stock exhaust..no cat
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Joined: Nov 2001
Posts: 90
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stock exhaust..no cat
85 305 TPI 45,000 actual.Have done free mods, plus k&ns.Have gutted cat, still have stock G.M. exhaust ,including cast iron manifolds.(3-in into & out of cat,narrows down to 2-1/2 into crossflow muffler.) Nice rumble,mellow,but deep and throaty.Not too loud. Seems to pull harder on top. Am wondering if I go to Dyno-max ultra-flow muffler & t-pipes, will I lose too much backpressure? How much horsepower did I gain by gutting cat? How much power would I gain with dyno-max. Would a 305 breathe efficiently enough with stock crossflow & no cat? Would appreciate any thoughts.
Airfoil, screens & fins removed,Bosch 4's, timing bumped to 12, 92 octane,ram air & k&n's,3:42 posi.160* thermostadt, manual fan toggle switch.
[This message has been edited by pauls (edited December 01, 2001).]
[This message has been edited by pauls (edited December 01, 2001).]
Airfoil, screens & fins removed,Bosch 4's, timing bumped to 12, 92 octane,ram air & k&n's,3:42 posi.160* thermostadt, manual fan toggle switch.
[This message has been edited by pauls (edited December 01, 2001).]
[This message has been edited by pauls (edited December 01, 2001).]
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Welcome aboard, in case you haven't been welcomed before.
Please go to this post https://www.thirdgen.org/messgboard/...ML/003460.html , read it carefully as well as the one referenced within that post, and please, never, ever again, in the future, refer to "backpressure" as a good thing.
In general, the stock pieces are not very good compared to aftermarket parts which are well-matched to your particular engine. With stock manifolds, it's almost impossible to increase the flow to the point where it will hurt you. How much benefit you can derive from improving everything behind the stock manifolds is subjective, but I doubt you could get much more than 15-20 horses until you go to headers.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ3/4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
Please go to this post https://www.thirdgen.org/messgboard/...ML/003460.html , read it carefully as well as the one referenced within that post, and please, never, ever again, in the future, refer to "backpressure" as a good thing.
In general, the stock pieces are not very good compared to aftermarket parts which are well-matched to your particular engine. With stock manifolds, it's almost impossible to increase the flow to the point where it will hurt you. How much benefit you can derive from improving everything behind the stock manifolds is subjective, but I doubt you could get much more than 15-20 horses until you go to headers.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ3/4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
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