PKVVTS (PorKen Variable Valve Timing System)
07-04-2006, 09:41 PM
#31
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I braved the highway for the first time, and nothing broke. 
I realized that even normal highway driving is still below 3000rpm, for example, 2500rpm @ 60mph. So I left the advance on the whole time. I'm thinking that it should be on all the time, except perhaps for starting, and over 3500rpm or so. So I need a way to lock it advanced until an rpm trigger releases it.
On the dyno, I figured that each cam degree advance lowered the torque peak rpm down by 200rpm. So five degrees would drop the '81 peak from 4000rpm down to around 3000rpm! It also makes more torque, three degrees added about five lbft of torque (at the expense of five HP).
The more I think about it, I think it might get better mileage at impulse highway speeds with more advance, not retarded as I used to believe. (I tried a little retard on the way down to Sharktoberfest, and it didn't appreciably increase the mileage.) Around town, the way I drive, the mileage will probably go down.
I can't wait to put in the '79 cams I have, as these should give even better results with more lift and duration.
I realized that even normal highway driving is still below 3000rpm, for example, 2500rpm @ 60mph. So I left the advance on the whole time. I'm thinking that it should be on all the time, except perhaps for starting, and over 3500rpm or so. So I need a way to lock it advanced until an rpm trigger releases it.
On the dyno, I figured that each cam degree advance lowered the torque peak rpm down by 200rpm. So five degrees would drop the '81 peak from 4000rpm down to around 3000rpm! It also makes more torque, three degrees added about five lbft of torque (at the expense of five HP).
The more I think about it, I think it might get better mileage at impulse highway speeds with more advance, not retarded as I used to believe. (I tried a little retard on the way down to Sharktoberfest, and it didn't appreciably increase the mileage.) Around town, the way I drive, the mileage will probably go down.
I can't wait to put in the '79 cams I have, as these should give even better results with more lift and duration.
07-06-2006, 01:53 AM
#32
Burning Brakes
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Ken,
I can appriciate the inventivness, and after spending 1100 bucks on a new timing belt last week, I can also appriciate the extra stress your belt is under. I'd love more low end torque, but not at the risk of an ever stressed-unstressed belt with less crank pully wrap than normal.
Obviously you are more secure with the whole timing belt issue than I am, and having an uncovered timing system is something I'd never consider, BUT, I DO appriciate the inventive sprit and if you could do this w/o stressing the belt I'd consider it. - Ruf
I can appriciate the inventivness, and after spending 1100 bucks on a new timing belt last week, I can also appriciate the extra stress your belt is under. I'd love more low end torque, but not at the risk of an ever stressed-unstressed belt with less crank pully wrap than normal.
Obviously you are more secure with the whole timing belt issue than I am, and having an uncovered timing system is something I'd never consider, BUT, I DO appriciate the inventive sprit and if you could do this w/o stressing the belt I'd consider it. - Ruf
07-06-2006, 02:21 AM
#33
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Ruf,
Ha! I wasn't going to mention it, but I am in awe of how strong the belt is.
My belt is a few years old, it's soaked in drip oil, and my HTD gears are shiny and sharp. I have been doing nasty things to the belt for it's entire life, and it shows no sign of degrading. In fact,
I managed, while idiotically trying to adjust the PKVVTS beam with the engine running, to dislodge the belt from the oil pump gear, and the engine ran with the belt twisted past the oil pump gear, until I could shut it off! The belt still works! (Another cool thing, the PorKensioner took up the slack, and the cams stayed in time!)
I am going to replace the belt here soon, and with the damper off, I can see how much belt wrap there actually is. I'm hoping that I can get even more range of advance.
I'm addicted to torque!
Ha! I wasn't going to mention it, but I am in awe of how strong the belt is.
My belt is a few years old, it's soaked in drip oil, and my HTD gears are shiny and sharp. I have been doing nasty things to the belt for it's entire life, and it shows no sign of degrading. In fact,
I managed, while idiotically trying to adjust the PKVVTS beam with the engine running, to dislodge the belt from the oil pump gear, and the engine ran with the belt twisted past the oil pump gear, until I could shut it off! The belt still works! (Another cool thing, the PorKensioner took up the slack, and the cams stayed in time!)I am going to replace the belt here soon, and with the damper off, I can see how much belt wrap there actually is. I'm hoping that I can get even more range of advance.
I'm addicted to torque!
07-06-2006, 05:30 PM
#34
Burning Brakes
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Ken,
Wow man. I would have had a heart attack before I got to the ingition key! You surely got more TB guts than I'll ever have. I guess you should keep at it until you get what you want or something breaks!
Nice to know the belt can take a little oil... and yes my HTD teeth were sharp enough for the shop to say so. (What whould the old gears look like I wonder...) - Ruf
Wow man. I would have had a heart attack before I got to the ingition key! You surely got more TB guts than I'll ever have. I guess you should keep at it until you get what you want or something breaks!
Nice to know the belt can take a little oil... and yes my HTD teeth were sharp enough for the shop to say so. (What whould the old gears look like I wonder...) - Ruf
07-06-2006, 06:04 PM
#35
Three Wheelin'
Originally Posted by PorKen
I'm still not sure about how to engage it - it takes a good amount of force to push the belt. I'm hoping that if I put a heavy spring on it, and get the pressure right, it might be automatic, just by virtue of the engine spinning faster, and exerting more force against the bar.
