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Detached Member
Join Date: May 2003
Location: southern California
Posts: 26,964
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Idle Questions on Turbos
After reading a number of posts on Turbos, (I have a NA 84 ROW Targa), I was wondering a few things, This is what I've gathered, sorry, I haven't got the exact numbers but here goes (BTW, I'm not looking to buy or create a Turbo, at this time). It looks to me that a Turbo has relatively low compression like 6.7 or something like that and runs at about 0.7 atmosphere of boost above ambient. So that sounds to me like you get a resulting effective compression ratio of 6.7 x 1.7 = 11.4 or so. Is that right? My ROW is 10.5:1 compression ratio, so is a Turbo that much faster, expecially since I have 10.5:1 all the time, and the Turbo has to spool up and doesn't start spooling until about 3,000 RPM. I'm sure that above 3,000 the Turbo is faster, is the boost linear from 3K up to redline, or is it full boost at some lower RPM? By faster, I mean both from 0 to whatever and from say 3000 rpm in whatever gear up to redline.
Any idle thoughts on this would be appreciated. 
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Hugh |
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05-04-2004, 03:10 PM
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Registered
Join Date: Jun 2001
Location: Sweden
Posts: 5,911
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75 to 77 have 6.5:1 CR, 78 to 89 have 7:1 CR.
When boosting, effective CR will jump, yes. Also, much more air/fuel mixture will be crammed into the engine making it perform like 4.5L one instead of 3.3. And yes, turbo engine will have somewhat worse torque/lazier spinup until turbochargers starts boosting at apporx 3000 revs.
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Thank you for your time, |
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05-04-2004, 03:20 PM
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