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06-03-2010
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#21 | |
 
Join Date: Dec 2003
Location: Chicagoland,IL
Posts: 2,679
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Re: Porting a stock LT5
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 I would take LocoBob up on his offer,he has done a few port jobs he does good work.  Pete
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'91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage |
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06-03-2010
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#22 |
  
Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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Re: Porting a stock LT5
I'm a DIY'er as well. I learn more by doing than watching, but I can tell ya from first hand experience too that education costs money, especially when it comes to heads! Honestly, unless you stay under 35mm, as Marc H told me; "85% of the risk comes from 15% of the gain!
Leaving heads on: One of our Canadian engine builder friends  told me that a 4% taper is "a good thing". I did some reading on the subject, and dayam if he wasn't right - or at least agreed with 2 other sources I found. Bottom line: tapering from 36mm to 33ish at the valve guide or a cm above it is mathematically poifecto (according to some sages). Unfortunately, I can't quantify the results, cuz I never got the chance to dyno it against the 390/400 rwhp benchmark for a top end porting. But, I can tell you it was a friggin amazing leap in performance! Heads off (full porting): 1) For a proven way to go, send your heads to Pete for a CNC and be done. In the end, the cost is 'bout the same as DIY...or so it was for me. 2) See #1 or make sure you have a professional head repair outfit lined up, just in case.  Don't worry 'bout pin-holes in the weld (there is a cheap way to fix those). Do worry about pin holes where welds did not take place - as a thin spot will eventually crack and you'll have coolant or oil (depending) gushing in. Gotta run just now. But from one DIY to another, if ya just hafta, then PM me and I'll show you in painful detail where the quicksand is  and how to avoid at least some of it!P.
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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06-03-2010
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#23 | |
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Banned
BANNED
Join Date: Oct 2006
Location: MD
Posts: 3,690
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Re: Porting a stock LT5
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06-03-2010
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#24 | |
Join Date: Apr 2009
Location: Portland OR
Posts: 173
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Re: Porting a stock LT5
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06-03-2010
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#25 | |
 
Join Date: Dec 2003
Location: Grand Island NE
Posts: 1,510
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Re: Porting a stock LT5
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I remembered you were both in Oregon, didn't put it together you are in the same place...
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Dennis Fierstein 90 ZR-1 #2562 Atomic-Z ZR-1 Net Registry Chairman of the Board ZR-1 Net Registry Treasurer |
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06-03-2010
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#26 | |
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Join Date: Sep 2005
Location: Washington
Posts: 955
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Re: Porting a stock LT5
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 That's NJ cutting more after GVD has worked them over I never heard how that 427 ran 
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06-03-2010
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#27 | |
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Join Date: Jan 2004
Location: Portland, OR
Posts: 1,057
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Re: Porting a stock LT5
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Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368 |
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06-19-2010
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#28 |
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Join Date: Apr 2009
Location: Portland OR
Posts: 173
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Re: Porting a stock LT5
I'm about done with my rookie intake porting job. Here are some before and after Pics.
Look how big the injector port is on a 1990. BEFORE |
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06-19-2010
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#29 |
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Join Date: Apr 2009
Location: Portland OR
Posts: 173
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Re: Porting a stock LT5
AFTER
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06-19-2010
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#30 |
Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
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Re: Porting a stock LT5
Looks good, what are the specs??
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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Linear Mode
