Gday guys I would like some opinions on a Twin Charging setup... I would like to iron out problems with the design before I undertake the conversion, to save time and money. The s/charger is a SC14 and the turbo is a T3. My goal is a tuff street car, rather than max power, more max torque and getting the thing up and going! That is why i would be sticking with the T3 unless ppl think a highflow is more suitable. If i was to do some dragging, i would be stoked with a 13! Looking into it, i cant see this setup costing much more than $1500 considering i am getting the full turbo conversion for $600. I expect piping to be the issue and the cost. Cheers guys. The engine is a series II na block which has recently been reconed, port and polished head, 'lumpy' cam, chipped computer, genie extractors and is manual. Any help, ideas, critisism is appreciated. Cheers Steve Some original photos have not been recovered yet.

Maybe use a cooler with twin intakes, instead of joining the piping from the s/c with the piping from the t3.

yeah thats a good idea! i take it a welding shop can just weld another pipe onto the end of the intercooler chamber hey... it should reduce the return of airflow back into the chargers on a sudden throttle close, to help the bov aswell.

It won't work like that. The supercharger will blow air backwards out through the turbo compressor, and you will never get any boost at all. The air path should go pod filter, turbo compressor, then into the supercharger inlet, then out through the intercooler. I am probably one of very few people that have actually built and run a twincharge setup, so I know a bit about it. To work properly the turbo and supercharger need to be in series not parallel. Do a search, there is already at least one thread on this subject, and several on supercharging.

to my understanding.... the super charger is used to spool the turbo quicker.?? there was a toyota engine that came like this standard... its a interesting concept..the would be some serious head ****s when building a engine like this!

There's no problem with doing this however.... Getting a custom exahust manifold like mine for your T03 would achieve the same result. You just want more power early, thats easy. You have over complicated it by using a blower IMO.

id say this setup wouldnt be very efficient?..theyd both be blowing at different rates (s/charge constantly), i just think stick with either turbo OR super/charger then again, i might be just a ****head Some original photos have not been recovered yet.

The Nissan March Super Turbo was the car that was factory released with both a Turbocharger and a Supercharger and funnily enough i actually saw one of these only a few days ago. From memory the little Nissan ran 0.8bar on the supercharger and 0.9 bar on the turbo. If you have a look at some pictures of the Bandag Bullet you will see how the setup of running both Chargers needs to work with the turbo feeding the supercharger. Depending upon pulley sizes etc for the supercharger and the capacity of it will depend on what boost it produces but somewhere around 5psi would give you a rather healthy base line with the Turbo's wastegate set to limit turbo boost at 10psi or so. Make sure that the wastegate is getting it's boost signal from after the supercharger. You may also want to consider running two intercoolers i.e. one after the Turbocharger and one after the Supercharger. Corsa

Yup Corsa is spot on. The Nissan March was a factory twin charge setup, and so was the Lancia Delta. These Lancia rally cars were a small hatchback 4Wd with 1.8 Litre twin-charged rear mounted engine. These were a factory production car with 450 Bhp. The rally cars made a whole lot more. Inefficient ??? Well yes if 500 Bhp+ from 1.8 litres with unbelievable midrange torque is inefficient. The Group 5 rally class was discontinued because too many people died in high speed crashes. Note that all these cars have the turbo blowing into the supercharger. My 4WD Laser was like that as well, used a T03 blowing into an SC14. So it definitely works. That Bandag truck has four turbos and two superchargers, and two engines joined together, an incredible piece of engineering.

cant u get a TRD turbo kit for the factory supercharged mr2?? or maybe its the other way around? how does this work?

i thort the way that the piping is shaped would stop air going back into the turbo. the design i used would have the scharger going all the time and the turbo would add boost to the existing scharger boost. I can see how corsa said the boost reading for the turbo should be taken after the scharger. However, if i turned the scharger off, wouldnt the boost from the turbo find it hard to get thru the scharger? say if i was cruising the highway, this may reduce fuel economy? so, the setup should be something more like this.... Some original photos have not been recovered yet.

haha no the piping shape would pretty well do jack all to stop it doing that. your first picture is wrong, your second one is the way it has to be done. there is also the possibility of having a pull-through system (blower upstream of turbo) but tony reckons the blow-through works better and i believe him. it just makes more sense. if you're running upwards of 15psi total pressure then you may just reach the limits of the blower, that's what i plan to run on my setup. also a highflow or T04 turbo would be a lot better, with the blower on you will probably see 10psi with a standard T3 at about 1500rpm i would imagine.

okay thanx stocky, my engine has been fully reconditioned and im pretty sure the standard pistons should handle it okay. I am more worried about the standard manual going though. I will put in a heavy duty clutch to handle the power for now. 10psi at 1500rpm is sweet! Thanx for everyones help!

Quote: Originally Posted by ATMO_BT1 cant u get a TRD turbo kit for the factory supercharged mr2?? or maybe its the other way around? how does this work? 3sgte.com or some other website i was reading one day had a really good thread on this i have seen this conversion , but unfortunately didnt have the chance to go in his car. another mate put a 3sgte into a toyota curran (import celica of sorts) , and last time i heard he was planning on going full gt4 all wheel drive setup and twin charging it too , dont think it happened yet

Hi Stocky, yeah with the blower working, there is a hell of a lot more exhaust flow, and the turbo really kicks in hard at much lower Rpm. You can use a MUCH larger turbo than you can possibly get away with with just a turbo by itself. I think a hi flow TO3 is going to be far too small, a mid sized TO4 more like it. The second sketch looks much better, but I would also fit a bypass system around the supercharger, exactly like the one Stocky has fitted to his car. If you are really serious about this, start of first fitting just the supercharger. There are quite a few interesting little problems getting that going, as Stocky will tell you ! Sort it all out, then fit the turbo as stage two of the project. Trust me, about 80% of the work is getting the supercharger mounted, and working up a reliable blower drive system. Adding a monster turbo is pretty easy in comparison, it just takes money.

lord knows, i can vouch for that! get the huffer mounted and driven first, then put your cooler on, then fit all the exhaust stuff (turbocharger etc.) there's not too much piping to change all at once that way. what sort of aftermarket engine management are you going to use? oh yeah and use a bypass system, it's well worth it!

thanks guys for the very helpful advise. I will fit the supercharger first and get it going and then install the turbo gear after that. I will be fitting vl turbo injectors and the vlt computer with the supercharger setup and carry it over to the turbo installation. i actually havent really thought about computers, perhaps a piggybacked ECU or a Link might do the trick?

Ah group B.......I like the Lancia 037 Rally, but that has more to do with the shape rather than technology..... As far as turbo + superchargeing goes, there are several problems you can run into and some extra bits you need to make it work: First, you'll need two throttlebodys, and a split induction tract. One throttlebody sits in the normal position behind the turbo (the blower sits infront of the turbocharger) and the other one sits between the superchargers outlet and the turbo chargers inlet, in a "T" pattern eg the throttlebody doesn't block off the air, it just opens the pipe up.....kind of like a large BOV. This throttlebody is controlled by a Soleniod eg a electronic boot release soleniod found on GM cars, and has only 2 positions, on and off. You accelerator pedal is hooked up to the throttlebody behind the turbo and the second throttlebody is hooked up to a RPM trigger.... You also need a electronic device to "switch off" the supercharger and re-engage it a diffrent RPM. The superchargers I normally play around with are a Toyota SC14, which comes with a electronic clutch like a aircon comporessor. So in english, what this does is from idle to about 4000rpm the blower is on, when the RPM gets to above 4000rpm, a RPM trigger module turns the blower "off", and opens the throttlebody that sits between the blower and the turbo chargers inlet.... The problem in theroy this will only work at WOT (Wide open throttle) The main problem with a twin charged engine is the "supercharger-to-turbo" cross over point. Get it wrong and you have a boost dip, or a boost spike. A spike would double the boost (no good, goodbye pistons) a dip would create a flat spot in your power graph (not as bad) Then you have the same problem comeing down in RPM, you take your foot off the throttle and the BOV vents the air from the turbo, and then your RPM drops bellow 4000rpm and the blower turns on......uh oh.... Still the other thing is, how do the SC14's like getting the clutch activated when the motor is spinning @ 4000rpm? I haven't had my blower on my car for a while (long story), stocky could you please tell me if you've done this? This is the only way I could think that it would work....Warpspeed what do you think of this? like so....Sorry couln't help myself on the holden bit Some original photos have not been recovered yet.

no no, people have a big misconception about this. twin charging COULD be done that way, but 5hit it'd be complicated and i don't think it would work very well. the best way (that i can see) of doing it is in a blow-through setup like pictured above. when you put your foot down, the blower instantly (roots type remember) gives say 4 psi to the engine. this VASTLY increases low-end torque and "off boost" response. the car will not act like a conventional turbocharged car and have lag in the bottom end. instead, the boost being provided by the blower will create a lot more exhaust gas than would usually be supplied to the turbo at this rpm. this means your turbo will spool very quickly, much more quickly than usual. hence a bigger exhaust housing can be run, which means higher peak power. having induction pressure > exhaust back pressure also means a safer running engine, far further from the detonation threshold. the more "pure" cylinder charge will mean more power as well. then we get to the turbo end of things. it feeds into the inlet of the blower, and contributes to total boost pressure. say the blower boosts 4 psi, your turbo might only be producing 11psi but total pressure is 15 psi on full song. interestingly, the blower becomes MORE efficient when its inlet pressure is greater than atmospheric. total pressure increase across the blower will actually be greater the more boost your turbo pushes into it. a good aftercooler downstream of the blower completes the system. there's no funky throttle body setups, no on/off clutch electronics and you can still run a good bypass system to unload the blower. your turbo will spool early, and make huge power. the limits of the SC-14 may be reached if you push lots of boost into it at high rpm, but hey at $250 a go they're not as expensive as a turbo rebuild. oh and here's an extract of a pm i sent regarding the bypass system if anyone is interested. Quote: the bypass system is used to vent air around the blower (thus unloading it completely) at idle and light throttle openings. you will need an external turbo wastegate (i use a 32mm garrett item, but the bigger the better!) and whoever does your piping will make a flange/pipe attachment to the piping somewhere before the throttle body. the premise behind it is that a wastegate has 2 fittings, on either side of a diaphragm which "see" different pressures and thus act on the diaphragm. the diaphragm (and hence poppet valve which normally opens at a certain boost level and vents exhaust gasses) has a fitting above and below it, on the "cold" and "hot" sides of the wastegate respectively. the cold side is connected to your plenum (i use the brake booster line) and "sees" the pressure changes AFTER the throttle body. the hot side is connected to the intake piping after the blower, but before the throttle body. thus, it only ever sees atmospheric or above (boost) pressure. the idea is that the gate sees the pressure drop across the throttle body. now at idle, plenum vacuum sucks hard against the diaphragm and pulls the poppet valve open. this allows air to freely circulate out the open gate, the blower runs cooler and draws almost no power from the engine. when you close the throttle fully, plenum pressure = intake pressure, and the only thing acting at the wastegate is the internal spring, which holds the poppet valve closed hard. thus, you get full upstream boost. at any throttle openings between these two, the gate progressively closes and is fully proportional to your throttle opening. if you get your spring rate (stiffness) just right then you can cruise around all day without ever seeing upstream boost, but as soon as you put that foot down it's all there. mine is set up so that positive pressure is seen at about 3/4 throttle opening. i would suggest (if you have an intercooler) to position the wastegate upstream of the intercooler, this will keep air circulating through it at idle (may keep it cooler a bit) and will eliminate the SC-14's growly note. the closer the gate is to the blower, the more blower noise you will hear out through it. another option is to plumb the gate's outlet back into the blower inlet (or turbo inlet if it's twin charged) to reduce the noise. hope that helps, -Neill nizmodore: the clutch was used on the MR2's in an electronically controlled setup, at WOT they would engage and would turn back off when you backed off the throttle. i have engaged mine at 3000+rpm a few times in first gear just to see what it felt like going from atmo to full boost in a heartbeat. the car immediately broke traction the power hit was that sudden. the clutch doesn't seem to mind it too much, it's just metal on metal (if you've ever pulled one apart) and doesn't seem to wear too much. /end post. that was huge.

Quote: Originally Posted by StockyMcStock nizmodore: the clutch was used on the MR2's in an electronically controlled setup, at WOT they would engage and would turn back off when you backed off the throttle. i have engaged mine at 3000+rpm a few times in first gear just to see what it felt like going from atmo to full boost in a heartbeat. the car immediately broke traction the power hit was that sudden. the clutch doesn't seem to mind it too much, it's just metal on metal (if you've ever pulled one apart) and doesn't seem to wear too much. Yeah thats how I should have done it when I had the blower in my VL, the Blower activated through the TPS via relay...oh well...... I had a rather nasty crash, which ment the blower had to be taken off (I was sitting at the lights and got rear ended...really!) So almost a year later I'm back with a twin cam blown 3L this time.......(well If I finish it)