Mike what are your thoughts on turbo selection? I already have the procharger.
I chose the d1sc after looking through some stuff on the net and looking at cfm output and what I wanted to do, then after talking with empire diesel and a couple different guys from procharger I figured that would be a good supercharger for what I wanted hp wise.
I figured I would install a 50mm tial blow off to help with tuning.
Sorry for not answering sooner.
Some known info for calculations. Temps are 85 degrees f. Bsfs .38/hp Supercharger used as the atmosphere charger. A/F ratio of 22 to 1 for desired no smoke operating conditions. 500rwhp desired.
So some facts.
These figures will depend on cooling the charge.
With the desired hp you require, you will need 70lbs/min air flow. To get that you will need 68psia ( that's absolute ). So at sea level, this will be 53.3psig. If you really want to get that hp at 5000rpm, you'll decrease boost but will need the fuel up at that rpm. This pressure will be required at 3300rpm as calculated. As far as a turbo for this, not one I'd recommend by itself, and NOT saying I'd recommend, only saying a gt4202r compressor map shows it will work at it's upper limit. Problem is it's efficiency. 30% of the energy used in the compressor to compress the air is turned to heat. This map shows way close to surge. This charger will flow more cfm but no more pressure is recommended. See pic1 Topping off the draw backs to this charger is the turbine map. This charger turbine will require 18.5psia and 23lbs/min to even begin working the compressor. See pic 3. To give you an idea, your engine running n/a at 1500rpm is 6.78lbs/min at 85*f. Of course, you'd have a little more than 1lb/min fuel, for a 22 to 1 ratio for no smoke that would contribute.
So to move on. If your supercharger can develop say 23lbs/min at 1500rpm, you can select this charger and lower the pressure ratio required from this (4202) charger and have fun but battle surge like crazy ( actually from both ). Looking at a similar supercharger of close pr and cfm capabilities see pic 2, no matter what you do, you will battle pr and surge from this supercharger with a huge turbocharger if it works at all.
Now for the smaller turbo: For a GT3788r to work, you'd need to have 20lbs/min air flow at the 18.psia in the turbine to even begin to build 4psi boost and 10lbs/min air flow in the compressor. So it looks like the supercharger is still in surge and having to build crazy rpm to start the ball rolling at under 1500rpm. Remember, surge for any charger is a big no no. To get that kinda cfm to move the compressor wheel you'd need something like over 2 times the cfm at 1500rpm plus fuel to get the ball rolling - meaning at least 2 atmospheres from the supercharger. But, a 3788 would definately move the cfm through it, at the perfect pressure ratio and efficiency point, with those two atmospheres from the supercharger again in surge due to the two pressure ratio now being required.
Truthfully, I'd recommend a smaller supercharger and maybe then, I'd recommend a turbocharger. JMHO
I could be wrong, if you could move enough air at really low rpms with a turbocharger ( which would compound and add room for volume ) and that supercharger could move enough cfm to stay out of surge ( Venting ) to build psi. And, if that same turbocharger could flow enough cfm to handle the required hp through the compressor it would work. I just don't know what turbocharger that would be.
