This again is about single vs. duals.

Does anyone watch HorsePower TV? They just did a special on how to spend $1200 on aftermarket parts to get the most bang for the buck. They used both carbed cars and EFI cars for there advice. Chuck Hanson, who has been builing and rebuilding Chevys for 20+ yrs., showed a 3" single exhaust kit from Edelbrock for a '94 Z28. Even he said, and I quote, "Well, if you have the choice, a single 3" pipe WILL OUTFLOW a pair two and a halves." That is what I have been trying to tell everyone.

This guy only says what the writers write. AND they only state facts!!!!! They use Lunati, Barry Grant, Strange, etc. They know what they're doing. The proof is in the facts!!!! If ANYONE wants a copy of the show, send me a tape and I will send it back to you with the show on it!!!

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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

 

How about these facts:

When the 1993 LT-1 Z 28 came out it had 275 HP the LT-1 Vette had 300 HP.

The Vette had more horsepower partly because of a less restricted exhaust. The Vette has 2 2.5" the Z28 had a single 3".

Also (we discussed this right here on this forum over a year ago) using Fluid Dynamic equations (I'd have to find them from my FD textbook) flow thru a single pipe with a 3" diameter has slighty better flow than 2 2.25" pipes, but less than 2 2.5" pipes.

Like you said, the debate continues.



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1986 Black/Gold LG4 Z28
Original Owner, 200,000+ near trouble free miles.
Mostly Stock.

1995 Dark Red Metallic Corvette Coupe Original Owner

 

Oh yea, I've also wondered (and I noticed there is another post on the subject), if a single 3" is such good flow (and it is) why screw it up with a dual 2.5" outlet pipes?
Why not use a single 3" pipe?

 

Well geometry tells you that a 3.5" pipe has greater area than 2-2.5" pipes, but your right that a 3" pipe does not have the same are as 2-2.5" pipes. That bares no relevance on physics or pressure waves though. A cross over pipe helps one set of cylinders suck out exhaust from the others. Well the same concept would hold true for going into a single pipe. Maybe because that scaveging effect would be stronger in a single pipe, rather than seperating the pipes in two again after the cross over. I don't know. Just a concept.

It's kinda like over 80 yrs ago everyone thought that if you went faster than 100mph, your body would explode.

 

As far as the Vette statement. I used to sell Chevys and they said that the Vette had better exhaust "setup" (that would include muffler), intake manifold, diff. ECM programing, and valvetrain. That way they could still sell Vettes and not have every Z28 whoopin' a Vette's ace in the 1/4 mile.

 

Only way to prove it is to get a pair of bone stock identical cars and put duals on one and single on the other and stick em on a DYNO.

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1992 Pontiac Firebird (stock)
- 5.0L V8 TBI / Automatic Trans / Every option, excluding leather
- Killer car audio system:

• Aiwa CDC-MP3 head unit
• Rockford Fosgate 360a2 amp
• pair of 12" MTX Thunder 5000s in a custom box
• Pioneer 3-way 6x9s, soon to add more more more!

 

True dat. Or bench flow them like a head. I wonder if they could do that?

 

because single exaust looks like a$$

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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 27, 2001).]

 

Tas - I agree that a single does not look as well, but that's what you'll see if you race one!! lol!!

Actually area is not equal in flow. A single pipe with he same area of two smaller pipes will flow better because fluids slow down near the outsides. I just remember that when doing the equation, that laminer (sp) flow (I.e. a water pipe) is equal on a 3" and somewhere between 2.25 and 2.5".

In all fairness, exhaust is anything but laminer. But this poses another question. Is more flow actually better?

If so why not run open headers? Or jack your car up and put a 8" exhaust under your car?

I know I'm getting silly stupid here, but really now...

 

I once bought a truck four wheeling magazine once becuase it did a very professional dyno and speed test on the same truck with single and dual exhaust. The 2 2.5" dual exhaust system had around 15 more torque, but the single exhaust had around 20 more horsepower in the top end - around 4000 - 7000 rpm. Also they tested the top speed of the truck, and the single exhaust system was about 7 mph faster. Im in the process of looking for the magazine now.

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IROC-Z :
Jet Black, Tinted Windows, Racing 5 Spokes, Big Block Hood, 91-92 Ground FX, 91-92 Z28 Spoiler, Headlight and Tailight Covers, Lowered. BAD @$$!!

 

ok... there is more area in a 3.5" single pipe. regardless if the flow is newtonian, laminar whatever you still have more area in a 3.5" pipe. i saw that episode as well and he did state that a single 3" pipe would give you about 5 more HP then 2 2.5's. as for the lok you can get a dual outlet muffler and run 2 tailpipes...
Same good Looks.. More HP


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Mike
88 Iroc-Z 350 tpi, Hedmann Headers, 3.5 " Cat Back, MSD Ignition, K&N Cold Air kit

 

the idea is to keep the exhaust pulses separated - its why manifolds arent as good as shorty headers which don't make as much power as long tube headers- prolly why duals make more power than a single- but you gotta consider the car/cam/trans/cubes etc. combination as a whole

 

Its all irrelevant. You cant fit a true dual setup underneath a thirdgen without floorpan surgery or spending $1200 for an exhaust shop to "kink" you one. You can run it under the rear axle but that's idiotic. That is how my Z28 was when I bought it. It was 2.5" all the way back and exited out vette mufflers. It was very thick stainless and it was still smashed to hell. If you want info call Eli Naheed at CarPro. He will tell you what's involved.

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92Z28
89GTA

[This message has been edited by Acceld Z (edited May 30, 2001).]

 

Eli will tell you to cut up your drivers side floorboard where the rear seat goes. I called about 2 years ago and asked them about it before I purchased a mufflex exhaust. My mind was set after that. I dont want to hack up my rear end for an exhaust. The 4" mufflex I have works just fine.

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-86 IROC
Jacked up like a mother!
this years goal: 10.50 @ 130+ mph
-=ICON Motorsports=-

 

Thats what Eli told me too.He is very charming coincidentally

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92Z28
89GTA

 

Find that article dude!!

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89 RS

Looking For:
87 IROC-Z28 350 TPI