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Discussion Starter · #1 ·
After my pathetic RR results I have been burning up the lines to Maptun
It would seem that the most likely explanation for my lack of power is probably the valve timing is off
my boost is ok
the turbo is spooling ok
the fuelling is sufficient
the ignition timing is ok
so that leaves valve timing....
So what we are going to do tomorrow is file off the woodruff key on the cams and adjiust them by hand ..Fredrick says he has had to do this a few times
so we will see what this brings on Saturday...
 

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What boost are you running anyway?

I entered your car's parameters into the Javacalc from Ray Hall Turbocharging as best I could remember. Let me know if I need to make some corrections:

Bore: 3.543"
Stroke: 3.543"
Cylinders: 4
RPM: 5,800 (for horsepower peak)
Ambient Air temp: 25C
VE: 88 (good estimate for VE at peak power)
Boost Pressure: 22 psi
Compressor Efficiency: 79% (based on the GT30 comp map)
Intercooler efficiency: 75%


Based on that assumed setup I got 385 hp as the predicted output. If I raise the boost to 29 psi the power output changes to 452 hp.

The VE should not be higher than 88% at 5,800 rpm without custom intake and exhaust pulse tuning.

Any corrections?

Dubbya~
 

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Discussion Starter · #3 ·
boost is more like 26 psi
ambient air at 25 ??? this is scotland not california...currently is 17 c !! this is a hot summers day !!

otherwise looks ok...
 

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Changed parameters accordingly. (26 psi and 15C)

Hp: 432 @ 5,800

That assumes full ignition advance and good airflow over the intercooler. Towards the end of a dyno run if there isn't at least 1 psi pressure drop across it the efficiency will only be about 50-60%. With a 60% efficiency the power drops to 408 hp, and with 50% drops to 395.

Cams could still be a problem though. If you did a dyno run on a mixture of Toluene ignition retard shouldn't be an issue. Make sure to let us know if the cams did the trick! (The better cam timing will increase the VE at top end in that equation.)

Dubbya~
 

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Discussion Starter · #6 ·
I will try with and without toluene to see...

intrestingly when I tried it on the calc there was no difference between 15 c and 25

maybe I should have cleared it first ?

I need to run @ 2 bar to make the big hp....
 

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Originally posted by ylee coyote:
[qb]I will try with and without toluene to see...

intrestingly when I tried it on the calc there was no difference between 15 c and 25

maybe I should have cleared it first ?

I need to run @ 2 bar to make the big hp.... [/qb][/b]
I'm using this calculator: http://www.turbofast.com.au/tfcalc.html

The other turbo "map" one isn't affected by temperature in its calculations for some reason. But the one I used does take that into affect.

Remember that the calculators don't tell you how detonation sensitive different air temps are. They just calculate for density assuming no detonation. They're very accurate if you have enough octane, otherwise only good for turbo sizing.

To make the big power on pump gas you need intake and exhaust tuning!

Things like tubular equal length headers and (if you were so inclined) a custom intake manifold. Those will increase power without increasing detonation sensitivity. They make both the EGT and cyllinder temps cooler for the same amount of power by getting rid of hot residual exhaust gasses!

Very expensive though. If you can get away with 2 bar on your fuel go for it!


Dubbya~

edit: Also, if you were so inlined, water injection can be used. If you'd like I can mail you some NACA (aka NASA in the later years) papers on aviation engines using water injection (called anti-detonation injection) and the results! They found that an engine which normally required 100 octane could be run on about 85 octane with water injection! But sadly it's not always much cheaper than the other solutions out there.
 
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