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Me like track days
Join Date: Sep 2003
Location: Kirkland, WA
Posts: 10,205
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Stephen aka Porsche PHD - Your take on the boost/CR balance?
Generally speaking & for the benefit of everyone:
For a fully optimized and tuned CIS system (Adj WUR, IA fuel head, twin plug, K27 HF turbo, 965 IC, Tail WG, AFRs virtually level from top to bottom/12:1. Runs about 10 track days per year. What would you prefer to see - lower CRs and 'higher boost', or vice-versa? Could you elaborate? My own data point: I am currently at 7.5:1 with .9 bar boost. Intended as an open discussion with Stephen's input as to actual experience. Thanks in advance!
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- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ - "930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe Movie: 930 on the dyno |
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11-05-2006, 09:47 AM
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Registered User
Join Date: Mar 2002
Posts: 3,563
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IMO, if you're going to be tracking the car, where it sees high loads and sustained max boost levels, I think you're safer sticking with low C/R and moderate boost levels.
I'm sure Stephen will chime in with a more technical and scientific response though 
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Merv '89 911 Turbo Cab Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition 
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11-05-2006, 07:18 PM
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Registered User
Join Date: Jan 2003
Location: Burlington, Wisconsin
Posts: 9,566
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I wanted a bit higher CR so that off boost it was very streetable and I don't intand on tracking the car so this was what I went with.. A couple of folks using the BAE kits on their SCs with low boost and love it because it is very linear acceleration.. But for a monster turbo motor less CR is better and safer
it all depends on street or track applications
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Ben 914-6 2.4s GT tribute. 914-6werkshop.com manufacturer of 914-6, GT, Conversion parts |
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11-07-2006, 06:11 AM
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Registered User
Join Date: Jan 2003
Location: Burlington, Wisconsin
Posts: 9,566
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look at the CR of this car
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Ben 914-6 2.4s GT tribute. 914-6werkshop.com manufacturer of 914-6, GT, Conversion parts |
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11-07-2006, 06:16 AM
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I am trying out 9:1 CR on a 3.8ltr TT motor that is in the works. The plan is to limit boost to 0.7 bar - no lag, quick spool. The hope that this is a nice streetable tyre burner with quick acceleration. I am not planning to race the car, so i dont need high end HP. (where i drive i rarely get the car in 5th gear). But, if i decide to track the car (DE etc), i intend to run 100octane and crank the boost a couple of notches.
This was all under the recommendation of my builder who has build porsche race cars for several teams (incl. some that raced at daytona).
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Mike. 89 930 Turbo Cab.(soon for sale) |
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11-07-2006, 07:10 AM
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Registered User
Join Date: Nov 2006
Location: sterling, ohio
Posts: 18
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I am running a 1986 3.3 turbo with 8.0 to 1 cr euro fuel system powerhaus stage 2 tubo kolken ic 964 cams and extensive head work completed the engine about 2 years ago and the power gained in the low end was unbelievable. I have no detonation problems and has been worry free. Also running with 1.0 bar spring so it can be done with a lot of tuning.
1986 Porsche 930 Strosek Last edited by stephenshane237; 11-09-2006 at 03:49 PM.. |
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11-09-2006, 03:47 PM
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