Supercharger/turbo setup....

[TT_NS]

all right guys i got an interesting setup. i drew up two diagrams for the 1g dsm with a supercharger and a turbo. one is more basic then the other. on the first set up i have the turbo connected before the supercharger. The reason for this is that it is a simpler set up. You would not half to worry about "back wash" if you would. The idea behind this set up is that the supercharger would simply suck air threw the same intake as the turbo. giving the engine boost while the turbo is taking its time spooling up. then when the turbo spools up it will increase boost. Although i find this a really crapy set up . There would be so much air friction going on in this. First from the turbo being in the way of the supercharger and visa versa. So i thought id try something a little more interesting. Then i came up with the second diagram. In this one the supercharger has its own intake which will reduce friction. But this is where i run into a problem. When the boost being created transfers from the supercharger to the turbo i need to release all pressure being created by the supercharger so i can close off that entire area with a valve that will prevent the turbos pressure from being pushed back out the supercharger. Make since? Dose any one know of a anything that works like a BOV but releases under certain pressure? Any way the pressure from the turbo will shut the valve to the supercharger. hope you can picture how that would work. I was also thinking for either application i could fabricate a pulley or use the one off the A/C on the car so the Supercharger could be turned off and on by a clutch just like the A/C. Although i wouldn't have any idea how i could control the relay from turneing off and on without me hitting a button. that might be to complex for me. I noticed if you take out the A/C you have plenty of space for a Vortech supercharger in that area. That is my plan. Its nice to come up with something a little different then what other people are doing. Just another way to get the power so please don't bash the idea. But let me know some ideas you guys come up with. This would take allot of fabrication but im up for the work.

 

[dsmfa9nutter]

Like totaleclipse said earlier, the guy that built it is on these very forums. If you'd like to know how it performs, send him a message!

 

[pooker]

Thats amazing, plus one for doing it.

 

[95gsxtreme]

the supercharger is a screw type which is positive displacement, this would not allow the boost from the turbo to reach the manifold if they were set up in series so they must be parrallel right, so does the discharge side of the supercharger dump into the turbo piping? this seems like it wouldnt make sense tho since the backpressure on the turbo would cause it to spool a lot slower? idk can u offer any enlightenment on how the supercharger and turbo come into the intake manifold thx.

 

[95gsxtreme]

I may be wrong but I believe the s/c works solely off of a pressure ratio based on the speed of the drive gearing. -Like a certain size drive wheel equals a certain pressure ratio for the increase. Put in 14.7psi of atmospheric and get, for example, 24.7 absolute -while putting in 24.7psi absolute (+10psi already boosted air from the turbo) gets you like 41psi absolute, or near 27psi of gauge pressure.

I guess this is my answer? is this correct?

 

[RayPeters]

I may be wrong but I believe the s/c works solely off of a pressure ratio based on the speed of the drive gearing. -Like a certain size drive wheel equals a certain pressure ratio for the increase. Put in 14.7psi of atmospheric and get, for example, 24.7 absolute -while putting in 24.7psi absolute (+10psi already boosted air from the turbo) gets you like 41psi absolute, or near 27psi of gauge pressure.

I guess this is my answer? is this correct?

You got it, the turbo feeds the inlet of the supercharger, which multiplies the inlet pressure by the rpm ratio of the drive. The supercharger displaces 1 liter of air per rev and has as effeciency of ~75% so there are some losses in all this. The engine displaces 1 liter per rev as well, so to drive it at 1 to 1 would only pump as much air as the engine can use. to drive it at twice engine speed results in 1.5 liters of air being forced into the engine per revolution. 3 times engine speed is just outside the rated max rpm of the supercharger (18,000 or so) but for the math, 2.25 liters of air per rev. Now compound all this with the turbo, it can achieve 3 to 1 pressure ratios as well, so "in theory" it is possible to have a 6 to 1 ratio. now lets convert this to boost pressure,

Givens
14.7= atmospheric pressure
75%= supercharger effeciency

so

2:1 ratio = 14.7*2=29.4*75%=22.05-14.7 to get pressure above atmospheric = 7.35 psi
3:1 ratio = 14.7*3=44.1*75%=33.08-14.7 = 18.375 psi


now watch how scary this gets:

2:1 ratio turbo with 2:1 ratio supercharger
75% effeciency on both

2:1 ratio turbo= 14.7*2=29.4*75%=22.05*2(2:1 ratio supercharger)=44.1*75%=33.08-14.7=18.375psi boost. not scary but keep reading

3:1 ratio turbo=14.7*3=44.1*75%=33.08*2(2:1 ratio supercharger)=66.15*75%=49.6125-14.7=34.912 PSI now were getting someplace

and ...

3:1 ratio turbo= 14.7*3=44.1*75%=33.08*3(3:1 ratio supercharger)=99.225*75%=74.41875-14.7=59.71875 psi This will damage something.... but man would it feel good till it did


So if everyone is still with me, that's how this all works, and keep going with the questions, I appreciate your interest.

 

[DJ23GSX]

Is that part of the stock upper i/c pipe i see in the pic?

 

[adiffrentcity]

It seems that if you are having that much trouble with detonation in low rpms and tuning the ignition curve to deal with it that you could just run a different supercharger pulley for a lower boost ratio. Roots type superchargers push out additional heat at an exponential level when turned past their compressor efficiency range. Most have peak efficiency at 6 or 7 psi. Would like to know specific model # of supercharger and is 10 psi efficient for it? I could be way off with this line of thinking. Oh and to echo everyone else on this thread, you deserve a lot of respect for ingenuity and tuning prowess. I'm glad to see someone has finally explored the use of a supercharger on these engines. Be sure to become a supporting vendor so we can all buy the kit when you are done developing it!

 

[GST with PSI]

Are you serious? Something that has the GM 3.8 supercharger that actually goes fast. Now that is an accomplishment. It seems you have forgotten only one thing ray.....

Stick one of these on and you'll be good to go. Other than that I am speechless. Good stuff. Really good stuff.

 

[RayPeters]

Is that part of the stock upper i/c pipe i see in the pic?

stock parts????? What???? Where???? There'll be none of that around here!!

No, although the intake plumbing needs some attention, the guy I have here in phoenix to make the all aluminum kit is in the process of moving his shop across town so that ugly bugger of an upper intercooler pipe will be with me a little longer.

 

[Rob10_99]

didnt you say you had dyno sheets?
btw I couldnt see the video on these MWR computers =(

 

[RayPeters]

didnt you say you had dyno sheets?
btw I couldnt see the video on these MWR computers =(

No dyno stuff yet, still sorting out some tuning details, then we'll stretch some straps

I will try to host these on my local media server tomorrow night, as well,

The links are to quicktime files and they were slow when I tested them, worst case, pm me your email addy and I'll send them to you directly.

I saw in another thread a dsm meeting in SoCal on the 20th, if I'm not working I'll try to make that, should be an interesting trip.

Also there is a rallycross coming up in early feb in SoCal, will be there as well.

 

[Defiant]

So the blower accepts the pressurized air from the turbo, and pressurizes it further?

I'm feeling one of those bullets-from-a-supersonic-jet's-nose headaches coming on.

 

[slipstream808]

Personally, I'm curious to see the boost pressures at various RPM's side by side with intake temps as taken after the supercharger. In fact, if I were you, I'd install a temperature and boost gague somewhere after the turbo but before the supercharger. Just to compare all 4 readings.

 

[JayRolla]

Are you serious? Something that has the GM 3.8 supercharger that actually goes fast. Now that is an accomplishment. It seems you have forgotten only one thing ray.....

Stick one of these on and you'll be good to go. Other than that I am speechless. Good stuff. Really good stuff.

Dont talk like that unless you know what you talking about. Ive seen those Pontiacs haul some balls. All you do is take that supercharged motor and drop it right in a Fiero. Talk about a good power to weight ratio.

I also want to know what the intake temps are. You would think that the turbo and supercharger would heat up the intake temp way to much. Also wouldnt the supercharger slow down the compressed air from the turbo??

 

[RayPeters]

Dont talk like that unless you know what you talking about. Ive seen those Pontiacs haul some balls. All you do is take that supercharged motor and drop it right in a Fiero. Talk about a good power to weight ratio.

I also want to know what the intake temps are. You would think that the turbo and supercharger would heat up the intake temp way to much. Also wouldnt the supercharger slow down the compressed air from the turbo??

Umm, the fiero is as heavy as our cars, I'm not sure 265 hp in a 3000 lb car is anything to write home about. Although I will give it props for being a mid engine rear wheel drive car.

As for the intake temps, without methanol injection, they are 180 or so, but I occationally see heat soak into the 230 range. That starts being an issue. THe meth cools it 70-80 degrees.

The supercharger doesn't slow the air down, it is another compressor, so it compresses it yet further and pumps it into the engine.

 

[JayRolla]

No way the 4 cylinder fiero wieghs that much, maybe the GT larger version. There is a guy here with one that layed over 450whp. Who keeps the motor stock.

I just looked up the curb weights.

2590-2790 are the curb weights. The guy here had the small 4 cylinder version.

 

[RayPeters]

Personally, I'm curious to see the boost pressures at various RPM's side by side with intake temps as taken after the supercharger. In fact, if I were you, I'd install a temperature and boost gague somewhere after the turbo but before the supercharger. Just to compare all 4 readings.

I appreciate the thought, I've got that already, although I can't datalog it. It is interesting to see the turbo pressure multiplication thing really work. I'm trying to get a camera mount that I can stick on the glass and shoot some stuff in the cockpit, ala polish datalogger. Stay tuned.

 

[RayPeters]

No way the 4 cylinder fiero wieghs that much, maybe the GT larger version. There is a guy here with one that layed over 450whp. Who keeps the motor stock.

I just looked up the curb weights.

2590-2790 are the curb weights. The guy here had the small 4 cylinder version.

Well modifying the engine will help a bunch, I was using the stock 3.8 numbers, and I was going from memory on the weight stuff, I stand corrected. 450 in 2600# would be fun for sure.

 

[RayPeters]

So the blower accepts the pressurized air from the turbo, and pressurizes it further?

I'm feeling one of those bullets-from-a-supersonic-jet's-nose headaches coming on.

That's the short short version. I bypass the supercharger under several conditions, it mostly is used for low end punch to get the turbo going. Then at high rpm I bypass to limit power to what the engine can handle.

 

[TimG]

The supercharger idea has been done before, but not the series style double chargers. It's insane in thinking that the supercharger effectively takes the atmospheric pressure + boost pressure and increases the pressure even more by a multiple of whatever you want.

Did you guys do something similar to this? :
http://www.ecanfix.com/~mdhamilton/images/talon/blower.jpeg

 

[JayRolla]

The supercharger idea has been done before, but not the series style double chargers. It's insane in thinking that the supercharger effectively takes the atmospheric pressure + boost pressure and increases the pressure even more by a multiple of whatever you want.

Did you guys do something similar to this? :
http://www.ecanfix.com/~mdhamilton/images/talon/blower.jpeg

Wow thats a cool view of that mani. Looks like someone had fun putting that together.

 

[RayPeters]

The supercharger idea has been done before, but not the series style double chargers. It's insane in thinking that the supercharger effectively takes the atmospheric pressure + boost pressure and increases the pressure even more by a multiple of whatever you want.

Did you guys do something similar to this? :
http://www.ecanfix.com/~mdhamilton/images/talon/blower.jpeg

yeah that's the idea, but a smoother transition to the runners, what's that fit? looks hondaish maybe??

 

[mavisky]

nt 4g63 actually. Someguy built his own homebrew jackson racing style blower kit for one.

 

[TimG]

yeah that's the idea, but a smoother transition to the runners, what's that fit? looks hondaish maybe??

It was on a 4G63T motor (7.8:1 compression). Took off the turbo and tried the supercharger at around 10psi. Apparently worked well but it wasn't as fun and impressive when compared to the turbo set-up.

 

[lee101315]

So how are you keeping it below 30psi?