Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 12 of 12 Posts

·
Registered
Joined
·
14,305 Posts
Discussion Starter · #1 ·
Bubbles has recently spent a fair amount of time down at Abbott to attend to a couple of problems… poor/variable performance and economy and gearbox fragility.

I’m reporting the outcome here as an impartial and informative exercise for everyone, but nonetheless credit is due to Abbott for their knowledge.

Gearbox:
There is a known problem with early 9k gearboxes in substantially upgraded models that the circlip that holds the 3rd/4th gear hub in place fails under pressure. This is owing to the slant cut of the gears causing longitudinal pressure on the shaft under load. The slant cut has no benefit to synchromesh (this is taken care of by the synchro rings) but helps to keep noise down. Race boxes are straight cut.

Later models (MY94-) are not so susceptible to this failure because they have a washer behind the circlip. The “fix” for early boxes is to replace the 3rd/4th gear hub with the later model version and machine the shaft to accept the washer. I’ve had this done.

Also, there is a compression ring that tensions the gears along the shaft. This also has to absorb the shock/loads and can fail. I’ve had this replaced by a longer spacer from a much earlier box and shimmed (this can be labour intensive ‘cos you have to get it just right, and the only real true test is to bolt it all together).

Lastly on the gearbox I’ve had the very long (3.61) drive gear replaced with a 4.05.

The ‘box is now very nice indeed. The change is precise and easy.

Other news on the box- there are later, better synchro rings available but you have to change them all at the same time and convert to synthetic box oil.

On the engine management front, it gets more complicated. I originally asked Maptun for software to match the spec I provided them, which was equivalent to their stage 5, and should have netted 350hp.

However, 93 is a difficult year to programme Trionic, and the best I ever achieved was 309hp/358lbft. There were also difficulties with trying to get the software to cope with the very fast spool up of my roller bearing turbo.
[edit] This was Maptun SE, not UK, and they did say they could probably sort it, but I would have to take my car to Sweden. This wasn't a practical option for me, so I decided that I would live with it as it was.

Recently, the car just hasn’t been running right, as was shown by the Emerald RR.

I’ve increasingly been coming to the conclusion that whilst the lower stages of tune are pretty much plug and play, once you want to venture in to the higher power levels, you need to get the entire system custom mapped.

Pete at Abbott spent a long time trying different mappings, and has come up with a map that seems to work pretty well to contain the excesses of the turbo. It’s now holding nearly 1.3 bar up to the red line. I hope to get it dyno’d soon to see real numbers. Initially, it feels slower as the initial torque wallop isn’t as high at lower revs, but higher up it keeps pulling like a steam train. I’m living with the car for a wile now to see if I want to change the characteristics.

The end result is a car that Abbott call “very* quick”.

*actually the adjective was rather more crude, and I’m inclined to agree…

So, the conclusion of this episode in Bubbles’ development is fundamentally that once you seek more than modest upgrades, you’ve got to make sure all the elements are matched. In many ways we’ve been lulled in to a false sense of economy because Trionic upgrades coupled with generously rated stock components result in very significant power increases for relatively little money compared with other marques. However, if you want to go large, you do have to pay- to someone who will take on board the whole package.
 

·
Registered
Joined
·
1,261 Posts
whilst the lower stages of tune are pretty much plug and play, once you want to venture in to the higher power levels, you need to get the entire system custom mapped.[/b]
Not necessarily true. Higher stage packages are pretty much plug and play too, providing you do not deviate far from the required hardware spec. that has been tried and tested by the tuner and forms an integral part of the stage package. Simply asking for Stage X software because your hardware is 'similar' is no guarantee of success, as some people have found out. If your hardware does not match the requirements then yes, a custom map will be required. The only way this can be done effectively is by taking your car to the tuner and leaving it with them. Custom maps by mail are, at best, hit and miss. There are too many unknowns.
 

·
Registered
Joined
·
14,305 Posts
Discussion Starter · #3 ·
Yes, Julian, you're right- I should have been clearer on that, because that is what I really meant!

My point is that many folk buy the lower level packages, then add bits themsleves and don't get quite the results they hope for because the software is not matched to them. I also think the tuners should take more responsibility for making this clear.
 

·
Registered
Joined
·
128 Posts
Bubbles
When you are up grading a 900 or 9000 what is the best model to start with?
And which to avoid?

You mention the gearbox needs mods to handle the additional power.
Does this include the MY94 and onwards or are they o/k?

Is it best to have the gearbox mods done at the same time as the engine, or wait until you have problems?

Were the better syncro rings ever fitted as standard? If so when?

I assume all the above refers to a manual; does the auto suffer the same?

You mention the very fast spool up of your roller bearing turbo. Please tell me more.
Don’t they normally run on needle or roller bearings?

Isn’t it a standard Saab turbo (garat/mitsu), or have you had one custom built?

T.I.A.
Pete
 

·
Registered
Joined
·
1,448 Posts
I believe Bubbles is currently sporting the GT28R, rather than the RS ....



Similar, but the upper-most horizontal line indicates the maximum rated compressor rotational speed ... and a PR of 2.6 is about 1.6 bar or boost, or 23.52 psi. So be careful pushing much past this.

Could be wrong?

Dubbya~
 

·
Registered
Joined
·
14,305 Posts
Discussion Starter · #7 ·
My experiences relate to a 1993 9000CS 2.3T. The debate about 900 vs 9000 as a tuning package is another matter altogether...


AFAIK the turbo is a hybrid T3/T28, not the Garrett GT series. I can't find the original spec on it I'm afraid .
[edit] the p/n is 466541-001 if that means anything

The bearings on most turbos are simply a precision sleeve through which the shaft connecting the trubine and compressor wheels passes. The shaft is in effect held in place centrally by the film of oil that surrounds it.

Manual MY94 onwards boxes are stronger and should fare better. However it would still be possible to carry out similar work- but I would say you'd probably only need to do that once you're knocking out over 350lbft. That doesn't mean they won't still fail quicker than mormal as a result of the extra torque; it just means they'll last longer than the earlier ones for this particular problem/mode of failure.

The autos cannot reliably take such tuning. As stock, they're pretty much on the limit of their circa 200lbft design max. You need to have a tuner who can map the software to avoid exceeding this limit lower down the rev range whilst still increasing the power at the top end.

I don't think the improved synchro rings were fitted as standard to the later 9000s- I think they are from 9-5/9-3 internals, but I could be wrong.
 

·
Registered
Joined
·
778 Posts
I was assuming a 28RS, not a 28R, because the 'R is only rated to 290 hp, whereas the 'RS is, theoretically, good for 350 hp, which is what Bubbles was aiming for. My MHI TD04HL-15T (6 cm^2 turbine) was compressing to 1.65 bar and with adjusted timing and fuel maps I'm sure it was producing similar hp/torque figures that Bubbles' did. I've considered 'upgrading' to the disco potato, but I'm concerned about the quick spool. Regardless of the difficulties specific to the T5.2, I'll bet it's just as difficult doing 'long-distance' reprogramming of the T5 to the disco potato, if not impossible. When I was in Stockholm, I didn't hear of anyone using the disco potato. That may change soon, I bet, especially if exchange rates stay as they've been - the SEK is very strong against the $. So strong, it would probably offset the shipping cost.
 

·
Registered
Joined
·
14,305 Posts
Discussion Starter · #9 ·
The thing I do remember about the turbo is that it was quoted as being good for 350hp.
 

·
Registered
Joined
·
4,215 Posts
sounds good..

higher stage packages are pretty much plug and play too, providing you do not deviate far from the required hardware spec. that has been tried and tested by the tuner and forms an integral part of the stage package. Simply asking for Stage X software because your hardware is 'similar' is no guarantee of success, as some people have found out.[/b]
..oh yes...

still ..nearly there ( a year later !!!)
 

·
Registered
Joined
·
6,531 Posts
Originally posted by Bubbles:
[qb]My point is that many folk buy the lower level packages, then add bits themsleves and don't get quite the results they hope for because the software is not matched to them. I also think the tuners should take more responsibility for making this clear. [/qb][/b]
Very true, some tuners even advertise that individual components will increase bhp by x amount without mention of any further tuning required to realise that figure.
I think I'll stick with the advertised stages, seems a lot less hassle all round!
Glad bubbles is up and running!
 

·
Registered
Joined
·
1,448 Posts
The bearings on most turbos are simply a precision sleeve through which the shaft connecting the trubine and compressor wheels passes. The shaft is in effect held in place centrally by the film of oil that surrounds it.  [/b]
Actually the BIG difference (both have a shaft of some sort) is the thrust washers at the end of the main shaft.

Here's a traditional bearing layout. (The significant radius of the thrust washer creates significant torque on the shaft):


The GT25 is only good to 250 hp. The GT28R flows as much as the GT28RS, but doesn't like high boost as much as the RS does, and is less efficient. So it has to "work harder" to make the same flow. All of the Garrett GT "R" turbos are ball bearing.

Dubbya~
 
1 - 12 of 12 Posts
Top