1. Would we loose too much torque with open headers?

2. The mufflers are 2-chamber Flowmasters w/ 2 1/4 inch pipes. Could going from a 2.5 inch H-pipe to those mufflers cause a large restriction?

3. Should we ditch the tri-y's? I am not too keen on $300 for hooker super comps if I can avoid it.

I am thinking either we should run open headers at the track and keep the smaller Flowmaster mufflers for the street, or switch to some 2.5 inch Dynomax Ultra-Flow mufflers and pipes and run it through the mufflers at the track.

Thanks!!!

quote:

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Originally posted by 65_289:

1. Would we loose too much torque with open headers?

2. The mufflers are 2-chamber Flowmasters w/ 2 1/4 inch pipes. Could going from a 2.5 inch H-pipe to those mufflers cause a large restriction?

3. Should we ditch the tri-y's? I am not too keen on $300 for hooker super comps if I can avoid it.

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#1 If you launch like you mean it, the minimal loss of low-end power will not be an issue.

#2 A buddy of mine picked up a full second in his 351C by switching from manifolds/2.5" exhaust/turbo muffs/2.25" tailpipes to Headers/3" exhaust with turndowns.
The 2.25" tailpipes are choking the engine. If you require tailpipes, 2.5" mandrel bent units from Flowmaster or MAC are your only choice. Don't forget to choose a short muffler to give plenty of room to go up and over the axle.

#3 Hooker Super Comps are the best. They hang down a tad, so I welded a "skid plate" to the bottom of each one for protection. With the way I drive, and the roads around here, it's been a worthwhile addition.
Hooker also makes a regular "Competition" header that is made out of thicker material (longer lasting and more durable) but is a little heavier and since the tubing is thicker, the ID will be "slightly" smaller. Both are 1 5/8" OD. The "Competion" header looks similar to the Super Comp, and is probably the next best thing. Only thing, their advertisement lists them as not fitting World Products heads. (that is a Super Comp only) ...if that is an issue to anyone. These are probably around $120-130 now.

Good Luck!

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Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

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Originally posted by n2oMike:
...#2 A buddy of mine picked up a full second in his 351C by switching from manifolds/2.5" exhaust/turbo muffs/2.25" tailpipes to Headers/3" exhaust with turndowns.
The 2.25" tailpipes are choking the engine. If you require tailpipes, 2.5" mandrel bent units from Flowmaster or MAC are your only choice. Don't forget to choose a short muffler to give plenty of room to go up and over the axle...

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A full second is a lot of time. But that is a hopped-up 351C that needs to rev high versus my little 302.

It was a 2bbl 351C engine with a 750 vacuum secondary carb, performer intake and unknown hydraulic cam. It was never run over 6k rpm... not exactly a high rpm only screamer.

Just my $0.02 worth of advice. Take it or leave it.

Good Luck!

quote:

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Originally posted by n2oMike:
You're free to do whatever you want...

It was a 2bbl 351C engine with a 750 vacuum secondary carb, performer intake and unknown hydraulic cam. It was never run over 6k rpm... not exactly a high rpm only screamer.

Just my $0.02 worth of advice. Take it or leave it.

Good Luck!

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I appreciate the advice. All I was saying was that the air flow needs of a 351C and a 302 are probably quite different, ergo they need different exhaust set-ups. That's all.

Would open headers be that much more advantageous than say 2.5 inch pipe all the way back to 2.5 inch Dynomax Ultra-Flows with 2.5 inch turndowns at the axle?

quote:

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Originally posted by 65_289:
Ok, now I gotta think about it like this. If I run open headers at the track, then I will have to re-jet for the track and re-jet for daily driving.

Would open headers be that much more advantageous than say 2.5 inch pipe all the way back to 2.5 inch Dynomax Ultra-Flows with 2.5 inch turndowns at the axle?

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#1 If your exhaust system isn't very restrictive, the tune for capped vs. uncapped won't be that much different... so different jetting won't really be required.

#2 The best way to determine how much you have to gain by going uncapped, is to just do it. Me believes you are thinking too hard.
To find out how it runs uncapped, just unbolt the exhaust from the collectors and move it over. Then re-connect it with one fastener to the header with the pipes off to the side... no cutouts needed. This is a LOT easier than removing the whole exhaust system. If the exhaust system is fairly restrictive (which yours is) jetting it up a size or two might give the best results.

Good Luck!

quote:

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Originally posted by n2oMike:

#2 The best way to determine how much you have to gain by going uncapped, is to just do it. Me believes you are thinking too hard.

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Me agrees with Mike!

Try it you'll like it, look Mikey likes it. Stevie likes it too.