Ok, I’ve been trying to figure out what turbo setup to use (by setup I mean trim/housings/etc), but can’t figure out how to really determine what trims to go with on either wheel. I think I want to go with a t3/t04e hybrid, but all the formulae I’ve seen for determining what trim wheels work for the compressor seem to rely on too many variables, and I don’t see how it’s possible to determine what trim would work well on my engine without either knowing waaay more about the exact details of my engine and it’s operating ranges. Am I reading too much into the turbo sizing stuff?
I mean, the input temps, v.e. (I think) of an engine and adiabetic efficiency of a turbo can vary to my understanding, and when running through a number of the calculations at various rpms using a range of numbers (reasonable ranges of numbers) for all the variables I don’t know for sure (input temp, v.e., a.e.) I get a huge range of answers to plot on a compressor map, many of which work, and many of which go past the surge limit on the map. Anyone have suggestions for easier turbo sizing or good ranges of numbers to use for the variables I don’t know for sure, or am I just reading to much into it and should I just be assuming certain numbers for everything?
Also, how do I determine a good a/r ratio for the turbine wheel? Apparently turbine maps are hard to come by, and I haven’t seen any info for how to really determine what turbine setup to use (just going on the assumption that I’d probably want a t3 since it should take less time to spool with a small displacement engine like my b18a.)
Also, what are people’s straight suggestions for what compressor/turbine trims to run? Just wondering what people who are boosted are running specifically, and also curious if anyone knows the specs on the turbos included in some of the kits out there (I won’t be buying a kit though). I’m ultimately looking for a turbo that will have a little lag lower in the rpm range, but be capable of boosting to about 20psi. I’m not looking to boost over 15psi probably but I don’t want to be too close to the surge limit of the compressor boosting 15psi. I’d also only be boosting 15psi after fully rebuilding, and that won’t be for a while, I just don’t want to buy two turbos if I can help it, and just live with some lag initially while boosting 6-7psi on stock rods/pistons. Any suggestions are appreciated. I searched on here and got nothing much on what I’m looking for. Thanks!