coozer
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| posted on 28/8/09 at 08:09 PM |
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Tunign Megajolt?
I have a real rich spot just about 2500rpm> to 4200rpm where the VVT kicks in.
Giving WOT chucks petrol out the carbs (the wrong way)
Question is, can I use the ign advance to dial this out?
I've dropped the needles down but AFR still goes down to 10 ish with a strong smell of fuel.
After 4200 its hunky dory with superb acceleration and 13 ish AFR.
Anyone know where I can learn about constructing an ignition map??
I have Megajolt with TPS on a ST170 engine running ZX9R carbs.
Ta,
Steve
1972 V8 Jago
1980 Z750
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Slater
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| posted on 28/8/09 at 08:18 PM |
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Steve
Send me a U2U with your e-mail address, I will send you the map I have, it seems to work very well.
I have 1.8 Zetec, ZZR Carbs with TPS
Keith
Why do they call Port Harcourt "The Garden City"?...... Becauase they can't spell Stramash.
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RichardK
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| posted on 28/8/09 at 09:51 PM |
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I'd start with a 2d map first mate and then knob around introducing settings relating to tps.
I've stuck with my 2d, it works great on my pinto and can't see then benefit to be gained by arsing about.
Cheers
Rich
Gallery updated 11/01/2011
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paulf
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| posted on 28/8/09 at 10:03 PM |
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I don't think the ignition will make that much difference, it is more likely to be due to the valve timing with the larger overlap when the cam
advance operates.Have you tried disconnecting the VVT to see how it then behaves?
Ive thought about this on St 170 engines before and if I had one i would want a variable duty cycle system maybe operating on engine revs plus load
signal from the megajolt to allow the valve timing to adjust how it is designed to rather than just on or off.
Paul
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coozer
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| posted on 29/8/09 at 11:12 AM |
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Just been up to the rolling road for a power run. Last night had a fanny around changing the cut in rpm for the VVT.
With no VVT it drives real crap, woolly and rich in the midrange.
With the cut in set at 3K you can feel the change and off it goes..
So, 167bhp @ 6200rpm/111mph. Same as in the Focus but without Fords multimillion pound induction system.
So, on with the TB conversion to see if I can get more midrange torque as it drops off sharply after 5,500.
You can clearly see the 3k cut in on this graph
 
Rescued attachment P1000977.JPG
1972 V8 Jago
1980 Z750
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Guinness
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| posted on 29/8/09 at 11:26 AM |
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Nice graph there Steve!
And, as you say, with more to come!
Mike
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dave r
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| posted on 29/8/09 at 04:16 PM |
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post the same question on the robin hood site... there is a guy on there (gdc) that has been there and done it
he may have info for you
dave
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MikeRJ
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| posted on 29/8/09 at 08:56 PM |
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quote:
Originally posted by paulf
Ive thought about this on St 170 engines before and if I had one i would want a variable duty cycle system maybe operating on engine revs plus load
signal from the megajolt to allow the valve timing to adjust how it is designed to rather than just on or off.
Paul
Everything I have read on the ST170 says it is not a continuously variable system in standard form, it's either full advanced or full retarded.
FWIW this is works exactly the same way as the variators that Fiat/Alfa/Lancia use in some of their engines.
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coozer
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| posted on 1/9/09 at 06:17 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by paulf
Ive thought about this on St 170 engines before and if I had one i would want a variable duty cycle system maybe operating on engine revs plus load
signal from the megajolt to allow the valve timing to adjust how it is designed to rather than just on or off.
Paul
Everything I have read on the ST170 says it is not a continuously variable system in standard form, it's either full advanced or full retarded.
FWIW this is works exactly the same way as the variators that Fiat/Alfa/Lancia use in some of their engines.
From my understanding the solenoid opens a oilway at the 3K set point, theres no variation, its a 12v feed from a relay.
This allows oil into the front of the cam and as far as I can explain works bit like dizzy.. the oil advances the cam but as you back off oil pressure
drops and makes for a continuously changing overlap based on oil pressure. Although its probably full on most of the time.
1972 V8 Jago
1980 Z750
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MikeRJ
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| posted on 1/9/09 at 06:37 PM |
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quote:
Originally posted by coozer
This allows oil into the front of the cam and as far as I can explain works bit like dizzy.. the oil advances the cam but as you back off oil pressure
drops and makes for a continuously changing overlap based on oil pressure. Although its probably full on most of the time.
I've heard this before and I'm really not convinced, but I'd like to know for sure.
Oil pressure doesn't just depend on RPM; it depends on temperature, wear of the engine, how old the oil is and what additives have been used by
the oil manufacturer etc. I just don't think you could rely on the engines oil pressure to control something like valve timing accurately
under all conditions.
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coozer
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| posted on 1/9/09 at 10:55 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by coozer
This allows oil into the front of the cam and as far as I can explain works bit like dizzy.. the oil advances the cam but as you back off oil pressure
drops and makes for a continuously changing overlap based on oil pressure. Although its probably full on most of the time.
I've heard this before and I'm really not convinced, but I'd like to know for sure.
Oil pressure doesn't just depend on RPM; it depends on temperature, wear of the engine, how old the oil is and what additives have been used by
the oil manufacturer etc. I just don't think you could rely on the engines oil pressure to control something like valve timing accurately under
all conditions.
I can assure you Mike, its oil pressure. There is a solenoid valve on top of the head that is a simple open close control valve in an oilway that goes
forward to the cam. I am using a relay that is triggered by the Megajolt and can set the revs it cuts in.
On the St170 it is purely mechanical after the vavle is opened, there is no other external control.
I have seen and read tons of nutsack and based on my theory and set up what I'm saying is right. It may be that the cam needs very little oil
pressure to move the overlap but I can switch it off and it makes no power., is woolly to drive, runs very rich etc.
I have the relay set to come in at 3K and you can see the effect it has on the power, it takes off!
 
Rescued attachment P1000977.JPG
1972 V8 Jago
1980 Z750
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.jpg)
