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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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Just Picked up my 951S: drives like a slug: suggestions on what's wrong??
Ok, picked up my turbo S: here's my impressions:
Clean emissions test, decent (24mpg @ 80mpg) gas mileage (1000 miles of driving this weekend). Ran injector cleaner through it on 1/2 tanks to help remove some of the gas separation, evident from the odd readings during times, on the gas level indicator. Car does NOT want to "go" from a stop: acts like a heavy 944 until you hold the throttle down: takes a few seconds to build boost, very lethargic, low power (230hp or so?). Not sure what boost it's making, I need to put a gauge on it. Car has: *leaking Kirban Adj. FPR on it *MSD Ignition *Magnecor 10mm wires *Green-topped Bosch Fuel injectors (any idea if these are stock or not?) *some funky mushroom hex-head grey banjo bolt in it at the boost pipe. *Stock Air filter, exhausts, cat, muffler, nothing else visibly different. Also, e-brake engages kinda low, & car squats quickly on acceleration, so I'll check tonight to see if the cable is allowing the e-brake drums to not fully disengage. Thoughts my friends?? 
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-23-2008, 07:40 AM
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Registered
Join Date: Aug 2006
Location: Australia
Posts: 130
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When I bought mine I discovered that the inner skin of the exhaust ahead of the Cat had collapsed. It could be that if the exhaust is original. It could be a lot of other things also.....
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1981 930 headers, K27, 1 bar spring 1988 951S work in progress |
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06-23-2008, 02:19 PM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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Yes, I helped a guy in Austin 2 years ago via email trying to discover his issue: he found that too! I need to do the entire exhaust (cat too) to be sure it's not that: in the plans anyway.
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-23-2008, 02:21 PM
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Registered
Join Date: Dec 2007
Location: Mooresville, NC/Omaha, NE
Posts: 79
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They make a backpressure tester that screws into the O2 sensor bung. Anything over 1-2 pounds is too much IIRC.
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Doug 86 951 BBS, LSD, MBC, Zeitronix stuff, Rennbay stuff, Pelican stuff, Arneworx stuff, and stuff with more stuff. |
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06-23-2008, 05:23 PM
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Super Moderator
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get a boost gauge asap. what does the stock gauge read?
know what chips it's running on? have you performed a compression test yet? results?
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) |
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06-23-2008, 07:56 PM
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Super Moderator
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btw, the stock bosch injectors have green connectors;
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) Last edited by nize; 06-23-2008 at 07:59 PM.. |
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06-23-2008, 07:56 PM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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Pooh, I was hoping the green-top injectors were larger & that the chips were appropriate. I have yet to check the computers to see what chips are in it. I don't think it's boosting more than stock, but haven't checked it yet.
I plan to update the exhaust anyway, so not going to spend the time checking the backpressure, but a good note: didn't know that existed. I had Porsche do a PPI on the car: clean compression & leakdown. (nice o-rings on those injectors pictured above)> Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-24-2008, 05:28 AM
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Super Moderator
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hahah, that was the 'before witchhunter' shot. here are the same plugs after;
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) |
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06-24-2008, 08:12 AM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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Pretty. Does anyone know how much fuel the factory injectors will flow? I remember back 10+ years ago, my 951S dyno'd 357rwhp/345rwtq @ 17psi on pump gas through the stock injectors.
Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-24-2008, 10:17 AM
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Super Moderator
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http://www.clarks-garage.com/shop-manual/fuel-12.htm
stock bosch injectors = 384 cc/min @ 3 bar (approximately 36lb injectors) i would be interested in seeing that dyno from 10+ years ago with afr, as i'm sure you were either over-running the stock injectors at those settings, or losing a lot of power towards redline. on my original 2.5 motor with siemens 55lb injectors (approximately 578cc) at 17psi, the injectors were running very close to 98% duty cycle at 2.5bar, so i know the stock injectors would not have cut it.
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) |
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06-24-2008, 10:37 AM
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Architecture & Porsche's
Join Date: Jan 2006
Location: Austin, Texas
Posts: 3,189
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My dyno was just months before they bought the WB sniffer: so no AF's
 Mark
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Porsche Club Racing National Scrutineer '89 Andial 951 '82 928R '74 911 RSR 3.6 |
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06-24-2008, 11:17 AM
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