RWD_cossie_wil

iTrader: (9)

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?

Gaz 88

Will pedley will prob be your man to answer questions about this mate

creator

Simon norris has had awsome results doing this also as said above will is also doing this

TimC

iTrader: (1)

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)

rs-tuner

iTrader: (1)

It must be good when the small turbo is a gt35

Chip

iTrader: (3)

T4 = 500bhp ish = use a gt3071 instead and not have to worry about lag anyway

Compound charging is a really interesting subject but I cant really see the point unless going for massive power.
Simon Norris's results have been very impressive.

vaughant

iTrader: (1)

Wasn't this a common thing done on the vw g60 engines,namely supercharger&turbo?

rs-tuner

iTrader: (1)

There new tsi engine is supercharged and turbo charged.

Chip

iTrader: (3)

Heard of a couple, but certainly not something I would call common TBH

Chip

iTrader: (3)

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.

RWD_cossie_wil

iTrader: (9)

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

vaughant

iTrader: (1)

Yeah,that was pretty badly worded!!!interesting that the new tsi is both 'charged and turboed!!!

TimC

iTrader: (1)

Aint the vw compond charged cars done with the blower on an electric clutch so when the turbo is in range the blower switchs off to not be a restriction or an extra load

Chip

iTrader: (3)

Not really at once though, so its not really compound charged in the true sense of the word, although arguably is ideal for what the thread starter wants



as soon as it starts to use the turbo, it bypasses the supercharger

Red16

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.

RWD_cossie_wil

iTrader: (9)

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?

Chip

iTrader: (3)

the supercharger itself would be part of the restriction without the bypass being sufficiently sized as you would still be trying to breathe through it as well.

b63_rs

has anyone ever attempted it on a yb?

Red16

Yeah, some bloke, called Doug i think, had a compound turbocharged Escort Cosworth done by AVA iirc.

J1mbo

iTrader: (1)

Yes it wasn't successful back in the day due to the choice of superchargers available

TimC

iTrader: (1)

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??

markk

iTrader: (2)

the TSI is seamless, an amazing setup on a 1.4cc devloping over 180hp with ease.

not sure about compressing turbocharged hot air into a supercharger though - i'll have to think about that a bit longer

Chip

iTrader: (3)

can give the seals and bearings in the charger a hard life if its see boost on the intake side, but its not like any of us are looking to build 100K reliable engines here.

RWD_cossie_wil

iTrader: (9)

Next question, is there any reason the std cossie management couldn't cope with this? As you have all the map/ ACT sensors etc?

Chip

iTrader: (3)

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.

RWD_cossie_wil

iTrader: (9)

I wonder if you ran a purely pneumatic based valve set up, it would be constantly adjusting for load, so maintain a pretty constant back pressre?

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.

Chip

iTrader: (3)

It would still vary the back pressure as the emphasis switched from charger to turbo and back

RWD_cossie_wil

iTrader: (9)

I'm thinking use a vac operated blow-off valve infront of the supercharger, so as you release the throttle, it will bleed away the excess air,and close when you put your foot back down.

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

JPA

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

Joshy

this sounds interesting this is what i like PF for... the perspectives on difirent subjects

Trist

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

Chip

iTrader: (3)

Interesting stuff.

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!

Chip

iTrader: (3)

Im guessing transient fuelling is far less of an issue on marine engines due to the nature of the way they deliver power anyway?

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!

Joshy

could you run the bypass valve of of a solanoid controlled by a VCT function from the ECU, like a V-tech on-off setup?

caprizetec170

didn't lancia do this with group b 037's or something

Chip

iTrader: (3)

if you used the right valve then yes, but getting the map correct wouldnt be trivial, and i dont just mean the map controlling the valve, i mean the one responding to its new position etc too

Big Will_

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.

Roscco

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?

DangerousBryan

AVA did a black saph with 2 turbos and a huge intercooler. made quite silly power I think but never got properly finished.

Big Will_

AMS in the states did close to 1100bhp with this setup:

I believe its a GT30 and a GT42 with a nice series of wastegates and bypass valves.