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The Terminator
Turbo Cobras
How to pick AR for 1000+ twin turbo 4v?
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<blockquote data-quote="tt335ci03cobra" data-source="post: 15521070" data-attributes="member: 68944"><p>Race or street, the rpm range, displacement, turbo size and driving characteristics are what will matter. If the goal is power production at xyz rpm, spec the a/r accordingly. </p><p></p><p>Obviously we are talking about area ratio relative to the compressor wheel. </p><p></p><p>If the op will need the car to run strong from 7000-9000rpm, then yes, a .83 a/r, or possibly even .88 a/r (or what the turbo manufacturer has closest to those values) is a great choice. </p><p></p><p>Op, what will you rev this engine to, and what rear ratio, tire height, and auto will you be running? </p><p></p><p>Take those numbers, calculate your rpm range per gear, and tailer your a/r accordingly. </p><p></p><p>Example:</p><p></p><p>28" tire</p><p>4.10 rear</p><p>th400</p><p>8000rpm</p><p></p><p>Running a .83 is an excellent choice because you'll be between 7100-8000rpm most of the strip.</p><p></p><p>28" tire</p><p>4.56</p><p>C4</p><p>9200rpm</p><p></p><p>Running a larger .88 a/r makes sense because you'll be between roughly 7700-9200rpm most of the strip.</p><p></p><p>26" tire</p><p>3.73</p><p>4r70w</p><p>7500rpm</p><p></p><p>A .70 ar is great because this is a street car setup that likes 6000-7500rpm.</p><p></p><p>26" tire</p><p>3.55</p><p>4r70w</p><p>6500rpm </p><p></p><p>.60 ar is great.</p><p></p><p>Ar is area ratio. Discharge relative to compresser opening. The closer/larger than 1:1 you go, the more rpm needed to reach optimal flow.</p><p></p><p>A 12,000 rpm cbr1000 will run a 1.5+ a/r. </p><p></p><p>A 5000rpm stock turbo car will run a tiny .30-.50 a/r.</p><p></p><p>There's plenty of good YouTube videos that explain the science, and the way to calculate what you'll need.</p></blockquote><p></p>
[QUOTE="tt335ci03cobra, post: 15521070, member: 68944"] Race or street, the rpm range, displacement, turbo size and driving characteristics are what will matter. If the goal is power production at xyz rpm, spec the a/r accordingly. Obviously we are talking about area ratio relative to the compressor wheel. If the op will need the car to run strong from 7000-9000rpm, then yes, a .83 a/r, or possibly even .88 a/r (or what the turbo manufacturer has closest to those values) is a great choice. Op, what will you rev this engine to, and what rear ratio, tire height, and auto will you be running? Take those numbers, calculate your rpm range per gear, and tailer your a/r accordingly. Example: 28" tire 4.10 rear th400 8000rpm Running a .83 is an excellent choice because you'll be between 7100-8000rpm most of the strip. 28" tire 4.56 C4 9200rpm Running a larger .88 a/r makes sense because you'll be between roughly 7700-9200rpm most of the strip. 26" tire 3.73 4r70w 7500rpm A .70 ar is great because this is a street car setup that likes 6000-7500rpm. 26" tire 3.55 4r70w 6500rpm .60 ar is great. Ar is area ratio. Discharge relative to compresser opening. The closer/larger than 1:1 you go, the more rpm needed to reach optimal flow. A 12,000 rpm cbr1000 will run a 1.5+ a/r. A 5000rpm stock turbo car will run a tiny .30-.50 a/r. There's plenty of good YouTube videos that explain the science, and the way to calculate what you'll need. [/QUOTE]
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How to pick AR for 1000+ twin turbo 4v?
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