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:
†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So, I like to read outdated How-To books and, a long time ago, I read in one entitled "How to Drive Sports Cars" --or something like that-- that a sports car should have at least 250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 |
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I like your "mission statement", so to speak. Will keep an eye on your build
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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 |
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That my “real” hobby is planning my hobbies. |
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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. |
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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. |
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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. |
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