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
when I gave my car its 200,000 mile service I gave the engine to ctm performance (reference in this months ppc !!)and they did all the balancing/match weighting and porting for me (as well as big valves and a lightened flywheel ) and a jolly good job they did too
total cost for everything was a very reasonable £1750 not including assembly
yours is a little simpler so I would expect a little less
most of the cost was putting the big valves in...
runs sweet (now that the cams are dialled in)all the way up to 6,700....
total cost for everything was a very reasonable £1750 not including assembly
yours is a little simpler so I would expect a little less
most of the cost was putting the big valves in...
runs sweet (now that the cams are dialled in)all the way up to 6,700....
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
If you're going to the trouble of stripping the engine to lighten and balance it then why don't you fit the later higher compression pistons from the 8V APC engine. If pinking then rears its ugly head you could also fit WI.
Regarding fitting an IC I did this with our 99T, to keep inlet temps down when the car was being used for serious towing duties. It certainly cured the mid boost pinking that I was experiencing, but the trade off was that the dam thing was even more gutless off boost making hill-starts a real pain (I was always getting left behind at the lights by Grannies in Micras, but now it's buses as well
)
I noticed that you're having grief with your gearbox - what is the serial number of it?
can you hit the rev limiter in top?
if so
at what rpm?
Mr saf
Regarding fitting an IC I did this with our 99T, to keep inlet temps down when the car was being used for serious towing duties. It certainly cured the mid boost pinking that I was experiencing, but the trade off was that the dam thing was even more gutless off boost making hill-starts a real pain (I was always getting left behind at the lights by Grannies in Micras, but now it's buses as well
) I noticed that you're having grief with your gearbox - what is the serial number of it?
can you hit the rev limiter in top?
if so
at what rpm?
Mr saf
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!
nutcase1 said:
the tyres I have on currently ... 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.
If the speedo reads 3.7% fast then you were going slower than it said you were - ie about 109mph.
It's dangerous to assume that higher gearing will give you a higher top speed - you might find you don't have enough power to pull the higher gearing. Years ago I had a Vauxhall Nova which did 23mph/1000rpm in fifth, but there's no way it would have got to its peak power revs in that gear. If it had it would have been doing 152mph!
The 113.something mph was measured with GPS, and he [I]was at the rev limiter at that point. The speedo went off the scale at 120, as seen in the video of his run.
No doubt the gearing is way too low for a 99T - the standard item did 122ish mph with 145 horses, at about 5,800 rpm. With the current power, he should be able to see 126-128 mph or so.
No doubt the gearing is way too low for a 99T - the standard item did 122ish mph with 145 horses, at about 5,800 rpm. With the current power, he should be able to see 126-128 mph or so.
Andrew Noakes said:
the tyres I have on currently ... 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.
If the speedo reads 3.7% fast then you were going slower than it said you were - ie about 109mph.
It's dangerous to assume that higher gearing will give you a higher top speed - you might find you don't have enough power to pull the higher gearing. Years ago I had a Vauxhall Nova which did 23mph/1000rpm in fifth, but there's no way it would have got to its peak power revs in that gear. If it had it would have been doing 152mph!
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
its very unlikely to need bore work..
Saab engines are legendery in this respect
at 200k the origonal honing marks were still evident
all I replaced was the piston rings !!
I would guess you could do the head porting and a bit of engine work for the kind of money you are talking about ....
Saab engines are legendery in this respect
at 200k the origonal honing marks were still evident
all I replaced was the piston rings !!
I would guess you could do the head porting and a bit of engine work for the kind of money you are talking about ....
looked up an old thread in SAABSCENE...
mark in Ireland said ...
got all my work done down in London, they were the only company that could do everything I wanted done on their own premises. They are located next to and under Burton Speed and are called CTM Performance Engineering. Tel No.020 8554 3534. Owner is a guy called Charlie, very helpful and prices are very reasonable.
Bore and hone block:- £60.00
Skim block and mig wire block face:- £120.00
Supply Cossie Pistons machined to fit:- £490
Grind Crank:- £70.00
Knife Edge Crank:- £230.00
Stress Relieve Rods:- £100.00
Lighten Flywheel:- £180.00
Full Balance:- £90.00
Fast Road Race gas flow on cylinderhead + rebuild:- £330.00
Hybrid Turbo VNT unit:- £900.00
Bearing Shells:- £125.00
All plus VAT
Note these are 2002 prices...
mark in Ireland said ...
got all my work done down in London, they were the only company that could do everything I wanted done on their own premises. They are located next to and under Burton Speed and are called CTM Performance Engineering. Tel No.020 8554 3534. Owner is a guy called Charlie, very helpful and prices are very reasonable.
Bore and hone block:- £60.00
Skim block and mig wire block face:- £120.00
Supply Cossie Pistons machined to fit:- £490
Grind Crank:- £70.00
Knife Edge Crank:- £230.00
Stress Relieve Rods:- £100.00
Lighten Flywheel:- £180.00
Full Balance:- £90.00
Fast Road Race gas flow on cylinderhead + rebuild:- £330.00
Hybrid Turbo VNT unit:- £900.00
Bearing Shells:- £125.00
All plus VAT
Note these are 2002 prices...
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.
no sooner said but done ...
www.saabscene.co.uk/cgi-bin/ultimatebb.cgi?/topic/23/337.html
cheers
george
ps happy new year !!
www.saabscene.co.uk/cgi-bin/ultimatebb.cgi?/topic/23/337.html
cheers
george
ps happy new year !!
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 Provided you keep detonation under control (which as you retrofitted APC is sort of a given), the OE Elring head gasket is plenty strong without O-ringing the block.
Saabines hardware (block and head) is the same as what Sweedspeed uses for B202-based motorsport projects up to 400 bhp - no O-rings in the block...
As for your original query - if you are going to improve breathing by porting the head, using alternative camshafts etc. you might well have to llok at a bigger turbo compressor than the '40 trim' you have now. Your head work will shift the point where the engine reaches its highest efficiency higher up the rev range (which negates the faster spoolup of a small turbo); at which point the turbo already has reached its flow limit. You have to look at the whole engine config as a system, and bring everything back into balance when you significantly uprate the flow capacity of one part.
Personally (and particularly given that you're retaining the stock 7.2:1 CR) I'd replace the 99T exhaust manifold and exhaust-actuated wastegate with a 900T8 one, and a Mitsubishi TE05-12B turbo including internal wastegate of a late 900T16/900S lpt.
Saabines hardware (block and head) is the same as what Sweedspeed uses for B202-based motorsport projects up to 400 bhp - no O-rings in the block...
As for your original query - if you are going to improve breathing by porting the head, using alternative camshafts etc. you might well have to llok at a bigger turbo compressor than the '40 trim' you have now. Your head work will shift the point where the engine reaches its highest efficiency higher up the rev range (which negates the faster spoolup of a small turbo); at which point the turbo already has reached its flow limit. You have to look at the whole engine config as a system, and bring everything back into balance when you significantly uprate the flow capacity of one part.
Personally (and particularly given that you're retaining the stock 7.2:1 CR) I'd replace the 99T exhaust manifold and exhaust-actuated wastegate with a 900T8 one, and a Mitsubishi TE05-12B turbo including internal wastegate of a late 900T16/900S lpt.
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?
nutcase1 said:
I did measure the turbine diamter once. I forget what it was but I have a feeling it was a 35.
It's a 'trim 40' (which has to do with the ratio between the inducer and exducer diameters) - indeed, when you measure the side of the compressor wheel you can see from outside (the inducer) it will be 34 mm on your turbo.
Both the T03 (trim 45) of '84-('89?)'90 900T16's and the Mitsu TE05-12B of later T16s and S lpt models have a 40 (ish) mm inducer.
The Mitsu, being of a somewhat later and lighter deisgn with a better flowing wastegate, has the advantage of better spool up/low down torque, but does not pull as quite as well at the top end as the Garett.
nutcase1 said:
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
Fair enough, but then I think you'll be restricted to rebuilding/upgrading your B-engine turbo - a later one less wastegate flapper housing won't bolt up to your downpipe ['cause there will be two holes coming out the turbine instead of one
. nutcase said:
What's the difference between the 99T and H engine 7v T manifolds?
You dropped a valve?
Apart from having not having he mounting for the external wastegate, I don't think there's much difference indeed. It's just that when you lose the external set up, the later manifold will bolt on (you would need to go custom on the downpipe, tho'). Anyways, as you're retaining the external wastegate, it's a moot point.
edited because I'm lame at quotation
>> Edited by 900T-R on Sunday 2nd January 16:38
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