well, back to the water injection. when spraying the meth, it evaporates creating a very dense cold charge, allowing you to tune it higher, or run lower octane. The dynoflash EVO benefited thanks to the water injection. an all motor vehicle can benefit from it, just because of the drop in temps. instead of upgrading the intercooler, my buddies srt4 is water injected when running 100 octane. resulting in about 320whp. ss/sc can totally benefit from the water injection, imagine being able to run a "high boost mode" with 93 octane? hope this clears it up.

 

Uh, Im not sure what point youre trying to make with the supercharger and the turbocharger. PSI is not an issue. Just think of the mechanics behind each component:

The supercharger: Belt driven directly from the motor. Automatically forces air into the engine everytime engine is revved.

The turbocharger: Turbine driven from exhaust. All flow from exhaust turns turbine and forces air into the engine.

With this set up, the S/C would create a faster, more powerful flow of exhaust from engine. This in turn, would power the turbo, and force more air into the supercharger.

So:
-S/C forces more air into Turbo
-Turbo forces more air into S/C

The air flow into the engine would be GREATLY increased. More air = higher rate of combustion. Higher rate of combustion = more power. From this point, all you would need to do is make sure your fuel injectors can support the upgrade, get a wicked tune up, and replace some internals to support added power levels safely.

 

I get what your saying but what i'm getting at is that you have to look at how much boost is getting forced in there and i guess also how much air the motor can flow. Since I dont know how much cfm's the car can flow on the boost side of things if the turbo is compressing the air to lets say 20 psi than trying to shove it into the supercharger which can only compress air to 15psi how is that really helping the turbo out? Granted theres gonna be a gain but If you put a decent size turbo on the car theres no need for the twincharged set up. It's not gonna be as efficent as a properly tuned single turbo set up. Hell Even that Sti that they twin turboed and supercharged only uses the supercharger power adder for the first 2 gears than its bypassed to let the turbos do there job because the super chargers can flow as well as them so its just hindering the process. I'm go look for it and post it up here.

 

here you go.
http://forums.nasioc.com/forums/show...6&page=1&pp=25
its alot of read so I'll quote some key points.

"I'm sure some will think its quite impractical, but it really isnt(in most respects). The supercharger gets the turbo's fully spooled by 2300RPM, with the SC off, the turbo's dont hit full boost til 7100RPM. The production kit will come with 2 GT25's and wont include the SC. If I remember right its running ~25psi. Stock block and pushing well over 400HP."

"supercharger on 6mpg and off 26mpg"

This is what I was trying to exsplain but wasn't doing it well.

"Some of this is wrong. First and foremost, you don't magincally get more air into the motor by adding another compressor, just like you don't magically get more air by moving to a larger compressor. If the two hotsides are still .63, the engine will be able to move more air at a given psi. However, this is mainly for higher boost as the delta would normally start to get high. You are still going to need a healthy amount of boost form the motor to flow 60lb/min. At modest boost levels the difference is not going to be that large. You only start taking advantge of additional airflow once the other compressor was being maxed out. A true GT35r shouldn't have any problems making 600+whp. It has been done countless times.

I like the whole supercharger to spool as well, but it adds a lot of complexity and a WHOLE lot of cost to the deal. In your scenario with the porsche, a suby driver with a gt35 would only need to down shift. Not a bad way to save 4k, huh."

 

first you say this:

then you say this:


it's a blatent example of what i was suggesting.

 

And that is? It's one thing if you try and tell me that the supercharger is helping the turbo spool because its so big its got tons of lag I don't see that supercharger really helps things out as much up top once the turbos spooled whats the super charger really doing? Even when they dynoed the sti with and without the super charger on. It still made the same peak Hp but with the supercharger on the power band was much fatter down low. Might as well just spray for the begining to spool the turbos quicker its cheaper and I would figure much easier to tune. Like I said before I don't think twin charging is worth the headache but people on this sit seem to think its the best solution at the end of the day. I think its too much going on when you can find easier soulutions to make the same amount of power with less trouble/tuning/ troubleshooting involved.

 

The turbo will be spooled quicker with the supercharger providing instant boost, but the main advantage is allowing a much larger turbo. If you are boosting a 2.0 litre engine to 14.7 psi, you are putting out as much exhaust as a 4.0 litre engine. This allows a turbo sized for a much larger displacement engine, like one off a GNX or something. But instead of having ridiculous boost lag because of the large turbo, it feels like a good match, resulting in solid power in the whole RPM range.

And about the turbo having more psi than the supercharger, a roots blower is pumping the air in, so it will amplify the pressure, maybe not very much, but it wont hurt until very high RPMs at very high boost levels.

 

Wow
Last time I checked it is the power under the peak that wins races. Twincharging makes for a very fat power band. In my setup I have the turbo producing the majority of the boost. I actually increase the pully size over stock to a 3.8" resulting in 8psi out of the blower. The turbo makes up the rest to hit the target boost of 20psi. The turbo come up instantly which is good for a 3076r on a 2 liter. I do not bypass the blower otherwise it would not be twincharging. The way I sized the blower pulley and turbo, everything is in it's sweet spot for best performance. As far as 450whp right now I would say no way, but soon I will add water injection and bump the boost. I think it is possible in the near future.

 

Ok well since this thread was hijacked anyways i will post my .02.

Selfinfliction, could you tell me what twincharged would be running without the S/C on the car with just his turbo? He would prolly still be running close to the 405hp marker you are claiming. The difference would be that it would take much longer for a large turbo to spool up and his actuall boost would not kick in till a later time. But adding the S/C (which he even runs at 8psi now) you are allowing the turbo to spool up faster as well as having full time boost, meaning an almost perfect power band.

Don't get me wrong i have loved the idea of twincharging since it came out, but really the only benifit of it will be full time boost.

Twincharged, i think you have been talking with a guy named Josh, he owns a twincharged sunfire. He is in our Car club and he is predicting that he may actuall lose a bit of hp by having it twin charged but thinks it will make up for its self with ful time boost. Whats your take on that?

 

I would first like to state that it was in my mind that both your turbo and supercharger would need to be running the same amount of boost... just thinking about this logically one single engine can only produce one pressure reading (boost/ vacuum) you cant have to different boost readings at the same time just because you have to types of forced induction... But i maybe seriously wrong please correct me if i am

 

His biggest problem is that the intercooler needs to be the last thing in the line and he doesn't have one after the supercharger. He is relying on water injection for this (see back on topic ) As far as loosing power I don't think it is an issue. Remember it all comes down to CFM and a turbo can only flow a max of what it is rated. Being that it is the first on the line it will dictate the peak HP.

 

**Back to the topic of the thread **

Water/Alky injection is definately worth the effort . Problem with the Cobalt guys pertaining to it is , we do not have any access yet to our PCM's , just maf meters or piggybacks . Once full access to the PCM is acheived , water/alky injection would then prove it worth . You could get away with a more agressive timing curve , as well as leaner mix = more HP/tq . Just putting H20 injection on a untuned car would be pretty useless , which is why the guy that had prolly took it off . Competent tuners on turbocharged LS1 Camaros/Firebirds have made as much as 70 addition hp with alcohol injection , just by being able to run a much more aggressive tune . This is the route I will be going when I can get inside my PCM with laptop , pcm access seems like its never gonna happen though

As far as out converters go , they are just pure junk to begin with . A frind of mine is tech at Saturn , and has replaced countless converters on the ION's . A few members here have had theirs blow out as well . I personally think GM is gonna be warrantying ALOT of converters on SS's and Redlines when the stg. 2 kit comes out .

 

Well thanks for clearing alot of things up with your post. I was thinking it was weird if you had the supercharger at stock or higher boost plus than try and boost even more with a turbo. Also in my last thread I gave credit that the supercharger would create a fatter power band down low but mostly it was there to help the turbo spool faster. I'll give you credit for trying something new but unless a kit like that came prefabed with an ecu to do all the work maybe 3 percent of the members on this site could handle, take care, upkeep a kit like that. Its not exactly plug and play I'm sure you've got countless hours loged into tuning that thing. If you can answer me honestly though could you get similar results to the twincharged set up by spraying the car instead of using the supercharger? Im not trying to knock your twincharge setup but I am looking at the ease of fabing up / instillation / Headaches involved with tuning for another power adder, and If twincharging is really that much better than trying to add nitrous.

 

The problem with twincharging is that you need to do the math the best placce to start is with measuring boost a turbo that is "6psi" that means it adds 6psi to the 14 psi of the atmosphere now if you get fake numbers with saying that they are running 40 psi that is total not generated from the turbo/sc so if you have 2 forced air inductors in line then you should put a big turbo that produces all of its power at high rpms.

So now for a example if you take a 7 psi sc and put a 7 psi turbo right after it don't add or mulitply directly you need to take the fact that the supercharger it increasing the air pressure from 14psi to 21psi for a compresssion ratio of 1:1.5 now with the turbo adding 7 psi to the regular 14 psi. So now you add your turbo into the line and it will turn the 21psi from the sc by another 1.5 so for a total of 1.5X1.5X14=31.5psi total now those cars caiming 40 psi is only running 25 psi of boost.

Now the problem with that much boost of course the fuel at this point my car is a stock car (mostly) and my car is pinging with 91 octane fuel so if you are going to runn boost like this miz your own high octane fuel otherwise you are going to lose all of your power to your knock sensor now if you want to add some serious kick and you don't mind enginge work add a second head gasket and get spacers made to support the head. brass works realy well. this will stop you from using the car just to runaround I only reccomend this to people that are only building drag cars or people that don't care about fuel ecconomy.

 

I heard the same thing too. My theory is, water injection is worthless on our cars till we pass our intercoolers effective cooling level. I heard once we hit 400whp our intercoolers wont be able to keep up. Not sure if its true or not. I dont think theres many redlines or ss/sc that have hit the 400whp mark. But if its true, the fine evaporated mist from the alky will drop temps. Allowing us to a)Tune for more power or b)Leave as is for added reliability. Any thoughts?

 

Water-methanol injection can have a great positive influence whether you are making 200hp or 400hp. The more heat and pressure there is the more benefit is available, but even at stock boost levels, if you would benefit from running more ignition advance and 116 octane race gas, and a cooler inlet charge, you will benefit from water-methanol injection.

Even on a very low-boost application, there are benefits to be had, you just have to look at the cost vs. potential gains - like any mod, really.