Getting back what I'm going to lose.
Discussion
I think you lot are pretty knowledgable, so I'm going to throw this one open 
Car: 1978 Saab 99 Turbo. APC system retrofitted and free-flow exhaust. Not much else on the powertrain side of things. 160bhp/~200lb/ft torque (the torque dependent on how I've set the APC up at the time HP seems to remain fairly constant but peak point moves about the rev range with APC settings).
My car in it's present form accelerates nicely for my wants and needs. However, as I discovered at the USD, its top speed is lacking somewhat. This has confirmed I have the wrong gearbox
I'm currently achieving ~29km/h per 1000rpm in 4th gear. I've now found a gearbox which if its innards match the serial plate should give me ~35km/h per 1000 rpm. That's more like it! However, this will obviously make the engine have to work harder for the same acceleration rate.
I have a number of things in mind to alter to get some acceleration back. Ideally I don't want to have to up the boost any more as I'm already running nearly double the original (I'm running up to about 1.2 bar, standard is 0.7). I'm more looking for standard power/torque achieving technuiques:
1) balance and lighten the rotating parts. i.e. crank, rods, flywheel etc.
2) port match the head with the inlet manifold and mess with the exhaust side too - got to look into it but IIRC a bigger manifold port size to head is good to prevent backflow into the cylinder.
3) maybe a touch of other head work to clean things up a a bit in there.
4) maybe a cam change. I should hopefully have a standard injection cam soon, might need reprofiling as it's done a few miles, but they're supposed to add a bit of power. A concern is the off boost performance though...
5) Get a vernier sprocket made up so I can "dial in" the cam a bit better.
6) Maybe have another bash at finding room for an intercooler or give in and fit water injection.
7) Open up the intake tract and get a cooler air path to it.
Any of thise I *shouldn't* be doing? What have I missed off?
I don't want to have to go away from the K jetronic and un-managed FI if I don't have to. Ok, I accept I won't be getting the best out of it, but I want to keep some originality in there - and simplicity for diagnosing problems etc.!
Car: 1978 Saab 99 Turbo. APC system retrofitted and free-flow exhaust. Not much else on the powertrain side of things. 160bhp/~200lb/ft torque (the torque dependent on how I've set the APC up at the time HP seems to remain fairly constant but peak point moves about the rev range with APC settings).
My car in it's present form accelerates nicely for my wants and needs. However, as I discovered at the USD, its top speed is lacking somewhat. This has confirmed I have the wrong gearbox
I'm currently achieving ~29km/h per 1000rpm in 4th gear. I've now found a gearbox which if its innards match the serial plate should give me ~35km/h per 1000 rpm. That's more like it! However, this will obviously make the engine have to work harder for the same acceleration rate. I have a number of things in mind to alter to get some acceleration back. Ideally I don't want to have to up the boost any more as I'm already running nearly double the original (I'm running up to about 1.2 bar, standard is 0.7). I'm more looking for standard power/torque achieving technuiques:
1) balance and lighten the rotating parts. i.e. crank, rods, flywheel etc.
2) port match the head with the inlet manifold and mess with the exhaust side too - got to look into it but IIRC a bigger manifold port size to head is good to prevent backflow into the cylinder.
3) maybe a touch of other head work to clean things up a a bit in there.
4) maybe a cam change. I should hopefully have a standard injection cam soon, might need reprofiling as it's done a few miles, but they're supposed to add a bit of power. A concern is the off boost performance though...
5) Get a vernier sprocket made up so I can "dial in" the cam a bit better.
6) Maybe have another bash at finding room for an intercooler or give in and fit water injection.
7) Open up the intake tract and get a cooler air path to it.
Any of thise I *shouldn't* be doing? What have I missed off?
I don't want to have to go away from the K jetronic and un-managed FI if I don't have to. Ok, I accept I won't be getting the best out of it, but I want to keep some originality in there - and simplicity for diagnosing problems etc.!
Anyone? Noone? 
I think I'm going to see Burton Power about the mods as they're localish and I know someone who's had engine work done there. Can anyone suggest what levels of balance I should be looking for (1 gramme, 0.5 gramme? 0.1 gramme? etc.) and what kind of price I should be looking at for a good job. Also what sort of cost for good head work?
Ta
I think I'm going to see Burton Power about the mods as they're localish and I know someone who's had engine work done there. Can anyone suggest what levels of balance I should be looking for (1 gramme, 0.5 gramme? 0.1 gramme? etc.) and what kind of price I should be looking at for a good job. Also what sort of cost for good head work?
Ta
Cor you had me worried there for a minute with that kind of money! But if the bulk of it was the valves then that should make life easier. I'm hoping to get everything done for about £5-600, but a lot of that depends on how much is left over from getting one door reskinned, the other repaired and the sides tarted up a bit The only thing's I've seen are ~£250-£300 for head porting, and ~1 hour to balance the rotating parts of a 4 pot engine. That seems very quick though! Removing and dismantling the engine I'd do myself, along with rebuilding and reinstalling.
I'm thinking quite a bit ahead with the engine project, but that gives me the time to build up a bit more cash if need be
The only thing's I've seen are ~£250-£300 for head porting, and ~1 hour to balance the rotating parts of a 4 pot engine. That seems very quick though! Removing and dismantling the engine I'd do myself, along with rebuilding and reinstalling. I'm thinking quite a bit ahead with the engine project, but that gives me the time to build up a bit more cash if need be
Hmm, not something I had considered, I think mainly beacause the engine has only done just over 80k miles, so I'm hoping that the pistons rings and bores are perfectly servicable. Of course when its all opened up I may find that they aren't.
I think the cost of pistons, rings etc. on my budget would be prohibitive. ~£50-60 per cylinder at a rough guess? Plus the cost of the extra machining the open the bores out a size. Ok, if it NEEDS doing then I'll have no choice! I've also seen a few people looking about for pre-APC pistons so they can lower their CR's - to up the boost. I'm running quite high boost already, which presumedly would have to come down quite a bit (not necessarily a bad thing, I know). The lower CR I think is probably best to stick to so I can keep the on-boost power up. The way the engine is off-boost is fine for me at the moment, yes it's a bit laggy, but I don't have an isse with that.
Which intercooler did you fit? I'm hoping to get a crossflow NG900 one soon. I think if I move the battery to the boot, improve the heat shielding and use the duct for the battery cooler I might be able to fit it in that area (probably have to use a larger bore tube though). When the battery's gone I'll also offer up the late c900 one I have. I think a small crossflow unit should be quite a good one though, hopfully not adding too much lag. Son't really know until I try it of course! My big issue with WI is the active nature of it. The APC is active but pretty much failsafe and was very cheap for me to fit. WI tends to be a bit more expensive, and can run out of water or fail otherwise. I guess there might be provision for interrupting the supply to the APC solenoid, it's not something I've looked into as yet. I like the idea of an intercooler as it's passive.
Gearbox. Here we go...
I'm even more confused now than I was then! My gearbox serial starts with an S. I forget the exact serial number. http://saabpics.org:3000/albums/album110/99_gear_ratios This shows with OE tyre size 30.7km/h per 1000 rpm in 4th. About 114mph at 6,000rpm.
Now I may be doing something wrong here, but the tyres I have on currently are calculated on one of those tyre size calculators to make the speedo read 3.7% fast. I got a recorded top speed of 113 mph at USD and that was at a visual just over 6,000 rpm on the rev counter. Add the 3.7% to get back to if I had OE tyre size and that gives 117mph.
Assuming the S gearbox I have has the stated internals, I would have been doing ~6130rpm to get 113mph on those tyres.
Assuming (BIG assumption!) that is correct, if I had the T box, at 6130rpm on OE tyres I would have been doing 125.5mph. Again factor in the different tyre size and you get 121mph.
The tyres I have aren't brand new, so the diamter will be slightly smaller than calculated. Which would probably mean I was doing slightly over the 6130 calculated RPM. No rev limiter on the car currenltly as I damaged it. Oops! I was keeping careful note of the RPM and engine note!
Looking at the table in the link again, the "T" box states 33.0km/h per 1000 RPM in 4th with the OE tyre size. That gives 123mph at 6000 rpm. Factor in the tyre size difference and that would give a theoretical top speed of 118mph at 6000 rpm.
If what I've done there is correct (and maths was never my strong point...), then that tells me I definitely have the S gearbox. Or I guess my rev counter reads high and I don't have an S gearbox despite what's stamped on it. However...
This is where I'm more confused. That linked page states I should have a "T" gearbox. Yet I found last week on the intro pages of the microfiches a section that narrows engine and gearbox serials down to model year produced. And for the 78 turbo it says teh gearbox should begine with an "S". No mention of a "T" gearbox anywhere! The table linked to is from a service book, 197something to 1980. All markets. My microfiches are 1974-1981 all markets. My own manual, Service manual M75- doesn't mention S or T boxes at all!
Confused? Moi?
I think the cost of pistons, rings etc. on my budget would be prohibitive. ~£50-60 per cylinder at a rough guess? Plus the cost of the extra machining the open the bores out a size. Ok, if it NEEDS doing then I'll have no choice! I've also seen a few people looking about for pre-APC pistons so they can lower their CR's - to up the boost. I'm running quite high boost already, which presumedly would have to come down quite a bit (not necessarily a bad thing, I know). The lower CR I think is probably best to stick to so I can keep the on-boost power up. The way the engine is off-boost is fine for me at the moment, yes it's a bit laggy, but I don't have an isse with that.
Which intercooler did you fit? I'm hoping to get a crossflow NG900 one soon. I think if I move the battery to the boot, improve the heat shielding and use the duct for the battery cooler I might be able to fit it in that area (probably have to use a larger bore tube though). When the battery's gone I'll also offer up the late c900 one I have. I think a small crossflow unit should be quite a good one though, hopfully not adding too much lag. Son't really know until I try it of course! My big issue with WI is the active nature of it. The APC is active but pretty much failsafe and was very cheap for me to fit. WI tends to be a bit more expensive, and can run out of water or fail otherwise. I guess there might be provision for interrupting the supply to the APC solenoid, it's not something I've looked into as yet. I like the idea of an intercooler as it's passive.
Gearbox. Here we go...
I'm even more confused now than I was then! My gearbox serial starts with an S. I forget the exact serial number. http://saabpics.org:3000/albums/album110/99_gear_ratios This shows with OE tyre size 30.7km/h per 1000 rpm in 4th. About 114mph at 6,000rpm.
Now I may be doing something wrong here, but the tyres I have on currently are calculated on one of those tyre size calculators to make the speedo read 3.7% fast. I got a recorded top speed of 113 mph at USD and that was at a visual just over 6,000 rpm on the rev counter. Add the 3.7% to get back to if I had OE tyre size and that gives 117mph.
Assuming the S gearbox I have has the stated internals, I would have been doing ~6130rpm to get 113mph on those tyres.
Assuming (BIG assumption!) that is correct, if I had the T box, at 6130rpm on OE tyres I would have been doing 125.5mph. Again factor in the different tyre size and you get 121mph.
The tyres I have aren't brand new, so the diamter will be slightly smaller than calculated. Which would probably mean I was doing slightly over the 6130 calculated RPM. No rev limiter on the car currenltly as I damaged it. Oops! I was keeping careful note of the RPM and engine note!
Looking at the table in the link again, the "T" box states 33.0km/h per 1000 RPM in 4th with the OE tyre size. That gives 123mph at 6000 rpm. Factor in the tyre size difference and that would give a theoretical top speed of 118mph at 6000 rpm.
If what I've done there is correct (and maths was never my strong point...), then that tells me I definitely have the S gearbox. Or I guess my rev counter reads high and I don't have an S gearbox despite what's stamped on it. However...
This is where I'm more confused. That linked page states I should have a "T" gearbox. Yet I found last week on the intro pages of the microfiches a section that narrows engine and gearbox serials down to model year produced. And for the 78 turbo it says teh gearbox should begine with an "S". No mention of a "T" gearbox anywhere! The table linked to is from a service book, 197something to 1980. All markets. My microfiches are 1974-1981 all markets. My own manual, Service manual M75- doesn't mention S or T boxes at all!
Confused? Moi?
Oh, I guess I should point out it's not a T box I'll be fitting but a G44601 so it should (on OE tyres) go from ~30km/h/1000rpm to ~35km/h/1000rpm it wouldn't really be worth it to go from an S to a T.
Should give a top speed of about 125mph, maybe a bit more with a worked and balanced engine. And my trackday tyres aren't my normal size anyway. Not sure what really limits the revs. It's got solid lifters etc. so shouldn't be too bad. Wouldn't be very often I'd go that high anyway!
Should give a top speed of about 125mph, maybe a bit more with a worked and balanced engine. And my trackday tyres aren't my normal size anyway. Not sure what really limits the revs. It's got solid lifters etc. so shouldn't be too bad. Wouldn't be very often I'd go that high anyway!
Sorry, yes I should have pointed out that the speeds achieved was measured using the AX22 GPS thingy The video shows it going off the clock, but that was the morning run which wasn't logged - I took it a bit further in the afternoon. There still seemed to be a reasonable amount left in it though - that wasn't flat out, it was as fast as I dared take it over redline!
I know that I need to up the power to regain the acceleration I'm currentyl getting, and possibly to actually get the ~125-130 mph top speed at max revs. But that's why I'm looking at the various tweaks in the thread
The video shows it going off the clock, but that was the morning run which wasn't logged - I took it a bit further in the afternoon. There still seemed to be a reasonable amount left in it though - that wasn't flat out, it was as fast as I dared take it over redline! I know that I need to up the power to regain the acceleration I'm currentyl getting, and possibly to actually get the ~125-130 mph top speed at max revs. But that's why I'm looking at the various tweaks in the thread
I saw the ad for CTM in PPC, was that the mention you, er, mentioned? The ad says they're moving, but just checked and they currently show the same address as Burton. I wonder if Burton use them for machining? I thought they did it themsleves.
I am seriously hoping for good condition bores and pistons. Would save me a lot of money! I know the legend, I've just never seen it (and I'm a permanent sceptic!).
Thanks for digging out that costing. I' hope that the prices would only really go up with inflation. Soon I'll be getting prices from a few places anyway, but that does give me a good idea!
£90 sounds about right for balancing I guess. About an hour's labour and some materials maybe. Looks like a bit more saving up to do I guess things like flywheel etc. I could get done at a later date if need be - as long as I get all the internal work done at once, anything that can be done without pulling the engine out and to pieces can be done later. Obviously I'd rather get it all done at once though...
Becuase I'm only going for a relatively mild increase in power (160bhp up to circa 200bhp), I'm hoping not to need some of the more costly processes. Also, £180 seems quite a lot to lighten a flywheel. I probably need to speak to Mark about it, but I wonder if that was heavily lightened?
On the subject of pistons, it looks like the only standard compression pistons still available are +0.50 oversize from Mahle. Scantech list standard size, but I don't know who make them and it's very difficult getting info out of them I've found! Rings are available from Mahle in all sizes. Pistons for the higher compression engines don't appear to be available, or was it a different manufacturer to Mahle by that time?The only other OE was Karl Schmidt I think. It's proving a pain in the bottom to get info on their products though! They appear to be linked with Elring though, so when I get gasket info I'll tag a piston/ring enquiry on as well!
For some reason I can;t find that thread on saabscen depsite searching. COuld you post a link for me please
Cheers!
Richard.
The ad says they're moving, but just checked and they currently show the same address as Burton. I wonder if Burton use them for machining? I thought they did it themsleves. I am seriously hoping for good condition bores and pistons. Would save me a lot of money! I know the legend, I've just never seen it (and I'm a permanent sceptic!).
Thanks for digging out that costing. I' hope that the prices would only really go up with inflation. Soon I'll be getting prices from a few places anyway, but that does give me a good idea!
£90 sounds about right for balancing I guess. About an hour's labour and some materials maybe. Looks like a bit more saving up to do
I guess things like flywheel etc. I could get done at a later date if need be - as long as I get all the internal work done at once, anything that can be done without pulling the engine out and to pieces can be done later. Obviously I'd rather get it all done at once though... Becuase I'm only going for a relatively mild increase in power (160bhp up to circa 200bhp), I'm hoping not to need some of the more costly processes. Also, £180 seems quite a lot to lighten a flywheel. I probably need to speak to Mark about it, but I wonder if that was heavily lightened?
On the subject of pistons, it looks like the only standard compression pistons still available are +0.50 oversize from Mahle. Scantech list standard size, but I don't know who make them and it's very difficult getting info out of them I've found! Rings are available from Mahle in all sizes. Pistons for the higher compression engines don't appear to be available, or was it a different manufacturer to Mahle by that time?The only other OE was Karl Schmidt I think. It's proving a pain in the bottom to get info on their products though! They appear to be linked with Elring though, so when I get gasket info I'll tag a piston/ring enquiry on as well!
For some reason I can;t find that thread on saabscen depsite searching. COuld you post a link for me please
Cheers!
Richard.
Nice one And it's answered another question - the mig wire thingy. Essentially O-ringing the block, something the 99T rally car had done. Again, I'm not intending to go near that level of power or boost, so I *hopfully* don't need to consider that! Ok it looks fairly cheap as an individual process, but it all adds up!
I see the stress relieving of the rods also involved x-rays etc. as well. That explains the higher costs. Does sound like this company can do the job proper like
And a happy new year to yourself as well! And everyone on here I get the feeling you lot are going to cost me a fortune 
And it's answered another question - the mig wire thingy. Essentially O-ringing the block, something the 99T rally car had done. Again, I'm not intending to go near that level of power or boost, so I *hopfully* don't need to consider that! Ok it looks fairly cheap as an individual process, but it all adds up! I see the stress relieving of the rods also involved x-rays etc. as well. That explains the higher costs. Does sound like this company can do the job proper like
And a happy new year to yourself as well! And everyone on here
I get the feeling you lot are going to cost me a fortune I did measure the turbine diamter once. I forget what it was but I have a feeling it was a 35. However, I do wonder if I'm wrong, because it does hold boost very well, all the way up the rev range. There's only a kmited amount of life left in the turbo anyway, as it sitting idle for so long hasn't done it any favours. When the time comes for a replacement I'll be lookng at alternatives. I'd also probably look at weater cooled units as well, although that does put a touch more load on the cooling system
One thing I *don't* want to have to consider is losing the external wastegate. It's part of the character of the car One of the first jobs on the engine side of things was to change the wastegate pressure feed from the exhaust to the inlet. Mainly to increase teh diaphragm lifespan. When I then fitted the APC I had to change it again to the compressor outlet.
What's the difference between the 99T and H engine 7v T manifolds? I thought they used the same casting for it? I know they added a web on to help reduce the cracks that appear, but I didn't think there was any real-world difference?
One thing I *don't* want to have to consider is losing the external wastegate. It's part of the character of the car
One of the first jobs on the engine side of things was to change the wastegate pressure feed from the exhaust to the inlet. Mainly to increase teh diaphragm lifespan. When I then fitted the APC I had to change it again to the compressor outlet. What's the difference between the 99T and H engine 7v T manifolds? I thought they used the same casting for it? I know they added a web on to help reduce the cracks that appear, but I didn't think there was any real-world difference?
[quote]You dropped a valve? [/quote]
Well, you know how it is. Got to save the weight where I can
Either that or learn how to type
I did look at a turbo a while back that someone was selling. My car was in pieces at the time so I took my existing unit with me to make sure all the holes were in the right places etc. The compressor wheel was definitely bigger than mine. Problem is, I don't know what the spec of that unit was either! The turbo on my car is a Garrett recon unit. Garrett couldn't tell me the spec from the serial though. Hmm. Next time I have the pipes off I'll measure again and rememebr to write it down! Looking at Widde's tables the trim 35 and 40 are similar sized wheels. I had thought it was the size of the unit, but I'm wrong again
I know I'm limiting my options in a lot of areas, such as turbo choice etc. but that's not a huge issue for me. I do want to retain as much originality as possible, but allowing for development and progression of the 1970's technology. Hmm, that's a bit of a contradiction!
Another reason I don't want to change the wastegate is I've only recently got my exhaust built and it cost me a lot of money I'm on a low budget here
But all help and suggestions very gratefully received and appreciated Even if my responses do ocassionally dismiss them for no sane reason!
Well, you know how it is. Got to save the weight where I can
Either that or learn how to type I did look at a turbo a while back that someone was selling. My car was in pieces at the time so I took my existing unit with me to make sure all the holes were in the right places etc. The compressor wheel was definitely bigger than mine. Problem is, I don't know what the spec of that unit was either! The turbo on my car is a Garrett recon unit. Garrett couldn't tell me the spec from the serial though. Hmm. Next time I have the pipes off I'll measure again and rememebr to write it down! Looking at Widde's tables the trim 35 and 40 are similar sized wheels. I had thought it was the size of the unit, but I'm wrong again
I know I'm limiting my options in a lot of areas, such as turbo choice etc. but that's not a huge issue for me. I do want to retain as much originality as possible, but allowing for development and progression of the 1970's technology. Hmm, that's a bit of a contradiction!
Another reason I don't want to change the wastegate is I've only recently got my exhaust built and it cost me a lot of money
I'm on a low budget here But all help and suggestions very gratefully received and appreciated
Even if my responses do ocassionally dismiss them for no sane reason!Hmm, looks like Mahle can't supply ANY 99T pistons. Better hope they're ok! They did say they were always cast (not a great suprise).
Does anyone know anything about Zephyr cams? Apparently they were OEM for a number of manufacturers, does anyone know if they made them for Saab at all? I cna get a NOS Zephyr 99 injection cam for £25 but I don't know their quality.
I've finally got the metro back into driveable condition (well, as driveable as a pilchards tin can ever get...), which means I can get on with the Saab. First the bodywork gets done, then I can concentrate on the engine yay!
Does anyone know anything about Zephyr cams? Apparently they were OEM for a number of manufacturers, does anyone know if they made them for Saab at all? I cna get a NOS Zephyr 99 injection cam for £25 but I don't know their quality.
I've finally got the metro back into driveable condition (well, as driveable as a pilchards tin can ever get...), which means I can get on with the Saab. First the bodywork gets done, then I can concentrate on the engine yay!
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