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| xcabbi |
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All this tuned length this and tuned length that. Well what about Smokey Younick's proposal for "tuned flow" headers, where each runner is flow tested one at a time (with the others all blocked off).
In the end you end up with unequal length runners but which all flow the same. Therefore in theory, the mass flow pulses for all runners are exactly the same, and delivered in perfect time right across the rev range, resulting in one very broad spread of torque. Think about it for a minute. Most race style tuned length headers looked like tangled spaghetti. Surely some of those runners flow noticeably less than others due to the sharp bends required in order to achieve tuned length. Even the pressure waves would be out of whack at certain rpm due to the unequal bend radii. What if tuned length was the wrong approach all along but it just happened to work okay? Now I've opened up a mans can of worms. |
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| fairlane6970 |
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I always thought that the two basic designs were Tri - Y and tuned length, tri-y for street ie:- torque and tuned length for race apps? I could be wrong as so many people who nothig about headers are posting here!
 
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| xcabbi |
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fairlane6970 wrote: I always thought that the two basic designs were Tri - Y and tuned length, tri-y for street ie:- torque and tuned length for race apps? I could be wrong as so many people who nothig about headers are posting here! Up until recently that was the general consensus but in recent years the definitions of "street" and "race" have changed somewhat. People have become more accepting of highly strung engines with poor manners. Its not uncommon to see an angry high compression cammed up small block backed by 4000rpm+ converter roll into Harry's on a Friday night. As a daily driver it would be absolute hell to live with but more and more people are building cars like this with the intention of them being daily (or possibly weekly) driven street cars. Oops I've sidetracked myself. Back OT. The above example is probably why people no longer bother with try y's much anymore unless they couldn't afford a set of tuned lengths. |
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| TimmyA |
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you do raise some good points in those two posts there xcabbi...
always food for thought...  Cheers...
_________________ 93 Red ED 5spd Manual Build Thread |
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| xcabbi |
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timmytimtim wrote: you do raise some good points in those two posts there xcabbi... always food for thought... Cheers... Thanks, I always try to push the boundaries of conventional thinking. Its what engineers are born to do. |
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| TimmyA |
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if you had the time, the know how, the gear, the test equipment and the money...
All in all you could make some sick performing headers... 
_________________ 93 Red ED 5spd Manual Build Thread |
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| xcabbi |
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Hold that thought for a moment.
If I wasn't MC hammer broke and tied up driving cabs I'd have a flow bench, tig welder and a whole pandoras box of temp probes air flow meters and all sorts of funky stuff. |
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| TimmyA |
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Hey Its OK...
Your not god mate... We don't expect you to be able to work miracles... Maybe one day you'll win the lotto and be doing it as a hobby... And then put pacemaker out of business... And in 10 years time we'll all be driving around with xcabbi headers on our hydrogen powered cars 
_________________ 93 Red ED 5spd Manual Build Thread |
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| xcabbi |
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Having said that. I did have a hand in building a set of full exhausts for a 71 Elfin Can-AM type sports car with a repco V8. Admittedly most of the stuff was "hold this, hold that" type of stuff for the boss I was working for at the time, but I actually got to see how a set of hand built exhausts were made. |
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| TimmyA |
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a lot of forethought?
and when it didn't work out, or line up, a lot of swearing and cursing? I have seen some custom sets to get them to fit into hotrods and that (prob have no performance benefit what-so-ever) and some people really put some time and effort into them... 
_________________ 93 Red ED 5spd Manual Build Thread |
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| xcabbi |
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A bit of swearing during fitments cause they were a slip on style with spring retainers. Then things hurt when you let them slip with the pliers.
And there was quite a bit of head scratching during fitment as the muffler mounting points on the car were asymmetrical from factory. Left side was about an inch higher than the right side. Nothing we could do about it. The thing is even though those headers were turned length, they all had similar bend radii for each individual runner. They are the closest to Theoretically tuned flow that I have seen so far. However some pro stock headers come pretty close. |
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| MAD |
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Tuned headers are not 'just' tuned length. That length can be tuned to a particular RPM where the engine will receive a noticable boost for maximum effect this is aligned with the maximum power of the cam in use. The length can be long for low RPM or short for high RPM. Then you get into the size of the primaries and secondaries which will change how much they assist scavenging.
Some people racing Saloon cars actually extend the three secondaries of the 4480's and achieve a good boost over the entire rev range. This isnt so practical for road cars as you need to fit the cat somewhere. I know 'about it', but wouldnt have a clue how to 'do' it. It's all too complicated for me. On topic though, does anyone have a sound clip of a Hooker aero-chamber on a Ford I6? |
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| xcabbi |
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That's why you see some cars with 2" primaries but the runners are stupidly long, and these things are designed for 8000rpm.
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| skidder |
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MAD wrote: On topic though, does anyone have a sound clip of a Hooker aero-chamber on a Ford I6? I had one on my old car in 2.5in and fitted a second as it was fairly loud. Will be getting one for my new car in a few weeks (not sure if 2.25 or 2.5) and I will post up a clip. If anyone wants to know more about the design of headers I would recommend 'Scientific Design of Intake and Exhaust Systems'. Warning; you will end up buying it though as it takes a few reads in some parts (mmm...pulse tuning).
_________________ EVL098 wrote: Cramping in the hand from having it on your Wang for an excessive period of time is a definate con. Seriously do people google "f**k up modifications for Fords owned by Jews" and get linked straight to this site nowadays? AU,factory fitted tickford kit/IRS, t5,Sports ryder/KYB: gone. |
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