Any one running just one 3" pipe off the cat, no mufflers. I took both mufflers off and ran just one 3" pipe off the cat. It sounds real good and not to loud till you get on it hard then it sound even better. So what do you think will
I lose any thing by running just one pipe and no mufflers. :crazy: :crazy:


[Modified by blk90, 11:20 PM 9/6/2001]

 

Just the appearance.

 

The stock pipe is 2.25 inches right? If you had dual pipes you'd have 4.5 inches for air to flow through, now you're restricting it to 3 inches...not much of a problem because the rest of the exhaust won't support the 4.5 inches at the end, but if you go with a better exhaust from the head back, I'd do something else.

 

No... the stock pipe is not 2.25 inches. Before anyone tries to tell me I'm wrong... measure the pipe at the bends... My 85 had a measurement of approx 1.75 at the bend where it went from the two side by side tubes out to the mufflers. The stock pipe might be 2.25 where it is straight but it can only flow equivalent to the most restrictive portion... 1.75 inches. The stock rear y-pipe is a piece of crap! Putting aftermarket mufflers on it is a waste of time. Buy an aftermarket y-pipe or go single.
In truth, a single 2.5 mandrel bent exhaust would probably give the stock rear Y-pipe a run for its money. There is no way that a stock rear y-pipe can even be considered to have the same effective diameter, or as an even greater leap the same flow capability as a 4.5 pipe. Dual 3's are for serious HP business.
In any event mandrel bent pipe is the best way to go.

Cory

 

For a long time I ran headers to front 2.5" Y pipe through a GM cat, and out 2.5" rear pipe to free flow Monza style muffler tips with resonators.... this is a great sound !!!! Now if you gut the cat and run this, it really livens up and probably too loud for the majority, but performance was better with my modified motor.

I am currently converting to a full true 3" dual exhaust with either Magnaflows or Hooker Aerochambers.... haven't decided which quite yet.

As a note the best I could find as far as power requirements are from Flowmaster:

2 1/4" true duals = Up to 320 HP
2 1/2" true duals = Up to 400 HP
3" true duals = Up to 600 HP

They're not saying you cannot run strong with a 500 hp with 2 1/2" duals, they're just saying your power is not fully optimized.

Here is a little further information:

2" single pipe = 3.14" flow area

Dual 2" pipe = 6.28" total flow area

Single 2 1/4" pipe = 3.97" flow area

Dual 2 1/4" pipe = 7.94" total flow area

Single 2 1/2" pipe = 4.90" flow area

Dual 2 1/2" pipe = 9.80" total flow area

Single 3" pipe = 7.06" flow area

Dual 3" pipe = 14.12" total flow area

Be careful with some of those exhaust tips you use, they can restrict you and not even know it. Some have just 1" to 1.25" diameters per pipe, with a total of 4 of these you still won't be able to flow as well as a single 3" pipe.

hope this helps.

Beach


[Modified by Beach Bum, 2:48 PM 9/7/2001]

 

Thanks for posting that info, Beach, I had it at home but couldn't find it online. I believe that those figures are assuming mandrel bends in the pipe.

Cory

P.S. I've decided to try out a single oval pipe down the center of the car that is equivalent to a 3.5 inch round pipe. I'll run this into a single muffler for now but may feel the need to add a second muffler later. I'll try it with one and if it doesn't meet my goals I'll put the second in.

 

Thanks Cory..

But actually, I re-read my post and found I had made a mistake, I had the 2" pipe flow listed in-correctly as 2 1/4" pipe flow ... I've corrected the above post and now it stands 100% correct.

later
Beach

 

NoWorries
If the cat out let is 3" and you run a 3" pipe on mufflers, I would think
it would work better than a set up with the y pipe. The y pipe is moer
restricting than a 3" pipe. :rolleyes: :rolleyes: