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Twin charging - (supercharger and turbo) pros and cons ?


plasticdash

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what kind of motor is that!? intake manif between the plug valley and exhaust out both sides?? wtf!\

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lancia_ecv2.jpg

The 1800 power unit of the ECV1 & 2 was known as the triflux. This was due to the design which had one exhaust and one inlet valve on each side of the cylinder head, with the resulting twin exhaust manifolds each feeding one turbocharger. At low engine speeds one turbocharger exhaust was shut-off, forcing all the exhaust gases through one unit and thus providing good low speed performance. As the engine speed rose, the second turbocharger was gradually introduced, until at high engine speeds both turbochargers ran in parallel.

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...both in parallel

push the turbo though a reed valve

job done

s/c supplys the boost ...then as teh turbo creates pressure ....it blows though the reed valve..and you turn the s/c off as it builds past the set s/c boost

v

That solves an issue I had :)

I think I'm going to ditch the VG and finnish this...

STTOP.jpg

ste_sde.jpg

This was a setup I did for the 2L. SC14 and Evo5 turbo :wink:

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what kind of motor is that!? intake manif between the plug valley

Mazda do a quite common motor like that too, forget what its called. Its direct injection though. And exhaust out only one side.

i know mazda "did" do a miller cycle engine , i like the idea of that alot , it never caught on enough by the sounds was one of the only things i read about and i liked the idea of it

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I would like to see a compounded twin turbo setup on a car one day. They work well on Diesels.

You will . Someone in welly is building one.

Might be 2 years away though.

Steve

fuck off , 1200 rpm stall then snail wind up and youve been thunderstruck

etc

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With the Mazda engine I was more referring to having the intake down parallel to the spark plugs. Did a bit of work at an engine reconditioner and popped one apart out of curiosity.

Miller cycle is a good idea I think , but to turbo it you would have to twincharge? (Im in the right thread then :lol:)

oh my bad , mind throwing me the info my way? keen as to know

and you you would cos it wont work without it

that idea has economy a kw written all over it with research , however cheaper ideas exist

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I would like to see a compounded twin turbo setup on a car one day. They work well on Diesels.

The diesel engines these work well on don't rev much over 2500rpm.

The problem is still there of when the first turbo starts to stall it crates a turbulance affect in the second one.

If it stalls the second one the chance of them both is highly increased (40% I think was the figure)

The coolest thing I ever saw was a proto type turbo for a Nissan truck engine, It was fucken huge and the exhaust housing had a 2 stage wastegate. The intake side was variable opening actuated by boost pressure and the compressor wheel was variable pitch (altered trim as the boost changed to keep it smooth).

The engine had the same torque and HP throughout over 2/3rds of the rev range. It also pulled from just over idle.

The downside was the amount of moving parts although I never saw any issues after it had done many hours of dyno work.

Corey

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One problem with a reed valve in front on a turbo would be compressor surge. It would surge like mad as it starts spooling.

There souldn't be any surging at all cause the supercharger will keep the boost levels consistant as the turbo is spooling up.

I can't even see a way of VVega's set up stalling the turbine wheel on deceleration which means you could nearly run an open exhaust with little noise.

I have been around almost every type of turbo setup there is including working on plane engines for Air New Zealand and the idea of the reed valves is the most simple yet effective I have ever heard of. The only draw back I can see is the life of the reeds depending on their design.

But VVega has a reputation for being a very clever guy so I'm sure he has worked out the best way to do that.

Corey

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One problem with a reed valve in front on a turbo would be compressor surge. It would surge like mad as it starts spooling.

There souldn't be any surging at all cause the supercharger will keep the boost levels consistant as the turbo is spooling up.

I can't even see a way of VVega's set up stalling the turbine wheel on deceleration which means you could nearly run an open exhaust with little noise.

I have been around almost every type of turbo setup there is including working on plane engines for Air New Zealand and the idea of the reed valves is the most simple yet effective I have ever heard of. The only draw back I can see is the life of the reeds depending on their design.

But VVega has a reputation for being a very clever guy so I'm sure he has worked out the best way to do that.

Corey

The reed valve on the turbo will stay closed though (i.e. zero compressor flow lb/min) untill the turbo pressure equals the manifold pressure provided by the SC. Lets say thats 10psi. On say a TO4E 50 trim compressor 10psi @ anything under 12lb/min = surge. The more boost provided by the SC the worse it gets. If the boost was kept quite low it may work ok.

Fig13.gif

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surge happens when the turbo can make more boost and is restricted to less that the surge line amount via wastegate or inlet (not pressure side) restrictor

it surges because it cannot maintain less that that pressure at a flow less that that value and more than 0

as it spools it hits a point were there is not enough ex gas to force compression but enough to make some pressure but not maintain it

so it surges to presure...then the pressure overcomes the turbine drive and stalls the compressor

because the motor is supercharged it has far more ex presure than what a normal engine of a given size woudl normally have so sized correctly you wont have the intake pressure exceed the given turbine power

compressor maps are a good basis but you need to overlay them with turbine maps and engine flow to get a idea on what it will do

you still need to size your turbine/compressor combo corectly for the application and twincharging will not bode well with a poorly designed setup

just my 2 cents

ive written this as simply as i can so everyone can get a idea of what im saying ..so somethings are not exact for teh sake of understanding

cheers

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