Quote:
Originally Posted by chetrickerman
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.
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Yeah, the 74mm turbine does not have the overspeed issues with it coming apart that the 80mm wheel does, but I have to question if it'd have enough flow to breath at the top end. I've done the 9174 on a F22 platform with extremely high compression and I ran out of turbine before I ran out of compressor.
How bad was the fit on the g42-1450? Have you seen the Comp CTX turbos? They can do up to a 78/108mm inducer on their mid-frame turbo and you pick which compressor housing you want, obviously the smaller housing the less efficient it is, but you should get some good power out of it. You can also spec extended tip or anything you want. They are very helpful in helping you get exactly what you need.
As for flanges, I like vband because it's not a complete pain in the ass to work with. Typically getting one of the bolts in a well designed manifold is a matter of compromise or making some custom tools to get it good n' tight. I had high hopes for the divided vband housings but they are the smaller t3 variety so completely not applicable for high power applications.
Yes, I do not like 304L and it always cracks over time if it's coated, and you wanted coated so it doesn't heat up your entire bay like an oven. 321 or inconel 725 are the only ways to go. Typically if you do a better material you can spec sch 10 and have some support for the turbo and have better high end flow at the expense of a bit of velocity at the lower end.