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Join Date: Nov 2007
Posts: 58
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danger in overboosting!
Oh what fun it is to take a perfectly good Porsche 3.3 engine, install an in-cab boost knob, turn it way too far and have detonation… rule of thumb; less is more.
munchovie.  
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11-28-2007, 08:15 PM
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Yikes!
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11-28-2007, 08:16 PM
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Posts: 58
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here is a closeup - it's a shame because the engine looked so nice on the outside
 
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11-28-2007, 08:25 PM
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That's why I stay at 0,8... that picture scares the hell out of me. I think the 930 is a pretty fast car at stock boost.
I am sorry that happened toyou.. I am sure you'll build it faster, stronger and lighter than it was before the grenade went off. |
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11-28-2007, 09:34 PM
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Join Date: Jan 2007
Location: PARIS & BURGUNDY....FRANCE
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Really sorry for you wmunchovie.....it's a pity...so much damage.....how much pressure did you have...?.....I heard about racing engine runing with 1.85 Bar and no damage...?...so...?...what's going on...?
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Serge, Gentleman Driver https://www.facebook.com/photo.php?fbid=10207116408000968&set=gm.1723624077 855805&type=3&theater |
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11-28-2007, 11:32 PM
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Crotchety Old Bastard
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What boost level caused the damage? What are the specs on that engine?
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8 |
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11-29-2007, 05:38 AM
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Forced Induction Junkie
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It appears there are/were higher compression pistons in the engine. 7.5 or 8.0 : 1?
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Dave '85 930 Factory Special Wishes Flachbau Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P |
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11-29-2007, 06:27 AM
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Join Date: Jul 2005
Location: Reno, NV
Posts: 5,941
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bummer
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"Todd" 98 Tahoe ,2007 Saturn Vue 86 930 black and stock, 80 930 blue tracdog 91 Spec Miata (yeah I race a chick car) "life"ll kill ya" Warren Zevon |
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11-29-2007, 07:43 AM
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looks like your broke the ringland (hole in the piston) on the what could have been the leanest cylinder . the temperatures in that cylinder must have been staggering.
but you threw the rod as well , a forged rod for that matter, you must have overrevved or something else . that is alot of damage for just overboosting . the head studs should have snapped way before that would have happened. it looks like the whole engine is scrap now ... btw. newb to this forum here ... |
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11-29-2007, 10:53 AM
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Wo ist die Rennstrecke?
Join Date: Mar 2004
Location: St Johns, FL
Posts: 1,210
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I feel your pain - don't ask how, or I'll send you my pics.....
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11-29-2007, 05:03 PM
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Me like track days
Join Date: Sep 2003
Location: Kirkland, WA
Posts: 10,209
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Last known statment prior to destruction:
"Hey doods, look my boost is ad-just-able........let's crank it up!"
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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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11-29-2007, 06:06 PM
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Posts: 58
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Well, I’m happy to let you guys know that I bought the car after the damage was done; I just never got around to taking the engine apart. After further inspection it seems as though the 930 was a 3.4 - Ross pistons 8.0:1 101.5mm and had nitrous rings – so I suspect now that not only over-boosted but the big nitrous switch was stuck on… This could account for destroyed rod, it seems.
Anyway, the crank on no. two is pretty bunged up; boat anchor or have the crank repaired? It seems that three of the six cylinders are ok, but I’m just a little shy about using anything from the bottom-end. The heads looks pretty good; I’m going to disassemble them this weekend, clean them up and check the valves, etc. They are twin plug heads with 38mm intakes. Munchovie. |
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11-29-2007, 06:08 PM
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The nitrous is where the rod blew up (Nos backfire?) and way too much timing. Unless the boost went way to high. Ive run my car for short sprints at 25 Psi and no problems.
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Kris @ Tech9 86' 930/GT-40R Sold  94' Rustang GT daily (long gone) 2008 C6/Z51 Corvette |
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11-29-2007, 07:31 PM
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Metal Guru
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I was told by an engine expert where I work that the magic number to a failure of the rod-snapping sort is 10,000 psi in the cylinder.
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Paul B. '91 964 3.3 Turbo Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, H&R Coilovers, ESB spring plates- 210 lb |
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11-30-2007, 06:39 AM
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78 Porsche 911SC 3.0L, 3.3Turbo soon. 
1985 Porsche 930 Fac. Slantnose 3.3l
2002 Porsche 996TT
1991 Porsche 964 Turbo
