UKSaabs

Yesterday I have made the upgrade from Stage 3 to stage 5 on my 9000 2.0.
I installed a 3bar map sensor, Deca 630 Injectors and a ported/polished Garrett bigT28 from Gpop-Shop.
With the new map from Karl, so far everything works fine. I have to do some fine tuning with base boost. There is a green spring in the forge wastegate and it is to weak. I ordered a set of stiffer springs. Yellow would be perfect for 1.5bar peak boost.

Here are some pics of the Turbo I installed (compared to the stock T25).

Are you planning to get it on a rolling road to see what she's pushing?

_________________
Gone
04 9-5 Aero S1
99 9-3 SE HOT S3
98 9K 2.3
92 9k CD 18T
99 9-3 19T
00 9-5 Aero S3
96 9K Aero S3

I thought the T28 only had a max power rating of around 250bhp ?.

Thus a stock TD04-15T would have been better, as they will run at 1.4 / 1.5 bar and produce 300bhp on a B234.

_________________
92 9000 CSE 2.0T TD04, Street Terrorist.
97 9000 Aero 2.3T JulesTune Stage 2+
05 Astra 1.8 Elite

there was a 9000 with this turbo and a b204 ( I actually bought it ) and it made 340 iirc ,green giant's ,jr downpipe and a good tune

_________________
Turbo X wagon +hirsch
900 t16 s carlsson under renovation
M-power Clan Crusader
Volvo xc90
mazda2

The b204 can reach 270hp with his standard T25 on Stage 3.
The big T28 is a standard T25 with compressor and exhaust housings machined out to accept a T28 complete new centre section. Wheel dimensions are identical to the GT2860RS. It only flows 5% less than the Gt2860RS because of the little smaller compressor housing.
Compared to the Mitsubishi, the exhaust housing of the big T28 is 6.67CM2 and the compressor housing has almost the same size like the 19T. So it is comparable to the TD04-19T-7.
I know, it's an old school Turbo with journal bearing but it is 100% plug and play and from the practice I can say that it spools at 2500/min and has good mid and top end power. Smoother, more gearbox-friendly acceleration than my past 18T Stage 5 9K Aero and better rev capability. My conversion still has potential because of the standard clutch (I think it is already the 240mm version) and the weak wastegate spring.
340 is exactly the power I expect. As soon as the conversion is optimized, I will get it on a rolling road and post the Dyno Chart.

if you need the green giants ,I may still have them ....

_________________
Turbo X wagon +hirsch
900 t16 s carlsson under renovation
M-power Clan Crusader
Volvo xc90
mazda2

Ive certainly not seen a T25 achieve that much. About 250 something is the highest ive seen on a dyno. Problem is by 5000rpm they are down to 0.7 bar, and by 5500 they are at 0.6bar max.
They will make about 1.3bar up to 4000rpm, but it rapidly tails off after that. They also do not last long when pushing higher pressures.
On the 9000 Carlsson the T25 was pushed to 1bar max with the Red DI/APC box. Rated at 205bhp on the 2.0T.

_________________
92 9000 CSE 2.0T TD04, Street Terrorist.
97 9000 Aero 2.3T JulesTune Stage 2+
05 Astra 1.8 Elite

Plenty of folk have broke 250bhp with a t25. Iirc a few have broke 280 on the dyno. 270 is definitely achievable. Pretty sure I've seen it with my own eyes on a couple of Dyno days I've attended.

_________________
Gone
04 9-5 Aero S1
99 9-3 SE HOT S3
98 9K 2.3
92 9k CD 18T
99 9-3 19T
00 9-5 Aero S3
96 9K Aero S3

I did 267Bhp on a Stage 3 B204 dyno to prove.

_________________
Project 9-3GT 484Bhp+ RWD
trackcar.

Paul is referring to the fact that the T25 on the 9000 is different (smaller) to the T25 found on the 900/9-3. Heck there may well be more than one T25 used on the 9000.

The T25 used on the 900 is actually a remarkably good turbo and can achieve 260-280hp. It's flow is roughly 7% less than the TD04-15T, but it has a bigger exhaust housing so probably makes up some of the distance there in reduced back pressure. I've data logged one on the dyno which made 284hp, still hanging on to 1 bar boost at 6k.

_________________
Homebrew Stage 3 - No longer nobbled by heatplates

I didnt even know they were different T25 models to be honest. Learn something every day.
How on earth did you get it to hold 1 bar until 6000 ?. As they tail off to 0.6 bar by then.

The Carlssons ran 1 bar boost on the T25.
9000 Carlsson 2.0T was 205bhp.
And the 9000 CS 2.3 Carlsson was 220bhp.
Both with boost requests of 1bar. But they tailed off at high rpm even when new.
That was the main reason my son converted his to TD04. Pics halfway down this thread >>

viewtopic.php?f=35&t=157801&start=40

_________________
92 9000 CSE 2.0T TD04, Street Terrorist.
97 9000 Aero 2.3T JulesTune Stage 2+
05 Astra 1.8 Elite

Yup my 9-3 was reliably putting down 280bhp on a T25....and it got a hiding on a daily basis from me, removed the T25 to fit a TT hybrid and found some of the compressor blades were damaged on it from a previous owner.

I actually have a good bit of respect for the little T25 after that

My other halfs 9000 made 267bhp at stage 3 using a standard 9000 T25

I also didn't know they were different T25 models between 900 and 9000. Thanks for this info.

Yesterday I replaced the green spring with a yellow one on the wastegate and 1 ½ turns of preload. I hoped that I would have between 0.6 and 0.7bar base boost.
With this setting I was getting successive boost spikes from 2500 to 3500rpm up to 2 bar (see video: https://www.youtube.com/watch?v=RsAIrfBya78).
Then I measured base boost and the gauge showed 0.85 bar.
So I reduced preload first to 1 and then to nearly zero but still have 0.85 bar base and this bad spikes.
I tried two different (used) t7 APC but without success.
Maybe both APC are fault or should I play with removing APC restrictors?

The T25 on the 900/9-3 is definitely a bigger turbo than the T25 on the 9000. Probably need someone to measure the wheel sizes and housing aspect ratios to find out the specifics of it. These two plots are both from T25 based B204 stage 3 cars. One with the dreaded heat plates (mine) and one without. Both happily hold onto 1 bar past 6k, though the heatplates on mine cause temperatures to soar past 70, no heatplates barely breaks 50.


On previous experience, taming boost overshoot can be quite difficult. I'd say stick with base boost being around the 0.5-0.6 bar mark. You could remove the restrictor in the APC as this ought to have the effect of really damping out boost climb rate, though it's normally quite severe and prevents making boost request. Higher base boost usually requires the boost control maps to be live tuned to suit the hardware which can take some time to iron out. When I did mine, it took me a few days of trial and error runs to tune the PID and boost regulation constant maps on my 900. It was definitely a worthwhile investment as the boost behaviour afterwards was almost perfect, with no overshoot and a nice smooth curve. (as can be seen in the dyno plot above, green being boost for mine, pink being boost for the other car)

_________________
Homebrew Stage 3 - No longer nobbled by heatplates