I <3 how stuff works in these situations (and of course you too 8cd03gro )! I read about that yesterday, about superchargers/turbochargers to try to learn a bunch more. Okay, that makes a ton of sense. I'll wait to see numbers on the twin-screw to see what type of boost I should go with.

Another question. Now, what about all the dual charge setups people are going with? Those create a massive amount of heat, correct? But with the roots supercharger's draining, wouldn't you lose more hp than with a regular turbo setup? Or would it be just as efficient or even more efficient for better HP and TQ gains?

 

well you will inevitably lose a higher percentage of your power than a normal turbo setup would, but there are some benefits. Since you don't need a tiny ass pulley on the blower with a twin-charge setup because the turbo is going to be the big boost maker here, you won't have to spin the blower as quickly. Every time you increase boost on your eaton by going with a smaller pulley, you will gain power yes, but you will also get higher parasitic loss because it takes more energy from the engine to spin the blower faster. Now one of the greatest things about the twincharge setup is you can run a larger turbo than you would want to with just a single turbo setup. You will basically eliminate lag because of the eaton, and you can make the big boost of the turbo. Really, if you get rid of the cats, with a twin-charge system, you shouldn't really lose much more power to parasitic loss than you would to your stock setup, but you will make A LOT more power.

 

Rep +1, thanks for being so helpful. So lemme make sure I understand. Though you still have a parasitic SC up there, with the bigger turbo you would gain a lot more than you would lose?

Wouldn't smaller pullies help to push more boost into the turbo though, or would it just cause unnecessary crank loss/totally unnecessary in the first place?

 

Ok i'll try to exlpain this best i can without going into a HUGE lecture haha. You may want to do some reading on forced induction to better understand, but ill try to make it easy to understand. A supercharger compresses air, which is a type of work. Whenever you do work, energy is needed right? Well since a supercharger takes the energy it needs to compress the air from the engine directly, the more air you try to compress, the more energy it has to rob from the engine. You will make more power with more boost, but like i said, you will lose a larger amount also. For example....stock at 12 psi, the m62(your stock supercharger) needs, lets say 30hp to spin fast enough to compress that 12 psi (these are probably not super accurate numbers as i can't find any efficiceny maps, but just an example). Now the faster you spin that rotors of the m62, the more air you are going to compress, but the more energy it needs. So if you are making 19 psi the supercharger may be taking 45-50hp to create that boost. Now, notice that the parasitic loss only went up by about 15-20hp with a 7 psi change. With an extra 7 psi you are going to GAIN quite a bit more than 20hp, so you are still going to end up putting down more power than you did at 12 psi. The only reason this is important is this - With a supercharger, you can be making, say 210hp, but since the supercharger is robbing like 30, your internal engine components (pistons, rods, crank, etc.) are actually feeling the stress of 240hp. Since your stock supercharger is being overspun like crazy with the 2.5" pulleys some people are putting on them, they are robbing quite a bit more power than they did stock, and they are running much hotter. For those reasons, the guys putting down like...265whp ( around 305 crank hp) are actually putting their engine through the stress of closer to 350 crank hp, which is close to the limits of the stock pistons. The reason for this is the turbo is using exhaust gasses to spin a turbine, which in turn spins a compressor and compresses the air....the kinetic and thermal energy of the exhaust gasses would otherwise be wasted, so you are basically using wasted energy with a turbo where a supercharger would use some of the energy you want to preserve (torque/hp), so you want to use as little energy to spin the supercharger as possible and leave as much of the boosting as possible to the turbo in a twincharge setup. This way you will be able to make more power, with less stress on the engine and when you have hypereutectic pistons, that is important! Any turbo can make a HUGE amount of boost. The turbo will use as much exhaust energy to make 6 psi as it will to make 15 psi, it all depends on the wastegate. The wastegate is set to let the turbine spin to a certain speed (certain amount of boost) then start bleeding off gasses, so the turbine doesn't spin any faster. So you aren't robbing yourself of anymore power by upping the boost, unlike a supercharger. From all this you will see that you want to leave as much of the work to the turbo as possible because it needs the least to do the work, but here's the catch. A very small turbo can spool pretty quickly, but the smaller it is the less efficicent it is, so you gotta find a happy medium which is very hard. With a twin-charge setup, you can keep the stock pulley on the supercharger and only rob maybe 30hp from the engine still and only push 12 psi out of the blower, but still make 300+hp, and the greatest part is you will spool VERY quickly, you wont even notice any lag, but you can still run a big, efficient, turbo. So basically, you can get more power than the 2.5" pulley guys, with the same or less stress on the engine. I think i'm getting a little bit too in-depth here hahaha, if you have anymore questions, just send me a pm and i can help you out from there, i dont wanna jack this thread any more than i already have lol.

 

I think you may be confused on something here as well as what 8cd03gro stated. As far as the intake is concerned the Turbo is BEFORE the Supercharger. The turbo forces air into the SC which then forces it into the engine. Yes a smaller pulley on the SC will make even more boost with a turbo than the stock pulley and the turbo, but as 8cd03gro stated, the majority of the work should be done by the Turbo, not the SC, due to heat and parasitic loss considerations.

The twinscrew charger will be far more efficient than just the stock M62 Roots but it will still not equal the efficiency of the twincharger setup.

The major benefit of the twincharger vs the turbo only setup is the complete lack of lag. It is true that with the twincharger you will not make max power right off idle but you will make more power off idle than you would with a turbo only. The SC will essentially fill the gap between idle and turbo spin up since it is spinning all the time.

I am really considering a twincharger setup and maybe even a TVM or TwinScrew swap with it.