shane661
Needs a life
Posts: 11494
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posted November 22, 2006 12:58 PM
 Edited By: shane661 on 22 Nov 2006 13:04
Compression: How High is Too High?
Just looking for some input (again).
For a street engine, running pump gas, what would be the max streetable compression? Is 13.5:1 too high on a stock bore engine with stock cams?
Also, what would be the maximum that you would want to spray on such compression, using a) race gas and b) pump gas? Assume forged pistons.
Thanks.
  
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VincentHill
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posted November 22, 2006 01:20 PM
It always depends on the SIZE of the SHOT!! The People from South Florida only sprayed 15 HP
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psycho1122
Pro
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posted November 22, 2006 05:54 PM
I Run close to or over 14:1 compression and run 91 Pump.
Quench area is a tight .027 with 1270 Muzzy JE's in conjunction with some special piston massaging  I also keep the A/F ratio on my map under 13:1.
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You say PSYCHO like it's a BAD thing!!
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Johnnycheese
Pro
Posts: 1008
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posted November 22, 2006 06:47 PM
well if you are putting in new piston bore it, if you are cheating and pulling the b gasket bore it. either way you need valve springs and a stock motor will hold a 60 shot if you have the fuel and timing but you better have springs
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Builder and tuner of some of the fastest N.A. and P/A Hayabusas and ZX12 /14 in Texas
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supra5677
Pro
Posts: 1279
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posted November 22, 2006 08:47 PM
a stock zx6rr runs 13.9 to 1 compression. Usually to compensate for
increased compression you can retard the ignition timing. Mathematically
the thin head gasket on my zx12r with my cam timing yields 12.8 to 1
compression. California only has 91 octane. hope this helps.
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shane661
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posted November 23, 2006 05:34 AM
So, it is apparent that 13.5:1 is quite do-able for the street. Now my question is: With stock bore (not stock pistons) forged pistons how much could I safely spray on that, wet or dry?
With an upgraded fuel delivery, and timing retard, of course.
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Johnnycheese
Pro
Posts: 1008
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posted November 23, 2006 01:41 PM
again if you are changing pistons go bigger
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Builder and tuner of some of the fastest N.A. and P/A Hayabusas and ZX12 /14 in Texas
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shane661
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Posts: 11494
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posted November 23, 2006 02:04 PM
Ok man, ok. Then...on a big bore, with 13.5:1....how much spray can it take? (Say Muzzy 1270, or JE 1290's)? Thanks.
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supra5677
Pro
Posts: 1279
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posted November 23, 2006 03:49 PM
you can probably go to 14.1 to 1. with spray. but you should probably retard
the ignition timing a few degrees. Im only guessing
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Johnnycheese
Pro
Posts: 1008
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posted November 24, 2006 07:27 AM
quote:
Ok man, ok. Then...on a big bore, with 13.5:1....how much spray can it take? (Say Muzzy 1270, or JE 1290's)? Thanks.
I did one with a 170 shot on a 1270 with 13.8:1 and it still is alive. I did do a teardown for some inspection and overdrive gears (Thank you Mr. Hill) by the way the mains looked mint
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Builder and tuner of some of the fastest N.A. and P/A Hayabusas and ZX12 /14 in Texas
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01zx12r
Expert Class
Posts: 338
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posted November 25, 2006 04:33 PM
Im in the 14.3 to 1 area with my 1427. Ive only sprayed about 70 hp so far...This thing is such a monster without spray I cant wait to put the full shot to it.
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Lovett Racing/Pedigo Performance
8.40 @170
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osti33
Needs a job
Posts: 2973
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posted November 25, 2006 08:31 PM
Edited By: osti33 on 25 Nov 2006 20:32
Edit. Nevermind.
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