August 16, 2018, 12:26:27 AM

Author Topic: Ronin RX-LS Swap Headers!  (Read 2413 times)

Online Exidous

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Re: Ronin RX-LS Swap Headers!
« Reply #45 on: July 29, 2018, 10:22:13 AM »
How close are the runner lengths? Doesn't look quite equal length from the photo but could just be the angle.

94 BB SBE LS1 Full Mamo top, MS3ProU with TC, RONIN 8.8 and another custom dual 2.5" stainless exhaust. Too loud, need bigger muffler....

Offline frijolee

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Re: Ronin RX-LS Swap Headers!
« Reply #46 on: July 29, 2018, 10:59:26 PM »
How close are the runner lengths? Doesn't look quite equal length from the photo but could just be the angle.

They're as close as we could reasonably package but to be honest equal length was only a secondary goal.  To quote David Vizard, equal length is far less important than the right length.  Case in point, perfectly identical equal length "3/4 length" headers just mean that none of the tubes will achieve pulse wave tuning.  In a properly designed long tube header, length is driven by the shock wave at exhaust valve open that heads down the primary at the speed of sound, then when it hits the first major change in cross sectional area the negative reflected pulse wave heads up stream.  You want to time this negative pressure front to occur at valve overlap.  However the math only works perfects for one length, one exhaust temperature, for one ideal RPM.  In practice we see a great deal of benefit over a range of RPMs since the shock wave has some duration to it.

The key point is that, yes equal length is nice to but it's not that big a deal if one runner is ideal at 5800 rpm while the one next to it is ideal at 6500 rpm.  But that would still be a 10% runner length difference.   However, if the shorter tube only comes into play at 8000 rpm, that doesn't work so well for our engines. The RIGHT length, that matters a great deal and that's where we spent our major effort.

Joel
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Online Exidous

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Re: Ronin RX-LS Swap Headers!
« Reply #47 on: July 30, 2018, 02:41:42 AM »
Fair enough. If be curious if you could phase match the runners similarly to electrical length of RF cables. Meaning, as long as the length is in whole wavelength steps you get no interference.
94 BB SBE LS1 Full Mamo top, MS3ProU with TC, RONIN 8.8 and another custom dual 2.5" stainless exhaust. Too loud, need bigger muffler....

Offline freeskier7791

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Re: Ronin RX-LS Swap Headers!
« Reply #48 on: July 30, 2018, 05:55:09 AM »
Nice job joel.  Always good to see a set of headers with long runners.  Are you gonna dyno test these?

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