RallyReason
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| posted on 10/4/13 at 07:50 PM |
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ST170 VCT PWM valve
I am looking for the voltage that the VCT PWM valve on the ST170 engine operates at?
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big_wasa
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| posted on 10/4/13 at 07:55 PM |
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12v
well 13 and a bit 
[Edited on 10/4/13 by big_wasa]
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RallyReason
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| posted on 10/4/13 at 07:58 PM |
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do you know if it is a regulated 12v or battery voltage?
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big_wasa
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| posted on 10/4/13 at 08:04 PM |
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Its battery voltage.
It takes a switched live one side and is earthed via the ecu in the st on the other side.
How do you plan on controlling it ?
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RallyReason
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| posted on 10/4/13 at 08:29 PM |
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Damaged my blacktop the other week.
So i have finally decided to replace it with a ST170 lump. I am looking at one locally in the next few days.
I am planning on still using my current Bike carbs and mega jolt. I have read and had conversations with various people on how they have controlled
the valve or not. I have received a very mixed view. There are people that say just supplying 12 volts at a set RPM is working very well and some say
that this hasn't worked for them and they have chosen the delete kit.
The way i see it if i understand correctly is that the cam timing is designed to be altered depending on various factors. Possibly RPM, load, throttle
position? If this is the case then theoretically just giving a constant switched 12v should not work well.
But i was going to try it and see for myself.
If this doesn't work i was going to speak to my colleagues in the software department at work and see if they can knock me up a simple PWM
driver. I may be able to just use the TPS sensor on my carbs to tell the driver what Pulse duration is needed. IE low TPS a very wide pulse duration (
no or little advance?) then as the TPS increases shorten the pulse duration ( to simulate more of a constant 12 v). This should then increase the
advanced up to max. I may have the pulse duration the worn way around but you get the picture.
If the above doesn't work, just fit a delete kit.
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coozer
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| posted on 10/4/13 at 08:36 PM |
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I switched mine with a relay and used the switch light output on the MegaJolt to earth it at 3000 rpm.. instant 100bhp jump
1972 V8 Jago
1980 Z750
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RallyReason
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| posted on 10/4/13 at 08:46 PM |
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This would be my first plan and if it all works ok happy days.
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coozer
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| posted on 10/4/13 at 08:56 PM |
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Here you go, this what I got, ignore the top end the carbs needed jetting correctly..
Handy 100bhp in 250 revs...
1972 V8 Jago
1980 Z750
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RallyReason
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| posted on 10/4/13 at 09:06 PM |
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What carbs are you using?
The confusing part of all this is there has been reports of this way of activation has not worked, yet there are defiantly some that it has worked ok
for.
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coozer
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| posted on 10/4/13 at 09:14 PM |
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They where ZX9R carbs. Just wish I'd stuck with them instead of going injection.
Worked OK for me, nice kick as the cam advanced
1972 V8 Jago
1980 Z750
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silky16v
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| posted on 10/4/13 at 09:22 PM |
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Mixed views on the ST170 VCT, but having now completed the delete VCT I wouldn't have it any other way, before the power band was too narrow and
really unusable while I live.
See my previous thread regarding this its very cheap for the delete kit, and I have a Vernier to sell as well
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RallyReason
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| posted on 11/4/13 at 07:16 AM |
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you are correct in the mixed views.
I have read your previous threads along with others.
There is also another guy on RHOCAR that has just the switch option and is making very good power also.
However i want know for certain until i try myself, but i am not expecting the simple switch idea to work that great.
Did you ever have yours set on a RR or was it all done by yourself? What was the final out come of the cam timings?
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silky16v
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| posted on 11/4/13 at 11:21 AM |
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quote:
Originally posted by RallyReason
you are correct in the mixed views.
I have read your previous threads along with others.
There is also another guy on RHOCAR that has just the switch option and is making very good power also.
However i want know for certain until i try myself, but i am not expecting the simple switch idea to work that great.
Did you ever have yours set on a RR or was it all done by yourself? What was the final out come of the cam timings?
it could well be making good power mine did, but it starts to tail off after 5000rpm, if the PWM is set to on/off it will be like this any RR saying
different will be in-correct
it depends on what you want?
1. low down torque & power (engine struggles to rev freely after 5500rpm)
2. lose a little low down torque & power (an engine that comes alive after 5000rpm and rev's freely)
in a 7 style car option 2 in my opinion is the best as you don't want such a kick of power/torque when the PWM solenoid switches
i set my cam timing as per my thread VCT Delete Thread i haven't yet had
time to play with the camshaft timing but shall be going back soon to see
[Edited on 11/4/13 by silky16v]
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Rob Allison
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| posted on 11/4/13 at 10:41 PM |
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On/Off just gives retarded or Advanced timing. You can't get it at it's optimum.
From most switched setups they seem to make less then 180bhp.
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