Quote:
Originally Posted by chetrickerman
Hold up, for the record, there is a big difference in boost threshold/ time to torque when running V-band T3 vs T4 twinscroll. I have seen 500-1,000 rpm spool difference between the v-band/T4 TS on the same turbo on multiple engines, which makes a huge difference in driving characteristics.
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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?