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Author
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Topic: How important are flowtubes.
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KCmustangboy
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Member # 1927
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posted
 
 
Here is a basic question, My 5.0 has long tubes into 2.5 inch dr. gas x pipe and flows dumped, however the 18inchs or so of the flow tubes is still 2.25, is this hurting me? and if so, how much?
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03 Cobra... Factory long block, with Whipple and AED tune... 812rwhp 10.0s @ 140... almost there!
WWW.AEDHP.COM
Posts: 1691 | From: San Jose, CA | Registered: Oct 2002
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Elapid
GOROBGO
Member # 50
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posted
that is a really ugly fluid dynamics question
(they are ALL ugly imo)
that's why they use flow meters to test heads, cuz theory is a bitch and doesn't work out well, much easier to measure actual flow and go from there.
what kind of motor mods?
on a stock car, larger exhaust might actually slow it down, on a highly modded car it will help alot.
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98 Cobra
83 Notch rolling chassis - fs
Posts: 1797 | From: Grass Valley, CA USA | Registered: Jul 2000
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KCmustangboy
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Member # 1927
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Motor is stock, I was just thinking that if the bigger headers and bigger xpipe were gaining me so much power, wouldn't the 18 inchs right at the end be hurting me? Seems to me if you have been headers and then big x, not that big, 2 1/2 inch. and then right at the end you go to 2 1/4 doesn't that kind of kill what your trying to do anyways? I know too much is bad but I just want to find out for sure and get them replaced if I need too. Thanks Casey
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03 Cobra... Factory long block, with Whipple and AED tune... 812rwhp 10.0s @ 140... almost there!
WWW.AEDHP.COM
Posts: 1691 | From: San Jose, CA | Registered: Oct 2002
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JoeT
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Member # 298
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posted
I only gained a tenth from longtubes and a complete 2.5" exhaust system over stock, so I imagine you're not playing with much more than a tenth.
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1984 Ford Tempo AOD--- RIP
Posts: 6785 | From: San Jose | Registered: Jun 2001
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MINGRYGT
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Member # 2439
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your exhaust is only as big as the narrowest part.. does that make sense?? if your 2.25 in on any part of your exaust and 3 in every where else then you only flow as good as the 2.25 in part.
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R.I.P. MIKE STARKEY 5-17-03
Posts: 488 | From: Concord | Registered: Feb 2003
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KCmustangboy
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Member # 1927
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posted
quote:
Originally posted by MINGRYGT:
your exhaust is only as big as the narrowest part.. does that make sense?? if your 2.25 in on any part of your exaust and 3 in every where else then you only flow as good as the 2.25 in part.
Thats what I was thinking... but I think everyone is trying to say I don't need it.
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03 Cobra... Factory long block, with Whipple and AED tune... 812rwhp 10.0s @ 140... almost there!
WWW.AEDHP.COM
Posts: 1691 | From: San Jose, CA | Registered: Oct 2002
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Primer GR40
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Member # 476
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posted
My flow tubes are 2.5" but they aren't mandrel bent. Is that hurting me? 460rwhp w/longtubes?
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Superdupercharged Cobra
No Transmatic Notch
Posts: 2108 | Registered: Sep 2001
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KCmustangboy
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Member # 1927
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posted
quote:
Originally posted by shade-tree:
I only gained a tenth from longtubes and a complete 2.5" exhaust system over stock, so I imagine you're not playing with much more than a tenth.
Your telling me, stock manifolds, stock cats, stock mufflers all 2 1/4 changed all out for after market stuff including longtubes matching pipe and flows only gainied you a tenth? I am think the weather was different, or tires fucked up, track sucked, something. It HAS to be more than 1 tenth.
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03 Cobra... Factory long block, with Whipple and AED tune... 812rwhp 10.0s @ 140... almost there!
WWW.AEDHP.COM
Posts: 1691 | From: San Jose, CA | Registered: Oct 2002
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cheap
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Member # 858
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posted
Why does it have to be more than a tenth? How restricted do you think Ford engineered the stock exhaust to be? Also LTs are known to sacrifice down-low power for high-end power, so depending on how that guy shifts he might not have had much of a total power gain.
Also, in theory your exhaust is NOT only as big as the smallest part. This crazy cat named Venturi realized that when air moving thru something gets squeezed down, the air speeds up to compensate (which his how lift was discovered, and hence aircraft... more or less). But that's more for the physics and fluid dynamics peeps to talk about.
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1965 Spyder GT
Posts: 1358 | From: Maine | Registered: Feb 2002
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KCmustangboy
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Member # 1927
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posted
quote:
Originally posted by cheap:
Why does it have to be more than a tenth? How restricted do you think Ford engineered the stock exhaust to be? Also LTs are known to sacrifice down-low power for high-end power, so depending on how that guy shifts he might not have had much of a total power gain.
Also, in theory your exhaust is NOT only as big as the smallest part. This crazy cat named Venturi realized that when air moving thru something gets squeezed down, the air speeds up to compensate (which his how lift was discovered, and hence aircraft... more or less). But that's more for the physics and fluid dynamics peeps to talk about.
WELL SAID ![[patriot]](graemlins/patriot.gif)
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03 Cobra... Factory long block, with Whipple and AED tune... 812rwhp 10.0s @ 140... almost there!
WWW.AEDHP.COM
Posts: 1691 | From: San Jose, CA | Registered: Oct 2002
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JoeT
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Member # 298
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posted
quote:
Originally posted by KCmustangboy:
Your telling me, stock manifolds, stock cats, stock mufflers all 2 1/4 changed all out for after market stuff including longtubes matching pipe and flows only gainied you a tenth? I am think the weather was different, or tires fucked up, track sucked, something. It HAS to be more than 1 tenth.
yeah, I probably can't drive ![[Wink]](wink.gif)
50+ passes on ET Streets, 60's within 0.02 to 0.03 of eachother,
threw on the longtubes and flowmaster catback, gained about 0.12 seconds net in the next 20 odd passes...
Like was said above, I probably can't pick the shift points on my tach appropriately with the tremendous power that an NA stock 302 longblock puts out in front of a T5. I was probably all over the map and using an excel spreadsheet with ~ 100 runs and looking at density altitude conversion data means my results were pretty meaningless
(you know I'm just kidding. but I am kinda serious. Well sorta)
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1984 Ford Tempo AOD--- RIP
Posts: 6785 | From: San Jose | Registered: Jun 2001
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Luke87GT
Lay'n more stripes
than Caltrans
Member # 21
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posted
67stang made 304rwhp through a 2.25 inch stock catback on his 93cobra. No, the flowtubes are NOT hurting you at your power level.
Luke
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Stangless
Posts: 7802 | From: San Mateo | Registered: Jul 2000
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Red97SVT
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Member # 2811
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posted
quote:
Originally posted by KCmustangboy:
Here is a basic question, My 5.0 has long tubes into 2.5 inch dr. gas x pipe and flows dumped, however the 18inchs or so of the flow tubes is still 2.25, is this hurting me? and if so, how much?
That isn't as "basic" as many people think. Flow through an exhaust with the effects of diameter and and bends is a crazy science.
Venturi had a friend named Brounelli (sp?) that therorized that pressure in a cylinder (or exhaust tube) will increase in direct proportion to a decrease in diameter. The increase in pressure is what causes the increase in velocity as a medium passes through it. So by decreasing the diameter at some point, you are increasing the back pressure prior to that point. Additionally any increase in velocity is lost as soon as the diameter increases again. You might assume that an increase in back pressure would be bad but not neccessarilly so, as you need some back pressure to promote scavenging for low end torque.
So what does all this mean? I'm bored and, I think it would be safe to say that in your case (from your sig I assume you have stock compression, heads and no power adder) your exhaust will not hurt you at all. It may even help!
Posts: 246 | From: Manteca | Registered: May 2003
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xcessive50
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Member # 2995
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posted
it's probably helping you in the low end and since the motor is stock and doesnt have any top end anyway, i'd leave em alone.
Posts: 363 | Registered: Jun 2003
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xcessive50
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Member # 2995
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posted
Oh, and I now see that Red97SVT has explained it much better than I
Posts: 363 | Registered: Jun 2003
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svt306snake
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Member # 1967
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kc you already know who you should be asking this question too your cousin has damn near all the answers i'll get ahold of him and get back to you where those things you were holding for me man i'm going to call you head and shoulders mr flake
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F*** TPS MOTORSPORTS F *** TPS MOTORSPORTS THEY SUCK ASS
TEAM TRUE FORGED X 2 SPONSORED
CAPITAL MUSTANG C.C.
Posts: 5841 | From: SACRAMENTO "916" YA KNOW | Registered: Oct 2002
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
quote:
Originally posted by Red97SVT:
I think it would be safe to say that in your case (from your sig I assume you have stock compression, heads and no power adder) your exhaust will not hurt you at all. It may even help!
~yep
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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