Quote:
Originally Posted by x622
What kind of engines and platform? Did you see redesigns of the merge collector or see just slapped on vband flanges? My experience stems from testing a quantity of custom Comps, Garrets with Tial housings and some EFRs (7163, 7194 and 9180). I did not see anywhere close to this level of variance on any platform I've worked with (F22, K24, J32, 2jz, b18, ej257, 4g63 & lsx).
Worst I saw was a ~450rpm delta on a ej257 on a 76/108 compressor wheel + 42r turbine wheel on a custom garrett turbo (extended tip wheel), large frame compressor housing) but this was on a drag application and was a t6 vband. Granted this was still a POS subaru engine that doesn't breath at all, but you get the idea.
I think it's important to stress that tight radius bends, merge collector length and angle, as well as overall runner length play a larger role than going divided T4 than vband. It's not apples to apples to compare a super simple vband manifold with very short runners to a long runner front mount turbo on a s2000 f22 platform for example.
I'm not going to say I'm the end all be all expert on manifold design, but I've spent a good bit of time and built cars with real world results. I've also played with Quick spool valves and all sorts of other fun stuff, I am just mainly interested in building the fastest spooling (read, time to torque) m3 that I can get, and I'm between the G42 G series, custom comp and an EFR 9280 for my next setup.
to the OP: If your manifold is 304L would you take an extra payment and make it in 321?
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My experience is with 4g63, 4B11T, D16, B18, K20, 13B-MSP, S55 and B58. I noticed a much larger effect on transient response and spool up (time to torque) when going to T4 twinscroll from v-band or T3. Yes, runner diameter and length does play a part, but separating the exhaust pulses is what makes the biggest difference. I can see based on some of your experience how you would prioritize runner length and diameter over the type of flange used though. In those applications it does make sense. The merge collector was reshaped because of the different flange so that flow was properly directed at the turbine.
Also, the G42-1450 would not fit, we already tried. The G42-1200 compact may fit as the large compressor housing was the main fitment issue.
If you want the fastest spool, I would suggest the EFR 9274. That turbo with a short runner manifold on the S55 would be wicked. Im thinking of doing it myself.