One of these days I'll get around to sitting down and putting up a compressor map. For now, use this:
As the early GM series are definately RHC6. Looking at the choke line, you'll see that it is roughly 17.5 M^3/min which would be 618.0068 CFM. This doesn't mean that this turbo can and
should be pushed to 618cfm, only that it is capable of it, BUT, at that point would be at its choke line and mostly flowing hot air.
The *choke line* as you know, or
should know is described as: the maximum centrifugal compressor volume flow rate that is normally limited by the cross section at the compressor inlet. When flow at the wheel inlet reaches sonic velocity, no further flow rate increase is possible. the choke line can be recognised by the steeply descending speed lines at the right of the compressor map. Which essentially means that you've gone beyond the turbines maximum permissable speed regardless of boost presure ratio.
I haven't gone back and checked
your maximum rpm as my settings allow 9 pages to choose from and I am knee deep into a 12 pack at the moment lol
If you could give me
your redline, and
your max hp and torque at N/A rpm and I can plug in the numbers based on RPM to see how this turbo would work at various VE. Again, they will be guesstimates at best but I can come relatively (realistically) close to the numbers your engine puts out naturally aspirated.
But keep in mind these numbers will be for your stock motor, not ported and polished, no insane compression ratio of the pistons, oversized valves, etc etc etc.
Once I have the compression ratio of your pistons, I can plug in the numbers to find out theoretical Cr under boost, etc etc etc. But again they will be guesstimates at best, but at least better than nothing.
Hope this helps?
Damian.
Edit: Looking back, I see you don't plan on intercooling? ehhhhhh, I don't know about that one? Sure the turbine itself will have less backpressure therefor less EGT's, but once you get into an appropriate *sweet spot* for the turbo, that 6 psi goes out the window as 6 psi is hardly anywhere near this turbos *island/sweet spot*. You might want to retink that non intercooling and at least use SOMETHING as once you get it spooling, it won't want to sto on it's own and will make plenty of boost/will run your engine hotter/will be more room for error/adding an intercooler could easily mean the difference between catastrophic failure and "I told ya I could do it".
I don't mean to spoil the fun, but the guy that you guys are talking about in such high regard for using this same turbo, as far as I could see didn't run it for all that long without getting rid of the motor in the first place. if I am wrong please tell me as I am in no way trying to flame. But following in someone elses footsteps with a thought that "he did it so I can too" and forgetting that "guy A" never much testing on beyond
one dyno could very well lead
you to think to think "WTF did I do wrong?" when the only thing you've done wrong is followed in someone elses footsteps/see what I'm saying?
EDIT again: I just went back and looked at the maps here:
And the RHC6 would be closer to the RHE61. Originally I was planning on basing the RHC6 map on the RHF6 and adding Pr as I went being that they are closest as far as total flow rate at the choke line. I think what I'll have to do is come up with a compromised map between the RHF6, RCH6 Pr chart that I posted above, and the RHE61 Pr chart being that the RHE61 flows more at it's choke line, a higher overall Pr, but the RHF6 flows around the same (17.5^3/min) at it's maximum permissable speed line, but also has a lower Pr of 3.0 (3.3 max according to the charrt)
Either way, the max Pr for the RHC6 would be 14.7+29=43.7/14.7=2.97 Pr or 29 psi.
I need to work from the bottom to the top (surge line) then back through the choke line and down, find a happy medium to designate an *island* which would be the compressors sweet spot, and work outward from there.
This will help
kind of, but not really:
Note that the RHF6 would flow 109.5~582.7 cfm and the RHE61 would flow 116.5~610.0 cfm.
My calculations using the RCH6 Pr map at 17.5M^3/min without looking at the RHF series map put me dead on at 618cfm at it's choke line.
Not bad for a 17 year old ehhhh????????
Just joking, I'm 30 and work in surgery
