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A place for you to create build diaries of the basket cases at the bottom of the garden/driveway.

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PostPosted: Tue Aug 31, 2010 9:21 am 
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Light Pressure Turbo

Joined: Mon Mar 01, 2010 4:12 pm
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Location: Somerset / London
Never mind the fan, that must be the world's biggest axle stand, lol


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PostPosted: Tue Aug 31, 2010 1:11 pm 
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Car Model: Saab 900 and 99
chip-nova wrote:
Never mind the fan, that must be the world's biggest axle stand, lol


They are the small ones, the induction fan stands are bigger :P

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PostPosted: Wed Sep 01, 2010 9:12 am 
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sonett wrote:
OK, back on topic. I removed the exhaust manifold and reduced the secondaries from 30'' to 18'', the results were mixed and it didn't have the effect i was expecting, top end power was increased, but i lost some torque low down.
We took the revs a little bit further this time and at around 6700rpm the power is still not tailing off :), on the road i have taken it to 7000 rpm for a short while and there is no valve bounce


I've dug out the valve train weights I originally collected and run the valve bounce calculations again. There is small margin of error because I don't know the exact fitted length the heads were actually assembled at since I didn't do that so I've assumed the optimal situation where the valve springs have been properly shimmed up to be just away from going coil bound (by about 1.5mm) at full lift. I'm also aware that you didn't actually do any of that so the engines might not meet the targets below.

Also I've had to estimate the spring rate of the standard springs from their dimensions using a program of my own devising since I don't have a measured spring rate for them on my spring tester. I do have the exact figures for my own uprated springs.

Anyway the results I get are as follows.

1) Stock valve train on stock springs - 7000 rpm

2) Using my lighter inlet valves (82g instead of 94g) which is how the 44m valve head actually is but still on stock springs - 7200 rpm

3) As above but using my uprated springs - 7600 rpm

4) Adding the lighter cam followers (69g instead of 95g) but still on stock springs - 7600 rpm

5) As above but on my uprated springs which is how the 46mm valve head is - 8000 rpm

So what revs do we actually need? Well I'm astonished that with the modified exhaust manifold the power still hasn't started to drop at 6700 rpm given that it first peaks at about 6200 rpm on most of the power runs. The head must be flowing a godawful amount of air to be able to keep supplying the cylinders that high up on a not particularly long duration cam. I'm beginning to wish I'd actually flow tested both heads now.

It's also an established fact that to get the best acceleration it's necessary to rev any engine about 500 rpm above the point where the power starts to drop which means at least 7200 rpm and we still don't know what the power curve actually does above 6700. It might hold on even higher.

So it's looking like even the 44m valve head needs the uprated springs to let it run out to 7600 rpm. The 46mm valve head should be ok with its 8000 rpm limit but anyway there's not much else we can do short of finding even stronger springs.

It goes to show how important light weight valve train components are though and how badly Saab got things wrong originally. The stock 42mm inlet valve didn't need to be anywhere near 94g with proper design if I can make a perfectly reliable 44mm one at 82g. The stock cam follower is also ridiculously overweight and could easily have been as light as the ones I used in the 46mm valve head. Together these two items give an extra 600 rpm which means if Saab had done so too the stock valve springs could have been much softer and therefore less power sapping and causing less wear.

Running the equations, to retain the same 7000 stock rpm limit, which in fact is far higher than the stock engine needs, but with properly designed light valves and followers the stock springs could have been 15% softer than they actually are. With a 6500 rpm limit which would have been ample for the stock engine the springs could have been nearly 30% softer than they actually are.


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PostPosted: Wed Sep 01, 2010 10:45 am 
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Joined: Mon Feb 07, 2005 4:48 pm
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Location: Fliptop Towers, North Yorks...the flat bit.
Car Model: One or two...
Interesting. I'm pretty sure that all of the Saab "H" engines (dissie on cam), whether carb, injection or turbo, ran with a stock red line of 6000, but Dave B, doesn't the earlier Jetronic (not CI) EMS like yours rev to 6500+? I seem to recall this from Dad's 76 car but that's going back 30 years...:lol: Certainly the few B-engined 99s I have driven seemed to be more revvy than H-engined cars.

I wonder if there is any difference in the valve springs for the 8V turbo engines and if not, could this be why they are so "over-engineered"?

Dave P - how does this compare with other manufacturer's engines of a similar period and age of design? Pintos and the like I guess.

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PostPosted: Wed Sep 01, 2010 3:20 pm 
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Location: Cheshire
Car Model: Saab 900 and 99
Fliptop wrote:
Interesting. I'm pretty sure that all of the Saab "H" engines (dissie on cam), whether carb, injection or turbo, ran with a stock red line of 6000, but Dave B, doesn't the earlier Jetronic (not CI) EMS like yours rev to 6500+? I seem to recall this from Dad's 76 car but that's going back 30 years...:lol: Certainly the few B-engined 99s I have driven seemed to be more revvy than H-engined cars.

I wonder if there is any difference in the valve springs for the 8V turbo engines and if not, could this be why they are so "over-engineered"?

Dave P - how does this compare with other manufacturer's engines of a similar period and age of design? Pintos and the like I guess.


All of the production EMS cars had peak power at 5500 rpm, although the earlier d-jet cars had a red line at 6500, the later k-jet had a red line at 6000, if the power peaks at 5500 there is no benefit to take it to 6500, even the published graphs show the power falling well before this, which is probably why saab reduced the limit on the later cars.
If your dad had a 76 car I'm sure this would be on k-jet.
I'll have a look at the spring part numbers when I get home, but I'll be surprised if they are different between the B and H engines.
Just for general interest, the B series engine was designed by the Scania truck division.

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PostPosted: Wed Sep 01, 2010 3:49 pm 
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Location: Fliptop Towers, North Yorks...the flat bit.
Car Model: One or two...
Dad's 76 car was definitely the earlier injection and lower ratio box, it was the type with the air filter on the end of the throttle body, like this:
Image

Our 78 EMS was k-jet. Either way, partly as a result of the lower ratio box I guess, I do remember it used to rev like hell compared with the later car. The later cars was much happier on the motorway, didn't rev its nuts off in the same way...

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PostPosted: Wed Sep 01, 2010 4:53 pm 
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Car Model: Saab 900 and 99
Probably down to the ratios.
That's quite late for a d-jet, do you know the chassis number?

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PostPosted: Wed Sep 01, 2010 5:41 pm 
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Location: Fliptop Towers, North Yorks...the flat bit.
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Come on mate, it was 30 years ago!!

It was a silver 76 2 door, registration was MFR2P, might have been a late registered 75??

I thought the K-jet came in 77, that's also when they started doing different colours and the DRLs were introduced.

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PostPosted: Thu Sep 02, 2010 7:35 am 
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Light Pressure Turbo

Joined: Fri Feb 04, 2005 2:54 pm
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Car Model: 9-5 Aero
sonett wrote:
Probably down to the ratios.
That's quite late for a d-jet, do you know the chassis number?

Chassis no 99742029311

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PostPosted: Thu Sep 02, 2010 8:09 am 
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Car Model: Saab 900 and 99
Fliptop wrote:
Come on mate, it was 30 years ago!!

It was a silver 76 2 door, registration was MFR2P, might have been a late registered 75??

I thought the K-jet came in 77, that's also when they started doing different colours and the DRLs were introduced.


The D-jet was dropped in 1975 and in the same year K-jet was introduced, so it's likely your dads EMS was an early '75 registered in '76, Saab did have some difficulty selling the EMS cars, because of the price.

I have found some info on the B series engine valve springs. The part numbers for the B and H engines are different, but i have measured the height and spring wire diameter of a '77 B and '83 H and they appear to be the same, although they are used springs.
This is all acedemic anyway, i have been out in the 99 and valve bounce starts around 7100 to 7200, it's difficult to tell because the tach only goes up to 7000, i may need a different tach.
STM = Standard Triumph Motor.
Image

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Last edited by 99 EMS on Thu Sep 02, 2010 8:15 am, edited 1 time in total.

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PostPosted: Thu Sep 02, 2010 8:13 am 
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Car Model: Saab 900 and 99
wessy wrote:
sonett wrote:
Probably down to the ratios.
That's quite late for a d-jet, do you know the chassis number?

Chassis no 99742029311


Nice one Wes, obviously you have a better memory than Al :)
So it looks like a '74 registered in '76 ?

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PostPosted: Thu Sep 02, 2010 8:52 am 
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Joined: Mon Feb 07, 2005 4:48 pm
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Location: Fliptop Towers, North Yorks...the flat bit.
Car Model: One or two...
wessy wrote:
sonett wrote:
Probably down to the ratios.
That's quite late for a d-jet, do you know the chassis number?

Chassis no 99742029311

Chuffin ell mate, how did you find that out?! :lol:
Least I know me memory isn't completely mullered...

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PostPosted: Fri Sep 03, 2010 10:16 am 
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Fliptop wrote:
I wonder if there is any difference in the valve springs for the 8V turbo engines and if not, could this be why they are so "over-engineered"?


I've just had a look at a later parts fiche and the same valve spring is listed for all variants of the B and H engines.

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PostPosted: Wed Sep 29, 2010 3:24 pm 
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Car Model: Saab 900 and 99
'Turbo Killer' had its annual MOT today, passed without any problems.
Emissions CO=2.24% (max 4.5%) HC=120ppm (max 1200ppm)

I have the new stiffer valve springs to fit to the head, they should be fitted this week, then back to the rollers to see where the power drops off with the new RPM increase.

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PostPosted: Tue Oct 05, 2010 3:28 pm 
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I fitted the stronger valve springs yesterday, i also had to shim them up to get the correct clearance, by this time it was getting a little late, so i took the car out for a test drive. Engine performance has improved, it delivers power stronger than before. I failed to check on the map where the rev limiter was set, so i just went off the tach in the car, which turned out to be useless, it appears to stop reading at around 7000rpm ish, so this was throwing me a red herring. This afternoon i had a look at the settings on the laptop, the limit was set at 7100rpm, so i lifted it to 7600rpm, out again for another test run, it revs right up to the limiter in 1st gear with no problem at all, not a hint of valve bounce, it feels as though it would easily go past this. Taking the revs just before the limiter really keeps the engine on song, the problem is i keep running out of road or someone gets in the way. I need to get it back to the rollers and see what's really happening with the power curve.
When changing the valve springs i didn't need to remove the head, which saved more hassle and expense. I used the original Saab valve spring tool and compressed air in the cylinder to keep the valves up, i also locked the bottom end to stop it from moving when the compressed was applied.

Valve compression tool in place and compressed air.
Image

Flywheel locked.
Image

Compressing a valve spring.
Image

Proof the compressed air works.
Image

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PostPosted: Sun Oct 10, 2010 4:51 pm 
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The car is booked in at the rolling road tomorrow, rev limit set to 7600, I'll take the laptop just in case.

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PostPosted: Sun Oct 10, 2010 6:31 pm 
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As always, watching with much interest 8)


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PostPosted: Sun Oct 10, 2010 10:18 pm 
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Thats a handy looking tool that, neat trick with the compressed air too.

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PostPosted: Mon Oct 11, 2010 12:35 pm 
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Saw and heard this beast yesterday. Sends shivers up your spine it does 8) and I am so :envy: that I tried to get Dave to sell it! :lol: Strangely he refused, :evil: , but I am patient. Took me 8 years to get the Sonett off him........ :lol:

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PostPosted: Mon Oct 11, 2010 1:54 pm 
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Here is the dyno run from this mornings session at the rollers, i knew the extra revs had made the car quicker because the revs are falling back into the power band, the car also felt as though it could rev even higher than 7600rpm, i didn't think it would hold on to it's power the way it is doing.
Image

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Last edited by 99 EMS on Tue Oct 12, 2010 4:34 pm, edited 2 times in total.

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