I'm sorry about the location part of my profile. I thought it would prompt me to enter that when I registered and forgot about it. Regarding the squirrel performance calculator, it just seems really off to me whenever I plotted any points in. It doesn't seem to like the AFRs that diesels run. I literally went through every map that calculator has and none of them worked. Granted, I have my ideal AFR set leaner than what most people probably run on theirs, but if the turbo is sized properly for a given application, the engine should run lean and have minimal smoke output. I don't like the calculator because I calculated these equations for plotting compressor map points by hand and I trust my brain and the equations more than the calculator. I'll have to re-run my calculations with a VE of 85 percent and a lower BSFC and see what happens.
RabbitJockey, you're definitely right about the P/R. I goofed on that. After going through all the calculations again, I came up with a MAP of 55.11 PSIA, which equates to 43.64 PSIG and a P/R of 3.8 with an AFR of 20:1. I've looked through some builds, and, as far as I know, no one has used that much boost on these engines. With an AFR of 18:1, I came up with 38 PSIG and a P/R of 3.3. That's still pretty high on most maps. I'm wracking my brain trying to figure out why this seems so difficult because there are people who've made 200 whp on these engines. Perhaps they have a lot more fuel than I'm accounting for. Here are the equations I used from Garrett's site:
http://www.turbobygarrett.com/turbobygarrett/choosing_turboHere are my calculations:
Wa = HP x AFR x (BSFC/60)
Wa = 200 x 20 x (0.372/60) = 24.8 lbs/min
MAP = (Wa x R x (460 + T)) / (VE x (N/2) x Vd)
MAP = (24.8 x 639.6 x (460 + 130)) / (0.85 x (4500/2) x 97.6) = 50.14 PSIA - 11.47 PSI = 38.67 PSIG, P/R 3.4
As you can see, lowering the AFR results in a lower Wa, which decreases the MAP and required boost. I would rather not run richer than 18:1 and ideally stay around 20:1 to maximize combustion efficiency. This is obnoxious because it seems like the only way to get near 20:1 is through the use of compound turbos, which I'm not averse to, but I'd prefer to stay with a single. A VGT could help here, but they have reliability issues compared to their fixed geometry brethren. Does anyone know a turbo I can use that will work here?