the exhaust is installed, I can hear exactly which frequencies are missing relative to the 308 benchmark, but I knew it wouldn't be perfect.
I am probably going to see how far I can get the car with tuning, intake manifold work, and E85, before committing to headers. The dB level is right where I want it.

If you are worried about the inside of your intake manifold, may I recommend looking into getting a pcv catch can.
2cents

Yeah, the A350 was part of my original plan. We'll see how I feel after a few months, when everything has settled in.

Thinking about Intake Manifolds again...
 

After a brief chat about intake manifolds with my local tuner (I was still trying to source a local extrude hone or manetic abrasive honing shop), I came away with an interesting notion. He pointed out to me that the stock aluminum manifold for the new twins has an inherent design flaw from a flow perspective. The intake charge enters the plenum from the front, the plenum is more or less rectangular, and the runners are arranged longitudinally along the path of airflow. So, basically, the front two cylinders/runners get cleaner air than the back two.

Now, I don't know how much of a difference this actually makes in real life. But I started flipping through a couple books and the internets and I noticed a conspicuous trend. If you look at high performance intake manifolds, they are all designed to account for even air distribution between different cylinders. Even the STI manifold has a different way of directing air to the runners:

http://dsportmag.com/word/wp-content...fold-SpecC.jpg

So... what's this all about? Well, now I'm toying with the idea of modifying an intake manifold by chopping the throttle body off, welding up the side where it once was and moving the throttle body to the top. I measured... Kinda... It might fit.

I'm thinking something along the lines of an old school single-plane manifold.

I'd be interested to see how that would go. In general I'm not sure how much there is to be gained on NA from intake mods, but I'd imagine if anything works that will be it.

Not sure if you've seen this but it's a good read.

http://www.ft86club.com/forums/showthread.php?t=82479

Yeah, I wish that had worked out for them. The way they've got that designed, it looks like they're aiming for high rev power, probably beyond 7400rpm.

My hope is to find a bit of power still hidden in the stock manifold. It's also likely that, for the stock redline, there is none left. That would mean I need to increase the rpm range, which would require cracking open the front cover and pulling the heads/valvetrain (in order to make any effective AND safe changes).

Eventually, I'm going to get brave enough to pull this pristine intake manifold off my engine and get some measurements.

Here's the shape of what I'm thinking...

https://i.imgur.com/4nWlhmo.png

A quick note:

I got to take the car out for an East Tennessee backroad drive. This exhaust system is perfect. Total fizzy feelings running through my nervous system when I wind it out. Didn’t record. Don’t care.

Highly recommend.


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Update: Found out about one more option for polishing the intake manifold interior. Talking with my father-in-law, a retired engineer, I learned that some folks used abrasive balls with just plain old vibration to do the job.

Unfortunately, he doesn't know anyone with the balls to help with my project.

:shrug:

I am tempted by the Corsa exhaust as well. I think the high strung sound fits the car's personality better than the subie rumble I had with my UEL + FT86 V1 combo on my previous FR-S.

Just waiting on the black tips to go on sale... ;)

This weekend I installed a Pioneer AVH1440 head unit. Honestly this was a "safety" issue, because I can't put my phone down. Basically, using the factory head unit required me to mount my phone on a suction cup mount attached to the little triangle window to the left of the steering wheel. That meant using my left hand to interact with the phone (changing music, using Maps). Also, I like to wear driving gloves, and the combination of left hand touchscreen use and having to take gloves off was just plain dangerous. Third, I had to run the USB charging cable over the steering wheel, which was just sloppy, AND every now and then I would forget it was plugged in and open the door. Finally, suction cups just can't be trusted long term. It always eventually fell off, usually when the door was open.

Apple Carplay solves all this. I can stow the phone, keep my gloves on, use maps without contortionism, and no infotainment structural collapses like before. To top it all, the new head unit just works better than the old one. Two thumbs up!

Sometime back, I moved a JVC sub amplifier and an Alpine dual-voice coil subwoofer from another vehicle. I had a sealed box I had already built for the sub, but hadn't used because the other vehicle was a van and needed a ported box. It fits perfectly behind the rear seats and takes up very little space, and it's easily removed.

When I had the OEM head unit in, I used the high level inputs to drive it. All I had to do to swap was unplug the high level input at the amp and run RCA cable from the new head unit. Easy!

I'm still fighting with the OBDII functionality of the Maestro RR, but I'm probably just expecting too much from a function that was most likely an afterthought. [shrug] OBDII gauges are much better now. I learned from a forum member that my scrolling technique wasn't quite right. Gotta do more of a dragonfly dipping down to sip from a lake motion and not so much the osprey diving to grab a fish. Also, an update is available which should make TPMS data available where it is not currently.

Verus Rear Diffuser
 

Added a Verus-Engineering Non-aggressive Rear Diffuser. It was not aggressive at all. Generally, it just sat there until I picked it up to install. :iono:

The only issue I had was the axle-back portion of the Corsa Exhaust system had some minor interference with the corner of the vertical flange on the passenger side of the exhaust cutout. Easily remedied (per Verus suggestion) with a pair of tin snips and removing a one-inch triangle. That leaves about 1/4" of clearance, which appears to be more than sufficient. The exhaust is solidly mounted, as is the diffuser, so I don't anticipate them rubbing or otherwise getting into trouble while I'm not looking

Also, there was a minor difference between my diffuser and the ones described in the FT86Speedfactory install video and the Verus print instructions. The brackets to connect the forward end of my diffuser were separate pieces, while the same brackets in those were built into the diffuser:
https://youtu.be/54ynNLxkp-s?t=187

You can see the version I installed in the Verus Engineering installation video:
https://youtu.be/tCo7zgyId3c?t=254

https://i.imgur.com/91PChsk.jpg

https://i.imgur.com/HO7jnrU.jpg

https://i.imgur.com/3I9KcpZ.jpg

https://i.imgur.com/GyNagQc.jpg

Today, I accidentally installed a set of RS-R Down lowering springs. Obviously this was my mistake, as I clearly stated I was leaving the suspension alone. Whoops. :shrug"

But...the ride is nice. I can tell I'll need an alignment. Steering feels a bit muted. Might be just me. We'll see when everything gets settled in. Pics when the sun moves from directly behind my car as it sits for the best shot.

Yeah, lowering springs will affect both the camber and the toe settings. Steering is probably not feeling as sharp due to wheels no longer pointing quite where you want them. Get the alignment asap. Nothing eats through a set of tire faster than mis-aligned wheels; especially if the toe is way out of whack.

Nice mods!

How close are the tips to touching the diffuser? Any plans to get the other rear covers Verus sells? The car is looking good!

Thanks!


The clearance looks okay to me. Maybe could use a spacer but I'm honestly not certain.
https://i.imgur.com/oSwlAKG.jpg

I do eventually want to add the full Ventus 1 package, mostly because long, high speed corners intimidate me, but also because I really like the way it looks.

ATM I've fallen down a rabbit hole by trying some modest lowering springs. Which led to alignment off. Which led to LCA's.... it just never seems to end.

That is the danger of straying from your mission statement. Moditis can be fatal...........


..................to your wallet!

I made use of Tire Discounters' "Free Alignment Check", and after considerable haggling, they let me have my car back without doing anything to it besides checking the alignment.

I've got SPC adjustable control arms ordered to correct the rear camber. Also ordered camber bolts for the front, just in case, and also because by adding the bolts, I got free shipping, which, when combined with a discount code, ended up costing less than the LCA's + free shipping. :happyanim:


Any recommendations on target values that I should request in the actual alignment, or should I just let the tech shoot for OEM specs?

https://i.imgur.com/58P9EH0.jpg

Thanks for the pics, looks to be plenty of space between the diffuser and tips.


I have RCE yellow springs, Verus camber plates and SPC rear LCAs. Had to get camber plates due to strut/tire interference with camber bolts.


I have -2.5 degrees camber in the front, -2.0 in the rear, and just a small amount of toe in the rear. No abnormal wear in 13k miles with this setup.



Seems to be the general consensus that the car benefits from some negative camber up front. Below are RCE's suggestions for their yellow springs. Not sure how the RS-R springs compare.



https://s3.amazonaws.com/racecompengineering/instructions/rceyellowsettings.pdf

No definitely do not run stock alignment specs. Shoot for max camber in the front with the bolts and whatever you want in the rear maybe -1.5 on both sides. Zero out the toe in the front and 1/16th toe-in rear.