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#1 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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![]() I recently purchased a B23 to replace my exploded B21. It reportedly has flat top pistons at 10:1 CR. I realize I'm not going to be able to throw 25psi at it but hoping I can get to 15psi. Anyone have experience with this? I'm on MS2 extra so I can pull timing etc, and am using 100 octane non ethanol gas.
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"i will destroy all of you!" -Sheldon Plankton Booty Scooty https://youtu.be/i4oAOZ8nbq4 |
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#2 |
Board Member
Join Date: Apr 2013
Location: Cornholio, OR
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![]() 10 to 1 CR with what head?
You can only make a flat top piston come up so far..... Use a head that has not been milled and do not use a thin gasket.
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I don't know who I am when I am somebody else. |
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#3 |
Board Member
Join Date: Feb 2014
Location: Midwest
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![]() Turn it up until it blows up, then install a new engine with 1 less psi.
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#4 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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#5 |
Board Member
Join Date: Oct 2009
Location: Marionville, Ontario, Canada
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![]() I wouldn't worry about it. With enough octane, and a good tune, you will have no worries.
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1984 244/ AQ140A / M46 |
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#6 |
Hurlurd?Harland?Bueller?
![]() Join Date: May 2007
Location: PDX
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![]() Your PSI is irrelevant without context on what your manifold/cam/turbo/EMS/fuel type are.
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#7 |
K-jet For Life
Join Date: Mar 2007
Location: - Stock PSI Or Bust -
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![]() 15 psi on blue 140 Av gas.
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#8 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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#9 |
Board Member
Join Date: Sep 2006
Location: Quebec, CAN
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![]() All the boost...
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![]() 1990, Volvo 740 16v +T 1991, Volvo 745T 16V - crushed build thread: http://forums.turbobricks.com/showthread.php?t=249553 |
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#10 |
Happy playing the blues
Join Date: Jun 2002
Location: S NJ, a suburb of Phila.
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![]() Big intercooler? The high octane gas burns hotter so keeping it cooler will help a lot. If you have the large intercooler then maybe some water injection will help it live?
Maybe consider using a cylinder head with some work done so it flows through easier? This contributes less heat to the overall picture. |
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#11 | |
Board Member
Join Date: Mar 2005
Location: Sleezattle, WA, USA
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![]() Quote:
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John Vanlandingham/JVAB Imports Sleezattle WA, USA --> CALL (206) 431-9696<---- www.rallyrace.net/jvab www.rallyanarchy.com Vive le Prole-le-ralliat "When a man tells you that he got rich through hard work, ask him: 'Whose?'" — Don Marquis |
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#12 |
Astro Zombie
Join Date: Nov 2007
Location: Reading pa
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![]() I enjoy porting and gasket matching aluminum heads for some weird reason, hit me up if you want. I'll even do SS grooves
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Feedback thread https://forums.tbforums.com/showthread.php?t=144924 1978 242, 5.3 L33 1979 242, MS, R brakes 2006 V50 T5 AWD @ 17 PSI |
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#13 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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![]() After a lengthy conversation with John V last night, I'm going to take it all apart and check the bearings, pistons and CC the head to see what the actual c/r is. He said he might have some turbo pistons for it, if not I might open up the head and/or get a thick cometic to reduce the c/r.
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#14 | |
Board Member
Join Date: Feb 2014
Location: Midwest
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![]() Quote:
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#15 | ||
Board Member
Join Date: Mar 2005
Location: Sleezattle, WA, USA
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![]() Quote:
Quote:
OK went out and check and looks like any B23T pistons got re-cycled... Found some B21 flat tops and 1 B21T piston...So As regards flywheel I'm going thru the stack now..gonna find that OLD B21t pressureplate to confirm 100% OK? |
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#16 |
Board Member
Join Date: Mar 2005
Location: Sleezattle, WA, USA
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![]() Found one...dual pattern, confirmed B21T pattern will PM more
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#17 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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#18 |
Board Member
Join Date: Mar 2005
Location: Sleezattle, WA, USA
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![]() Looks good.
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#19 |
cone dodging dilettante
Join Date: May 2015
Location: In bed, probably
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![]() My experience has been that Volvo published CR has turned out to be pretty optimistic. No way to know until measuring but I'd love to see what the fabled "high compression" B23 actually turns out to be. If I recall correctly what really matters is the dynamic compression ratio, not static so you can protect yourself with a big cam (and pulling timing of course).
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1993 944 B230FT/M90 thread here: http://forums.turbobricks.com/showthread.php?t=345277 2x 1991 245 B230F/M47 (LeMons car, street car) I sell chips for LH 2.4! |
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#20 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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![]() I cc'd the head and it appears to be 49.7cc's. my thinnest feeler gauge .008" was a little tight, so I'm assuming John V is correct at the pistons being in .007" , this gives 10.94-1 on the summit calculator. I'm going to get the head skimmed and check it again. I'll probably order up a cometic thick enough to reduce the CR below 9-1. The pistons appear to be forged, but I'm no expert, I'll have the machinist look at one when I drop off the head.
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#21 |
Dann sind wir Helden
Join Date: Sep 2011
Location: 4D space-time
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![]() I ordered a .140" cometic, it should knock the c/r down to around 8.6-1, depending on how much comes off the head. Now my concern is getting the timing belt on.
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#22 |
Hurlurd?Harland?Bueller?
![]() Join Date: May 2007
Location: PDX
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#23 |
Board Member
![]() Join Date: Jul 2009
Location: Monterey/Falun
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![]() this isn't the 60s, you have a after market ecu, just get it tuned and run the higher compression. it will be so much nicer to drive. no need to knock your compression into the ****ter
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1974 AMC Gremlin, lq4, 7875 billet, ss2 cam, 80e, 3600 stall converter, Holley Terminator x 1984 Volvo 245 1995 Porsche 993 2013 VW Passat TDI |
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#24 |
K-jet For Life
Join Date: Mar 2007
Location: - Stock PSI Or Bust -
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![]() Or do what Volvo did.
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#25 |
Board Member
Join Date: Feb 2014
Location: Midwest
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