Mercules
Spiltting lanes
Had a very interesting day today... my clothes and hair stink of exhasut fumes but I have learnt quite a bit about k-jetronic, adjusting it and found some excellent results.
After some warm-up and checking cruise mixtures, the furst dyno run saw 141 horsepower at the rear wheels with 845 lb. of torque and kicked out an enromous amount of smoke - just clearing its throat for what was to come!(please note this is a dyno measurement - not a comparison to factory specifications).
The mixtures were pretty much bang on stoich from idle to redline, which was quite dissapointing because I have been so unhappy with the fuel economy (24 L/100km) I was expecting to see an overly rich reading!!! A quick check of the ignition timing comfirmed the engine was set to factory specs!
To see if we could achieve a leaner mixture, better fuel economy and still make decent power, we adjusted the mixture slightly leaner... second run made 148 hp. We adjusted it some more... third run made 152 hp. This was getting a little weird - we were pulling fuel out but making more power with each adjustment and there was definately no pinging! A fourth adjustment made no difference so we thought we would try advancing the timing a little...
RED INDICATES FIRST RUN - BLUE INDICATES LAST RUN - SOLID LINE INDICATES POWER - DOTTED LINE INDICATES TORQUE
5 degrees advance resulted in the figure above of 157 hp and 931 lb. of torque. That equates to an 11.5% increase in power and a 10% increase in torque... not bad for a few adjustments.
On the road the engine feels very different - light throttle produces an irresistable surge and when full throttle is applied, you can really notice an improvement in response and acelleration.
THIS IS THE IMPORTANT PART THAT I WANT EVERYONE TO READ!!!
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When the air cleaner was refitted, we checked the power with another dyno run and found it LOST POWER but the mixtures became RICHER!!!!! This explains the precise reason why some of you may have noticed an improvement in engine performance after fitting a free-flowing induction or cold-air setup - your engine is actually running RICH and making less power to start with, so by improving the induction airflow, the mixture is LEANING OUT slightly - bringing it closer to an optimum ratio and making more power!!!
After having travelled almost 240,000km and never been opened, my engine is in average condition... a couple of the lifters are ticking and there is noticeable blow-by coming from the rocker breather pipes - so while new piston rings and some valve adjustment may be an expensive way of bringing this engine back to its former glory, there is a lot to be said for some tinkering with the fuel and timing.
If you are interested in a dyno tune to get the most from your k-jetted beast then call Pulse Racing on (02) 9543 5007. I am very glad I did
Cam
After some warm-up and checking cruise mixtures, the furst dyno run saw 141 horsepower at the rear wheels with 845 lb. of torque and kicked out an enromous amount of smoke - just clearing its throat for what was to come!(please note this is a dyno measurement - not a comparison to factory specifications).
The mixtures were pretty much bang on stoich from idle to redline, which was quite dissapointing because I have been so unhappy with the fuel economy (24 L/100km) I was expecting to see an overly rich reading!!! A quick check of the ignition timing comfirmed the engine was set to factory specs!
To see if we could achieve a leaner mixture, better fuel economy and still make decent power, we adjusted the mixture slightly leaner... second run made 148 hp. We adjusted it some more... third run made 152 hp. This was getting a little weird - we were pulling fuel out but making more power with each adjustment and there was definately no pinging! A fourth adjustment made no difference so we thought we would try advancing the timing a little...
RED INDICATES FIRST RUN - BLUE INDICATES LAST RUN - SOLID LINE INDICATES POWER - DOTTED LINE INDICATES TORQUE
5 degrees advance resulted in the figure above of 157 hp and 931 lb. of torque. That equates to an 11.5% increase in power and a 10% increase in torque... not bad for a few adjustments.
On the road the engine feels very different - light throttle produces an irresistable surge and when full throttle is applied, you can really notice an improvement in response and acelleration.
THIS IS THE IMPORTANT PART THAT I WANT EVERYONE TO READ!!!
==================================================
When the air cleaner was refitted, we checked the power with another dyno run and found it LOST POWER but the mixtures became RICHER!!!!! This explains the precise reason why some of you may have noticed an improvement in engine performance after fitting a free-flowing induction or cold-air setup - your engine is actually running RICH and making less power to start with, so by improving the induction airflow, the mixture is LEANING OUT slightly - bringing it closer to an optimum ratio and making more power!!!
After having travelled almost 240,000km and never been opened, my engine is in average condition... a couple of the lifters are ticking and there is noticeable blow-by coming from the rocker breather pipes - so while new piston rings and some valve adjustment may be an expensive way of bringing this engine back to its former glory, there is a lot to be said for some tinkering with the fuel and timing.
If you are interested in a dyno tune to get the most from your k-jetted beast then call Pulse Racing on (02) 9543 5007. I am very glad I did
Cam
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