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Author Topic: Compression Ratio Question????? 88bird ¯ Member # 1424 posted                              With aluminum heads, whats the highest ratio I should run on the street??? 331, w/ afr's and custom ground cam... Posts: 149 | From: Citrus Heights | Registered: Jun 2002  |  : AaronC ¯ Member # 86 posted                              Your typical 331 with SRP -5cc valve relief piston and 58cc AFR head will give around 10.5 compression which is good. A 347 with the same piston and 56cc AFR will give 11.0. 10.5-11.0 is pretty common on street/strip strokers these days running 91pump gas. Camara90 ran 11.1 on 91 without any problems [ December 09, 2003, 05:31 PM: Message edited by: AaronC ] -------------------- 1991 GT Convertible: Stock 157k mile shortblock, HiTech cam, AFR 165 heads, Edelbrock RPM intake, 1 3/4 headers 12.23 at 112.99 Best MPH 113.97 Posts: 776 | From: woodland | Registered: Dec 2000  |  : Bounty Hunter ¯ Member # 1422 posted                              if you want to stick with pump gas I would go with a 10:1 motor Posts: 257 | From: All over | Registered: Jun 2002  |  : Blue Oval ¯ Member # 2548 posted                              Ive run 10.5 and its a PERFECT street compression. it runs on pump gas NO PROBLEM Id go 10.5. [ December 09, 2003, 05:03 PM: Message edited by: Blue Oval ] -------------------- 65 Coupe 306, AFR's 89 Cali. Ed. Saleen "sold" BAB 89 GT 08 Yamaha R6 Posts: 2345 | From: Sacramento | Registered: Mar 2003  |  : Yellow94GT Mr. 60 FT Member # 431 posted                                 My 11:1 motor runs fine on 91 octane -------------------- AED 1994 GT Bucket that will likely never run 1999 SLOLEEN Twin Turbo Coyote 2008 F250 580 RWHP 1129 RWTQ Posts: 5990 | From: Cameron Park, Ca | Registered: Sep 2001  |  : mustanggt5091 All I need is..... Member # 444 posted                              so does my 11:1 -------------------- 88 GT 357w (SOLD):( 06 Limited Edition R6 !!!!! Posts: 2353 | From: Fairfield / Santa Rosa , Ca | Registered: Sep 2001  |  : 4RS FED ¯ Member # 2067 posted                                 by 12:1 91 octane 383chevy engine ran great on pump gas, i even shifted her at 9800rpm -------------------- i have a twin turbo mustang and you don't! Posts: 3686 | From: 650 | Registered: Nov 2002  |  : BlueOvalRacing ¯ Member # 1531 posted                              ttt Posts: 1159 | From: Pioneer | Registered: Jul 2002  |  : Stimson _ Member # 51 posted                              another vote for 10.X:1 Posts: 2373 | Registered: Jun 2000  |  : z ya ¯ Member # 1327 posted                              If you plan to run 10.5 to 1 and above you better have a fairly stout cam in there or your dynamic comp ratio will be too high and it will ping. If you have a fairly stout cam in it ...it will help bleed of cylinder pressure so that pump 91 can be used. -------------------- 03 Yukon 6" RCD/welds/MTR's 69 Camaro 72 Commando/500 caddy/39.5 Boggers 96 Dodge Cummins/2" Procomp/35's Posts: 414 | From: stockton,ca | Registered: May 2002  |  :

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