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Old 09-27-2013, 11:29 AM
if you beat my boat, well race
 
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exhaust crossovers.

hello!
i am doing exhaust work on a 57 chevy belair.
460 hp 383 small block
6 speed and a 9"
i have a set of (shortys)sanderson headers 1 5/8 primary
3" collector.
3 " mandrel bent exhaust. with electric cut outs.
magnaflow mufflers
im looking to do a cross over right after the tranmission mount.
my questions are:
is there a set dimention i should use from the collector to the cross over?
where is the best place to install the cut outs?

ive seen the cut outs mounted after the collector, after the cross over and right before the mufflers.

my thoughts were to install dumps right before the rearend , then over the 9" with mufflers under the trunk.

what are your guys's thoughts?

thanks in advance!

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Old 09-27-2013, 11:58 AM
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Crossing over

The shorty headers, while good for ease of install, are not that great for exhaust flow. Full lentgth Tri-Y's would give you much better low end torque and better high end flow. Keep the crossover the same diameter as the pipes and mount the dumps after the crossover. The further back you go, the less net gain in flow you have. I usually run the crossover right through the space where the trans and bellhousing meet. (In my case, right after the collectors.) Mufflers are also better suited mounted closer to the collectors. Considering the length of the pipe is shorter, there is less room for backpressure. Besides, all the pipe after the muffler, depending on how you route it all, can help scavenge the exhaust through the mufflers. I would stack it up like this if it were me.... Headers, crossover, dumps, mufflers, then tailpipes dumping out infront of the rear wheels with the ends split in two for about the last foot in the same diameter as the rest of the system. We did the split on our '67 TransAm series Camaro, and wow, woke it right up. Have a peek at this picture I took after the RMVR TransAm invitational several years ago. See those two big cannons under the door? A single 3 1/2 split into dual 3 1/2 on both banks.
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Old 09-27-2013, 02:18 PM
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If you want your exhaust to "rap" more, then put the headers closer to the mufflers. It's a well known fact that longer lengths of exhaust after the muffler with really help the exhaust get louder. We used to do these long exhausts back in the 60's to get that pop when we let off the throttle.
Exhaust systems with a longer primary pipe ahead of the muffler will reduce the sound level through this length, making it easier for the muffler to further reduce sound decibels. I would also run the tail pipes clear out the back and install the mufflers just before the rear axle.
If you're planning on exhaust cutouts, then install them ahead of the X pipe, as they'll work better closer to the engine.
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Old 09-27-2013, 08:30 PM
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did the engine make 460 hp using those shorty headers, on the dyno?

all the electric cutouts I've seen lately are really poor design as far as having a good low restriction exhaust system
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Old 09-28-2013, 01:08 PM
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Quote:
Originally Posted by vinniekq2 View Post
did the engine make 460 hp using those shorty headers, on the dyno?

all the electric cutouts I've seen lately are really poor design as far as having a good low restriction exhaust system
Take a look at Badlandz HPE electric cutouts. Way better sealing than others, along with the largest diameter for the collector size, and best warranty.(5 yrs) They also have infinite adjustability, so getting the motors out of harms way, or sight is easy. To top it all off they are the best price around too!
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Old 09-29-2013, 10:15 AM
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i would have loved to run long tube headers, however i purchased the headers along with the rack and pinion, and i didnt have alot of options.

i have done a few cars in my days and long tube headers, while being awesome, are a pain in the *** and most of the time need to be modified.
these shortys fit in nicely.

looks like im going to have to go aginst the grain on this one guys.
i greatly appreciate your input!
but i would like to have the complete exhaust system no lower than the frame rails. which puts my cross over point right behind the tranny mount.
thanks guys!
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Old 09-29-2013, 12:58 PM
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Quote:
Originally Posted by h0trod View Post
these shortys fit in nicely.
So do stock cast iron manifolds....and they're cheaper.
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