Chip

iTrader: (3)

Am guessing that big square block on the intake to the big turbo is a valve to shut off the airfilter during spool up?

If so thats again not really compound charged by the looks of it, its just one swapping to another.

The thing is that with GT turbos able to make 3bar of boost in one go, there really isnt any need to actually compound charge to increase boost!

ECU Monitor Enthusiast

iTrader: (1)

Yes it could. As long as the map sensor and the charge air sensor are in the intake manifold, it is irrelivant how the boost pressure is created.

XRT_si

iTrader: (2)

Very interesting! Did you ever consider seeking advice from Chris Todd out of interest?

I remember reading Harvey Gibbs had a play with getting a supercharger to work on Mike Rainbird's car, which is what I assume Jimbo is referring to.

chaffe

Not entirley sure about that chip, as the seal on the compressor side will see boost under normal circumstances anyway as the are on the pressurized side of the compressor wheel, certainly a very interesting subject, tractor pulling tractors use twin charging to bump the boost up from 20psi to 60psi, they are also using power washer pumps for water injection!

chaffe

looks that way, i think something like this would be easy to achieve with two different sized turbos, or with a supercharger and a turbo

Chip

iTrader: (3)

Yeah tractor pulling is an interesting situation, but as you mention they are only generally going for 60psi, which is achievable on a single turbo anyway.

You have to think about what fuel you are using, for road fuel I am not convinced that 60psi+ is actually what I would ever want anyway.

chaffe

i agree, but then for a road car twin charging is not prehaps the best solution. I think they twin charge on the tractors as a big enough turbo is not available cheap enough

Big Will_

Chip,

As I understand it, the way AMS did their setup was:

From low rpms, the valve in the intake block was shut allowing no air to be drawn through the air filter to the GT42.

All exhaust gas was divided both into the 42R and into the GT30 turbine housings. As the boost from the 30 was produced it was all blown into the intake of the 42R.

At this point the 42R starts to spin as the boost is blown through it, the boost then goes through the intercooler and into the engine. As it is pressurising already pressurised air, it is actually giving a net result of pressure ratios squared meaning high pressure boost is quickly achieved at lower engine speeds.

Through some clever ECU algorithms, boost control solenoids and stepper motor control - the wastegate for the 30 is opened to recirculate all the exhaust gas into the 42 turbine and the intake block valve now moves to close the 30 boost pipe and open the air filter path.

In effect, its using a GT30 to get a GT42R 'on song' and then letting the 42R do the hard work!

chaffe

worth noting saab do a twin turbo 1.9tdi engine, my father had one. uses a tiny turbo and a reasonable one, cant remember for the life of me how it was piped up though! i think thier thinking is to prehaps steer away from the variable vane technology, prehaps due to the problems with reliability?

the mk1 kid

Not in the 037 (i dont think) but definately in the S4 - both group B cars as i'm sure you know. Not read about it for ages, but Lancia took a while to get it working nicely, i remember that.

Plenty on youtube of both group b cars and those used later for hill climbs...

I'd swap my left nut for this one:

http://www.youtube.com/watch?v=X-6SguDEwIg

Tom

Chip

iTrader: (3)

Indeed mate, exactly how it looks, like I have said before though, its not really compound charging in the true sense of the word in that when on song the larger turbo receieves no assitance, this is very different to something like tractor pull engines where the turbos are blowing through each other the whole time.

Still a good idea, but its about spool not increasing max possible boost supplied, so its quite a different concept, and in that respect is much more in common with the TSi etc.

B16JUS

TWIN TURBO YB

5tox

Wow! ... that is very cool

Red16

I've just trawled through my photo library and found the Sapph Cosworth that AVA worked on, think the lads pf username may have been Dumped... anyway, here are the photos.

chaffe

a little unnecesary on a 2 litre lol

chaffe

wow that looks mental

chaffe

looking at it, the exhaust spools the small turbo, which is being fed by the bigger turbo, so when the small one comes on song it will spool the larger one and start the twin charging process. the exhaust from the small turbo feeds the turbine on the big one, at a lower pressure. Would the small turbo not become a restriction in the system?

Chip

iTrader: (3)

Certainly a lovely piece of fabrication, not sure its required though.

Lambchop

iTrader: (1)

Hmmm...

Flint!

I was going to post this. I think space under the bonnet was an issue.

Correct

joffy

iTrader: (1)

Did turbosystems not do one? Or am I thinking or a twin turbo setup?

Fezman1

iTrader: (1)

The tractor pulling boost pressures quoted are abit off- they are much more
a typical superstock tractor -compound charged- will see boost pressures of upto 100psi, producing power outputs of 2500hp and more

Fezman1

iTrader: (1)

And some people seem to have the 'compound' concept the wrong way round.
You have the high pressure turbo(small one) and a low pressure turbo(the big one).
In true compound charging the large turbo flows alot of air, the small turbo multiplys the pressure that the large one makes.
With large intercoolers and/or charge coolers both turbos can easily make 3:1 pressure ratio efficiently, so with 1 bar of atmospheric pressure going in the theoretical boost available is:
1 x 3 x 3 - 1 = 8 bar (120psi approx).

b63_rs

must say that looks a cracking bit of fabrication!

Fezman1

iTrader: (1)

It is not to do with budgets, yes in some cases you could find a large enough turbo to do it but there are two major issues
- try getting it to build up boost before you dump the clutch
- egt's, compound charging lowers exhaust gas temps

chaffe

Not sure, i am just going by what i was told at a local event, there is all sorts competing, not just TD stuff but petrols too. Im led to belive they run no headgasket either, as they just get blown out. cast to cast with a wipe of hylomar

chaffe

i just like the black smoke and sound of turbos tbh

Fezman1

iTrader: (1)

Aye, me too

Joshy

I would be interested trying something like this on my mini 1275,

maybe using a GT25 and somthing smaller... whats smaller than a GT25?

they can be made to pull some usefull revs so to have a 6k powerband with a redline of 8.5k would make for some good progress around town

Lambchop

iTrader: (1)

A T2

SiZT

The pictures in the above post are of the infamous Y-gate system where a T3 and T4 were used with a divider in the exhaust mainfold controlled by an ECU or actuator I guess.

A work of art, IIRC it was just a standard engine with skimmed pistons. Again from what I can remember it was on a Turbonetics thumper series turbo which was at full boost by 4,000rpm and it was making 515rwhp at 5,000rpm but it bent the crank.

I believe in tractor pulling they use turbo's of the same size which blow into each other. To get spool and power you would open the wastegate (on the smaller turbo) when the big turbo is coming on song.

GT15 diesel turbo, however in a mini I doubt you'd have the space.

Joshy

with a fiberglass front i might

crumpet

who owned and built that white twin turbo cossie? and when was it?! looks years agO!

RWD_cossie_wil

iTrader: (9)

Was Prism motorsport I seem to remember?

In my inital post I was actually talking about 2 different systems, compound charging being 2 turbos in series as shown by the AVA saff, and twin charging like the VW GT engine.

Both are interesting

stevieturbo

There is plenty of room in a Mini for a variety of turbos.

Joshy

but a variety all at the same time

big_wig_074

that was never a group b car,its an integrale,not an s4

THIS is an s4 hillclimber!listen for the supercharger whining away,looks totally different too
http://www.youtube.com/watch?v=LTIKU...eature=related

AustenW

Good Thread

Chip

iTrader: (3)

And room for a better engine, I do love the old A series as its what I cut my teeth tuning 15 years or so ago but ultimately its just not up to the sort of power levels I like these days, particuarly the drop gears and gearbox.

Mini's are still my favourite car, but its all about having one with a modern multivalve engine these days I reckon!

the mk1 kid

You're absolutely right - out of all the tabs open of 037's, S4's and such like i should have paid more attention to which one i copied into my reply, particularly as that video is entitled 'Felix Pailer - Lancia Delta HF Integrale'!

Tom

chaffe

i used a t15 off of a vw tdi passat on my very first turbo conversion, it lasted less than a week as the heat from the petrol engine was too much for the diesel turbo.