PONTIMANIAC 90

I my opinion, a true dual exhaust depends on your point of veiw. If you got headers going to dual cats and the whole thing leads to a single "thick" pipe w/a free-flowing muffer. Why would anyone wanna run 2 pipes,just so they can say: "I got 2 pipes". My car is a true dual exhaust! I got 2 of everything up until after the 2 cats. After that I got a 3" pipe that goes to a Flowmaster w/single outlet. I love the "single exhaust" look. People think I have a V6 'cause I got one pipe-out-the-back.
My point is, our cars have limmited space in the underbelly. Trying to piggie-back two pipes is self defeating, if anything. If you got a Radical Motor and you need FLOW, just get a 4" or a 5" pipe out the back!
What's with this "true dual" fetish? If someone can tell me the benefit of this, I'll gladly listen. Hell, you need FLOW, get a 6 inch tube, for crying out loud.
What gives?

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1990 Formula
Factory:TPI-305/Dual Cat(230hp),5 Speed,3.42 rear, Dealer:Aluminum Drive Shaft
Mods:SLP air foil,K&N Filter, Accel:wires,coil cap,rotor.Hypertech Thermomaster chip,Stat,Fan switch,TES headers,MSD6AL,AFPR(46), Harwood fiberglass hood,original GM "Notchback GTA" hatch.
Flowmaster 3" Cat-back exhaust,TB coolant bypass, Centerforce dual friction clutch.
DIRECT LINK TO PICS OF MY CAR. NO WEB-PAGE. http://community-2.webtv.net/MZavraz...A90/page9.html

AJ_92RS

I always wondered the same thing. Why do they say you should have a crossover pipe with true duals? So that it smooths out the difference in wave pressures from the cylinders boosting low end torque. That and it sounds smoother too. Well wouldn't running that "crossover pipe" into one pipe do about the same thing? Two 2.5" pipes together equal 8 7/8 sq in. of area. One 3" pipe = 6.5 sq in. A 3.5" pipe = 8 15/16 sq in. So run two 2.5" collectors into one 3.5" pipe and it equals about the same area. Actually the 3.5" pipe has 1/16" more area. But a 3" pipe would work for Street/Strip use. Then you could put cut outs on BEFORE the 3" pipe for Strip use. TRUE DUAL, OPEN EXHAUST!!! YEA BABY!!! WWHHAAAAAAAAAAAA!!!!!!! HEHE!!! LOL!!!

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

[This message has been edited by AJ_92RS (edited May 24, 2001).]

PONTIMANIAC 90

Word up, brother. Now let all the "true dual" exhaust riggers put their hands up in the air, like they just don't care......
Blah, BLAH, bLAH.

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1990 Formula
Factory:TPI-305/Dual Cat(230hp),5 Speed,3.42 rear, Dealer:Aluminum Drive Shaft
Mods:SLP air foil,K&N Filter, Accel:wires,coil cap,rotor.Hypertech Thermomaster chip,Stat,Fan switch,TES headers,MSD6AL,AFPR(46), Harwood fiberglass hood,original GM "Notchback GTA" hatch.
Flowmaster 3" Cat-back exhaust,TB coolant bypass, Centerforce dual friction clutch.
DIRECT LINK TO PICS OF MY CAR. NO WEB-PAGE. http://community-2.webtv.net/MZavraz...A90/page9.html

Tas

This board went dual exaust crazy about 3 months ago. I dunno why, most systems that guys came up with suck compared with a good 3" or 3.5" system, but whatever. As long as you're happy. I made a dual exaust page to at least organise things a bit. As for the crossover pipe, it lets each side of the engine aid in the scavaging effect of the other side. Dual exaust is having a pipe for each side of the V engine. True dual exaust is when one side of the exaust is a mirror image of the other side.

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-Tas
'89 Formula WS-6

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Soon to be installed:
Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248), Catco 3" cat, and injector spacer.

Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options
AOL IM: superGRtaz


[This message has been edited by Tas (edited May 25, 2001).]

3.1 firebird

here we go again.
1. true duals flow better than a single pipe.(I can post quotes from the book "how to build horsepower" if you want to argue)

2. true duals sound better than a single pipe. This isnt a fact, just my opinion.

You might not get a whole lot more power from a true dual system, but the sound would be the main reason I'd do a true dual.

RW91B4C

True dual, when done right, are better.
But in a 3rdgen you cant do it, unless its a race car.
A "good" true dual has its benefits.
1. You can run the right size primery tube + length - 1 3/4" X 32" - full length header.
2. You can run a tri-y or merge-collector.
3. you can run a H-pipe or X-pipe.
4. You can run 2 mufflers, more area and quieter then 1 huge muffler.
5. eliminate all those nasty bends right after the shorty header on 3rdgens.
You could cut an easy 1/2 a second off your ET with a "good" exhaust like that.
But is it really worth it on a street car?
I have shortys, dual 2 1/2" to the cats, a home made Y-pipe (dual 2 1/2" x single 3 1/2") to a single flowmaster. Thats OK for a street car the 3 1/2" has almost the same area as 2 - 2 1/2" pipes so it works good.
So unless you are building a street/strip car you can get by with a decent single, but a good true dual defenetly has its advantages and will cut your ET by atleast 1/2 a second!!!

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91 B4C 305 TPI - SOON TO BE 383
TREMEC 5-SP, STOCK 1-BOLT REAREAND w/342 GEARS
K&N, AIRFOIL
EDELBROCK HEADERS, DUAL CAT TO HOMEMADE Y-PIPE & 3.5" SINGLE PIPE W/ FLOWMASTER
CRANK PULLEY, MSD, FUEL PRESS REG
COWL HOOD, WELD WHEELS
14.1@ 98MPH
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OTHER RIDE
67 CAMARO - STREET CAR
BIG BLOCK, PUMP GAS
350TH w/ATI 10"
12-BOLT w/373 GEARS
10.90s ON MOTOR - ET-STREETs w/MUFFLERS

SUPER-SPORT-CHEVY

Performance issues apply!
I have 2, 3rd gen fbodys 1 has true dual exhaust 2.5 pipes. The other has a single 3ich pipe no cat all the way back into a high performance muffler. I dont like headders personaly, so i dont use them. The 2 cars were at one time equal as possible and the duals flow much better increasing power fuel economy and sound. The 3 inch pipe and performance muffler, sound is good not as good but the flow is not there. 3= 3 while 2.5+2.5= 5 more area= more flow. BigBlock454 has a his personal resutls on a post here but you need to search for it im too lazy.
If your happy with your setup than good, but it is impossible to compare a backwards sport dual to true duals. Btw you donot need to beat floor boards or hurt the integrity of you car in anyway to run true duals.
SSC

AJ_92RS

I wasn't at all saying that shorty headers are just as good as full length. That is by no means true. True headers have a MUCH better scaveging effect due to egual length primaries. Shorty headers for our cars are not "true" headers. They are just manifolds with better flow. Not all of the primaries are the same length. But they do help a lot over the stock "coffee cans".

But if you do your geometry, a 3.5" pipe has more area than 2-2.5" pipes. It isn't as easy as 2.5 + 2.5 = 5. A 2"x2" square has 4 sq.in. A 3"x3" square has 9 sq.in., not 6. You know what I mean? The formula for the area of a circle is (radius squared x pi). You also have to subtract the thickness of the pipe wall (approx. 1/16" or .125") from the radius, or 1/8" from the diameter, to get I.D. because that is where the air flows. A 3" pipe is O.D. Therefore a 3.5" pipe will flow as much air, and as fast, as 2-2.5" pipes. As long as both setups are attached to full length headers. It's simple physics.

AJ