Stavros

i can barely think of a turbo that hasnt got any turbine housing a/r options.

they not hybrids, they just different options to suit an engines characteristics.

Mike Rainbird

iTrader: (3)

Stav,
But usually it is sized to flow a certain amount of air and then it has options on the housing in an attempt to suit as many engine size applications as possible. Normal you get a choice of three or four aspect ratios.

ECU Monitor Enthusiast

iTrader: (1)

How many pages

And what have we learned,

1) my very first post saying that Stu was keeping it simple for everyone to understand is true.

2) Mike needs experience to understand things but has none

3) Stu was a fat bloke but now is has trimmed up

4) Chip and Tony are c*nts. (Which I disagree)

foreigneRS

this post has grown since i went away for a few days

despite all the for him so far, there is still something that i think mike is slightly wrong with though

the bigger the turbo, the more inertia the wheels & shaft will have (assuming same materials etc). so if you get that shaft spinning with ALS it will keep spinning for longer with a higher inertia whereas it reads to me like mike is saying it will slow down quicker once back on the gas and the ALS switches off

JamesH

iTrader: (21)

Not read all this topic, 9 pages... fook that

But Mike,

I agree with what you say, however the way you put/explain ALS makes it sound a bit shit, as if it doesn't actually help that much.

I'm sure that is infact DOES, and don't forget Stu is marketing his own product so he must try and make it sound as appealing as possible

The rest of the confusion I believe is down to mistaken meanings or use of different "terms" i.e boost threshold etc

RWD_cossie_wil

iTrader: (9)

Mate, I don't belive for 1 second Stu would try to make somthing sound better than it is to sell it, bit of a harsh comment there

rapidcossie

Im bored

dojj

iTrader: (3)

how many thou oversized and will it affect the use of only one supplier of pistons?
also will it affect the amount of boost yu will produce?

again, this is based on the meat and pies aspect of the thread

Benni

My meat pie went cold on page 6.

JamesH

iTrader: (21)

Alright maybe that came out wrong then...

Instead of using terms like "boost threshold" he'd say something else to try and explain it as simply as possible. Then Mike has got hold of these with his term correctness syndrome and we now have this topic!

Mike Rainbird

iTrader: (3)

Smidsey,
In my own experience "ALS" does nothing more than remove the lag in the true sense of the description of "lag", otherwise it would be called something else . It does exactly what it says on the in, so I think your assumption of that it doesn't seem to be the miracle everyone thinks it is, is actually quite accurate.

However, this improvement in lag is definitely worth while IMO and the car feels amazingly responsive within it's boost threshold - so much so, that it feels like a smaller turbo has been fitted.

But even with my 1 bar absolute set up on my car, I experimented on the way home last night and it still feels no different outside it's boost threshold. However, I haven't had a chance to datalog yet.

Chip

iTrader: (3)

On a T34 Mike, you can get a .48 a .55 or a .63 exhaust housing.

The larger housing (.63) is slower to spool, but better flowing at the top end.


Hope that helps

Mike Rainbird

iTrader: (3)

I know you can, as I have had every single one of those on my cars at some point .

I was meaning the generic ones that weren't originally designed for a specific application. They often have a much wider range of turbine wheel / compressor wheel / exhaust a/r size to suit varying capacities and applications in the guise of a generic name "GT30" or "GT35".

Chip

iTrader: (3)

Well then you shouldnt be so surprised they exist

ECU Monitor Enthusiast

iTrader: (1)

Lets not forget the smaller the turbine housing, the more exhaust restriction

Chip

iTrader: (3)

I dont think we did mate, hence I said about the larger housing:

but better flowing at the top end

Mike Rainbird

iTrader: (3)

It's not quite as straight forward as that, and I "think" what Simon is hinting at is also where I made a similar comment. What I meant by this is that where you "think" a particular size is restricting spool up because it is too big, by going bigger on the turbine housing actually frees up the restriction and instead of raising the boost threshold point, it actually lowers it, where-as if you had made it smaller, you would have increased back-pressure and made it worse .

ECU Monitor Enthusiast

iTrader: (1)

Mike,

Spot on.

Turbosystems

iTrader: (5)

I see you have been thinking about this all weekend mike.

Chip

iTrader: (3)

Absolutely, what you are talking about of course is that it increased the engines ability to flow (by reducing pumping losses)

Like you so rightly point out, the turbo and the engine need to be considered as a package not just on their own

Physio

Roll on 10 pages

foreigneRS

any comment on this mike?

dojj

iTrader: (3)

but won't you still be flowing more air at any given turbo rpm than the smaller ones?

i thought thats why you dind't need so much boost on a bigger turbo as per one of the explanations stu gave (possibly) when he was on about compressor maps and stuff way back?
so even if you were going to be bolting a big arse turbo on, the als, even when you put your foot down and turned it off, would still be giving that turbo less slow down speeds once it was off as it's got more mass, and therefore, more inertia/momentum to keep it spinning longer
?
the way i see it, mike may be right in asking if the inial spool up speed will be compromised with a bigger turbo, but after tha, i can't see any downsides other than the heat/mram shaft issue

Turbosystems

iTrader: (5)

10 pages it is

ECU Monitor Enthusiast

iTrader: (1)

So who is right then ?

dojj

iTrader: (3)

but i asked a question, rather than making a post about turning it to ten pages

Mike Rainbird

iTrader: (3)

In my experience, it doesn't seem to work like that. As soon as you come off the throttle on a T4, the boost drops off pretty dramatically, and then seems to take a LOT longer to spool back up than say a T34 (of any housing size). If what you were saying was true, then lag would decrease with bigger turbos, not increase - as the exhaust gases seem to generate more rotational engergy than ALS, yet still you get more lag with a bigger turbo .

ECU Monitor Enthusiast

iTrader: (1)

I suppose it depends how much the RPM drops once you have changed
from one gear to another.

So you could say the "lag" is dependant on gearbox type/ratios etc ... another factor

foreigneRS

with a larger turbo, and hence a higher inertia, of course the lag (without ALS) will be worse. it takes more energy to get the bigger mass spinning so the time needed will be longer.

but what i'm trying to say is that i expect a bigger turbo with a higher inertia to be more likely to keep boosting once the ALS is de-activated by coming back on the throttle - once it is spinning, the higher inertia keeps it spinning and that is self perpetuating in the way chip describes when he was talking about when NOS is used but then runs out

Mike Rainbird

iTrader: (3)

Nick,
I have not experienced ALS on anything other than a T4, so I couldn't answer that. If the smaller turbo has LESS retained inertia than a big one, then ALS must be wank on a smaller turbo, whereas Stav's experience of it seems to be the opposite.

foreigneRS

by definition it does

maybe the differences that you both have experience of are just due to different settings then

Azrael

I don't know if this input help anything but I experienced positive boost at idle(ish) engine speed (I will explain) on T4. This was a car running T4 of Escort Cosworth race car but I presume in rather small trim. Anyway the ALS was made as it is made on group N cars nowadays - 20+% open throttle constant (Evo and Impreza stepper motors are unable to open the throttle enough so it's just bleked and won't close below that). The car was running Motec and with ALS on it wouldn'd fall below nearly 4000 rpm, with ALS of it would idle like all GrpN. rallycars - very rough between 1500 and 2000 rpm and with very hiigh EGT's at idle, as idle speed is managed by retarding and advancing ignition.


Although I must admit Mike is kind of right - it was still laggy at low revs it was much better then with ALS of. I never went far into detail of mapping the car I was only once let drive it.


Another thing I can put here is that from my experience with rally cars (we suply parts for Group N teams and have good contacts with them) they don't really run to rev's so low so they cannot get any boost. In special stage ECU mode they simply won['t fall to such revs, but they have very modern turbos and quite small at the same time.

By the way - it's sad to see a thread with such a atmosphere after long time without looking to the PF.

markk

iTrader: (2)

a pretty MAJOR factor i would say, but then how many people have experiance on close ratio gearboxes in turbocharged cars ?

Azrael

Me me me

I have company car with short-ratio gearbox. In fact too short one...

markk

iTrader: (2)

what about with ALS ?

Redkop

Me

JamesH

iTrader: (21)

Mike,

I've never been in a car with antilag, but it's just the way you describe it that does not make it sound like a miracle - as most seem to assume that it does actually make the turbo spool up quicker

Data logging would be very interesting

Azrael

I did not have both in car to drive by myself. We are just finishing hill-climbing race car (Evo) that has both and do-box as well. We'll see

Gatecrasher

Only on Page 2 but its late so tagging for another day

Physio

Me too