pork
Posted a lot
Posts: 1,662
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Dec 17, 2013 18:50:47 GMT
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I think the clutched way would be better, especially on a little 1.3. So would like it disengaged on e turbos spooled up.
How would the bypass be controlled, just by boost pressure?
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Dec 17, 2013 20:10:22 GMT
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Ive just remembered, you're using bike carbs, this is going to cause all sorts of problems because you really need the throttlebody or carbs before the Supercharger or you are going to cause yourself a heap of trouble when you shut the throttle at 6k rpm, all that boost out of the SC is going to want to go somewhere, the plumbing and control to bypass the SC would be a nightmare.
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pork
Posted a lot
Posts: 1,662
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Dec 17, 2013 20:16:13 GMT
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That's why I was thinking of using a magnetic clutch to disengage the s/c whilst turbo is running.........if I'm talking curse word, please enlighten me, I'm here to learn There's a chap on here that has a supercharged cossie Capri on bike carbs, he used 2 throttle plates lol
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pork
Posted a lot
Posts: 1,662
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Dec 17, 2013 20:31:56 GMT
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There it is
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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Super charger and turbosowen
@sowen
Club Retro Rides Member 24
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Dec 17, 2013 21:11:32 GMT
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Anything can be made to work, it's just how complex do you want to make it! What pressures can the the bike carbs physically hold before they just dump air and fuel out of the joints and seals?
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pork
Posted a lot
Posts: 1,662
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Dec 17, 2013 21:25:34 GMT
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Havnt tried pushing that far yet, more worried about the floats collapsing than seals.
I was considering swapping to cbr600 itb's in future too, as it'll fit straight onto my bogg bros manifold.
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Dec 18, 2013 20:09:24 GMT
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You can just use a big bypass valve actuated by vacuum in the inlet manifold, like a dump valve but bigger. I may or may not have one of those for sale too J
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pork
Posted a lot
Posts: 1,662
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Dec 18, 2013 20:14:27 GMT
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Haha, what else you got!,
I wonder what that large amount off air would sound like...........pppaaaaaaahhhhhhh
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Dec 20, 2013 16:37:35 GMT
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Forced induction in a blow-through carb system will require the carbs to be sealed in some way and/ or fed with boost pressure for the venturi/s to work as intended. Given that the working pressure differential here is quite small relative to boost pressure, you could easily run into problems with leakage etc causing trouble or other fuelling issues.
To supercharge alone would be fairly simple, but if you want to stay with a carb it might be easier to switch to a type intended for this?
For a compound system, something like what Claymore has done makes sense. The supercharger is a pump which displaces a fixed volume at any particular rpm. These types of blowers get inefficient at higher rotational speeds and pressure ratios, but if they are being fed by a turbo they can run like that at a fairly low pressure ratio and still produce a dense charge at high flow rates with a high combined boost pressure....the supercharger only sees the pressure differential across its rotors. The turbocharger only has to shift a high volume of air, but not pressurise it to the full extent that it would if the supercharger were not in circuit.
In this case though, you would definitely want a compressor bypass valve or blow-off valve post supercharger.
The two big down sides to this are firstly that at lower engine rpm before the turbo's own boost threshold its own compressor side may cause some intake restriction, as by definition its intercooler stage also will.
Secondly, the hot side of the turbo will still cause some additional top-end exhaust restriction as well (compared to with supercharger only), but if it is sized correctly this should be minimal.
Correct selection of the turbocharger here will be critical to all sorts of things, but it can likely afford to be larger than normal for a similar non-compound supercharged installation.
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 18:12:02 GMT
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Allready running turbo bike carbs Running really well too at 8psi just bought an eaton m24 with electromagnetic clutch Plsn is to run s/c to 3.5K, that's when turbo is spooled, then bypass sc and disengage clutch Worth a go
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Dec 20, 2013 19:15:15 GMT
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So what set-up are you planning? Turbo feeding charger, charger feeding turbo, or both independent and parallel?
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froggy
Posted a lot
Posts: 1,099
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Dec 20, 2013 19:50:11 GMT
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your best plan is to feed the turbo with the charger with a vac actuated bypass to divert air past the s/c into the turbo under vaccum and a micro switch to engage the clutch after a certain throttle position and a hobbs switch to turn it off once you get to the boost you want
this way round means no plumbing changes just finding somewhere to hang and drive the supercharger
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 20:00:24 GMT
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Turbo into charger was plan , then bypass at desired pressure.
Controlling the switch over, havnt thought that all way through yet.
Never played with a s/c before, would I need any throttle plate pre charger?
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 20:44:22 GMT
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I'd imagine the s/c will be making boost at idle too, so with the throttle closed, would a BOV. Be sufficient to relieve the pressure
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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Super charger and turbosowen
@sowen
Club Retro Rides Member 24
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Dec 20, 2013 21:23:07 GMT
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I'd imagine the s/c will be making boost at idle too, so with the throttle closed, would a BOV. Be sufficient to relieve the pressure I reckon you'd be better off fitting an oem vacuum bypass valve off a BMW Mini or Jaguar, made for the job!
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 21:41:48 GMT
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Was just looking at that. Would I need 2? One for s/c to turbo only bypass, and one for idle? Or would a dump valve be enough , or am I getting it wrong
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 21:43:24 GMT
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Hang on, u say it's vacuum operated, so that valve will only open when throttle is closed, so that'll sort idle issue out
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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Super charger and turbosowen
@sowen
Club Retro Rides Member 24
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Dec 20, 2013 22:10:15 GMT
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They're an idle bypass, using vacuum after the throttle to open the bypass valve. I have one buried somewhere from a Jaguar XJR6 on and M90, though bypass valves from Mini's look like nice neat units.
I have no idea how a complete supercharger bypass system to be implemented. If it were me I'd just try it permanently engaged first and monitor the engine stats and go from there.
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 22:25:32 GMT
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Cool, again, massive learning experience ahead..... That's the point though
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pork
Posted a lot
Posts: 1,662
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Dec 20, 2013 22:53:19 GMT
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The way I understand it, a s / c can only compress the air that's actually going into it, so shut it off at inlet , no boost created (leaving enough to idle though) Am I reading this lancia flow diagram right? There's a recirculating valve after the sc into inlet of turbo Could I use the BMW mini bypass valve to do the sane!
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