May be of interest

[George Elliott]

Have been curious to know how the BB turbo on my car spools up, so did a 3rd gear run to video the Engine speed / boost increase data recently.
Having analysed it in slow motion the figures are:

1900 rpm (0.1bar)
2000 rpm (0.2 bar)
2200 rpm (0.45 bar)
2400 rpm (0.8 bar)
2600 rpm (1.05 bar)
2800 rpm (1.15 bar)
2900 rpm (1.2 bar - Boost limit)

Conditions:
Ambient 15 degC
Altitude 160ft above sea level
Pure Irish air []

Other info:
SPS Turbo (KKK hotside / Garrett)
2.5 Litre with LSD
Lindsay Stage 1 I/C
FQS setting "2"
Std throttle body
3inch DP & Exhaust
Dry tarmac

Don't know if thats OK, good or great, but it is nice to drive, and from memory, it is more frisky than my old std K26/8 car.
I realise it is tame compared to some of the big tuning projects here, but in everyday use it returns 28mpg and has managed over 400miles on a tank of BP Ultimate.

It's the good air y' see...[]
George
944t

 

[Lowtimer]

That seems an impressively low boost threshold to me for a 2.5 litre engine on a biggish turbo. What boost do you get at the top end, say 6000 rpm?Does it hold 1.2 bar all the way up?

Mine ( DPW and Promax chipset, but standard exhaust and 26/8 turbo) is doing about 0.5 bar at 2500 by which stage yours is well on the way to 1 bar. Looking at your numbers I reckon yours is doing pretty much the same as mine but about 400 rpm earlier throughout.

I'd better earn some money so I can get one of those BB turbos...

 

[zcacogp]

Interesting. I did something similar with my S2 last week. The results are thus:

1900 rpm (1.013 bar - boost limit)
2000 rpm (1.013 bar - boost limit)
2200 rpm (1.013 bar - boost limit)
2400 rpm (1.013 bar - boost limit)
2600 rpm (1.013 bar - boost limit)
2800 rpm (1.013 bar - boost limit)
2900 rpm (1.013 bar - boost limit)

Conditions:
Ambient 15 degC
Altitude 50ft above sea level
Pure London air []

Don't know if thats OK, good or great, but it is nice to drive, and from memory, it is more frisky than any Turbo, ever.

I realise it is tame compared to some of the big tuning projects here, but in everyday use it returns 30mpg and has managed over 450miles on a tank of Shell Optimax (or whatever it is called now).

It's the S2 engine y' see...[]


Oli.

 

[simkin911]

[][][]

 

[GPF]

One big difference you missed is that George had to replay his in slow motion......

 

[sulzeruk]

Meow!

 

[George Elliott]

Simon, will check the 6k boost...

I fink the Lahndahn smog may be affecting the old Chair lifter Oli.....[]

good night
George
944t

 

[zcacogp]

ORIGINAL: GPF
One big difference you missed is that George had to replay his in slow motion......

Yeah, well, his eyesight's not as sharp as it once was, he mislaid his glasses and he does have a commendable desire for accuracy in these matters.

Not my fault that a turbo is an old man's car!

[]

Oli.

(George, no offence meant old chum. All for the sake of winning the argument, eh?)

 

[TTM]

Is that running against the wastegate spring or do you use an electronic boost controller?

 

[Lowtimer]

ORIGINAL: zcacogp

Interesting. I did something similar with my S2 last week. The results are thus:

<delightful and witty abuse of statistics>

Oli.

Oli, you have outdone yourself. You really should become a political spin doctor. Your sleight of hand is enterprising and impressive indeed.

(For those not familiar with political statistics, Oli is quoting absolute manifold pressure; George is quoting boost above ambient. Translating both sets of numbers into absolute manifold pressure, and assuming the same 1013 millibar ambient pressure that Oli takes, this is how the comparison looks: )

Oli George
1900 rpm 1.013 bar 1.113 bar
2000 rpm 1.013 bar 1.213 bar
2200 rpm 1.013 bar 1.413 bar
2400 rpm 1.013 bar 1.813 bar
2600 rpm 1.013 bar 2.063 bar
2800 rpm 1.013 bar 2.163 bar
2900 rpm 1.013 bar 2.213 bar

Making due arithmetic allowance for your larger capacity and higher compression I must concede that this leaves you steaming ahead all the way from 1000 rpm to 2000 rpm, before George's car vanishes into the distance. Of course, that London air might give you a *slight* advantage in friskiness, what with all the richness and vitality that comes from other people's unburned hydrocarbons and nitrous oxides.

 

[vitesse]

Wow,
Never experienced such wit & incredulity on this forum before-must test my Turbo Diesel BMW (except I haven't got a boost gauge[&o])-that is with the DSC button depressed for over 16 secs

 

[zcacogp]

Simon (Lowtimer),

Thanks. You flatter me with your kind comments!

I've made a couple of small edits to your paragraph below - for educational purposes, you must understand. I can't bring myself not to help you out in your understanding of these simple facts! []

ORIGINAL: Lowtimer

Making due arithmetic allowance for your larger capacity and higher compression I must concede that this leaves you steaming ahead all the way from 1000 rpm to the horizon, before George's car vanishes into the rear view mirror. Of course, that London air might give you *slight* breathing problems, what with all the richness and vitality that comes from other people's unburned hydrocarbons and nitrous oxides.

[]

Oli.

 

[Lowtimer]

Yes, well, of course in Lahndahn with all that smog and buildings and stuff the horizon is only about 50 yards away, on average, so I'll give you that...

 

[George Elliott]

Oli, I enjoy every word of it...keep it up

OK, other questions; I should have said MBC and Tial wastegate

I have since opened a 2" hole in the snorkel close to the Airbox

The 1.2 bar boost is maintained at 6k

George
944t

 

[TTM]

I forgot to ask the stiffness of the spring in the Tial?

 

[George Elliott]

Just took the elapsed times off the video

1800rpm Zero Seconds
1900 rpm (0.1bar) +1 sec (lag zone)
2000 rpm (0.2 bar) +2 sec (lag zone)
2200 rpm (0.45 bar) +4 sec
2400 rpm (0.8 bar) +5 sec
2600 rpm (1.05 bar) +5.8 sec
2800 rpm (1.15 bar) +6.8 sec
2900 rpm (1.2 bar - Boost limit) +7.5

I guess the 2200rpm onwards performance is the nice bit as it takes 3.5 seconds to achieve full boost.

Or - for a greater sense of urgency, prepare 2600rpm prior to the event, and full boost takes less than 2 seconds.

Or for an all out rip, get 3000rpm into the flywheel, and its all instant go when your ready

So, if I get chased out of London by an S2, at least I should be able to escape (if i don't run out of fuel) []

I think the snorkel mod helps maintain a feed of air at high rpm, just try removing it to see the difference.

George
944t

 

[colin944]

Lo ve this.I Laughed so hard I frightened the cat.It's just a shame you turbo boys just don't get that there is no substitute for cc's.

 

[mike220]

What kkk and garrett hot/cold side sizes are they George ? And where was the turbo from, plus a cost ? Did you install it yourself or have someone do the swap for you ?

Sorry if some of the answers are common knowledge, my time on the forum has been sporadic lately due to a lot of travel with work.

Cheers,

Mike

 

[George Elliott]

Mike, its a SPS hybrid turbo, based on the KKK 26/8. It retains the KKK hotside and water cooled bearing housing as I understand, but with a Garrett coldside. The original fit plain bearing is changed for a ball bearing and benefits from reduced friction, and faster spool.

The yanks said that about cc's I think Colin, but when I see an MP4 12C, I realise again, like the TAG F1 engine, there is no substitute for forced induction.

George
944t

 

[Paul 290T]

My '86 turbo manages 0.5bar (gauge pressure) at 2500rpm and hits 0.95bar by 3000rpm, in third.