TWINcharged SC ???

bowez

Registered User
If you put a wastegate after the MAF you will be unable to tune it, referring to the one at the SC. Looked again and that goes for the blow off valve too.
 
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Mike8675309

Registered User
Sorry, but that is almost essentially completely incorrect.

I get a feeling you need to plan on dumping a MAF and using a different engine controlling system then the stock one. Your diagrams have continued to show that understanding the needs of a maf controlled system are not clear to you nor your friends.
 

Mike8675309

Registered User
here, I am a terrible artist but maybe this helps.
For maf you need blow through maf. Any air that passes the MAF MUST NOT EVER leave the engine other than through the cylinder.
You only need one blow of valve and that is in front of the throttle plates and MAF.
Your waste gate pressure reference must be plumbed to the intake manifold, not the compressor side of the turbo.

Twincharging with a positive displacement blower is relatively easy. You don't need all those blow off valves, only one in front of the throttle plates for when the snap closed. (and by rule in a MAF system the blow off valve must also be in front of the MAF.

the really only complexity is sizing the turbo. As the blower being in the mix changes things enough that you can't simply rely on the standard I want to add a turbo charts. Ideally find your net boost you want in the system. Then you can essentially cut that in half and you now now how much boost you need from the turbo. Size to that pressure ratio on the compressor side. The turbine side you will want slightly larger than might normally be recommended as the exhaust air flow rises much faster in a twin charged system allowing you to leverage a larger turbine AR.
 

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fasterthanyou

Registered User
Just plumb the turbo as if there was no supercharger. Pretend it doesn't even exist. Its the same function. Turbo blows air to the throttle body as if it were a naturally aspirated motor. You can put a blow off valve between the throttle body and turbo if you want, but make sure the maf is between the bov and throttle body. Get a double intercooler from ken or someone else on here and use meth injection. Seems pretty straight forward and it kind of is straight forward, on paper anyways. Good luck with it.
 

JT's03

Registered User
I think you are going to end up with a lot of turbulence with the maf location in both drawings. I would suggest true blow through design. I would want the maf to be in a straight shot to where it enters the engine.
 

Mike8675309

Registered User
I think you are going to end up with a lot of turbulence with the maf location in both drawings. I would suggest true blow through design. I would want the maf to be in a straight shot to where it enters the engine.

My drawing is intended only to show relation of the components and is no way intended to indicate scale. proper location of the blow off valve in relation to the MAF will be critical and may require some trial and error.
 

JT's03

Registered User
My drawing is intended only to show relation of the components and is no way intended to indicate scale. proper location of the blow off valve in relation to the MAF will be critical and may require some trial and error.


What happens when you run a turbocharger at low boost with high volume of piping you get compressor surge. This will create a lot of turbulence at part throttle and make it very difficult to tune some maf counts correctly. Also it's recommended to reference boost at the compressor outlet. I don't even use a bov on my setup for what I do and because my car is an auto. If it were me I'd run a slot maf right before it enters the engine, back as far as I can get it and after any bov or recirculation valve.
 

DV_17

Registered User
here, I am a terrible artist but maybe this helps.
For maf you need blow through maf. Any air that passes the MAF MUST NOT EVER leave the engine other than through the cylinder.
You only need one blow of valve and that is in front of the throttle plates and MAF.
Your waste gate pressure reference must be plumbed to the intake manifold, not the compressor side of the turbo.

Twincharging with a positive displacement blower is relatively easy. You don't need all those blow off valves, only one in front of the throttle plates for when the snap closed. (and by rule in a MAF system the blow off valve must also be in front of the MAF.

the really only complexity is sizing the turbo. As the blower being in the mix changes things enough that you can't simply rely on the standard I want to add a turbo charts. Ideally find your net boost you want in the system. Then you can essentially cut that in half and you now now how much boost you need from the turbo. Size to that pressure ratio on the compressor side. The turbine side you will want slightly larger than might normally be recommended as the exhaust air flow rises much faster in a twin charged system allowing you to leverage a larger turbine AR.


One thing im confused about in the picture design, is the waste gate plumbing. could someone explain the waste gate piping from the intake? would it being there keep the ambient pressure in the engine 20lbs of boost (in this set up I plan on boosting a max of 20)? what happens if it opens cause boost on the intake side is above 20 but pressure on the exhaust size isn't 20? would it only open for the intake side? how would you control the trubo? then?
 

Mike8675309

Registered User
What happens when you run a turbocharger at low boost with high volume of piping you get compressor surge. This will create a lot of turbulence at part throttle and make it very difficult to tune some maf counts correctly. Also it's recommended to reference boost at the compressor outlet. I don't even use a bov on my setup for what I do and because my car is an auto. If it were me I'd run a slot maf right before it enters the engine, back as far as I can get it and after any bov or recirculation valve.

I didn't say it was easy to implement, but if you want to use MAF on a compound system you need the MAF after the BOF. Someone could always go to speed density, then the maf issues go away.

I'm unaware of any compound boost setup where the compressor is the "recommended" reference location for the wastegate. Without placing the reference on the intake manifold, tuning the turbo becomes much...much...much more complex. I highly suggest reading this thread (again): http://www.eng-tips.com/viewthread.cfm?qid=174690
 

Mike8675309

Registered User
One thing im confused about in the picture design, is the waste gate plumbing. could someone explain the waste gate piping from the intake? would it being there keep the ambient pressure in the engine 20lbs of boost (in this set up I plan on boosting a max of 20)? what happens if it opens cause boost on the intake side is above 20 but pressure on the exhaust size isn't 20? would it only open for the intake side? how would you control the trubo? then?

In that diagram the line going from the waste gate to the intake manifold would just be a vacuum line which connects to the waste gate to set sense pressure. The purpose is to set the system total pressure. The waste gate works off a sense pressure. In turbo applications that sense pressure comes from the outlet of the compressor to set the net total boost out of the turbo. In a compound setup you want to drive that sense pressure off the intake manifold since total system pressure will be a function of the combined boost from the turbo and the blower.

The waste gate maintains overall pressure by bleeding off exhaust energy around the blower turbine which corresponds to a decrease in pressure from the compressor side. Ideally you will have sized your blower overdrive and your turbo size so that at your various RPM's they will allow it to work well together.


Turbo control is driven by the total system pressure you want.
Using my spreadsheet linked above, on a 3.8l Motor using a M90 blower and 20psi total boost.
Net pressure needed 33.99psi (ambient plus Target boost)
System pressure ratio 2.4
Device pressure ratio 1.55 (Square Root of the total system pressure)
M90 Overdrive needed is 2 which is a slight underdrive. (stock is 2.77)
For 20psi At 5000 rpm you need a turbo with a mass flow rate of 28.19
For 20psi at 2500 rpm you need a turbo with a mass flow rate of 14.10

Those mas flow rates along with the device pressure ratio can then be checked against turbo maps to find a turbo that has efficiency that fits well. (I would contact a turbo vendor directly as I doubt most stock turbo's would match up well)
 

David Neibert

SCCoA Admin
In that diagram the line going from the waste gate to the intake manifold would just be a vacuum line which connects to the waste gate to set sense pressure. The purpose is to set the system total pressure. The waste gate works off a sense pressure. In turbo applications that sense pressure comes from the outlet of the compressor to set the net total boost out of the turbo. In a compound setup you want to drive that sense pressure off the intake manifold since total system pressure will be a function of the combined boost from the turbo and the blower.

The waste gate maintains overall pressure by bleeding off exhaust energy around the blower turbine which corresponds to a decrease in pressure from the compressor side. Ideally you will have sized your blower overdrive and your turbo size so that at your various RPM's they will allow it to work well together.

Mike,

I think it would be easier to maintain a set amount of boost/pressure at the inlet of the supercharger, by referencing the waste gate to the compressor housing as opposed to the intake manifold. I understand that total manifold pressure can only be referenced after the supercharger, and this would be necessary for controlling the fuel pressure regulator or measuring the air pressure at the intake valves. If using the total pressure to control the waste gate you will need to use a much heavier spring to counteract the total manifold pressure of around 20 psi, instead of controlling only around 5 psi at the supercharger inlet.

Either way would work and our drawings are essentially the same.

David
 

Mike8675309

Registered User
Mike,

I think it would be easier to maintain a set amount of boost/pressure at the inlet of the supercharger, by referencing the waste gate to the compressor housing as opposed to the intake manifold. I understand that total manifold pressure can only be referenced after the supercharger, and this would be necessary for controlling the fuel pressure regulator or measuring the air pressure at the intake valves. If using the total pressure to control the waste gate you will need to use a much heavier spring to counteract the total manifold pressure of around 20 psi, instead of controlling only around 5 psi at the supercharger inlet.

Either way would work and our drawings are essentially the same.

While I can see the point about the spring size, the pressure at the intake manifold will be much more accurate vs the pressure at the inlet of the blower. Consider both the heating of the air from the blower and the cooling of the air at the intercooler.

Since no one that I know of has done this in a daily driven street car, I think the actual design will be many trade offs from the theory. Personally I would rather drive off the intake manifold pressure, but it certainly isn't necessary. Just be aware that if you put it somewhere else then your total pressure value could vary materially.
 

DV_17

Registered User
MAF vs. MAP

Ok, I've been doing some research and was wondering what you guys thought would be better/easier for the system, MAF or MAP.

On that same note I've also been looking at aftermarket PCM/ ECM s. I wanted to know if you guys had any recommendations on a brand or style that would work well on a tuning aspect. with that would I/ could I get rid of the obd I?

Finally, I just realize that I would have to replace most of the sensors; O2 (wide band), MAF or MAP, oil pressure (since the one on there is a joke), coolant would be alright, defiantly a more accurate boost gauge, probably a digital Fuel/ Air ratio gauge..ect.

with getting and aftermarket ECM would I have to change the ignition system, could I? and with all this extra boost and cfm what size fuel injectors would you suggest. Ive rebuilt engines b4 but nothing like this im just try to encompass everything :)

p.s. I wanted to thank everyone for donating their time and energy to help me further understands and facilitate my project. I've owned my SC for awhile now and im just coming to the realization of, when you buy an SC you don't just by a car. you also just bought a membership into the world of the elite. the possibilities with this car are endless and there are so many specialist out there (on here) willing to help and share knowledge. It's truly like a Family. :D
 

DV_17

Registered User
Design 4

I know you guys are probably getting tired of my redesigns but here we go I think this one is the best yet and make the most sense. in earlier drawlings my vacuum line for my waste gate wasn't drawn that was just the excess exhaust piped to the exhaust. Also im not trying to imply a FMIC in this design but I think it would be worth it to put it in. twincharged prototype 4.png
 

Mike8675309

Registered User
The picture shows you are understanding some of the basic principles which is a step in the right direction. you are at the point now that you could have some level of success with that hardware configuration though there are others that may or may not be better depending on packaging room and such. If you keep in mind you are on the bleeding edge of what people are doing and that there is risk with that, you should do fine. Also remember, twincharging is almost expressly an oddity. It is something to play with but with the way turbos and positive displacement blowers are available today there is nothing a twincharging system can take over a properly setup turbo only or blower only system.

Twincharging is just playing around.

If starting with an SC, I would use the EEC-IV and the Quarterhorse using MAF and simply work out the issues related to using a blow through MAF device of sufficient size for the build. The stock MAF meter will be too small and not work in blow through reliably. So you should consider the expense of a good blow throw maf.

If starting from scratch "today" I would use a speed density or hybrid system from MegaSquirt or if I just wanted to write a check I would use FAST XFI. MegaSquirt to tinker, and FAST XFI for plug and play. That removes the MAF from the equation but adds some other complexities.

Ford EDIS or DIS is easily controlled buy nearly all aftermarket engine controls. So no, you should have to switch ignition systems if you switch computers. At 20psi using a twincharged system on gasoline I would want a minimum 80lb/hr injector and the proper fueling system to back all that up. New larger supply and return lines new fuel pump.
 

David Neibert

SCCoA Admin
While I can see the point about the spring size, the pressure at the intake manifold will be much more accurate vs the pressure at the inlet of the blower. Consider both the heating of the air from the blower and the cooling of the air at the intercooler.

Since no one that I know of has done this in a daily driven street car, I think the actual design will be many trade offs from the theory. Personally I would rather drive off the intake manifold pressure, but it certainly isn't necessary. Just be aware that if you put it somewhere else then your total pressure value could vary materially.

I'm not sure which would work better, but in either case you would be controlling the waste gate to regulate total manifold pressure. What combination of pressure ratio from the turbo vs supercharger would require some trial and error experimentation. Frankly I'm with you on the whole twin charging concept being something to play around with, and definitely not something I would recommend trying if your a broke 17 year old high school student.

David
 

DV_17

Registered User
Thank you guys

thanks you guys for all your help and insight. I didn't realize how much goes into each system, turbocharged and supercharged by themselves. when I thought of this Idea a couple of months ago I felt it was was a pretty cool set up. I found having sufficient boost through the entire rpm range fascinating. also my cousin told me that a twincharged set up was impossible, I have now proven him wrong. I understand that with twincharging a vehicle you cant get the result you could from just a good set up turbo or blower, but I do find the set up to be truly unique and surprising. I am a big fan of turbos and I know if done right there is little to no trubo lag, but I like this Idea for the instantaneous power offered by twincharging. versus just a big supercharger or turbo. this isn't a project that I plan on doing tomorrow, but this is something I want to own. I want a twincharged vehicle it may not fly down the track cutting into the 10s but it is something that you wouldn't see everyday. imagine the looks you would get when people hear a whining form the supercharger followed by an intense whistle of a turbo. since this is such an unexplored design It would be awesome to have the prestige to say yeah I did that.
 

Mike8675309

Registered User
Today's blowers available, i.e. a twin screw blower with the right cam and valves and such will give you no less than 80% of peak engine torque through the entire RPM range from as low as 1800 rpm to 5500 rpm with horsepower growing through the entire rpm range. That means almost immediately you have access over 400 lb/ft of rear wheel torque and the number only gets bigger as engine rpm increases. What more could you want then that?

Either of those power adders without the right cam, valves, heads, intercooler, will result in less than that.
 

David Neibert

SCCoA Admin
thanks you guys for all your help and insight. I didn't realize how much goes into each system, turbocharged and supercharged by themselves. when I thought of this Idea a couple of months ago I felt it was was a pretty cool set up. I found having sufficient boost through the entire rpm range fascinating. also my cousin told me that a twincharged set up was impossible, I have now proven him wrong. I understand that with twincharging a vehicle you cant get the result you could from just a good set up turbo or blower, but I do find the set up to be truly unique and surprising. I am a big fan of turbos and I know if done right there is little to no trubo lag, but I like this Idea for the instantaneous power offered by twincharging. versus just a big supercharger or turbo. this isn't a project that I plan on doing tomorrow, but this is something I want to own. I want a twincharged vehicle it may not fly down the track cutting into the 10s but it is something that you wouldn't see everyday. imagine the looks you would get when people hear a whining form the supercharger followed by an intense whistle of a turbo. since this is such an unexplored design It would be awesome to have the prestige to say yeah I did that.

I think you may be seriously underestimating the difficulty of building a functional twin charged system on an SC. Not saying it can't be done, but if your serious about it I strongly suggest you learn to do your own fabrication because there will be numerous components needed. On a project like this it's all the details that make it difficult, like where to position the turbo and how to route pipes that will impact the other components.

It's not really an unexplored design and lots of people have done it, including at least one automobile company. It's just considered, expensive, unnecessary and overly complicated. If your not looking for huge performance numbers, then it makes even less sense. Unless your looking to make 600 rwhp with tire burning torque from just off idle to redline....there are much easier ways to accomplish it.

That said...Simplest way to do this is by using a rear mounted turbo (STS style) to feed the stock supercharger system. I imagine that making 300 rwhp could be accomplished with not much more done to the motor than larger fuel injectors and a bigger IC. Getting the compressed air up to the supercharger will be the difficult part.

David
 
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SteeleSC

Registered User
Twincharged SC

Hey, My name is Daniel. I've been a proud owner of my 92 for years now and btw im 17
I have some big plans for my sc and I was wondering what you guys think. I'm planning on twin charging my sc in the future but I was wondering what you guys think, and some things I should think about.

Current mods:
10% overdrive pulley
stage 2 cam
matched port and polished heads
cold air intake
no cats/2.5 in. exhaust pipe/ flow master
stage 2 clutch
3200lb pressure plate
t56 tranny (97 Selene mustang 6 speed)
limited slip 2:1 differential
100hp shot of nos (wet kit)

what I was planning was mounting the turbo in the back like mid way theres room to mount next to the tranny and run a pipe off the air intake after the MAF sensor to the turbo , use the exhaust on the way back to the engine as the intercooler for the turbo. reroute the supercharger boost pipe to follow down over the air intake pipe. get an aftermarket intercooler, then a Y pipe to hook the turbo and the supercharger into the ic. put a butterfly valve or what ever its called before each pipe hooks into the Y pipe. then a blow off on the supercharger pipe for when the turbo out boost the supercharger and the door closes it can just blow off. I know I will probably have to rebuild the bottom end.

My questions are:
how much boost should I push (turbo)
what kind of turbo?
bottom end rebuild tips and upgrades?
-pistons
-arms
-crank
fuel system upgrades?

anything else im not thinking of?

thank you so much for your help and input, I wanna try to cover anything possible so I can start compiling a list of parts to buy. I can do the pipe work myself, and finally Ive researched other set-ups with the supercharger feeding into the intake side of the turbo but I can see that causing problems as it will pull more air than the sc can push. right?


Hello I am fairly new to SCCOA and I have a 1989 T-BIRD that was given to me by my father which he bought brand new in ‘89 I also bought a ‘93 T-Bird because I loved the ‘89 so much. I am just curious did you ever Twincharge your SC?
 
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