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I raced a guy in my mach 1. He had a 72 mustang with also a 351C 4V with about 138000 miles on the engine, a stock c6 he put on and stock 3.00:1 gears. I have a posi track, 3.50 gears and a stock engine with about 35000 on a rebuild and a 4 speed. We took off and I had about 1 1/2 maybe two car lenghts on him out of second gear, but towards the top of third, he caught up to me and then passed as I shifted to 4th. Could someone please help explain where the top end is on my car? I don't think the gears are big enough to cause so much of a problem are they? Is there anything quick I can do to get some better top end pull (4500-5500)?
 

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I really dont know how to explain it, but my truck is the same as that guy's mustang. With 2.50 rear gears, it wont get out of the hole very well, but when the 460 starts winding a little, it will come on like a 2 stroke motorcross bike. I've surprised many, many unweary nitrous and blown mustangs like this. The high gears will allow him to make more mph before a shift, say around 60 mph or so in low whereas the 4 speed you have to shift a couple times losing precious time. That's my explanation, for what it's worth.
 

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You just discovered the performance difference of an automatic versus a 4 speed. An automatic will shift like lightning, time after time, where a 4 speed can only shift as well as the hand pulling the lever. It's hard to say for sure, but if you had speed or power shifted through the gears, you may not have lost.
 

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If you fall over on the top end its usually from the carb going lean, the motor running out of flow capability or your top end rpms are way beyond the horsepower range of the motor. On the other hand if your opponent hits the Go Baby Go button that would do it too.
 

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Discussion Starter #6
He has headers on his. I just have the stock exhaust manifold and from there back its 2 1/4 inch with flowmaster mufflers.
 

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351C's NEED to breathe. Assuming there is no great differences between the engines, and both are tuned fine, the exhaust is why he is making so much more power than you. It is why is 138,000 mile C6 351C is outrunning your much fresher 4-speed car. A set of headers and a GOOD exhaust system will put you right back in front of him!

Get a set of headers and install a 2.5" exhaust. For tailpipes, purchase a set of Flowmaster MANDREL BENT units. They are only $99 through Summit. Local muffler shops can NOT do these 'crush free' bends on their hydraulic benders. They crush the pipe down to nothing making those tight bends that go up and over the axle. Most shops are more than happy to install the Flowmaster units if you bring them in. (Custom tailpipes can be a PITA to make)

Install some long tube headers and get a 2.5" exhaust installed with Flowmaster 2.5" mandrel bent tailpipes... and you'll be ready to spank his a**.


Good Luck!
 
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