CVTCS System & Cams
09-09-2004, 04:50 PM
#1
CVTCS System & Cams
Heres what I know, the CVTCS system adjusts the intake cam timing depending on RPM. It adjusts the cam timing at different RPM making the cams more efficient at those RPMs giving us more power and torque. I thought the system advanced at low RPM and retarded at high RPM, but just did a search on the net and found this on the subject:
"CVTC improves overall engine performance by supplying Constant Valve Timing Control through all operating conditions. The crankshaft position, camshaft position, engine speed, and engine coolant temperature input signals are sent to the ECU. The ECU sends a variable duty cycle to a pulse width modulated solenoid that works like an injector. By adjusting and directing the amount of oil pumped into the CVTC's chambers and allowed to drain back into the engine, the ECU controls the retard or advance of the cam up to 30 crank degrees (vs. 14 degrees on the older VTC motors). The cam is retarded at idle to create a smoother idle and decrease emissions, advanced in the mid range to increase breathing, and retarded at high rpm to increase peak horsepower and fuel efficiency."
There is a NISMO VTC pulley which can advance the timing a further 15 degrees at low RPM, making torque come on earlier. Now what I would like to know is, if you were to use this pulley with a set of performance camshafts which rob low rpm power/torque, would this pulley reduce / remove the losses normally associated with the hi lift / long duration cams?
The cams would still be hi lift / long duration, but by changing the timing of the intake cam you are essentially controling the overlap of the two cams which should be enough to reduce the low rpm effects of the performance cams. Isnt this how we get so much torque at such a low rpm at the moment.
Anybodys thoughts, corrections?
"CVTC improves overall engine performance by supplying Constant Valve Timing Control through all operating conditions. The crankshaft position, camshaft position, engine speed, and engine coolant temperature input signals are sent to the ECU. The ECU sends a variable duty cycle to a pulse width modulated solenoid that works like an injector. By adjusting and directing the amount of oil pumped into the CVTC's chambers and allowed to drain back into the engine, the ECU controls the retard or advance of the cam up to 30 crank degrees (vs. 14 degrees on the older VTC motors). The cam is retarded at idle to create a smoother idle and decrease emissions, advanced in the mid range to increase breathing, and retarded at high rpm to increase peak horsepower and fuel efficiency."
There is a NISMO VTC pulley which can advance the timing a further 15 degrees at low RPM, making torque come on earlier. Now what I would like to know is, if you were to use this pulley with a set of performance camshafts which rob low rpm power/torque, would this pulley reduce / remove the losses normally associated with the hi lift / long duration cams?
The cams would still be hi lift / long duration, but by changing the timing of the intake cam you are essentially controling the overlap of the two cams which should be enough to reduce the low rpm effects of the performance cams. Isnt this how we get so much torque at such a low rpm at the moment.
Anybodys thoughts, corrections?
Last edited by mchapman; 09-09-2004 at 05:44 PM.
09-09-2004, 05:42 PM
#2
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That's exactly what I'm thinking. The guy from z1auto.com (who sells them) had plans on installing them, but I've not heard anything since. You might want to check with him on his progress. Also to my knowledge to make full use of them we would have to reprogram the ecu.
I would prefer to get the NISMO VTC pulley and cams like the NISMO Spec-1 over a super/turbocharger.
I just hope that TS figures out how to control those solenoids.
I would prefer to get the NISMO VTC pulley and cams like the NISMO Spec-1 over a super/turbocharger.
I just hope that TS figures out how to control those solenoids.
09-09-2004, 06:00 PM
#3
I spoke to APS yesterday about the Unichip and cam timing, and it CAN control the cam timing. I didnt ask about controlling the CVTCS system, i'll call him back today and ask. I wouldnt think it could, but with most cams you need to change the cam timing by a couple degrees anyway, and i think you would have a hard time getting Nissan to do that for you with the consult.
Last edited by mchapman; 09-09-2004 at 06:03 PM.
09-09-2004, 06:20 PM
#4
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cool.... keep us posted... I will be VERY VERY VERY interested in this and would like to have a s1 engine components in my car as well.... it might be better off to change all the valve springs and the valves too... save all the labours!
cheers,
richie
cheers,
richie
09-09-2004, 06:29 PM
#5
If you are intending to raise the rev limit to S1 specs (7200rpm) then it would be a good idea to change your rod bolts as well, Peter has done this and its the same in the S1 engine. I spoke to Peter about doing this at the same time as the cam install and he said it wouldnt be much more to change the rod bolts, he would just do the cam install with the engine out and change the rod bolts at the same time.
Also the guy in Australia with the Tecton machine can reset the speed and rev limiters.
Also the guy in Australia with the Tecton machine can reset the speed and rev limiters.
Last edited by mchapman; 09-09-2004 at 06:44 PM.
09-09-2004, 06:48 PM
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yup... that's what I am planning to do.... also need to get another car to drive around just like what David C does...
am also thinking about the crank shaft as well... because it can take up to 8500 rpm of abuse.... and I am sure it will be a hell of fast N/A car by then... (in terms of 0-100)
cheers,
richie
am also thinking about the crank shaft as well... because it can take up to 8500 rpm of abuse.... and I am sure it will be a hell of fast N/A car by then... (in terms of 0-100)
cheers,
richie
09-09-2004, 07:01 PM
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Murray, how far along are the guys with the TS machine? The last time I spoke to Peter they were just starting to do testing. It would be great if they were able to change cam timing as well.
By the way, I just notice that z1auto offers stage 2 competition Nismo heads. Huge price difference, but it doesn't say much what's different.
By the way, I just notice that z1auto offers stage 2 competition Nismo heads. Huge price difference, but it doesn't say much what's different.
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09-09-2004, 08:26 PM
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and nuff... if you go to Nismo site, it says that you will require modifications to fit the heads... and also Peter has got that I believe and he told me it was not a straight bolt-on.... but I am not too sure what needs to be done...
cheers,
richie
cheers,
richie
09-09-2004, 08:36 PM
#9
Originally posted by Z350Lover
yup... that's what I am planning to do.... also need to get another car to drive around just like what David C does...
Yeah im saving for another car. But the Zedd is my daily driver.
am also thinking about the crank shaft as well... because it can take up to 8500 rpm of abuse.... and I am sure it will be a hell of fast N/A car by then... (in terms of 0-100)
To get to 8500rpm you would have to change nearly everything, pistons, rods, crank, heads maybe, all induction, exhaust, cooling systems. But on the plus side it would be a very cool car.
Whats interesting is that everyone talks about the rods being weak but Peter runs the NISMO heads which increase the compression to 11.5-12:1 and he has a slightly higher rev limit but he hasnt had any dramas with them, he has however had dramas with the pistons. Its worth noting that for the whole life of his engine is spent at max rpm, but it should still give us a good indication of what parts should be considered.
yup... that's what I am planning to do.... also need to get another car to drive around just like what David C does...
Yeah im saving for another car. But the Zedd is my daily driver.
am also thinking about the crank shaft as well... because it can take up to 8500 rpm of abuse.... and I am sure it will be a hell of fast N/A car by then... (in terms of 0-100)
To get to 8500rpm you would have to change nearly everything, pistons, rods, crank, heads maybe, all induction, exhaust, cooling systems. But on the plus side it would be a very cool car.
Whats interesting is that everyone talks about the rods being weak but Peter runs the NISMO heads which increase the compression to 11.5-12:1 and he has a slightly higher rev limit but he hasnt had any dramas with them, he has however had dramas with the pistons. Its worth noting that for the whole life of his engine is spent at max rpm, but it should still give us a good indication of what parts should be considered.
09-09-2004, 08:40 PM
#10
Originally posted by nuff
Murray, how far along are the guys with the TS machine? The last time I spoke to Peter they were just starting to do testing. It would be great if they were able to change cam timing as well.
I think they are having a tuff time with it, but they can do the rev and speed limit.
Murray, how far along are the guys with the TS machine? The last time I spoke to Peter they were just starting to do testing. It would be great if they were able to change cam timing as well.
I think they are having a tuff time with it, but they can do the rev and speed limit.
09-09-2004, 09:00 PM
#11
Originally posted by Z350Lover
and nuff... if you go to Nismo site, it says that you will
require modifications to fit the heads... and also Peter has
got that I believe and he told me it was not a straight
bolt-on.... but I am not too sure what needs to be done...
Peter, please correct me if ive got this wrong.
For the heads Peter needs to get little metal shims made to make up the distance between the valve and tappet. You need 24 of them and each one needs to be manually ground down as the distances car vary.
Needed:
Tappets_____?
Shims______?
Heads______2000
Valves _____799
Springs_____240
Cams_______1200
US$4239 = AU$6100*
*Not including tax, shipping, labour, tappets or shims.
and nuff... if you go to Nismo site, it says that you will
require modifications to fit the heads... and also Peter has
got that I believe and he told me it was not a straight
bolt-on.... but I am not too sure what needs to be done...
Peter, please correct me if ive got this wrong.
For the heads Peter needs to get little metal shims made to make up the distance between the valve and tappet. You need 24 of them and each one needs to be manually ground down as the distances car vary.
Needed:
Tappets_____?
Shims______?
Heads______2000
Valves _____799
Springs_____240
Cams_______1200
US$4239 = AU$6100*
*Not including tax, shipping, labour, tappets or shims.
Last edited by mchapman; 09-09-2004 at 09:07 PM.
09-09-2004, 09:49 PM
#13
I wasnt drawing any conclusions on price, just showing you the info I had as I'd been looking at that option over the last week. You'd be making good power with those heads, if I had the cash I would definatly get them.
_____
I phoned APS and spoke to APS-Peter about the Unichip and he wasnt sure if it could control the CVTCS, they havnt tried and its possible they might look at it in the future but as adjusting the cam timing rarely gives any gains he doesnt think the cam area will get much attention. So the short answer is no.
I spoke to him for a bit and the tone of his voice on the phone is very different to here on the net. He is not a fan of low bang for your buck mods, as a result he finds cams rather amusing. We cant all have TTs
_____
I would buy the NISMO crank if it was a stroker crank.
Does anyone have any info on the Jun stroker crank?
_____
I phoned APS and spoke to APS-Peter about the Unichip and he wasnt sure if it could control the CVTCS, they havnt tried and its possible they might look at it in the future but as adjusting the cam timing rarely gives any gains he doesnt think the cam area will get much attention. So the short answer is no.
I spoke to him for a bit and the tone of his voice on the phone is very different to here on the net. He is not a fan of low bang for your buck mods, as a result he finds cams rather amusing. We cant all have TTs
_____
I would buy the NISMO crank if it was a stroker crank.
Does anyone have any info on the Jun stroker crank?
Last edited by mchapman; 09-09-2004 at 10:31 PM.
09-10-2004, 07:08 AM
#14
Found out the 3.8L Jun stroker is the same price as the AEBS 4.3L kit, and it doesnt include the sleeves or head gasket.
I saw in anther thread that you can bore out/ resleeve the block out to 100mm which is the same bore as the AEBS kit and it will give you 3.8L, with the same piston velocity as stock, so you can then make it rev hard and it should wear the same as the stock setup reving hard. We just need to find someone in AU to make the sleeves and the pistons. You can buy the AEBS parts seperatly supposedly. I might send them an email.
I saw in anther thread that you can bore out/ resleeve the block out to 100mm which is the same bore as the AEBS kit and it will give you 3.8L, with the same piston velocity as stock, so you can then make it rev hard and it should wear the same as the stock setup reving hard. We just need to find someone in AU to make the sleeves and the pistons. You can buy the AEBS parts seperatly supposedly. I might send them an email.
Last edited by mchapman; 09-10-2004 at 07:13 AM.
09-10-2004, 05:38 PM
#15
Some facts to consider
The Unichip or for that matter any other piggyback, will not control cvtc, vvti, vanos or any other type of continuously variable camshaft phasing. What they will do is turn on & off duel lobe camshafts like Honda's Vtec or Mitsubishi's Mivec.
The Nismo 46cc cylinder heads are not a cost effective modification for a road car.
Fitting camshafts, raising the revs, increasing compression ext, is a costly exersize for the power increase you get. Never the less they will make power
APS is a very succesful Co at designing & manufacturing turbo applications for existing turbo & non turbo cars, so his disdain for cams, HC pistons ext is understandable as NA mods are unlikely to acheive any where near the same result for your $.
I checked with an engineer yesterday about the legality of modifications for NSW. Maybe other states are simmiler.
The engineer can supply a certificate of modification for suspension & engine mods so that the car is legal for NSW.
He took a look at the Stillen supercharger conversion that I had done on a Z & as it has a CARB certificate & as the brakes, suspension, tyres ext are able to cope with the power increase, He said he would not hesitate to pass this mod. This would make the car legal with respect to Police & RTA.
The biggest problem will be those that make there own Laws: Insurance Company's
The Unichip or for that matter any other piggyback, will not control cvtc, vvti, vanos or any other type of continuously variable camshaft phasing. What they will do is turn on & off duel lobe camshafts like Honda's Vtec or Mitsubishi's Mivec.
The Nismo 46cc cylinder heads are not a cost effective modification for a road car.
Fitting camshafts, raising the revs, increasing compression ext, is a costly exersize for the power increase you get. Never the less they will make power
APS is a very succesful Co at designing & manufacturing turbo applications for existing turbo & non turbo cars, so his disdain for cams, HC pistons ext is understandable as NA mods are unlikely to acheive any where near the same result for your $.
I checked with an engineer yesterday about the legality of modifications for NSW. Maybe other states are simmiler.
The engineer can supply a certificate of modification for suspension & engine mods so that the car is legal for NSW.
He took a look at the Stillen supercharger conversion that I had done on a Z & as it has a CARB certificate & as the brakes, suspension, tyres ext are able to cope with the power increase, He said he would not hesitate to pass this mod. This would make the car legal with respect to Police & RTA.
The biggest problem will be those that make there own Laws: Insurance Company's
09-10-2004, 08:39 PM
#16
Originally posted by Nathan
The Unichip or for that matter any other piggyback, will not control cvtc, vvti, vanos or any other type of continuously variable camshaft phasing. What they will do is turn on & off duel lobe camshafts like Honda's Vtec or Mitsubishi's Mivec.
I will take your word for it, but in the interest of learning.. couldnt it just intercept the signal going to the solenoid?
How can we find out what changes the VTC pulley requires? If we can find out then we will know if this mod is possible for us or not.
APS is a very succesful Co at designing & manufacturing turbo applications for existing turbo & non turbo cars, so his disdain for cams, HC pistons ext is understandable as NA mods are unlikely to acheive any where near the same result for your $.
It is understandable, buts its also good to keep an open mind, the modifications do make power. And if you want more power and cant go forced induction there isnt any other option.
FYI APS-Peter mentioned that they had the TT kit certified to the most recent smog testing standards. Which is good news for those who were asking about it.
I checked with an engineer yesterday about the legality of modifications for NSW. Maybe other states are simmiler.
The engineer can supply a certificate of modification for suspension & engine mods so that the car is legal for NSW.
He took a look at the Stillen supercharger conversion that I had done on a Z & as it has a CARB certificate & as the brakes, suspension, tyres ext are able to cope with the power increase, He said he would not hesitate to pass this mod. This would make the car legal with respect to Police & RTA.
This is good news.
The biggest problem will be those that make there own Laws: Insurance Company's
All roads lead back to insurance companies.
Peter do you know anyone who can resleeve our blocks with a larger bore?
Or what sort of thing usualy entains?
The Unichip or for that matter any other piggyback, will not control cvtc, vvti, vanos or any other type of continuously variable camshaft phasing. What they will do is turn on & off duel lobe camshafts like Honda's Vtec or Mitsubishi's Mivec.
I will take your word for it, but in the interest of learning.. couldnt it just intercept the signal going to the solenoid?
How can we find out what changes the VTC pulley requires? If we can find out then we will know if this mod is possible for us or not.
APS is a very succesful Co at designing & manufacturing turbo applications for existing turbo & non turbo cars, so his disdain for cams, HC pistons ext is understandable as NA mods are unlikely to acheive any where near the same result for your $.
It is understandable, buts its also good to keep an open mind, the modifications do make power. And if you want more power and cant go forced induction there isnt any other option.
FYI APS-Peter mentioned that they had the TT kit certified to the most recent smog testing standards. Which is good news for those who were asking about it.
I checked with an engineer yesterday about the legality of modifications for NSW. Maybe other states are simmiler.
The engineer can supply a certificate of modification for suspension & engine mods so that the car is legal for NSW.
He took a look at the Stillen supercharger conversion that I had done on a Z & as it has a CARB certificate & as the brakes, suspension, tyres ext are able to cope with the power increase, He said he would not hesitate to pass this mod. This would make the car legal with respect to Police & RTA.
This is good news.
The biggest problem will be those that make there own Laws: Insurance Company's
All roads lead back to insurance companies.
Peter do you know anyone who can resleeve our blocks with a larger bore?
Or what sort of thing usualy entains?
Last edited by mchapman; 09-10-2004 at 09:01 PM.
09-11-2004, 05:05 PM
#17
I will take your word for it, but in the interest of learning.. couldnt it just intercept the signal going to the solenoid?
How can we find out what changes the VTC pulley requires? If we can find out then we will know if this mod is possible for us or not.
Murray
Piggyback's work on the principle of modifying the INPUT signals to the ECU. Useually only the crank angle sensor for ignition adjustment & the airflow meter for fuel. The signal to VTC solenoid is an output signal.
The splitsecond & the Stillen have inputs from the camangle sensors.
Running big cams in our motor does not rob low end TQ as much as you think.
I have had the VTC sprockets apart & it would not take much modification to the internals to get them to advance some more.
How can we find out what changes the VTC pulley requires? If we can find out then we will know if this mod is possible for us or not.
Murray
Piggyback's work on the principle of modifying the INPUT signals to the ECU. Useually only the crank angle sensor for ignition adjustment & the airflow meter for fuel. The signal to VTC solenoid is an output signal.
The splitsecond & the Stillen have inputs from the camangle sensors.
Running big cams in our motor does not rob low end TQ as much as you think.
I have had the VTC sprockets apart & it would not take much modification to the internals to get them to advance some more.
09-11-2004, 07:05 PM
#18
From the info above we know, the vtc pulley outputs are based on the input signals from... "crankshaft position, camshaft position, engine speed, and engine coolant temperature" so if the unichip can modify these input signals then we might be able to get the output signals to change as well. Unless the ECU uses those signals for other systems, which it probabally would and we wouldnt want to stuff those up.
09-23-2004, 06:42 PM
#19
Adam posted this info:
Here is the translation from the NISMO catalog:
High declination VTC pulley
While VTC (the system which changes the cam central angle of INT with the condition of the engine) being attached and with the engine, utilizing VTC function when it is compatible the output improvement in the high rotary limits and the stability of idling and the guaranty of concave fast torque, this commodity made the "declination 55°" vis-a-vis the genuine "declination 40°", made degree of freedom of camshaft selection increase.
* When you use the operation angular large camshaft and, combining VTC declination large,
The valve recess should be guaranteed sufficiently that there is no interference of the INT valve and the piston,
There is a necessity.
My translation:
The VTC pulley allows the use of higher lift/duration cams with smooth idle and reduced loss of torque lower in the RPM range by adjusting the VTC system / intake cam further than normal. (55 degree max.)
And you need to check the valve clearances.
So we were correct in our thoughts.
Here is the translation from the NISMO catalog:
High declination VTC pulley
While VTC (the system which changes the cam central angle of INT with the condition of the engine) being attached and with the engine, utilizing VTC function when it is compatible the output improvement in the high rotary limits and the stability of idling and the guaranty of concave fast torque, this commodity made the "declination 55°" vis-a-vis the genuine "declination 40°", made degree of freedom of camshaft selection increase.
* When you use the operation angular large camshaft and, combining VTC declination large,
The valve recess should be guaranteed sufficiently that there is no interference of the INT valve and the piston,
There is a necessity.
My translation:
The VTC pulley allows the use of higher lift/duration cams with smooth idle and reduced loss of torque lower in the RPM range by adjusting the VTC system / intake cam further than normal. (55 degree max.)
And you need to check the valve clearances.
So we were correct in our thoughts.
Last edited by mchapman; 09-23-2004 at 06:46 PM.
09-23-2004, 08:08 PM
#20
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So Murray,
Does that mean VTC is a plug & play things with higher angel cams and the piggyback?! If that's the case, it will be easier than...
cheers,
richie
Does that mean VTC is a plug & play things with higher angel cams and the piggyback?! If that's the case, it will be easier than...
cheers,
richie