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SVT Shelby GT500
2007 Shelby Weight Problem????
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<blockquote data-quote="Robert M" data-source="post: 3016307" data-attributes="member: 9628"><p>One thing I forgot to add, the 69 and 70 BOSS 429 could in no way be considered a "pre-emissions" Mustang. A correct "as it came from Ford" BOSS 429 had a full smog pump/A.I.R. (Air Injection Reactor) set-up bolted on the engine on the assy. line. The reproduction smog kit for a BOSS 429 runs around $1200. Most all of the upper end performance engines from approx. 1968-on had smog pumps including 302 Z/28's, BOSS 302's, 428CJ/SCJ's, 429CJ/SCJ's, 427 Corvettes etc. The Holley carb'ed engines seemed to be the ones that mainly got smog pumps. If anything these engines could be considered pre-Cat and EGR., that was a late 1974/1975-up thing.</p><p></p><p>BTW - We (Mustang Monthly editors and myself) chassis dyno'ed many concours correct big block Mustangs for a Big Block Blowout feature in 1999. Tested were 6 cars, 3-428 Shelby's (67PI,68CJ,70CJ), 1-1968 390GTA, 1-70 BOSS429 and my 71-429SCJ Mach 1. ALL of the concours restored "crisp/clean running" 428's ran in the 232-238 RWHP range, the BOSS 429 pulled a 242 (running rich) and my 71-429SCJ a 247 (running rich). The 68 390GTA pulled a 165 RWHP (running rich). I later did a Dyno Tune for Performance article for Mustang Monthly in 2001. I tweaked the factory 780 Holley to it's best performance level and was able to achieve a 290 RWHP/365Ft.Lbs. If tuned properly, that BOSS 429 with it's smaller factory installed 735cfm Holley "may" have achieved those same numbers 290 + or - RWHP in stock "as it came from Ford" configuration. This is why low 14's and very, very high 13's were the common numbers on these cars when stock, as they came from Ford. Remember these cars did not come with tubed headers, they had cast iron manifolds. It was like blowing your exhaust into a log. My 71-429 didn't even come from the factory with an aluminum intake. The 428CJ's were factory rated at 335h.p., I think that 67 428PI (dual quad) was 360h.p. and the BOSS 429 and 429SCJ were both rated at 375h.p. I think the 390GT was rated at 275h.p. On the old muscle cars you can basically bet on a 75 h.p. loss from the flywheel to the rear tires on a manual trans car, and 100 h.p. loss on an automatic. It takes much energy/power to turn those heavy drivetrain parts.</p><p></p><p>R</p></blockquote><p></p>
[QUOTE="Robert M, post: 3016307, member: 9628"] One thing I forgot to add, the 69 and 70 BOSS 429 could in no way be considered a "pre-emissions" Mustang. A correct "as it came from Ford" BOSS 429 had a full smog pump/A.I.R. (Air Injection Reactor) set-up bolted on the engine on the assy. line. The reproduction smog kit for a BOSS 429 runs around $1200. Most all of the upper end performance engines from approx. 1968-on had smog pumps including 302 Z/28's, BOSS 302's, 428CJ/SCJ's, 429CJ/SCJ's, 427 Corvettes etc. The Holley carb'ed engines seemed to be the ones that mainly got smog pumps. If anything these engines could be considered pre-Cat and EGR., that was a late 1974/1975-up thing. BTW - We (Mustang Monthly editors and myself) chassis dyno'ed many concours correct big block Mustangs for a Big Block Blowout feature in 1999. Tested were 6 cars, 3-428 Shelby's (67PI,68CJ,70CJ), 1-1968 390GTA, 1-70 BOSS429 and my 71-429SCJ Mach 1. ALL of the concours restored "crisp/clean running" 428's ran in the 232-238 RWHP range, the BOSS 429 pulled a 242 (running rich) and my 71-429SCJ a 247 (running rich). The 68 390GTA pulled a 165 RWHP (running rich). I later did a Dyno Tune for Performance article for Mustang Monthly in 2001. I tweaked the factory 780 Holley to it's best performance level and was able to achieve a 290 RWHP/365Ft.Lbs. If tuned properly, that BOSS 429 with it's smaller factory installed 735cfm Holley "may" have achieved those same numbers 290 + or - RWHP in stock "as it came from Ford" configuration. This is why low 14's and very, very high 13's were the common numbers on these cars when stock, as they came from Ford. Remember these cars did not come with tubed headers, they had cast iron manifolds. It was like blowing your exhaust into a log. My 71-429 didn't even come from the factory with an aluminum intake. The 428CJ's were factory rated at 335h.p., I think that 67 428PI (dual quad) was 360h.p. and the BOSS 429 and 429SCJ were both rated at 375h.p. I think the 390GT was rated at 275h.p. On the old muscle cars you can basically bet on a 75 h.p. loss from the flywheel to the rear tires on a manual trans car, and 100 h.p. loss on an automatic. It takes much energy/power to turn those heavy drivetrain parts. R [/QUOTE]
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