Have a look at Gale Banks "monster truck duramax" If you feed the supercharger with pressurised air, it will take more power to compress the air again after the supercharger. Gale proved that because his engine kept producing more power when he kept turning the supercharger down (using bigger pulleys) He did a Freightliner truck with a turbo and a supercharger and he had the supercharger premenantly feeding the turbo. You'll find that as the turbo starts sucking behind the supercharger and the supercharger makes less boost but flows more air, it will reduce the parasitic loss from the supercharger. Also, if you are going to permanently feed the turbo with the supercharger then you'd be just as well to intercooler between them as well as after them.
twinchanged 606 build? Reminiscent of Blacksmoke's OG w123 back in 2011 but seriously, the community can benefit from learning about this approach. Thanks for sharing the fabrication methodology.
Check out Richard Holdeners recent test on the AMR500 supercharger. He has it bolted to an LS and ran it venting to atmosphere (to measure total CFM), and also with a restrictor to see how much cfm it flowed while actually compressing air. He shows both dyno graphs of the engine to show JUST the difference in parasitic loss of a loaded vs. unloaded supercharger. Difference was surprisingly minimal. I know it doesn't cover your exact situation but has some relevance.
Thats an irrelevantly small supercharger on an enormous engine. That supercharger is probably suitably sized for a 1.0-1.4L engine that makes well under 100hp as standard...
Just doing some back of the envelope stuff here. Work=horsepower=force•displacement(distance not volume). Think the force required to spin the belt half a turn. Pressure=force/area. The volume that the supercharger moves is fixed per revolution as is the surface area of the screws that encounter the resistance to compression, but what isn't fixed is the pressure. The resistance to rotation/losses in the supercharger all the physical losses: bearings, intertia, belt deformation, noise, heat... those are all fairly constant. The largest resistance is compressing the air. Since the volume pumped by the supercharger is constant per rotation, if you have more pressure on the inlet side it's going to take more force to spin. It will however increase the pressure. That said, more pressure isn't always better, you want more density. Anyway, my speculation is it will be harder to spin with the turbo feeding it. Which should make sense if you consider compressing a piston in cylinder pressurized to 1 bar vs 2 bar. More pressure, harder to compress, more work because you have to move more particles.
You can set it up like Gale Banks did the Freightliner build, that was a super - turbo! Power to drive the supercharger is based on pressure ratio and inlet pressure, there is a formula somewhere. Also the power difference between gasoline and diesel on the same turbo is due to the air fuel ratio of diesel vs gasoline, diesel needs more air for the same volume of fuel.
Lovely to see Luke and Mrs Luke working well together, so rare. Engineering excellence as usual, I love the research and thinking aspects. This is how all cars should be made - from an engineering perspective and not the rapacious accountants. 👍👍👍
The blower is a fixed displacement pump. The work required to compress a quasi static ideal gas is the integral p.dV. Since the blower ratio is effectively constant regardless of incoming air density, gamma doesnt change (air is air), the change in pressure across the roots will be greater if fed with higher pressure air. Therefore, More Work is required (and more belt torque.). Ways around this would be a clutch on the blower or a diverter (blowoff) valve to bypass the roots when the turbocharger is spooled up. In industrial and aero twin-charging systems, it is common to turbo into blower. Interstage and Post coolers are common. Remember that the pressure ratios of the two multiple, not add! There is a good thread on eng-tips about twincharging (user warpspeed writes it up well.)
perhaps the mounting plate for the supercharger should have some recesses in it to create passive cooling fins as having that much direct contact is going to get it very hot
Now the Rover V8 has gone to the junkyard of history, Mercedes, BMW and Jaguar engines are filling the void left behind in hot rodding by the Rover V8’s demise. This is cutting edge stuff, it’s art.
The turbo will push the supercharger lobes as you will have the inlet side hit by a stream of denser air. Gale banks explains it in one of his viedos, and i trust him
I think i would keep the SC and the turbo separately. I would source a clutch setup from an E55 that way you can control engagement to make up for the low boost situations with turbo. In theory you could even run an oversized turbo since SC would make up for losses on bottom end. Shouldn't be too hard to tune engagement on a dyno where you can see both boost and hp on a graph. Looks like a fun project and cant wait to see it running.
Yes, the supercharger compresses air. Compressing air requires work. The work/power required to compress air is proportional to the volume of air being compressed (per second). Conversely, if you close the inlet and allow vacuum to accumulate, the load (perhaps counterintuitively) decreases. If you're concerned about the supercharger drawing more power from the crank than you want after the turbo is spooled, then you'll want a bypass valve across your supercharger. Ideally, your supercharger would be bypassed once the differential pressure from your turbo compressor inlet to outlet reaches a specific pressure i.e. 1 bar (with the turbo feeding the supercharger, this is easy because the pressure produced by the turbo can be tapped before it feeds the supercharger inlet, and used to move a pneumatic plunger and large bypass valve). You're left with minimal losses from the SC, and maximum boost pressure at the manifold that depends on only the turbo (and wg if you use one). One alternative, as someone else already pointed out, is you could otherwise use a magnetic clutch on the SC... but you would still need to bypass the SC so it doesn't become a serious restriction.
i like the idea of spending the time to simply try supercharger only, which i think may be surprisingly good, and both ways of feeding the charger with the turbo and vice versa.
The main thing that makes the screw comressor much more efficient than a roots blower is that it has internal compression. when the air is released in the outlet it is already compressed, a roots style superharger is just moving the air. If you feed it denser air it will use more power and the compressor bearings and such will see higher loads. In industrial applications they sometimes partly shut the inlet to create a vaccum(less dense air) and save energy.
Think Gale already answered that the turbo was pushing on his roots blower and making it harder for the super charger if i recall the video. i'm building a similar project but was going to use a 103mm throttle body (billet one for a LS Motor) infront of the turbo inlet with the supercharger blowing into the turbo from behind the throttle body. Hopefully allowing the turbo to suck on the supercharger to stop the Supercharger creating positive pressure thus lowering paracitic losses but then allowing a full 4" open inlet for the turbo. This is for a 2.4L diesel with an M45 from a merc with a mini pulley and Holset HX35 with added control from an arduino micro controler.
Hi Luke, You know volume of oil in the supercharger. You could make a new dipstick to suit your orientation. Just mark the stick where the oil level currently is. I like a dipstick....,
I'm concerned about the oil 'level' since the installation orientation has been changed dramatically. I work with drive systems at work (motor + gearbox units) and another shift mounted a drive in a different orientation, having filled the gearbox to it's natural (original orientation) level. Needless to say, the splash feed system could not supply enough lubrication to the 'higher' gears and the gearbox burned out way prematurely. Just a thought Luke.
I believe the supercharger would require more energy if it is fed with compressed air, but it is hard to predict how the roots blower will behave. Excited to see what happens as you test different configurations, hope you get high torque from idle to redline!
A screw or roots blower is hard on the bottom end. You'll be impressed with the zero lag for towing applications, but it really needs a disengaged drive for the supercharger with a bypass on the turbo for the best efficiency. A roots blower will act like a pneumatic powered motor if compressed air is forced into it or sucking on the outlet. A screw type may not budge at all.
For compounding, and your debate about turbo into SC vs SC into turbo, the low pressure device is always the power limiting factor. So if that S366 SXE can flow more that the 2.8 Kenne Bell, use the BW as the open to atmosphere device. You may look into some bypass for the SC unless you are cooling the air AFTER the SC as well, as once the turbo is online, the turbo should be the more efficient device. Air density is the name of the game.
They will make more power together. The blower will not become a restriction up until the point it overheats and seizes up!😅 if the blower has a 1.5 pr and draws 14psi atmospheric air, the output is 21 psi or a 7 psi increase. If the blower is instead fed 21 psi air (14+7 from a turbo) the outlet will be 32 psi or an 11 psi increase. I gather this is where the terminology for "compound" charging comes from. Standing by for Gale to scream about air density. He is, of course, correct on the issue. 😂
20:34 why not make a lever with a pulley on it, that allows you to put tension on the belt when you want to run the supercharger. And Vice versa, when you don’t want to run the supercharger.
id run it like a compound set up: feed the turbo with the supercharger, once the turbo overcomes the cfm of the supercharger, use a throttle body or ball valve or something to open up. having a clutch on the super charger would maybe be pretty cool too. im super excited to see how this turns out. ive been dreaming of doing this on a 1.9 TDI engine for a while now.
Great video and project. I worked on quite a few Detroit Diesel two stroke engines that were supercharged, but the construction equipment never got into the 92 series that was supercharged and turbocharged. It’s definitely a head scratcher for me which way it should go. I think ideally would be a clutch on the supercharger to disengage after the turbo is fully spooled and is doing its thing.
@@miguelsmith9622 on DD's the supercharger is blow through. makes the static pressure needed to make the engine run. never seen how the turbo's run, but in those days it wasnt high pressure, so it might as well have gone straight through the supercharger.
I am so happy to see this man, I'm building a twin turbo set up using td04s that make about 650hp on a well known petrol straight 6cyl. If that looks good I may be needing a Lil advice on what big turbo to compound it with. Your intake has been key to making this work, so thanks for that.
In theory, and that being said I could be completely wrong. The super charger relies on pulley speed to attain the desired compression. Meanining it only compresses the same psi or bar above what atmospheric pressure is. So my best guess is, if it raises the pressure 5-10 psi above open air, it would still only raise the turbo compressed air 5-10 lbs above the turbo output. I can only quote pressures from petrol turbo engines of the past but, if the turbo produces 12 psi, the super charger should boost that pressure up to 17-22 psi. Very roughly speaking of course. Volume of flow should be interesting though. Obviously a turbo will spin many times faster, but at lower engine speeds, the super charger could potentially provide a bit of vacuum to the turbo maybe, just maybe, causing a very slight vacuum at the exhaust manifold. 🤷♂️ Dunno, as I am not a pro, but air as a compressable liquid can lead to some very interesting side effects. You may end up needing just a tiny bit of a alcohol mist in the system, just to keep compression temps under control. Absolutely awesome build already though. Keep up the incredible work.
I'm pretty sure that the power required to drive the supercharger should be a function of RPM and the pressure differential across the blower - there might be a slight effect of air density but that's not the dominant factor. For basically any compressor, power is flow rate multiplied by pressure change, multiplied by an efficiency factor for the particular type of pump. The amount of boost the blower makes is of course determined by its displacement relative to the engine and the drive ratio, which is constant whether or not the turbo is feeding positive pressure into the blower. So I suppose one wants to bypass the blower once the turbo is spooled in order to both reduce the parasitic losses and keep the total boost pressure under control.
I think if you put booster air from the turbo into the blower it would turn with no belt on whatsoever- hence it would overcome the draw that the blower has in the engine. Just my theory. Love the channel and the puppers! Keep up the good work
I agree with you wholeheartedly. The volume and pressure from the turbo will push the supercharger to spin , therefore easing the load on the supercharger shaft. The pressures will compound however. Until it saturates the maximum internal flow of the supercharger itself. How does it do that ? Have the supercharger pump the initial flow into the engine drawing air from and thru the turbo. Instant boost. This action (vacuum)forces the turbo to start spinning before any exhaust flow/pressure gets to the turbo. As the exhaust flow increases, the turbo (already spinning) starts producing its own pressure that now is forced into the supercharger. This reduces the load at the shaft. The turbo actually helps the supercharger spin. Not the other way around.
Someone probably already mentioned this but Detroit Diesel used to make turbocharged/supercharged 2 stroke diesel engines. And if I remember correctly they fed turbocharged air into the supercharger. Because they were 2 stroke diesel engines they had to be supercharged to run, adding the turbocharger was for better power characteristics. Including higher horsepower than supercharged alone. Again if memory serves.
Looks very cool, thoroughly excited to see how it goes. Im assuming that you already know most of what Im about to say, because I started typing before I finnished watching the video (yeah, I know, rookie error) On smaller superchargerd engines (Im thinking mainly of the mini cooper s with its 1.6L engine and eaton M45) manufacturers don't bother with the clutch to disengage the supercharger when its not needed, they just use a bypass valve, which essentially means the supercharger doesnt make boost because the air is free to escape. On larger engines, they typically do use clutches because the superchargers are much bigger and the cars are already very thirsty - its more to do with emissions than it is to do with power. As for which way you route it - VW made a 1.4 TSI petrol engine which was twincharged, that used the supercharger at lower engine speeds and the turbo at higher engine speeds, really it was just a way of using a bigger turbo on a smaller engine without having a high boost threshold and too much lag. That has a clutch and a bypass valve I think, essentially deactivating the supercharger completely once the turbo is on song. 2 things I think you've not considered are as follows - if you feed the turbo into the intercooler and then into the supercharger, you wont be cooling the air between the supercharger and the engine, so that air is going to be very hot, because instead of compressing the atmostheric air, youll be compressing slightly, but significantly warmer air. The second thing you may or may not have considered is your turbo size. If the turbo is going to supply ample air/boost for your intended power goal at high RPMs, then you don't need the supercharger at those higher engine speeds, you just need it at the lower engine speeds when that great big turbo won't be spinning quick enough to make the boost you want. Guessing from the specs of the supercharger and engine displacement and the pulley ratios, your going to be making roughly 2 bar (30psi ish) of boost from the supercharger which in theory is going to give you 3 times the power of the NA engine, minus the drag of the supercharger. Whats your target boost pressure overall, and can the turbo supply that by its self at the top end? (Assumptions for that maths are that the supercharger is 2.8L and the engine is 3.0L and that the pulley ratio is just about more than 2:1) As for the potential increased drag of the supercharger by feeding it pressurised air - its not really a concern. If it works then itll make so much power and boost that you needn't worry about a bit of extra drag, and if it doesnt work youll melt the engine up because the air you fed it was too hot. I see two ways you could do this - you could feed the supercharger into the turbo inlet, then from the turbo to the intercooler and into the engine. If you do this, youll want to bypass the supercharger at the point that the turbo is spinning fast enough to make 30psi (I.e. let the supercharger spin without doing any work to compress the air) you dont want the turbo to try and suck air through the supercharger, thats just a restriction. The other way you could do it is to give each its own air filter, and then a pipe going into a shared intercooler with a valve that stops the supercharger forcing the turbo to spin backwards at lower engine speeds (essentially blocking the pipe between the turbo and the intercooler). You can read more about this here if you like: en.wikipedia.org/wiki/Twincharger Personally - if you want more than 30psi of boost, do it the way VW do it. If you dont want more than that, you dont need the turbo at all. To answer the question any better than that, you really need the charts from the supercharger manufacturer. These are easy to find for Eatons, probably less so for yours, but Ive not looked. As to how you would actually fabricate such a thing - Im really not one to talk. The way Id do it is to put an airbox on the side of the supercharger with the air filter in it, with 2 exits, one going backwards towards the supercharger inlet, and the other going to the supercharger outlet. Then you put the valve in the pipe going from the airbox to the supercharger outlet so that the turbo can suck more air than the supercharger can pump at higher engine speeds. Thinking about it, Id really want a clutch on the supercharger, that way you can turn it off on the motorway etc too. Perhaps you can adapt the pulley from a larger eaton to fit? (The clutches are built into the pulleys, a bit like an AC compressor). Alternatively you could just swap the supercharger for an Eaton M112, which is about 1.8L, but its the biggest one we got commonly in the UK I think. Eaton superchargers are available up to 3.1L in the US though. Personally I reckon that that 2.8L supercharger is a bit big for a 3.0L engine, especially with a turbo too, but Im not sure what boost pressure your aiming for. Hope this helps, happy to do some maths for you if you give me the numbers!
I think the simplest setup would be to route the supercharger into the turbocharger and have a valve AFTER the supercharger that opens below < 1 bar, that way when flow is too high for the supercharger it will just be left out of the equation but you still have the advantage of supercharging at low RPM. If you blow the turbo into the supercharger it will want to move the compressor and exhaust wheel which kind of negates the whole supercharger benefit in the first place. Plus you wont need an actuator. Also I think blowing hot air into the supercharger will just hurts its longevity since the oil in it isnt cooled. And to answer your question yes it will take more power to compound turbo -> supercharger since the supercharger is doing more work, ie compressing from 1 bar to 2 bar vs 2 bar to 4 bar is twice the work (since the ratio stays the same).
Awesome engineering in this build! The positive displacement supercharger compresses air whether it be atmospheric or boosted. If you run the turbo into the supercharger you will have zero lag plus linear boost, and a less complex intake system. Keep up the great content. Tim Australia.
Back in the 80s someone built a Latham supercharger/ twin turbo engine. I cannot remember if it was a chevy v8 or ferrari flat 12, anyway the super charger was belt driven and incorporated a flapper door between the supercharger and turbo. Once the turbo boost over pressured the Latham supercharger the flapper door would change position and only allow turbo boost pressure to flow into the engine. Once the flapper door cut out the Latham supercharger the parasitic loss to drive the supercharger went to near 0%. It was explained that once the supercharger could no longer move air there was no load and hence no load no parasitic loss. Latham superchargers were identical to turbine engines by way of having vanes instead of lobe, screws, or impellers. Never the less the logic is the same if the supercharger cannot move air it is just spinning in it's enclosure/housing. In other words, no need to be concerned about supercharger clutches.
Are you suggesting shut the inlet to the supercharger so it’s spinning in a vacuum therefore no losses? Or are you suggesting the outlet of the s/c goes to atmosphere with no resistance?
I believe supercharger-turbo-engine might have high rpm restrictions because turbos dont draw air through as well as they can push it. (that's what i understand with turbine impellers) but we're talking 4000 rpm plus. you might not need to rev that high to begin with. the turbo-supercharger-engine might need an overboost bypass (basically a dump valve opening at it's maximum pressure to allow more air through, like, idk...1.5 bars?) and it sounds the easiest to work through. your best answer is absolutely to ask the Gale Banks himself. he'll love to chat about that. dude's made several compound supercharger setups. might be the first to have run them at bonneville on diesel, too.
Why not plumb the two chargers separately with the supercharger handling the low speed boost and the turbo the highspeed boost? The two systems could flow direct into the inlet manifold with a valve(s) controlling which line operates i.e. parallel twin charging. It would mean that the supercharger would need a clutch pulley to disconnect it at the point the turbo takes over and solenoid valves to close/open the path to the inlet manifold. The answer as to whether you want a sequential system or a parallel system lies in the application and how it is to be used.
14:30 I’m guessing you’ll blow seals in the supercharger using the turbo to feed the supercharger, I believe the 2 stroke Detroits and almost every early application of “twin charging” has been supercharger feeds turbos with some type of bypass like you originally described but maybe sometime of valve other than ball valve, like a blow off valve in-line, on the vacuum side prior to supercharger and spring seat like a diesel injector on a pipe with the spring pressure that lets off at a certain cfm
Compound the boost. Intake to turbo, turbo to cooler then put a water to air intercooler after the SC or the reverse if your worried about the parasitic losses.
i would imagine running the supercharger air thru the compressor housing then thru intercooler would give the car boost from the get go and at the same time not cause to much restriction at the top where the turbo wants to pull the air thru the supercharger.
It might be the option to use them in parallel because it might be that your supercharger starts to restrict turbo in higher revs and turbo restricts your supercharger at lower revs. But you might need some active valving to prevent back-flow.
This is just a theory but if you direct the “waste air” from the supercharger after the turbo takes over to the exhaust it should create a capillary effect that will scavenge the exhaust gases more effective.
The power required to turn the supercharger when either on it's own or compounded with a turbo should remain roughly the same. The supercharger is a positive displacement compressor and the compression ratio remains the same regardless of the suction pressure, the compression ratio and the flow rate determines the power required to turn it .
It's a bit apples to pumpkins, but the Detroit 2-stroke diesel engines that ran both superchargers and turbochargers had the turbo feeding the blower. There were blower only, as it was needed for the 2-stroke to start and run, but no turbo only. However, if blower to turbo was in some way better to a worthwhile degree, I have to think Detroit would have made the change, or conversions would have been popular.
not sure if that was true. The supercharger is really integral to the 2-stroke detroit engines. it is gear driven. The turbo would bypass the compressor as well. What i read was that the turbo would eventually overdrive the compressor which in turn would drive the engine via the geardrive of the compressor. Clearly that would be counterproductive, hence the bypass.
Damn you!! I recently bought a Chevrolet 3100 -49 and was looking under the hood thinking "Hey! Maybe i'll finally have a reason to get a MB smoky-boi.." But NOW i cant do it! :D
@@DieselPumpUK Honestly, no real reason except it would be fun to have a unique combo... But i guess as long as i don't go for a 350 it'll be kinda unique.
I find the answer to the combined HP question is as you say the engine's ability to consume is a bit fixed. But the overall result will be Highly reduced turbo lag, so a larger turbo becomes of no consequence. Blower to turbo vs. turbo to blower is the question. Requiring "What"? controlling mechanism-'s.
16:52 I guess air filter - supercharger - intercooler- turbo intake -turbo outlet - intake manifold. Or you can plumb the cooler after the turbo it may heat up the turbo a little bit more. It may take multiple attempts on the dyno to figure it out.
Im definitely not that clever but i would imagine that the supercharger only really cares about pressure difference between it's inlet and outlet. So going by that theory if it was feeding itself from atmospheric and producing 10psi static pressure then having a turbo upstream producing 10psi and the supercharger compressing it to 20psi would be the same . The thing that makes me doubt my theory is that this is a dynamic system with changing flow and temperatures .
I would plump them both separately into the intercooler and have a electric throttle body on the supercharger pipe into the intercooler for when the turbo comes on song. Could do with a clutch on the supercharger for when the turbo on boost dor less power loss.
(P1xV1)/T1 = (P2xV2)/T2……..Density = mass per unit volume…. Drag = Cd x 1/2 density x vsquared x area…… so in theory for each unit increase in density you can expect a half unit increase in drag. Anyway, the fun is proportional to the fuel flow.
Also from my experience making my own serpentine set up on my van, I am slightly concerned about how far the tensioner is maxed out, I’m afraid it’s not in the middle of its range and potentially doesn’t have as much tension as designed. Just a thought
Hello Diesel Pump! Greatings from Argentina! I've been watching your videos lately and been loving every single minute of them! Keep up with the good work! I wanted to ask you what is more reliable, the om606 or om613? i want to buy a w210 cdi but i don't now which motor is better as i don't have much knowleage (i´m 23 yo). Down the road i hope i have the money and the means to make it faster! Hope your are well and thank you for your time!
I think if you get the blower drive ratio correct you can get it to make the power you want up top without having it come on too hard too early, and still have the throttle response since it makes x boost at x rpm regardless of how you have rolled into the throttle or any boost lag. Maybe an electronic boost controller mechanism could bleed some off at lower rpm to reduce unscheduled rapid disassembly?
Subject "compressor power loss" from a theoretical point of view: the compressor has 2 main ways to waste energy: Friction in bearings, belt-pulley, etc. - remains more or less the same - and friction with the fluid to be compressed (air). The higher the density/viscosity of the fluid, the higher the friction (more molecules available to "stick" to the moving surfaces and "don't let go"). So if you put the turbocharger's output at the supercharger's input (in series), the supercharger will work within a more dense environment and therefore will draw more parasitic power. Why don't you put the two in parallel with 1-way valves to a "boost rail" into which one of the two presses air depending on rpm? Besides, the supercharger is a pump & as such it'll multiply the pressure by x% output vs. input. Yet you can't put any pressure into the engine, so I suppose you'll use a wastegate or something similar to limit the pressure in the manifold. So, when the turbocharger kicks in, the supercharger will work harder, will of course get hotter and will ve no benefit for the engine power. By the way, it's great how passionate you are about your work and how much you understand about your builds! Keep up the good work!
Another awesome video. Just a minor question or minor critique.....Is that fuel tank a little low? I'm sure it'll be fine. Not like that truck will be a daily driver/work vehicle.
Think about it this way. The supercharger is a pump but if you feed it air it should act as a motor. So it should lesson the energy needed to drive it if you feed it air.
I would keep them compounded all the time. If the SC pressure ratio is 2x, and you feed it 3 bar air from the turbo, you'll have the potential for 6 bar without pushing either charger that hard. The trick would be to select a turbo that will flow as much air at 3 bar as the engine can eat at 6 bar. The SC won't take any more power to boost the air from 3 bar to 6 bar as it would to boost 1 bar to 2 bar. The ratio is what matters. Air density will be determined by your charge air cooling package.
Hi Dpuk, just an idea, try adding a clutch to the pulley of the supercharger to allow the possibility of disconnecting the drive of the supercharger without removing the belt. This may be useful when the turbo is fully spooled up and the supercharger is just soaking up usable power. Just a thought. Thanks Matthew Cowling. Australia.
Thanks for the suggestion, I cannot imagine making a clutch system to handle the near 100hp the kenne bell takes to turn would be easy or compact, I certainly have considered it.
Bench test the KB2.8 with an electric motor driving it. Compare the amps when building pressure to the amps when vented to atmosphere. Since screw superchargers build pressure internally I suspect the recovered HP from venting won't be a high percentage, but that's a very low confidence guess without testing.
I was wondering if any consideration has been given to an electric motor initial fast turbo spool, I believe they have been available on F1 engines with the Kers system. Does anyone, or Luke know anything of these? Is it possible to obtain an edrive fast turbo spin activator which would work from idle to say 2500 rpm?
Is it an idea to put on the SC a fluid clutch. The oil in the fluid clutch you let it out in a small tank and the SC is disconnected. To connect you pump the oil slowly back in the SC to get a smooth connection. This same principles you see it in the high torque MB Actros gearbox
My bet is the pressured air from the turbo would actually help the supercharger spin, as instead of the sc trying to suck and squeeze the air, the turbo is equalizing it, and applying pressurised to the sc so it doesn't need to suck, just blow through
