Rail Head

Just wondering if any one ever considered or tried a set-up with supercharger for low end and turbo for high end. Seems to me that the biggest problem with the FD's is still a lack of low end torque.

Wouldn't a supercharger help the low end launch and if switched over effectively to turbo on high end not rob any of the ultimate horse power.

Just food for thought

jd93rx7

I remember someone explained why this would not work, if you search the forum you could probably find the answer.

Lost Time

Aside from it being terribly overcomplicated with all the plumbing and venting that would be necessary, why? I don't find a need to increase low-end torque that much.

GsrSol

For one, a supercharger makes the exhauset alot hotter and you will have that going through the turbo.

Malachi151

There are plenty of turbo setups that will give all the low end you want. Both fast spooling singles like the RX6, and advanced twin turbo setups that can hit full boost by 2,500 RPM.

Other then that, just keep the RPMs up

Rail Head

First of all what could be more complicated than a stock sequential turbo? Difference is apparently that there is no bolt on version of Supercharger/ turbo set-up. This thread was simply to see if it made sense or not. Seems like a single turbo is limited on the low end even if small compressor is used and the supercharger would be limited in usefulness on high end because you have to continue to use horsepower to create the additional horses.

GsrSol

What could explain superchared exhaust gas being hotter than turbo charged? The both burn the same compressed air.

Single7

Hi Rail Head,

Nothing is impossible. It just depends on the amount of time, money, and fabrication you are willing to invest into such a project.

HKS use to produce a twincharger kit for the MR2 (they also produced one for another Japan/European only car). It consisted of a turbo feeding into a supercharger. It was good for (If I remember correctly) somewhere along the lines of 300 horsepower. These are extremely rear and from the few sites that talk about them only a handful (less than 5) ever made it into the states. The Meguiar's Integra is outfitted with a one-off HKS twincharger kit. Others have attempted to do twincharger kits with different layouts (supercharger feeding into turbo).

The issue with running a s/c to t/c setup is if you run a supercharger into a turbo, the turbo may out spool the s/c when it goes into boost so you have to have somekind of one-way check valve between the s/c and t/c to open if there is a vacuum created between the two.

The issue with running a t/c to a s/c is when the turbo builds boost, is all the boost routed directly through a s/c. If so, the pressurized turbo air (very hot) is going to be recompressed through the s/c and dependent on the amount of boost, are the seals on the s/c going to be able to handle that large amount of boost. The MR2 kit had a race bypass valve that circumvented the s/c once the t/c began to build boost. In addition, they had their own device to disengage the s/c pulley (like an a/c pulley) when the turbo had fully spooled.

Other things come into play with the piping. Are you going to be running an intercooler between the t/c and s/c. Are you going to be running an intercooler after the s/c? Air to air? Air to water?

What type of s/c? Centrifugal - probably not --> takes time to build boost (like a t/c). Roots (i.e. Eaton) probably --> not very efficient but most common of positive displacement blowers. Screw type (i.e. Whipple or Autorotor) --> efficient but expensive. Screw type will build boost of idle.

How are you going to mount it? You can't mount it on the exhaust manifold side - not really enough space but it would heat up the the intake air too much. Take out the power steering and a/c? Well that gives you about 6 to 6.5 inches of play on that side. The closest one to that size is 7 inches wide on an Eaton M45 (one of the smallest they make). That just squeezing it in - not mounted yet. You can just invert it where the s/c sits on the opposite side of the motor and the pulley facing it - but you can decide how you want to mount it yourself .

What will you be using as fuel management? Haltec? Motec? Staged injection?

Well, enough stupid nonsense and ramble from an idiot -- Later Tommy

Snufelupogus

iTrader: (2)

Okay, Im curious aboot something.
Say there is a setup that goes from supercharger to turbocharger to intercooler. How would boost be calculated for that?
What I mean is, if the supercharger was by itself, at 4000rpm it puts out say 5psi and the turbo by itself at 4000rpm is putting out 4psi. Now if they were working in together how much boost would that create at that 4000rpm? Would you add it together to get 9psi? or would it remain at 5psi and the turbo would just act as an extremely fast fan and move the air to the intake faster?

Anyone understand that?

@4000rpm = Supercharger (5psi) + Turbocharger (4psi) =9psi

or

@4000rpm = Supercharger (5psi) + Turbocharger (acting as fan) = 5psi

Thanks guys

I Killed Tupac

the air would be too hot by the time it hit the t/c, the air would be extremely hot and might detonate even if ran through an intercooler.

psi is measured as the pressure of the intake manifold. I guess alot of it depends on how hot the air is when it enters the turbo.

jf4828

Snufelupogus, I think you are on a track, but this is how it would really work. You would still only hit 4psi in your scenario but it would produce it very quickly, but each would have less stress therefore allowing higher boost out of each(bigger compressor). Think of it like inflating your tire. If the pump only produces 32psi and your tire has 32 psi, no air will pass in either direction. So if you are pumping 4 psi into a system that is already @ 4psi, it will have no net effect. In a tc sc setup, it would increase efficiency and spool for the turbo tremendously. The thing you have to think about is the volume of air being moved. It works just like the twin turbo setup. The secondary kicks in because it is needed for the increase in CFM's. I think the setup would work well for the street if it could be made to work. I'd love to see the wastegate for this one I think that the idea is great but there are more hurdles then any single member should dare persue. Unless you have 100's of 1000's to blow...... I'd love to get a sponsorship to create something like this(hint hint)

jf4828

What are you talking about? I think he means that they would work somewhat independently and not in series. Sure they would feed into the same intake, but I don't understand why you think this would effect charge temperatures. He's not talking about running the supercharged air through the turbo charger.... Atleast I hope not The only way I think it could be done is have the two systems somewhat independent and feeding into the intake or intercooler. I think a one way valve would solve the cross pressure problems which would be rather simple.....

Snufelupogus

iTrader: (2)

First off Id like to state that I dont have a 3rd gen, I have a 2nd gen n/a but I posted in here because the topic was already brought up and didnt want to start another thread Im inventive

That out of the way, let me see if I understand this correctly...

Turbo (4psi) -> intercooler \
......................................\
.............................................-> intake (~4psi)
....................................../
Super (4psi) -> intercooler /

Is that what you were saying? That if they are working together to create that 4psi then there will be less strain on the components and obviously you would get a faster spool out of both (especially the turbo).
Wait... I just realized something. Where it goes into the intake you would have to create some kind of y-pipe to connect the two together, but while the turbo is spooling up and the super is already working, it would force air back through the turbos tube and lower the boost. right? hmmm I dunno

Anyways, what I was kinda askin is instead of running the super and turbo in parallel like above, what if run in series? I understand that it will be really hot, Im not wondering aboot that, I can take care of that.

Fresh air --------------------valve
............................................\
Fresh air -> Super -> intercooler -> turbo -> aftercooler -> intake

Now the reason I put fresh air going to the turbo as well as the super is because the super I want to use has an electric clutch on it, so is will be able to be engaged via a switch in the kakpit. The valve will be controlled by pressure... once the super is running it will create pressure on that side of the valve forcing it closed, when the super isnt running air will still be able to flow through it, just without any pressure (it would act as a normal intake). So when the super is off it would allow fresh air to enter on both sides of the valve feeding the turbo. This would happen during normal driving conditions (ie: cruising, bootin around town) and once a certain rpm is reached where the super will be restrictin the cfm that the engine is getting.

So it would work like this: at a stop, you turn the super on. being a roots type super it would give a couple psi of boost off idle closing the valve almost imediently. you get on the gas. at ~2-2500rpm the super is at full boost (remains this way until it drops below 2000rpms again). this allows the turbo to spool without any trouble. from ~3-5000rpm (or something like that) both super and turbo will be working together creating max boost (lets say 8.5psi). at ~5-6000rpm the super will disengage so that it doesnt restrict the flow for the turbo. being no pressure from the super, the valve will then open to allow air flow from both sides (fresh air + fresh air thats flowing through a non working super). the turbo being at full boost will then take over and carry you all the way to redline.
As a safety, once the super is disengaged via high rpm, it must be re-engaged manually via the switch so that it doesnt distory the internals of the super if it engages at like 5000rpm.

How does that sound? Im sure I have forgot something or whatever, so lemme have it

$150FC

Turbo (4psi) -> intercooler \
......................................\
.............................................-> intake (~8psi)
....................................../
Super (4psi) -> intercooler /

That's the way it works. And someone asked if it would "act as 8psi, or just push the air into the intake really fast"...well, that's the same thing, when you think about it. If I put a 50 lb weight on a scale, and then put another 50 lb weight on the scale, it makes 100 lbs. That's an odd analogy, but it's the same principle.

jf4828

Fellas, open a physics book.... If something is going to produce 4psi max, it wont make 8 just because there are 2 sources. If you had a tire w/ 2 valve stems and a pump(superchargers and turbos are pumps btw) on each valve stem creating 32 psi, the pressure in the tire is still 32 psi. I don't care if you have 50 valve stems @ 32 psi, it is still 32 psi. Pressure and weight are 2 different ball games because the pressure of the first charged air is pushing against the new source. If you were pushing 4psi into a system that is 4psi already the air will remain stagnant(macroscopicaly). As far as the series idea goes, I'm not too sure it is necessary? A twin turbo is engineered to work sequentially but not in series. They both draw from their own air source and do not transfer compressed air to be recompressed for a few good reasons #1 being complexity. The principal is pretty simple in my eyes. Two systems that are seperate up to the point of intake. To keep supercharged air out of the turbo, it simply takes a 1 way valve that will not allow backflow of air into the turbo. The same type of valve would be required to keep turbo air out of the outflowed supercharger after transition. These one way valves are very common and very simple in engineering principle. I see how the series system would work, but it seems to complicate things too much. The ultimate goal is to pressurize the intake. So @ 2.5 or 3 K kill the supercharger w/a clutch and start bringing in turbo air. Of course you would have to phase out the supercharger and phase in the turbo for a smooth transition. I think it could be relatively simple as long as you can figure out the fuel maps as charge temps will vary alot based on RPM. Each unit can produce more boost independently than most people want so I don't see a need for series on a rotary... Prespooling a large turbo sounds like a hell of a good idea. Power below 2k sounds like a damn good idea too Can't wait till someone puts this on a 7!

Snufelupogus

iTrader: (2)

I dropped outa physics! lol
But yeah I understand what your saying now.

Yeah I was just brainstormin... yah know how it goes
The super I was lookin to use (and probably will end up putting on my car) is the sc14. Its a larger version of the sc12 which is found on the MKI MR2's.
Some specs of the sc12: This super is capable of putting out a safe 14psi on the MR2 with an ungraded crank pully (bigger pully), its a roots type super which means that off idle you will have ~2psi because it will be already forcing air into the engine on idle, it has an electronic clutch controlled by sensors, it flows enough air to satify the 1.6L engine in the MR2 all the way up to its 7500rpm redline, the engine flows 250cfms (I think). The sc14 is larger (the 12 and 14 stand for 1.2L and 1.4L of something) and will flow more than the sc12. sc14 comes off of a 2.0L 6cyl or something like that.

Now, if you just bolt the sc12 to our engine, the boost level would be very low (probably peakin at 4psi or something like that) due to the fact that our main pully is ~20mm smaller than the MR2's, it is possible that it could be driven off of say the p/s or a/c pully? which is far bigger than our main pully which might solve that boost problem. Another thing to solve that would be to make the pully on the s/c smaller (j-spec models have smaller pullies). Some of the guys on the MR2 forum have hooked up switches to their super so that they can turn it on and off whenever they want, so that is not a problem. What would be a bit more tricky would be to have the supers clutch disengage at a certain rpm and then remain off. I guess that wouldnt be too hard if you know electronics and such

Okay, now if we have the turbo and super always feeding off their own source of air, I have another question. With the one way valve in place stopping the turbos compressed air from entering while the super is boosting, what happens to the turbocharged air? BOV? The turbocharged air is being released at such a rate that it holds its pressure but doesnt fill the piping and cause it to backdraft. hmmm...

Okay, so we sittin at a light. flick the switch. super comes on and creates a boost of ~2psi off idle. as rpms rise so does the boost from the super as well as the boost from the turbo. the super reaches its max boost at lets say ~8psi. at this point the turbo has yet to reach this psi so the pressure is still rising in the piping after the turbo and is slowly vented through some type of BOV but not enough to drop the pressure. once the turbo has reached its ~8psi the BOV closes, this valve switches to block off the air from the super (car might jump or bog for a half sec at this point, not sure), then the air from the super disengages and is discharged and the turbo takes over all the way up to redline.
Sound good?

Well Im tired... I'll ponder more at work tomorrow

TriTurboGen3 RX-7

Wow, i jus had to say you ppl saying enough rabling and nonsense i just learned a hell of alot from what u just siad

Snufelupogus

iTrader: (2)

Geez... I dont think Ive ever writen so much in my life...

Blue Goose

That's 1.2L and 1.4L of positive displacement per full rotation of said blower. Most roots type blowers are rated this way (powerdyne 144, etc...) except the wieand 6-71 and 8-71, originally intended for diesel motors (6cyl or 8cyl, each cyl has 71 ci displacement)

spyfish007

Well you really want to learn about this kind of stuff ... well learn about pressure ratios .... Here is an example ... turbo #1 makes 14.7 psi boost and turbo #2 makes 14.7 psi of boost. Well the pressure ratio would of each turbo would be (14.7 + 14.7)/14.7 = 2.0

-> (boost + atm)/atm = pressure ratio

Well if you plumb the turbos correctly ... I'll leave that part out but here is a hint .. go talk to some tractor pullers! .... then pressure ratio #1 * #2 = 2.0 * 2.0 = 4.0 .... well to calculate the actual boost put that number in the above formula and work it backwords ...

(boost+14.7)/14.7 = 4.0 ... so boost = 44.1 psi of boost!!!

Well now we can talk about some of the problems on a rotary. One is being sure your apex seals can handle this amount of boost ... which was created from two turbos making 14.7 psi each and the second problem in the intake temp increasing too high which is definately not good for a rotary. One final thought ... the term intercooler actually comes from cooling between the turbos-what most people run on their cars is an aftercooler because it is after the turbos.

Just to note the above example could make up to 9 psi of boost IF the sizing of each unit was proper and the sizing of this setup is really what makes it go. Once again go find a tractor puller and hope he will tell you how--that is if he even has it working to its potential. Some of the so called experts out there are even way out there.

Oh yeah, one final comment. I do think it could be done and done well. The most practical application would be drag racing. Keep thinking and don't let others get you down.

jf4828

The 1 way valve idea is to keep the pressurized air from backflowing into the turbo. Once turbo pressure is @ supercharger pressure the one way valve will begin to open on its own. The valve does not even have to be spring loaded because it needs to open once pressure in the turbo reaches the level that is in the plenium. Start to bleed off super pressure through a waste gate and the turbo valve opens all the way and the supercharger valve closes. The simplicity of this type of system is sounding nicer every minute. The tricky part is setting up the wastegates so that the right amount of pressure is constantly maintained. I think a smooth transition is possible but only if you are looking @ serious waste management. The one way valve will only open in each case if the plenium pressure is less then the pressure behind the turbocharger or supercharger thus eliminating backflow. Since the supercharger provides instant(close enough) boost, it will take a few k for turbo to reach supercharger psi. When that happens, the valve simply opens and you can start to shut down the supercharger by bleeding off pressure and ultimately disengaging before it reaches high rpms. Gotta love dreamin? Hey Snuf, I saw a second gen w/ a supercharger in my area. It is an older gentleman and loves it for the daily driveability... Maybe us 3G's would last more then 30k/clutch if we didn't have to launch @ higher rpms?

jf4828

Are you talking about using nozzels to increase the pressure based on moving more volume of air? I understand what a pressure ratio is as it relates to hydraulics and to my understanding this requires the use of a nozzel. In form you can raise the pressure if you decrease the volume of air you are pushing. I'd love to read more on this as it relates to turbo systems and I'd love to understand exactly what you mean? Any links? Thnx

Snufelupogus

iTrader: (2)

rrrrrriiiiiiiiiiight.... well I think this conversation has just reached the point where I need more education! lol

"Well you really want to learn about this kind of stuff ... well learn about pressure ratios .... Here is an example ... turbo #1 makes 14.7 psi boost and turbo #2 makes 14.7 psi of boost. Well the pressure ratio would of each turbo would be (14.7 + 14.7)/14.7 = 2.0

-> (boost + atm)/atm = pressure ratio

Well if you plumb the turbos correctly ... I'll leave that part out but here is a hint .. go talk to some tractor pullers! .... then pressure ratio #1 * #2 = 2.0 * 2.0 = 4.0 .... well to calculate the actual boost put that number in the above formula and work it backwords ...

(boost+14.7)/14.7 = 4.0 ... so boost = 44.1 psi of boost!!!"

My brain hurts now!

spyfish007

Well I just thought I would give you guys some stuff to learn. Do a search for staged turbos on the internet and see what you can find. There is no magic nozzles, solenoids, valves. It is all in the plumbing and sizing of the chargers. jf4828 you are almost on track when you say you decrease the volume when you raise the pressure .... just think about this a little bit differently. Remember staged turbos .. and it wouldn't hurt to look for diesel trucks.

jf4828

Thanks, i'm going to check it out No more winded postulations tonight cause im goin out partying! Don't worry, the rex stays homes for nights like these!

rpm_pwr

Nissan March Super Turbo - the only factory twin charged car ever AFAIK. 110HP - They were an absolute rocket The HKS Twin charger kits were rubbish. The only ones I've seen were near un-tuneable.

-pete
http://www.j-garage.com/nissan/march/2410.htm

Pretty isnt it