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Join Date: Nov 2006
Location: Conway,AR
Posts: 1,579
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ITB Sizing
Is the rule of thumb for ITB sizing the same as for carbs? The 40 MM carbs have a venturi which provides some restriction. I am trying to determine what size ITB I should use on a stock 3.0 euro motor. Thanks for your help.
Tom
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1972 911T (with 3.2), 1985 930-EFI Conversion (in progress), 2016 Cayman GT4 |
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08-05-2013, 03:29 PM
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40 will be good. I have a 3.2SS and I use 40s. I was told by several pros that they are good and that I'm not leaving anything on the table. In fact most told me that 46 will be too big.
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08-05-2013, 03:39 PM
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Use the intake port diameter.
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Current: 914/6 GT Conversion, Cayman Old: Many PCars + Formula Racecars |
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08-05-2013, 05:31 PM
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Location: Conway,AR
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I think the intake port size on the "big" port SC heads is 39MM. If that is the case, then the 40MM ITB would be about the correct size. Thanks,
Tom
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1972 911T (with 3.2), 1985 930-EFI Conversion (in progress), 2016 Cayman GT4 |
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08-05-2013, 05:46 PM
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Join Date: Jul 2001
Location: mt. vernon Wa. USA
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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08-05-2013, 06:11 PM
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I just went through this and decided on 42mm Suzuki GSX-R750 throttle bodies for fabrication on my 3.2 engine. 40mm intake port. Close enough and leaving a bit of (small) room for expansion!
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Current: 914/6 GT Conversion, Cayman Old: Many PCars + Formula Racecars |
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08-05-2013, 07:41 PM
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Registered
Join Date: Jul 2001
Location: mt. vernon Wa. USA
Posts: 8,727
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D-Zug Tours RSR dyno
Here's a link to the Dzug RSR project. Justin and the crew have just installed my Speed Triple EFI/ITB kit and if you scroll down the thread a bit you will see the drive by. This RSR has a 3.2SS, formerly using CIS...now with the ITB's installed. They are 42mm. The sound that the RSR makes as it goes by is.........excellent. They are headed to the dyno shortly. regards, Al
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[B]Current projects: 69-911.5, Previous:73 911X (off to SanFrancisco/racing in Germany).77 911S (NY), 71E (France/Corsica), 66-912 ( France), 1970 914X (Wisconsin) 76 911S roller..off to Florida/Germany RGruppe #669 http://www.x-faktory.com/ |
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08-05-2013, 09:24 PM
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