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<blockquote data-quote="69ST" data-source="post: 144892" data-attributes="member: 5"><p>The combination of sky-high compression ratio, hairier cam profile, increased rpm and a piston with about half the skirt area of the stocker all work against longevity. I've gone through used stockers, with gazillions of miles on the clock, some of which were heavily stained...inside the cases...and looked, from the outside, as though they were suitable for scrap only. The former beasts of burden sometimes have a couple worn gears, scored oil pumps have been common, timing chain slap - bad enough to leave deep grooves in the tunnel has been far from rare. A few of them had visible wear on the countershaft, from the sprocket - how many miles does <em>that</em> take? Have yet to get one with a worn crank or shift fork.</p><p></p><p>With an estimated ~40% power increase, there's going to be a corresponding increase in mechanical stresses. Bone-stock, these things make ~1.5hp per cubic inch; this tune pushes specific output closer to 2.0. The average 2016 car engine makes less than half that. At some point, mechanical limits are reached...then exceeded. The Takegwawa piston is a high-quality piece but, it's a race-type design...nearly skirtless and with teflon strips on the thrust sides. Ostensibly, this reduces weight & friction. That comes at the cost of increased rocking inside the bore, which stresses the rod & crank, too. The OEM would never use this configuration. High compression & 21st century pump gas = increased risk of detonation and sky-high peak combustion temps, which can burn motor oil, as well as parts...either of which can result in rapid, seemingly instantaneous, failure. But, it's not like sourcing a set of pistons for a small block Chevy; choices are limited, unless one's budget is not.</p><p></p><p>It could have been a lot worse. Some race kits, like the Takegawa Scut (uses the classic 49cc lower end), are good for a few races. I know of guys who have run them on the street and consider 4K miles between top end rebuilds "pretty good". By that measure, this was "knocking it out of the park". There's a world of difference between OEM daily driver and race. And this may be the price of admission, for this level of performance, with available off-the-shelf aftermarket parts. I seriously doubt that there will ever be enough guys running these tunes, over enough miles, to ever get a clear picture of what constitutes a reasonable service life expectation. What keeps rattling round in my mind, in addition to loose marbles, is the number of stockers I've known about, still running, with 2-3x the mileage...</p></blockquote><p></p>
[QUOTE="69ST, post: 144892, member: 5"] The combination of sky-high compression ratio, hairier cam profile, increased rpm and a piston with about half the skirt area of the stocker all work against longevity. I've gone through used stockers, with gazillions of miles on the clock, some of which were heavily stained...inside the cases...and looked, from the outside, as though they were suitable for scrap only. The former beasts of burden sometimes have a couple worn gears, scored oil pumps have been common, timing chain slap - bad enough to leave deep grooves in the tunnel has been far from rare. A few of them had visible wear on the countershaft, from the sprocket - how many miles does [I]that[/I] take? Have yet to get one with a worn crank or shift fork. With an estimated ~40% power increase, there's going to be a corresponding increase in mechanical stresses. Bone-stock, these things make ~1.5hp per cubic inch; this tune pushes specific output closer to 2.0. The average 2016 car engine makes less than half that. At some point, mechanical limits are reached...then exceeded. The Takegwawa piston is a high-quality piece but, it's a race-type design...nearly skirtless and with teflon strips on the thrust sides. Ostensibly, this reduces weight & friction. That comes at the cost of increased rocking inside the bore, which stresses the rod & crank, too. The OEM would never use this configuration. High compression & 21st century pump gas = increased risk of detonation and sky-high peak combustion temps, which can burn motor oil, as well as parts...either of which can result in rapid, seemingly instantaneous, failure. But, it's not like sourcing a set of pistons for a small block Chevy; choices are limited, unless one's budget is not. It could have been a lot worse. Some race kits, like the Takegawa Scut (uses the classic 49cc lower end), are good for a few races. I know of guys who have run them on the street and consider 4K miles between top end rebuilds "pretty good". By that measure, this was "knocking it out of the park". There's a world of difference between OEM daily driver and race. And this may be the price of admission, for this level of performance, with available off-the-shelf aftermarket parts. I seriously doubt that there will ever be enough guys running these tunes, over enough miles, to ever get a clear picture of what constitutes a reasonable service life expectation. What keeps rattling round in my mind, in addition to loose marbles, is the number of stockers I've known about, still running, with 2-3x the mileage... [/QUOTE]
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