Time for a good tech thread for once! Twin charging...
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Time for a good tech thread for once! Twin charging...
Ok, time for a good old fashioned Passionford tech thread.
Twin Charging.
Either using 2 turbochargers in compound, or using a super charger and turbo together.
I would LOVE to work out a package to fit a roots type blower onto a big laggy T4 car .
What are the main problems (besides packaging) when twin charging an engine? Would the supercharger be better run in series with the turbo or in parallel?
From what I can find on the net, the biggest problem is getting a smooth transition from 'charger to turbo?
Twin Charging.
Either using 2 turbochargers in compound, or using a super charger and turbo together.
I would LOVE to work out a package to fit a roots type blower onto a big laggy T4 car .
What are the main problems (besides packaging) when twin charging an engine? Would the supercharger be better run in series with the turbo or in parallel?
From what I can find on the net, the biggest problem is getting a smooth transition from 'charger to turbo?
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CPR where using twin turbos this year in Time Attack.
Had a big turbo (gt40+) blowing into a small turbo (gt35) which led to better spool.
They have now removed all this set up due to similar gains being had with different turbo setups and the reduced weight which is quite far infront of the front axle (obviously different to a EscCos)
Had a big turbo (gt40+) blowing into a small turbo (gt35) which led to better spool.
They have now removed all this set up due to similar gains being had with different turbo setups and the reduced weight which is quite far infront of the front axle (obviously different to a EscCos)
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CPR where using twin turbos this year in Time Attack.
Had a big turbo (gt40+) blowing into a small turbo (gt35) which led to better spool.
They have now removed all this set up due to similar gains being had with different turbo setups and the reduced weight which is quite far infront of the front axle (obviously different to a EscCos)
Had a big turbo (gt40+) blowing into a small turbo (gt35) which led to better spool.
They have now removed all this set up due to similar gains being had with different turbo setups and the reduced weight which is quite far infront of the front axle (obviously different to a EscCos)
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#10
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That is a similar setup to the one I was going to use on my nova, with a gate that effectively means its either supercharger or turbo charged but not really both at the same time to any great extent, so its not really compound charged in the traditional sense TBH
Still a good setup though.
But in the end my car drove well enough on just the turbo so it seemed like extra weight and complexity for no point so I didnt bother finishing the supercharger side of it, i just stuck with turbo only instead.
Still a good setup though.
But in the end my car drove well enough on just the turbo so it seemed like extra weight and complexity for no point so I didnt bother finishing the supercharger side of it, i just stuck with turbo only instead.
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Would be more for a "just to make it work" sorta thing Chip, my current saff has a T4 on it, but I have a GT35 at home, so if I could get it working well, would be nice to have a big turbo with the charger' filling in the area under the graph, purely for drivability
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Nissan used to make a Micra Superturbo back in the day, iirc it was a 1.0 litre, done a quick google and came up with this diagram
Edited : as Chip says, this isn't strictly compound charging due to the bypass control valve.
Edited : as Chip says, this isn't strictly compound charging due to the bypass control valve.
Last edited by Red16; 22-11-2010 at 09:50 PM.
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Hmmm, I must be crap at google, as I couldn't find anything useful on the golf GT's
Interesting, so basically the charger is blowing through the turbo, then being completely bypassed by the butterfly valve once the turbo is going. Clutch disengages to stop parasitic losses..
I wonder if on a bigger turbo you would restrict the inlet with the bypass size?
Interesting, so basically the charger is blowing through the turbo, then being completely bypassed by the butterfly valve once the turbo is going. Clutch disengages to stop parasitic losses..
I wonder if on a bigger turbo you would restrict the inlet with the bypass size?
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I think AVA tried it, and it broke. But that could be Twin Turbo and not Compound.
Will Pedleys set up at mo seems different as the vw has the blower going into the turbo, where as Will has the turbo compressing an initial high volume of air to fit into the super charger, which then gets compressed further.
Clever stuff, Cant wait to see what hes going to do to keep his ACTs respectable as I cant see his charge cooler inside his SC being the best option??
Will Pedleys set up at mo seems different as the vw has the blower going into the turbo, where as Will has the turbo compressing an initial high volume of air to fit into the super charger, which then gets compressed further.
Clever stuff, Cant wait to see what hes going to do to keep his ACTs respectable as I cant see his charge cooler inside his SC being the best option??
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Yes, plenty of reason, as you are in a situation where you can have the same boost at the same rpm but for different reasons, and hence with varying back pressure.
Can imagine it being quite hard to get it fuelling and timing correctly TBH during the transitional period from one to the other and back again.
Can imagine it being quite hard to get it fuelling and timing correctly TBH during the transitional period from one to the other and back again.
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Yes, plenty of reason, as you are in a situation where you can have the same boost at the same rpm but for different reasons, and hence with varying back pressure.
Can imagine it being quite hard to get it fuelling and timing correctly TBH during the transitional period from one to the other and back again.
Can imagine it being quite hard to get it fuelling and timing correctly TBH during the transitional period from one to the other and back again.
It is a very similar system to what controls the bleed air demand off the APU on an aircraft , ie a pneumatic load sensing valve trims the fuel as the valve opens and closes agianst a load/demand diaphragm.... Obviously it's a bit easier with a rotating engine, not reciprocating as the fuel metering cycle is constant, not timing based.
Last edited by RWD_cossie_wil; 22-11-2010 at 10:32 PM.
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Obviously a lot more to it than that, but certainly be good fun engineering a solution ... I'm off to bed now, this thread could get interesting
#29
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ive done it on mk3 fiesta with frs engine , but like someone said already alot of complex stuff just for the sake of it , it drove fine on just the turbo , and still does
never really worked that well tbh tried it a couple of ways , both blowing through intercooler , charger blowing into turbo , also made up valve to stop charger blowing back into turbo but would open when turbo overcame presure on spring and let both blow
could'nt quite get the balance right , if it went well on boost then charger would try to stall engine on over run , if you got that fixed started blowing hoses off
its been consingned to the history books now
john
never really worked that well tbh tried it a couple of ways , both blowing through intercooler , charger blowing into turbo , also made up valve to stop charger blowing back into turbo but would open when turbo overcame presure on spring and let both blow
could'nt quite get the balance right , if it went well on boost then charger would try to stall engine on over run , if you got that fixed started blowing hoses off
its been consingned to the history books now
john
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I am a marine engineer and some of the Volvo penta marine engines run super charger and turbo (diesels) The charger is a roots type and is run off a magnetic clutch which runs up to 1700rpm then cuts off via clutch by then the turbo takes over. I have one of these chargers and magnetic clutches that I was going to try and put on my VR6 track car
#32
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ive done it on mk3 fiesta with frs engine , but like someone said already alot of complex stuff just for the sake of it , it drove fine on just the turbo , and still does
never really worked that well tbh tried it a couple of ways , both blowing through intercooler , charger blowing into turbo , also made up valve to stop charger blowing back into turbo but would open when turbo overcame presure on spring and let both blow
could'nt quite get the balance right , if it went well on boost then charger would try to stall engine on over run , if you got that fixed started blowing hoses off
its been consingned to the history books now
john
never really worked that well tbh tried it a couple of ways , both blowing through intercooler , charger blowing into turbo , also made up valve to stop charger blowing back into turbo but would open when turbo overcame presure on spring and let both blow
could'nt quite get the balance right , if it went well on boost then charger would try to stall engine on over run , if you got that fixed started blowing hoses off
its been consingned to the history books now
john
This is why most of the manufacturer systems were so complicated I guess!
Should imagine that there is a lot of clever mapping in the TSi setup to make it work more simply, as its got total control over the bypass valve etc.
Not something easy to replicate on an autronic etc without many many hours of development if at all I should imagine!
#33
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I am a marine engineer and some of the Volvo penta marine engines run super charger and turbo (diesels) The charger is a roots type and is run off a magnetic clutch which runs up to 1700rpm then cuts off via clutch by then the turbo takes over. I have one of these chargers and magnetic clutches that I was going to try and put on my VR6 track car
Is that the same volvo lump that they use the crank from for building nutty 16v converted turbo engines from? Ive got one to map soon on a dirty great holset hx52, they look like mental bits of kit, fuckign heavy though!
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The way i'm doing my setup is to use quite a large turbo (GT3076R in my case) to blow low boost into the intake of my supercharger. By putting around 6-8 psi out the turbo it should still be 'relatively' cool. Obviously not as cool as ambient air temps but not silly hot as you would get at 30psi+.
The supercharger is under driven to reduce speeds and air temps again and after the combined boost has left the supercharger it will go through an integral chargecooler core before entering the plenum section. Inside the plenum section it will be met with Aquamist which is mapped as an ECU controlled PWM to increase flow depending against air charge temps.
I'm expecting to see between 25 and 30 psi entering the engine without either the supercharger or turbocharger working ridiculously hard. What i'm also expecting is more response low end power, bearing in mind my supercharger would deliver 0.5 bar of boost the second you touched the throttle pedal!
I'm oversizing the chargecooler radiator too in an attempt to keep the water temps entering the chargecooler core nice and low.
We'll see how it goes, i'm going to be using fuel additives/race fuel anyway so should be able to tolerate higher air temperatures anyway before detonation becomes an issue.
The supercharger is under driven to reduce speeds and air temps again and after the combined boost has left the supercharger it will go through an integral chargecooler core before entering the plenum section. Inside the plenum section it will be met with Aquamist which is mapped as an ECU controlled PWM to increase flow depending against air charge temps.
I'm expecting to see between 25 and 30 psi entering the engine without either the supercharger or turbocharger working ridiculously hard. What i'm also expecting is more response low end power, bearing in mind my supercharger would deliver 0.5 bar of boost the second you touched the throttle pedal!
I'm oversizing the chargecooler radiator too in an attempt to keep the water temps entering the chargecooler core nice and low.
We'll see how it goes, i'm going to be using fuel additives/race fuel anyway so should be able to tolerate higher air temperatures anyway before detonation becomes an issue.
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I seem to remember a Maroon saph bein compound charged at somepoint, but i think it was unsuccessful ? Google hasn't shown me anything that looks familiar though so maybe i've imagined it?
I have a vivid memory of a pic of the setup lookin at the fromnt end with the bumper removed.
Ring any bells wi anyone else?
I have a vivid memory of a pic of the setup lookin at the fromnt end with the bumper removed.
Ring any bells wi anyone else?