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Discussion Starter · #1 ·
Hi,

want to pick the brains of the more perormance-orientated amongst us. Don't know if you've seen my thread in the 93 & 900 forum, but I'm thinking of a new car and want to know the difference between Trionic 5 & 7? I'm maybe looking at either a 93 Sport Hot or a 93 Aero, on paper the difference is just 5bhp, but what will the tuning potential differnce be between these two engines?

Sgould's given me some pretty sound advice about the 95 Aero being a better starting point for tuning potential, is the 2.3 enging really that much better?
 

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Originally posted by asp900:
[qb]Sgould's given me some pretty sound advice about the 95 Aero being a better starting point for tuning potential, is the 2.3 enging really that much better? [/qb][/b]
IMHO, yes it is ... because I'm a big lover of torque and the 2.3 makes much better torque at low revs than the 2.0. However, on the flipside the 2.0 is keener to rev, so if you're the kind of person who loves to stir the gears you may prefer the 2.0 anyway.
 

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There really is no difference between the two in terms of 'potential' performance. There are differences in the control designs: Essentially, the T7 is air-mass density (MAF) based and uses whatever boost is necessary to achieve preprogrammed torque values, whereas the T5 uses temperature and pressure (MAP) sensors to achieve preprogrammed boost values.
The constraints for performance tuning lie with hardware, not software. With knowledge, anything is possible - once one understands the control parameters, it's the same general principles involved with tuning a T7, a T5, or any turbo engine: with proper fueling, ignition timing and turbo control, then the sky (and depth of ones' pockets) are the limit. In terms of hardware, the B234 turbo engines were much more robust, internally, than the B235 engines: stronger pistons, & rods, basically. Whatever performance 'weaknesses' that exist between various Saab models seems to come from hardware issues, not software/control. The T7 is a very sophisticated and 'state-of-the-art' piece of engine management. Although it's almost 10 years old, I'd wager that it's still light-years ahead of most other marques, in terms of what it does, and how it does it. T5's are great, too, but the T7, takes the spark plugs as combustion sensors to a much higher level. I'm biased towards B234's, having owned many 9000's, but I can appreciate the refinement in control technology that the T7's represent.
 

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Discussion Starter · #4 ·
Would you say that a B234 based engine then has the ability to withstand modifications more if it has stronger internals than a comparable B235 engine?
 

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Originally posted by asp900:
[qb]Would you say that a B234 based engine then has the ability to withstand modifications more if it has stronger internals than a comparable B235 engine? [/qb][/b]
Generally, yes.

You can clearly see this just by flicking through the Maptun site and the changes required to get 340hp out of a B235R here compared to the changes required to get the same power (but more torque) out of a B234R here

The main difference is the B235R needs camshafts and pistons changed. But you'll see that you can go a further stage on the B234R to 400hp, still without needing to change the pistons.
No doubt also, this is a factor of T7 tuning against T5 tuning, as well as the physical engine spec.
 

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If you go with a T7 car, check the oil pressure and monitor it as the oil pumps are an area of weakness and often times won't supply enough oil with no warning light. Melted piston anyone?

Another area of concern is detonation. The MAF sensors should be treated as a maintenance item given T7's heavy reliance on air mass and failing ones can muck up your air fuel ratio.

If the T7 pistons can get enough oil and operate in a healthy combustion environment, I would bet they have a similar power handling capacity to the T5 pistons (ok maybe a little less but still better than most people give them credit for )
 

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Like I said, it depends upon your tuning aspirations.

If you only plan on doing a stage 1 or 2.. then the choice is irrelevant.

Beyond stage 3, both engines can be tuned with the required additional hardware changes.

Biggest element in curbing your aspirations?

Your pocket.
Your Gearbox. (There are few choices to aftermarket strengthen them)
 

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I agree T7 pistons aren't given the credit they are due. However, they are clearly weaker in design as they have smaller ring-lands. They, however, are possibly better for higher revving as they are lighter. With the use of the B234's camshafts (which shouldn't be too pricey), a T7 engine could be made to rev rather willingly and make comparable power, though with less torque. T7's pistons are also coated with Mahle's anti-friction piston-skirt coating.

Here's a picture comparing T5 and T7 pistons to show why the T7's are clearly weaker, but lighter as well: http://img.photobucket.com/albums/v14/Saab...Data/t7vst5.jpg

T7 has some advantages as well; the HOT T7 heads have Nimonic (similar to Inconel, a nickle-base superalloy) exhaust valves, smaller and lighter valves which flow better, principly because of a thinner valve-stem.

Anyway, both engines have much potential. There are plenty of people running the Hirsch 305 bhp T7 2.3L in the Troll-R's. So the pistons can handle at least that much, and that's a fair amount of power to handle. Few people ever request more power from a FWD vehicle.

Adrian~
 

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Discussion Starter · #10 ·
I think you guys are right, ultimately in my situation this decision is fairly acedemic. I'm never going to, at least with a front drive car, need to go past a Stage 3 modification. My main concern was that will reliability be an issue with one more than the other. Its impressive to know that these engines can so easily handle such extreme increases in modification with relative ease.

Thanks for this, I will be back to utilise your collective knowledge later though. A new (to me at least!) car purchase is imminent and whichever car it is there will certainly be some changes ahead for it.
 
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