compound charging?

6th July 2009, 15:24

hypothetically speaking, could it be done to a j4 or jp4 engine?
obviously im not considering doing it but just had a daydream about a compound charged engine running itb's

6th July 2009, 16:40

Yes you can. What sort of setup are you looking at?

6th July 2009, 17:35

before i start this is all speculation!
i would like to try and pull my engine out and completely rebuild it internally and get it on bodies by the end of the year but would love to take it off the road and keep going with it over the next couple of years though.
i want to specialise in tuning when i open my own garage so would love a saxo with stupid amounts of power!
i noticed threads saying t/b s/c or t/c, and thought why not all 3!?

6th July 2009, 17:39

how would you do it? air filter > turbo > s/c > intercooler > plenum over the bodies? i was thinking that way for the placement in the bay and if the turbo was after the s/c it would maybe restrict the boost from the charger before the turbo kicks in. or would you do the charger before the turbo?

6th July 2009, 17:42

Getting it running reliably would be fun.

6th July 2009, 17:45

ha ha im sure! maybe forged rods pistons and crank? uprated valves and springs and stuff?
ive not even started college yet and only just about managed an engine conversion which still needs wiring properly so i think i may be getting ahead of myself slightly ha ha! i just want to learn, and we dont learn without asking!

6th July 2009, 18:02

A compound charger is using two charging units one after another. These are normally only used in very high boost applications. Take for example a centrifugal super charger. Most will only boost to around 1 bar. If you are using such chargers and wish to boost to say 2 bar you can use one after another each boosting to 1 bar over the inlet pressure.

I think what you are trying to do is set up a something akin to the Lancia S4 to reduce lag bust still be reliable, is this correct? If so this is not a true compound charger. The S4 has a small positive displacement supercharger that boost from even low revs. Then it has a turbo running along side it feeding air to it. As the turbo starts to spool up there is a air bypass valve that effectively disconnects the supercharger. Its still spinning but not boosting and in so takes next to no power to spin.

Like this:

................................................Su per charger...........................Tbody
...............Turbo - Intercooler< ......................... > Intercooler <
Air Filter < ..................................Air Bypass .............................. Air Bypass-\
.............. \_________________________________________________ _________/

6th July 2009, 18:20

yeah thats what i was thinking a small supercharger to provide boost before the turbo kicks in. ive always heard this referred to as compound charging?
would the turbo sit before the spercharger then so when it starts boosting its pushing air past the supercharger disconnecting it? is there a specific supercharger that is designed for this or do you modify a normal one?

6th July 2009, 18:33

You can just use a normal positive displacement charger. The only difference is the big air bypass sat in parallel to it.

6th July 2009, 18:35

ok how does that work then? is the positive displacement the one that looks like half a turbo?

6th July 2009, 18:41

No a positive displacement super charger are normally the ones with what looks like two screws in them. Often found on Jaguars, Merks, Minis and so on.

The ones that look like half a turbo are centrifugal and work very differently. They do not produce much if any boost until they are spinning very quickly. A standard turbo setup will produce boost before this sort of supercharger does and in so is no good as a anti lag unit unless you are going to use a clutch or gearbox with it to stop it from over spinning at high revs.

6th July 2009, 18:45

ah ok, would a positive displacement one fit in a saxo bay if there was a turbo squashed in there too? how does the air bypas system work?

6th July 2009, 18:46

dp engineering did a twin turbo supercharged 206 1.4

worht giving them a shout linky = http://www.dp-engineering.nl/EN/projects/twinturbo.php

for the money you would have to spend to get it up to spec it may be worth considering going down just one route, that said go for it PUSH THE LIMITS

6th July 2009, 18:49

well, i wouldnt be doing it all at once lol! i'd wanna build it as a demo car with the idea that if someone wanted bodies or a turbo/supercharger they might consider the guy who put all 3 on a saxo lol

6th July 2009, 18:50

If its small enough you can fit them. There was a Swiss company selling a really nice kit to fit a small one just in front of the battery.

A air bypass valve us just some sort of valve that opens to let air past. There are many sorts out there that can be used. Common ones use on cars are diaphragm units that simply use air pressure to open them as a given pressure.

6th July 2009, 18:50

http://video.google.co.uk/videoplay?...in+turbo&hl=en

video it sound mean - enjoy

6th July 2009, 18:54

ah so you wouldnt run the turbo and s/c in sequence?

6th July 2009, 18:58

alot of setups only use it to fight the lag that you get from using a big turbo setup,

im not sure how vw use it on its scirocco TSI that may be in sequence??

6th July 2009, 19:00

im trying to get my head around exactly how it would be set up

6th July 2009, 19:03

really are best of getting in touch with someone like DP for the low down on it all lolim sure i have seen them in line though only to run huge boost

6th July 2009, 19:05

there was a fiesta a couple of years back running a s/c and turbo putting down some good 1\4 mile times iam sure that was on a 1.6 engine aswell. iam doing a conversion at the mo for a friends vtr using a r5 carb and a t5 turbo should be fun.
adam

6th July 2009, 19:05

Its quite simple really,

Air Filter – Turbo – IC1 – Super – IC2 – Tbody

Its just there are air bypass valves that control the air flow.

6th July 2009, 19:07

could it not be set up for the air to go through one intercooler? not much room for 2 coolers!

6th July 2009, 19:11

Quote:

Originally Posted by LeeM

could it not be set up for the air to go through one intercooler? not much room for 2 coolers!

Not really. Every time the air is compressed its heated up. You could easily use two small water cooled charge coolers as there a lot smaller than air ones. Then they could both be supplied from a single front mounted water rad.

6th July 2009, 19:13

why not whack some nitrous in the mix to lol 1 very very crazy car!!

6th July 2009, 19:13

so, what would you have to do about compression and cams?

6th July 2009, 19:15

forged internals con-rods ect maybe over bore it, custom profile cam, if your going to do it properly then you will really need to spend some money

6th July 2009, 19:18

also your drivetrain needs to be up to spec, brakes!! gearboxs would be destroyed on a regular basis id say with all that potential torque, shasis would need reinforcing ect

6th July 2009, 19:21

Try http://en.wikipedia.org/wiki/Twincharger

Its been done in a car of saxo size, there was a factory Micra that had both turbo & superchargers.

6th July 2009, 19:23

well when i eventually take the sax off the road it'll be to seam weld it and cage it. and i wouldnt want to weaken the engine by boring it.
would the compresion need to be lowered? ive never heard of it being done on bodies and never looked into superchargers.
and i really cant work out how bypass valves work lol

6th July 2009, 19:27

i think iirc a gti on owners was either turbo'd on bodies or charged on bodies and for the hassel of it the car was off the road more than it was on so he scrapped it and went with just a turbo i think?? but if you pull it off youll be well known and respected for it for sure!! if you dont push the boundries you dont know what they are go for it!!

6th July 2009, 19:30

i think the potential horsepower from the setup could be resticted by the standard inlet and tb?

6th July 2009, 19:42

Quote:

Originally Posted by LeeM

i really cant work out how bypass valves work lol

Mid RPM turbo provides some boost and the super charger compresses it the rest.

High RPM turbo is providing more then enough to the air bypass opens and all the air goes strait from the turbo to the engine.

Its simple really.

Just about any boosted application uses them to get the most from it. Most turbo charged road cars have at least two bypass valves.

6th July 2009, 20:03

Quote:

Originally Posted by Quick

Try http://en.wikipedia.org/wiki/Twincharger

Its been done in a car of saxo size, there was a factory Micra that had both turbo & superchargers.

gutted, i wanted to post that lol, ive drove one aswell, and its a 1 litre, super nismo, and by fuck does it go like stink for a small car