I've done a bit of calculations, according to Graham Bell's formulas, in order to better understand what would be the better turbo to select for my project. I calculated for 15psi & 22psi from 3600-7200rpms, then I did one for 25psi @ 7600 and one completely over-the-top at 30psi.
After going comparing all the compressorcharts, there are a few of the smaller (pre GT30) turbos that looks very promising. One is the new Garret GTX2867R. The first batch of these turbos are shipping very soon, so I sent some emails to ATP to get their opinion about it and they were extremely enthusiastic. It is promised to spool as well as the 2860RS but will deliver a whole lot more on the top end. See the comparison charts here
. They could also ship it with a T3-turbine that could fit my existing downpipe. Here's the flowchart:
Not too bad at all!! No issues with surge and even up to the higher boostlevels it operates inside the most efficient area of the compressor, hitting the sweepspot at the end of the RPM-ranges. Would be awesome to see full boost closer to 3000rpms and yet reaching well above 300whp! I am a bit surprised that this turbo has not been mentioned either here or at M.net! Am I missing something here - apart from the fact that it's a fairly new device..? Will be very interesting to see how it compares in real life, once we see the first builds on the dyno.
The BorgWarner EFR6258 also looks very very promising. This seems to be the one to beat - at least when it comes to delivering at the lower rpm-ranges. Will be interesting to see once more people finish their builds and show some dynoplots with higher boost than the 12psi that "fresh38
" was producing. Even then he produced 270rwhp on a more or less stock engine!!! Very impressive.
Edit: My first calculations were a bit off on this turbo, as I didn't scale it correctly. This now looks even better! Seems like the compressor is able to give 20psi all the way from 2800rpm to redline
Some other alternatives are also attached with overlayed flowcalculations, including the suggested GT35 that for sure will fit really well
To be continued...