This is topic How important are flowtubes. in forum Tech Talk at Northern California Ford Owners  .


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Posted by KCmustangboy (Member # 1927) on :
 
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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Posted by rob (Member # 50) on :
 
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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Posted by KCmustangboy (Member # 1927) on :
 
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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Posted by shade-tree (Member # 298) on :
 
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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Posted by Red95PonyGirl (Member # 3027) on :
 

 

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Posted by MINGRYGT (Member # 2439) on :
 
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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Posted by KCmustangboy (Member # 1927) on :
 

quote:

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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.

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quote:

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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.

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quote:

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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.

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WELL SAID
 

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Posted by shade-tree (Member # 298) on :
 

quote:

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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.

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yeah, I probably can't drive

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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Posted by Luke87GT (Member # 21) on :
 
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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Posted by Red97SVT (Member # 2811) on :
 

quote:

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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?

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quote:

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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!

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~yep
 

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