Combined Super / turbocharging?
Discussion
I'm pretty well versed with supercharging, and have made a good job of turbocharging my mini, but know the limitations with both systems.... Just like Lancia succeded in doing with the S4, i'm tempted to look into running both in a future project...
I've got a suitable turbocharger sized up, that will allow me shed loads of boost (20+) at high RPM, and have a suitable supercharger available to me aswell...
I'm having disagreements with myself as to how to do this however... My blower doesn't have a clutch incidentally.
So, do i run them sequentially, drawing air from the air filter, into the supercharger, then into the turbo inlet; The other way round; in parralell, or what??
I'm thinking of running them as per i first described, but using a 'butterfly' valve positioned between the supercharger outlet and turbo inlet, which can open, allowing the turbo to draw in more air from the air filter, and effectivly leaving the supercharger to continue spinning under little or no load...
What do you guys think?
BTW - i can find NO actual reference on the interweb of how Lancia actually achieved it on the S4...
Many thanks,
D
I've got a suitable turbocharger sized up, that will allow me shed loads of boost (20+) at high RPM, and have a suitable supercharger available to me aswell...
I'm having disagreements with myself as to how to do this however... My blower doesn't have a clutch incidentally.
So, do i run them sequentially, drawing air from the air filter, into the supercharger, then into the turbo inlet; The other way round; in parralell, or what??
I'm thinking of running them as per i first described, but using a 'butterfly' valve positioned between the supercharger outlet and turbo inlet, which can open, allowing the turbo to draw in more air from the air filter, and effectivly leaving the supercharger to continue spinning under little or no load...
What do you guys think?
BTW - i can find NO actual reference on the interweb of how Lancia actually achieved it on the S4...
Many thanks,
D
Its a good combination because the supercharger gives you instant boost while the turbo is more efficient for sustained power. But it's going to be bleeding complicated to plumb it all together, are you sure you've got enough space? Remember you'll need at least one stage of intercooling and probably two if you're aiming for very high boost.
If you're after maximum boost you want to run them in series rather than in parallel.
I assume your supercharger has little or no internal compression. I reckon you should aim to run the supercharger off load once the turbo is up to pressure, because the turbo will have much higher efficiency once it has crossed over. You'll also want to bypass the supercharger for part throttle work. You certainly don't want the turbo to pull from the supercharger otherwise it'll never flow more than the s/c flows.
There are several viable layouts but I reckon your best bet is along the following lines:
turbo -> intercooler -> carb -> supercharger -> intercooler -> throttle -> engine
I don't know how it was done on the Lancia but this general layout is the one Allard uses as his model for a hybrid turbo/supercharged system.
You would need a recirculating dump valve with an inlet just upstream of the throttle and an outlet upstream of the turbo. With this configuration you don't need a separate recirc valve for the supercharger, offload it will recirc via the dump valve.
Have you thought about how you're going to fuel this? You'll need to run the turbo dry but most superchargers prefer to be run wet. If you're thinking of running carbs, a blow-through carb between the turbo and supercharger would look quite good. If you're running FI then think about adding some upstream fuelling or water injection here instead.
I know this has been done before but not by anyone I've talked to, I'd be very interested in knowing how you get on if you do decide to go for it. It would be pretty wild, that's for sure!
If you're after maximum boost you want to run them in series rather than in parallel.
I assume your supercharger has little or no internal compression. I reckon you should aim to run the supercharger off load once the turbo is up to pressure, because the turbo will have much higher efficiency once it has crossed over. You'll also want to bypass the supercharger for part throttle work. You certainly don't want the turbo to pull from the supercharger otherwise it'll never flow more than the s/c flows.
There are several viable layouts but I reckon your best bet is along the following lines:
turbo -> intercooler -> carb -> supercharger -> intercooler -> throttle -> engine
I don't know how it was done on the Lancia but this general layout is the one Allard uses as his model for a hybrid turbo/supercharged system.
You would need a recirculating dump valve with an inlet just upstream of the throttle and an outlet upstream of the turbo. With this configuration you don't need a separate recirc valve for the supercharger, offload it will recirc via the dump valve.
Have you thought about how you're going to fuel this? You'll need to run the turbo dry but most superchargers prefer to be run wet. If you're thinking of running carbs, a blow-through carb between the turbo and supercharger would look quite good. If you're running FI then think about adding some upstream fuelling or water injection here instead.
I know this has been done before but not by anyone I've talked to, I'd be very interested in knowing how you get on if you do decide to go for it. It would be pretty wild, that's for sure!
. 
A lot of complexity for what ??? A well sized modern turbocharger should be able to satisfy most demands.
What size of engine are you using, and what sort of power do you want ?? What will it be used for ??
Either that, or just a supercharger. They may sap a lot of power, but modern centrifugal types are reasonably efficient.
Only real beneifit I could see for using both, would be on a very small engine in a heavy car.
What size of engine are you using, and what sort of power do you want ?? What will it be used for ??
Either that, or just a supercharger. They may sap a lot of power, but modern centrifugal types are reasonably efficient.
Only real beneifit I could see for using both, would be on a very small engine in a heavy car.
Your not a real PH'r unless you do!I remember an article in CCC a few months before its final demise, on a Mk1 Fiesta which had been turbocharged, supercharged AND Nitroused. If I rememeber rightly it was based around an RS turbo lump. I think it was done by one of the guys from an Uxbridge tuning firm, though I can't remember the company's name I'm afraid.
If anyone's really interested, I could try and dig out the article and email the scans of it to them at the weekend. Assuming I can find it of course...
Tom
If anyone's really interested, I could try and dig out the article and email the scans of it to them at the weekend. Assuming I can find it of course...
Tom
I noticed whilst playing Gran Turismo 2 that there is a Japanese-only Nissan Micra model called the "Super Turbo", which as you may have guessed used both a supercharger and a turbocharger.
By the power of Google, here is a link and here is a discussion on the subject
By the power of Google, here is a link and here is a discussion on the subject
Hi Guys,
Thanks for the suggestions thus far.
I would be using an Eaton M45 and a 0.63A/R turbine T25 series turbocharger for making high boost.
oh, it'll be on an A-Series circa 1300cc
I know about bypassing for part throttle, but this is not totally neccesary on a racer i understand - only for economy during cruising.
The Eaton is about as efficient a blower you can get, but the efficiencies drop of greatly under higher boost conditions... Certainly, these run 'dry' as they use their own lube system.
I now remember seeing that Mk2 Tina with the twin T2's and the Eaton M112 at York a good few times, but thanks to those twats at IPC media, i never recieved that issue with the fiesta Supersport with the combined induction layout..
I will be doing all this on a budget, probably blowing through a HIF but that's not to say i won't use what is right, or be in a quandry deciding which colour silicon hose to use!!!! Certainly, i will be using boost retard of some kind, probably the system my mate is nearly finishing developing... This will also have 'triggers' for RPM or boost, so i can use these for actuating things as required.
Guess i need to do some more searching, maybe try and track down the Cortina and fiesta owners...
This is still very much 'in the air' as i need to re-assemble my current mini engine (excessive piston blow-by) and finish my other project, but you can't rush these things!!!
(if you're interested, check my link of my existing mini(S) in my profile)
Cheers fellas!
D
Thanks for the suggestions thus far.
I would be using an Eaton M45 and a 0.63A/R turbine T25 series turbocharger for making high boost.
oh, it'll be on an A-Series circa 1300cc
I know about bypassing for part throttle, but this is not totally neccesary on a racer i understand - only for economy during cruising.
The Eaton is about as efficient a blower you can get, but the efficiencies drop of greatly under higher boost conditions... Certainly, these run 'dry' as they use their own lube system.
I now remember seeing that Mk2 Tina with the twin T2's and the Eaton M112 at York a good few times, but thanks to those twats at IPC media, i never recieved that issue with the fiesta Supersport with the combined induction layout..
I will be doing all this on a budget, probably blowing through a HIF but that's not to say i won't use what is right, or be in a quandry deciding which colour silicon hose to use!!!! Certainly, i will be using boost retard of some kind, probably the system my mate is nearly finishing developing... This will also have 'triggers' for RPM or boost, so i can use these for actuating things as required.
Guess i need to do some more searching, maybe try and track down the Cortina and fiesta owners...
This is still very much 'in the air' as i need to re-assemble my current mini engine (excessive piston blow-by) and finish my other project, but you can't rush these things!!!
(if you're interested, check my link of my existing mini(S) in my profile)
Cheers fellas!
D
If considering such a thing on a mini, unless its a lightweight, im not sure where you are going to find a box strong enough to take it.
I have a turbocharged mini, and it is a bit laggy. It makes good useable power from around 3500-7500rpm though. Even off boost it is very torquey. I have also broke a couple of sets of Tran-X gears. Casings also crack quite often, although it hasnt led to breakage yet.
I would imagine that the low down torque the supercharger would add, would only make gearbox problems even worse, not to mention traction problems.
Mine suffers very bad wheelspin til around 80mph, not to mention the torque steer :O
I havent drove it in years though. I wised up when I drove a decent car and realised minis were in fact crap.
Mine is using an ancient Garret turbo, but with a modern ballbearing turbo, Im sure it would make a lot more power, with a lot less lag.
Fair enough you may be doing it, just because you can or want to, but I doubt there is any need.
Im also still using in SU, but if I was doing it all over again, Id use mappable fuel injection/ignition. DTA is my preference.
I have a turbocharged mini, and it is a bit laggy. It makes good useable power from around 3500-7500rpm though. Even off boost it is very torquey. I have also broke a couple of sets of Tran-X gears. Casings also crack quite often, although it hasnt led to breakage yet.
I would imagine that the low down torque the supercharger would add, would only make gearbox problems even worse, not to mention traction problems.
Mine suffers very bad wheelspin til around 80mph, not to mention the torque steer :O
I havent drove it in years though. I wised up when I drove a decent car and realised minis were in fact crap.
Mine is using an ancient Garret turbo, but with a modern ballbearing turbo, Im sure it would make a lot more power, with a lot less lag.
Fair enough you may be doing it, just because you can or want to, but I doubt there is any need.
Im also still using in SU, but if I was doing it all over again, Id use mappable fuel injection/ignition. DTA is my preference.
The Eaton is pretty efficient compared to other Rootes blowers but it still doesn't have any internal compression so the more boost you run the worst it compares against the later blowers that do have compression. This is going to be a problem if you want to run high boost, but would probably be OK up to 7 PSI just to fill in.
The recirc isn't just for economy, these blowers don't like pumping vacuum, the recirc stops the rotor heating up while you're off load and also stops it stripping the coating off the rotor. This means you can run it on load harder for longer before you get heat buildup problems. If you run a recirc valve with upstream fuelling you can get enough evaporative cooling to take the whole thing well below ambiant which equates to more power when you come on boost, I've seen an SU/M90 combination which had ice round the manifold at tickover on a hot day. Upstream fuelling also helps seal the rotors at low RPM. Since you'll need a dump valve to protect the turbo and you can use this as a recirc valve too, I'd take it for granted and move on.
I guess you're doing this because you want to not because it makes sense, but I can't help thinking its a bit of a shame to put all this effort into such a small engine. Putting a bigger engine in would be a heck of a lot of work but probably easier than the super-turbo project. Mini V8 sir? That should easily put out more torque than your Mini can use. Put your hybrid system on a bigger engine and it gets a lot more interesting ...
Incidentally if you're feeling adventurous and into turbos, have you considered copying Nick Mann's hyperbar system? Fit the biggest turbo you can lay your hands on, put a burner downstream of the dump valve, feed the burner exhaust back into the exhaust manifold and you have a closed loop 'jet engine' system that will keep the inlet manifold pressure as high as you like. Sounds like a good way to blow up the engine, but it sure would make an interesting project!
The recirc isn't just for economy, these blowers don't like pumping vacuum, the recirc stops the rotor heating up while you're off load and also stops it stripping the coating off the rotor. This means you can run it on load harder for longer before you get heat buildup problems. If you run a recirc valve with upstream fuelling you can get enough evaporative cooling to take the whole thing well below ambiant which equates to more power when you come on boost, I've seen an SU/M90 combination which had ice round the manifold at tickover on a hot day. Upstream fuelling also helps seal the rotors at low RPM. Since you'll need a dump valve to protect the turbo and you can use this as a recirc valve too, I'd take it for granted and move on.
I guess you're doing this because you want to not because it makes sense, but I can't help thinking its a bit of a shame to put all this effort into such a small engine. Putting a bigger engine in would be a heck of a lot of work but probably easier than the super-turbo project. Mini V8 sir? That should easily put out more torque than your Mini can use. Put your hybrid system on a bigger engine and it gets a lot more interesting ...
Incidentally if you're feeling adventurous and into turbos, have you considered copying Nick Mann's hyperbar system? Fit the biggest turbo you can lay your hands on, put a burner downstream of the dump valve, feed the burner exhaust back into the exhaust manifold and you have a closed loop 'jet engine' system that will keep the inlet manifold pressure as high as you like. Sounds like a good way to blow up the engine, but it sure would make an interesting project!
GreenV8S said:
Incidentally if you're feeling adventurous and into turbos, have you considered copying Nick Mann's hyperbar system? Fit the biggest turbo you can lay your hands on, put a burner downstream of the dump valve, feed the burner exhaust back into the exhaust manifold and you have a closed loop 'jet engine' system that will keep the inlet manifold pressure as high as you like. Sounds like a good way to blow up the engine, but it sure would make an interesting project!
Is that similar to the anti-lag system used in WRC, or have I got the wrong end of the stick?
I think the anti-lag system is just something that injects fuel into the exhaust manifold so it burns and spins the turbo up. The hyperbar system is very different. In effect it converts the turbo into a simple form of jet engine, and force-feeds the engine from the excess pressurised air this generates. Quite ingenious when you get your head around it. The turbo runs on boost continuously. When the engine is on full power the turbo feeds fresh air to the engine and takes exhaust back from the engine. When the engine is idling the turbo feeds the burner and takes exhaust from the burner.
It's one of those things you see round the outside of a jet engine. Basically a chamber with pressurized air fed in one end, fuel injected into the middle (with sort of igniter to fire it up) and hot exhaust escaping out the far end. No moving parts, basically just a chamber with burning gas in it.
There are number of ways to use afterburn to reduce lag IIRC.
Though all are reasonably effective, there are drawbacks. The main one is that of turbo life, because mosy afterburn systems are very agressive, they put a lot of heat and stress into the turbo. For a race engine this isnt as much of a concern, but for a road car, that has to hold together for a reasonable milage, they are not really an effective solution.
One system which Is much better for road cars, is far more passive. I uses a secondary, soft rev limiter, that only kicks in when the clutch is depressed. therefore you do full throttle gearchanges, and the soft limiter holds the revs down for you.
This stops the engine grenading as the soft limiter is generally set lower than the hard one. this soft limiter, holds the revs by cutting the spark one cylinder at a time. This allows unburnt fuel to flow into the exhaust and burn, but because it is very late in the stroke the temperatures are far lower.
In addition, when using this method, the throttle is held open, thus keeping the flow of gasses through the turbo and not letting it back up and stall.
A combined turbo/supercharger installation would be very interesting to see. I can see that it would not be easy, but if it was, what would be the point
Though all are reasonably effective, there are drawbacks. The main one is that of turbo life, because mosy afterburn systems are very agressive, they put a lot of heat and stress into the turbo. For a race engine this isnt as much of a concern, but for a road car, that has to hold together for a reasonable milage, they are not really an effective solution.
One system which Is much better for road cars, is far more passive. I uses a secondary, soft rev limiter, that only kicks in when the clutch is depressed. therefore you do full throttle gearchanges, and the soft limiter holds the revs down for you.
This stops the engine grenading as the soft limiter is generally set lower than the hard one. this soft limiter, holds the revs by cutting the spark one cylinder at a time. This allows unburnt fuel to flow into the exhaust and burn, but because it is very late in the stroke the temperatures are far lower.
In addition, when using this method, the throttle is held open, thus keeping the flow of gasses through the turbo and not letting it back up and stall.
A combined turbo/supercharger installation would be very interesting to see. I can see that it would not be easy, but if it was, what would be the point
Stevie,
Been there done that on the EFI front, and my experiences are sore...
I've had a major falling out with DTA over it - put simply NO ecu (ok ONE specially developed by MBE and released last month) can properly fuel inject an A-series (siamese port) engine.
Check out the link in my profile for my mini spec, i've used WEBCON and DTA, but neither fuelled the engine well enough to make as much power as when the SU was substituted, both on a roling road and on the qtr mile...
Gearboxes aren't a serious problem either in my opinion - so long as you build them right - sure they are weak, but the reduced life is acceptable for me.
Wheelspin / torque steer is easilly overcome if you use wheels with sensible offsets, keep the driveshafts pretty near level, and keep tabs on the corner weights.
I appreciate Ballrace bearings, but there isn't one 'off the shelf' for smaller engines (with the exception of skyline R32 i think? - try finding one of them!), and i nearly fell over when i was given quotes form specialists about building me one to suit...
It's kinda taking away from what i want to achieve with this project.
Any more info on the theory behind this mucho appreciated.
Been there done that on the EFI front, and my experiences are sore...
I've had a major falling out with DTA over it - put simply NO ecu (ok ONE specially developed by MBE and released last month) can properly fuel inject an A-series (siamese port) engine.
Check out the link in my profile for my mini spec, i've used WEBCON and DTA, but neither fuelled the engine well enough to make as much power as when the SU was substituted, both on a roling road and on the qtr mile...
Gearboxes aren't a serious problem either in my opinion - so long as you build them right - sure they are weak, but the reduced life is acceptable for me.
Wheelspin / torque steer is easilly overcome if you use wheels with sensible offsets, keep the driveshafts pretty near level, and keep tabs on the corner weights.
I appreciate Ballrace bearings, but there isn't one 'off the shelf' for smaller engines (with the exception of skyline R32 i think? - try finding one of them!), and i nearly fell over when i was given quotes form specialists about building me one to suit...
It's kinda taking away from what i want to achieve with this project.
Any more info on the theory behind this mucho appreciated.
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