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Car Forum / Saab Cars / December 2005C900: differences soft turbo vs. standard turbo?
Hi, after a few years without a 900 i'm recently considering to get one again. By chance i ran across a 900 soft turbo today.. just had a quick look as the shop was closed, but at least the exterior condition seems pristine (black + aero kit), the mileage with 145tkm is pretty ok. However except for the lack of APC, intercooler and horsepower, i don't have an idea about the differences to a standard 16v turbo. My last 900 was a 88 t16V S.. great machine, excellent low fuel consumption, real bad bite when i hit it.. What's the softturbo engine like? Is it as durable and economic? Will the accel be dissapointing compared to the t16V or acceptable? Any pros and cons you could share? thx..  Signatureben > Hi, > [quoted text clipped - 11 lines] > the accel be dissapointing compared to the t16V or acceptable? > Any pros and cons you could share? Power is about 145 BHP, although there is still a good amount of torque, in excess on 230 lb/ft IIRC. Fuel economy is often quoted at around 25-30 MPG for mixed urban driving and over 30 MPG for motorway cruising. Simply put, driving the light pressure turbo (LPT), or soft turbo as you put it, is like driving the full pressure turbo models on APC "basic boost". If your old T16 every got that "no boost" feeling, where the needle would only just enter the yellow zone, then that's what driving the LPT is like. I wouldn't say it is disappointing, since it is still a cut above the normally aspirated car, but you just know there is more power there. It is quite common to find manual boost controllers and aftermarket intercoolers in the LPT cars, since they are very easy to tune. The turbo is very much capable of high pressure boosting, so long as your fuelling is good. I know of an LPT running 18 PSI of boost ... And the fuelling is quite capable of matching it. If you have a look here <http://www.900aero.com/> in the DIY section, there is a great article about retro-fitting APC to the LPT, but do also be aware that APC is often a cheap way of rigging up a knock sensor LED which would be invaluable if you do decide to turn up the power on the LPT. Of course, if you want a reasonably modern good-looker with a nice cruising feeling, without all that turbo lag and internal organs swishing about when you accelerate, then the LPT might well be for you. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ Hi Paul, > Power is about 145 BHP, although there is still a good amount of torque, in > excess on 230 lb/ft IIRC. Fuel economy is often quoted at around 25-30 MPG > for mixed urban driving and over 30 MPG for motorway cruising. *dooh*.. those ratings in MPG are awkward for.. have to recalculate them to l/100km firts. ;-) *later* ok, fine.. this is pretty much the same figure as my T16 gave me which was 30 to 23.5 MPG, good. before that one, I used to own a (afair 84') 900Gl, which was a shitty lame duck, plus had a much worse MPG than the T16. > Simply put, driving the light pressure turbo (LPT), or soft turbo as you put > it, is like driving the full pressure turbo models on APC "basic boost". If > your old T16 every got that "no boost" feeling, where the needle would only > just enter the yellow zone, then that's what driving the LPT is like. Yeah, my T16 had a somewhat shaky APC which from time to time wouldn't pass the yellow section more than half way.. never couldn't nail down the problem. ;-/ that also means..: > I wouldn't say it is disappointing, since it is still a cut above the > normally aspirated car, but you just know there is more power there. I guess i'll have to give it a test drive.. however i believe it eventually will be disaapointing. There's "nothing compared" to a T16 hitting the red.. ;-) > If you have a look here <http://www.900aero.com/> in the DIY section, there > is a great article about retro-fitting APC to the LPT, but do also be aware > that APC is often a cheap way of rigging up a knock sensor LED which would > be invaluable if you do decide to turn up the power on the LPT. Thx for that url.. however i consider any aftermarket conversions nonsense as long as i didn't own the LPT anyway. It'll make more sense to look for a good T16 in the first place. So for my understanding: The LPT engine, except for the APC/Intercooler is the same double camshaft 16V as the T16? Are there any differences in the chassis, suspension departement or anything else? Thx.. Signatureben >> Simply put, driving the light pressure turbo (LPT), or soft turbo as you put >> it, is like driving the full pressure turbo models on APC "basic boost". If [quoted text clipped - 4 lines] > pass the yellow section more than half way.. never couldn't nail down > the problem. ;-/ that also means..: Usually ground faults ... Got one at the moment on mine :( >> I wouldn't say it is disappointing, since it is still a cut above the >> normally aspirated car, but you just know there is more power there. > > I guess i'll have to give it a test drive.. however i believe it > eventually will be disaapointing. There's "nothing compared" to a T16 > hitting the red.. ;-) Well, there is ... An 8V smacking up to the redline :) >> If you have a look here <http://www.900aero.com/> in the DIY section, there >> is a great article about retro-fitting APC to the LPT, but do also be aware [quoted text clipped - 4 lines] > nonsense as long as i didn't own the LPT anyway. It'll make more sense > to look for a good T16 in the first place. Absolutely! You're talking yourself into waiting for the right T16/S ... If you can test-drive the LPT, then do it. You may well like it. You won't get that half-boost problem, afterall, since that is your top boost :) The power band is well worked out, but it is little more than a normally aspirated car, using the turbo for a little more push and good fuel economy. SAAB really mastered LPT charging on the 9000, rather than the 900 but it does still make a good car. > So for my understanding: The LPT engine, except for the APC/Intercooler > is the same double camshaft 16V as the T16? Are there any differences in > the chassis, suspension departement or anything else? Nope! The engines are the same in the LPT and the T16/S. The fuel injection systems *might* be different - the LPT is definitely Lucas, but the T16/S is Bosch. I'm a little hazy about the later T16s, which might well be Lucas as well ... Little help, someone? :) I'm a T8 pilot, afterall :) Paul 1989 900 Turbo S http://saab.go.dyndns.org/ > > Yeah, my T16 had a somewhat shaky APC .. > Usually ground faults ... Got one at the moment on mine :( See, i never considered gound faults! ;-) I checked all wiring, put the best gas in there.. in the end i thought it must be the knock sensor going haywise, as the boost often was totally erratic, going up and down in a very brisk way. Timing was ok.. well then, that's the past. ;-) When i was out for a fun ride, i simply disenabled the soleniod valve and drove the thingy by foot and APC gauge. .. well, a little solid red here and there didn't hurt. ;-) > Well, there is ... An 8V smacking up to the redline :) Really? A friend had a, dunno, 86' maybe, 8V turbo.. mechanic injecion IIRC, and that was no comparison to my T16. Generally the whole engine hab a really rough and odd way.. but maybe it was just a lemon. > Absolutely! You're talking yourself into waiting for the right T16/S ... If > you can test-drive the LPT, then do it. You may well like it. You won't get > that half-boost problem, afterall, since that is your top boost :) Yes, i'll give it a test drive.. maybe tomorrow.. just to know what we're talking about. > The engines are the same in the LPT and the T16/S. The fuel injection > systems *might* be different - the LPT is definitely Lucas, but the T16/S is > Bosch. Any known issues with the Lucas? > I think when the 900S (LPT in the UK market, maybe mainland Europe, too) was > combined with the Aero bodykit, you often got leather, aircon and lower > suspension. Oh, talking about comfy features it just came to my mind: I do want the sunroof.. I can live without aircon easily, but the roof is a must. ;-) Ah and yes: no whale tail this time.. that was a bit embarrasing. ;-) > Where are you from, BTW? The US certainly did not get the LPT, so I presume > somewhere in Europe by MPG faux pas. Krautsland that is.. ;-) cheers, and thx for sharing your knowledge! Signatureben >> Well, there is ... An 8V smacking up to the redline :) >Really? A friend had a, dunno, 86' maybe, 8V turbo.. mechanic injecion >IIRC, and that was no comparison to my T16. Generally the whole engine >hab a really rough and odd way.. but maybe it was just a lemon. My two existing NA 8V's are beauts. You don't get the 'growl' sound with the 16V heads. 8-) The one that's registered gets driven regularly and last weekend I did a 400 km round trip in it with super performance with the engine in it's peak power spot around 3500 to 4000 rpm doing a nicely sustained 115 to 125 kmh on the open freeways (and more would invite the attention of the constabulary!). Cruises really well and for a 23 year old car really puts a majority of modern vehicles to shame. The unregistered one runs well and I'm steadily fixing everything that's wrong as I learn more about the cars. I got a few patches of silicone sealant off the exterior paintwork yesterday btw using Selley's (Oz brand) Silicone Remover. Fitted a new sound system and learnt about where cabling, fuel and brake lines run through the car body over the last few weeks. Did balljoint, wheel hub, etc. replacements before that. I'm thinking of targetting that car to be the 'subject' for my planned auto to manual conversion 'trial' sometime next year. Don't feel comfy doing it on my good car until I know more about the process. 8-) Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Classic Saab Workshop -- For Saab 99/C900/9000 Enthusiasts world-wide! http://www.classicsaab.net http://www.saabnetwork.net c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. >>> Well, there is ... An 8V smacking up to the redline :) > [quoted text clipped - 4 lines] > My two existing NA 8V's are beauts. You don't get the 'growl' sound with the > 16V heads. 8-) Both my turbos have were/are 8V cars and I really thought the 8V NA was a great car - what a workhorse. Nothing like a turbo though. 8V turbos growl - much nicer than the T16 IMO. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ >>>>Well, there is ... An 8V smacking up to the redline :) >>>> [quoted text clipped - 14 lines] > http://saab.go.dyndns.org/ > I like my 16V turbo with the Red Box :-) You have to take it easy in 1st and 2nd. The V-rated tires are not cheap and I like to keep the transmission in good shape - so burning out of lights is not likely to happen why I drive. With careful driving, you can still make the "objects in the rearview mirror appear smaller" and still save the car. >>>>> Well, there is ... An 8V smacking up to the redline :) >>>>> [quoted text clipped - 8 lines] >> great car - what a workhorse. Nothing like a turbo though. 8V turbos growl - >> much nicer than the T16 IMO. > I like my 16V turbo with the Red Box :-) You have to take it easy in 1st > and 2nd. The V-rated tires are not cheap and I like to keep the > transmission in good shape - so burning out of lights is not likely to > happen why I drive. With careful driving, you can still make the > "objects in the rearview mirror appear smaller" and still save the car. I ran the 'Type M' settings on my spare APC box for a short while and killed the gearbox within 25,000 miles :( That *was* a tyre shredding setup. I could drag bikes off the line, so long as I could get out of first quick enough :O After re-building the gearbox (as well as an engine strip and re-build), I'm taking it easy and thoroughly enjoying the standard setup - it's amazing what that kind of work can do for your car's performance :) Paul 1989 900 Turbo S http://saab.go.dyndns.org/ >>>> Well, there is ... An 8V smacking up to the redline :) >> [quoted text clipped - 4 lines] >> My two existing NA 8V's are beauts. You don't get the 'growl' sound with the >> 16V heads. 8-) >Both my turbos have were/are 8V cars and I really thought the 8V NA was a >great car - what a workhorse. Nothing like a turbo though. 8V turbos growl - >much nicer than the T16 IMO. My 8V N/A's are exactly that - workhorses. Not as quick as some but they keep going. Excellent for highway/freeway driving in all the conditions I've done that in so far. It's going to be fun to experience the difference that having a turbo with a non-APC 8V engine makes! Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Classic Saab Workshop -- For Saab 99/C900/9000 Enthusiasts world-wide! http://www.classicsaab.net http://www.saabnetwork.net c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. > It's going to be fun to experience the difference that having a turbo with a > non-APC 8V engine makes! I gather the pre-APC pistons are a great find and the pre-APC turbo unit/actuator are a great improvement for the later cars. Perhaps an APC retro-fit would give you the best of both worlds? I take it you've seen the SAAB water injection manual kicking around and got some crafty ideas? I know some of the B type owners like it! Paul 1989 900 Turbo S http://saab.go.dyndns.org/ >> It's going to be fun to experience the difference that having a turbo with a >> non-APC 8V engine makes! >I gather the pre-APC pistons are a great find and the pre-APC turbo >unit/actuator are a great improvement for the later cars. Perhaps an APC >retro-fit would give you the best of both worlds? >I take it you've seen the SAAB water injection manual kicking around and got >some crafty ideas? I know some of the B type owners like it! I haven't seen the manual, but I do know that Saab's first use of water injection was on the C900 Enduro which is one thing that makes it a milestone vehicle. My turbo car has a H-block engine so I'm not sure from a turbo perspective what differences if any that brings, but I'll wait till the car is here and registered again before getting into plans for upgrades other than knowing that one of the first things I want to do is put a stainless exhaust system in such as the one made by Ferrita. Beyond that, it's hard to say. So many choices. It'll depend too on the internal condition of the turbo. Other than it's wastegate issue, nothing else has been evident so far. 8-) Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Classic Saab Workshop -- For Saab 99/C900/9000 Enthusiasts world-wide! http://www.classicsaab.net http://www.saabnetwork.net c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. > the LPT is definitely Lucas, but the T16/S is > Bosch. I'm a little hazy about the later T16s, which might well be Lucas as > well ... Little help, someone? :) I'm a T8 pilot, afterall :) My later 1992 T16S convertible is Lucas. And it gives better economy than my old 1984 very early T16S hard top did with Bosch. SignatureCarl Robson Car PC Build starts again. http://smallr.com/rz Homepage: http://www.bouncing-czechs.com > My later 1992 T16S convertible is Lucas. > > And it gives better economy than my old 1984 very early T16S hard top > did with Bosch. I might be wrong, but weren't the pre 88 injections mechanical units? This would explain differences in economy i guess.. Signatureben >> My later 1992 T16S convertible is Lucas. >> [quoted text clipped - 3 lines] > I might be wrong, but weren't the pre 88 injections mechanical units? > This would explain differences in economy i guess.. Nope, all 16v's were electronic... I personally prefer the 16v - IME has fewer issues and pulls better at high speed, but the old intercooled 8v has some rather good in-gear acceleration times... >> My later 1992 T16S convertible is Lucas. >> >> And it gives better economy than my old 1984 very early T16S hard top >> did with Bosch. >I might be wrong, but weren't the pre 88 injections mechanical units? Only if they are 8V engines. I haven't seen any 8V C900's past 1985 (here in Oz anyway), but the 16V C900's were all direct-injection from the outset. Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Classic Saab Workshop -- For Saab 99/C900/9000 Enthusiasts world-wide! http://www.classicsaab.net http://www.saabnetwork.net c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. > So for my understanding: The LPT engine, except for the APC/Intercooler > is the same double camshaft 16V as the T16? Are there any differences in > the chassis, suspension departement or anything else? Just thinking a little more about this one ... There are various trim and comfort specifications for the C900 from around 1991 when the LPT was introduced. Most are badged as 900S on the RHS of the boot/trunk. The later 1991-1993 SE and 1992-1994 XS models were also light pressure or normally aspirated in some cases on the SE badging. There were also some 'ep' badged cars (Eco-Power, with pre-heated catalysers), predominantly for the Italian market, but some seem to surface in the Netherlands and Belgium, particularly. I think when the 900S (LPT in the UK market, maybe mainland Europe, too) was combined with the Aero bodykit, you often got leather, aircon and lower suspension. Oddly enough, despite the 'Aero' being a common build for the T8/S and T16/S since around 1985, the word "Aero" did not appear on UK registration documents until the LPT Aero! I think the only differences you will find are with the Aero bodykit. I *think* that did have the lower suspension I mentioned, but might be wrong. Otherwise, they're the same ... Just internal comfort level and optional aircon and possibly ABS, but I think that was standard by about 1990. Interior sound systems might well vary across markets, as might whaletail spoilers and rear window louvres and vent covers, but we're well into the realm of aftermarket optional accessories and stuff by that point ... Where are you from, BTW? The US certainly did not get the LPT, so I presume somewhere in Europe by MPG faux pas. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ >> Power is about 145 BHP, although there is still a good amount of torque, in >> excess on 230 lb/ft IIRC. Fuel economy is often quoted at around 25-30 MPG >> for mixed urban driving and over 30 MPG for motorway cruising. >*dooh*.. those ratings in MPG are awkward for.. have to recalculate them >to l/100km firts. ;-) >*later* ok, fine.. this is pretty much the same figure as my T16 gave me >which was 30 to 23.5 MPG, good. before that one, I used to own a (afair >84') 900Gl, which was a shitty lame duck, plus had a much worse MPG than >the T16. I'm keen to see just how different the 1982-built 8T C900 is going to be performance-wise and fuel-comsumption wise compared to my existing NA 8V Saab's. Without the incumbency of APC it should do very well and as long as I run the car on 98+ fuel all the time, there shouldn't be any problems with fuel supply to the engine. Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Classic Saab Workshop -- For Saab 99/C900/9000 Enthusiasts world-wide! http://www.classicsaab.net http://www.saabnetwork.net c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. >Hi, > [quoted text clipped - 13 lines] > >thx.. The low boost turbo and full boost turbo are mechanically identical to the best of my knowledge for most of the years. A low boost turbo is more likely a better choice if you want to "tweak" a used car. They tend to be in much better condition and are able to produce as much power as virtually all of the others. The Aero's had a larger turbo to maintain higher boost at higher RPM's Buy a Low Pressure Turbo, Install a 3" Downpipe, APC valve and flash a better map into the CPU. You'll have a 250+ HP, excellent condition Saab turbo that's not been trashed.. Many of the LPT's have inter coolers already, check to see if the one you're looking at has one already. After a bit of tweaking my 96 "LPT" still returns 39 mpg Imperial on steady driving. "Enjoying" it drops the fuel economy to the 22-24 MPG range however. :( > A low boost turbo is more likely a better choice if you want to "tweak" a > used car. Well i don't really intend to tweak, however your point..: > They tend to be in much better condition .. .. came across my mind as well. I'd guess chances are higher a LPT eventually won't be as abused as a T16. > Buy a Low Pressure Turbo, Install a 3" Downpipe, APC valve and flash a > better map into the CPU. What's a downpipe? > Many of the LPT's have inter coolers already, check to see if the one > you're looking at has one already. I'll check that.. thx for your input! Signatureben ><snip> > >> Buy a Low Pressure Turbo, Install a 3" Downpipe, APC valve and flash a >> better map into the CPU. > >What's a downpipe? The pipe that connects the turbo exhaust output to the catalytic convertor. The factory pipe is too restrictive and cause too much turbo lag. Just fitting a larger exhaust from cat back won't give the desired results. With these cars, little tweaks yield good results Good luck, |
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