Dusty
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| posted on 19/9/09 at 12:48 PM |
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VVT
Calling electronic whiz type peeps. I'm using an ST170 zetec with VVT, jenveys and omex ecu. The ecu can do Off/On/Off for the VVT but ford used
PWM to an oil control valve for continuously variable which my ecu wont do. I'm out of cash for a new ecu which is one option.
1. Some use it on/off. Seeing as this is a 30 degree cam movement the timing is mostly wrong most of the time.
2. Some disable and choose a mid cam timing. Sometimes right but mostly wrong. 3. Some go aftermarket cams with or without VVT. Expensive for two new
cams and 16 new followers.
Would it be possible, cheapish, simple to use crank sensor and cam sensor inputs to construct a box of tricks with programable pwm output for
continuously variable cam timing as a stand alone separate from my ecu?
PS. I don't have a clue about electronics so although I imagine this is do-able I don't know how difficult, expensive, realistic it might
be.
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coozer
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| posted on 19/9/09 at 01:01 PM |
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I have a ST170 engine in mine and am using carbs and Megajolt.
The MJ has programmable outputs.. so my set up is as follows.
The Megajolt is programmed to switch at 3000rpm, this switches a relay that sends 12v up to the solenoid on top of the engine then its off like
firework...
The reason I use a relay as in the Ford Focus wiring diagram the solenoid has a 20amp fuse... and the MJ can only handle 500mv. The other way is to
have a switch on the dash and do it manually.
Heres a recent RR graph that shows what happens when the VVT kicks in, I used to have it at 4500rpm but it was too scary coming out of
roundabouts....
 
Rescued attachment P1000977.JPG
1972 V8 Jago
1980 Z750
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sebastiaan
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| posted on 19/9/09 at 02:46 PM |
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That would have to be one complicated box of tricks. It could be done, but you'd need to:
1) connect crank and cam position signals to you box 'o tricks (including interface electronics to shield them from electrical noise)
2) determine engine speed from crank
3) determine relative position of cam vs. crank (i.e. current VVT position)
4) adjust dutycycle to VVT valve based on the desired cam position for that engine speed (probably by having a lookup table and some form of PID
regulator in the software of the box 'o tricks)
5) pray it all works....
We did al this at work some years ago, but used really expensive hardware (that we had laying around  )
I'd go On/Off through your megajolt and experiment with different settings. If you are running an airbox you coudl connect a (spare?) MAF sensor
to its inlet and measure at what engine speed the airflow vs. engine speed curves cross with the VVT on and off.
Or just set it to come on at 3000 RPM
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Dusty
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| posted on 19/9/09 at 04:44 PM |
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It's currently set to come on at 3000rpm (ECU switches a relay) and off again at 6500rpm after a rolling road session earlier this
'summer'. Still very dissappointing figures for this engine. 15 HP less than the previous tuned silvertop that was in there from what
should be a belter of an engine. I've also lost over 2 seconds round the track at Barkstone compared to the old engine and I'm sure it is
mainly down to less power. Thats what makes me feel I am driving it with cam timing 'wrong' most of the time. The surge at 3000 is
impressive and I guess 30 cam advance (60 advance over the crank position) is huge and cam timing is probably close to ideal from 3-4000 ish. Then
power crashes at about 5800 and retarding the cam timing (30 deg again)prolongues the power but I'm sure if I could retard by 10 degrees for the
5-6000 band and then a further 10 from 6-7500 I would have much better figures.
I guess aftermarket cams or an ECU that will do the pwm thing is the way to go. Sad because the potential is there in this engine. I should have gone
to blacktop, cams and a decent exhaust for an easy and in the long run cheaper 200 horses.
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turbodisplay
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| posted on 19/9/09 at 06:16 PM |
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At 3000 to redline oil pressure an be considered constant.
An adjustable flow limit could be used to limit pressure, inline with the valve, to give lets say 20 degress. Another valve in parrallel to give 10
degrees advance.
By switching control of these 2 valves then 0, 10,20, 30 can be obtained. (making a few assumptions but the idea is sound)
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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coozer
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| posted on 19/9/09 at 06:27 PM |
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Whats disappointing about 167bhp? Ford claimed 168 so its not bad is it? After all I've junked the multi million pound variable length injection
system into touch for some 40mm carbs (not set up yet!)
Sorry chaps the reason the power drops off at 6500 there is because the main jet is too small, I haven't had time to get the carbs set up since
I changed the engine from a 1.8 zetec.
Once I get down to Blogg Brothers and get the carbs set up properly I expect more in the mid range and it should hold on to the torque at the top.
Maybe another 5~10bhp as well.
I reckon when I back off and the oil pressure drops the cam comes back as well so I'm thinking the constant adjustment of the cam is due to
changes in the oil pressure and thats because the solenoid on top of the engine is either open or closed allowing oil pressure into the front of the
cam.
My plans are for 200bhp and I think a set of cams is the way to go, or a supercharger for more. But before that an adjustable wheel on the exhaust cam
and some set up time, then I have some throttle bodies to try so its all just at the beginning and I think it looks (and drives) OK.
[Edited on 19/9/09 by coozer]
1972 V8 Jago
1980 Z750
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Dusty
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| posted on 19/9/09 at 06:55 PM |
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quote:
Whats disappointing about 167bhp
Maybe I'm expecting too much but a blacktop dressed up with aftermarket ecu, jenveys and a good exhaust produces about 170, up 15%
compared to the mondeo. The ST170, essentialy a tuned blacktop has a steel bottom end, bigger valves, much bigger and better shaped ports and a more
agressive cam. Tag on the afore mentioned ancilliaries, spend £350 on a rolling road and I have 155, down 10% on the focus ST. I was thinking solid
170 minimum and I would have been a bit dissappointed and then add in the gains of the VVT even switching off/on/off and I hoped for closer to
200horses. I sold a brand new blacktop still on its pallet in favour of this engine! That's why I'm dissappointed.
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Project7
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| posted on 19/9/09 at 06:57 PM |
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I think it might be possible to do what you want with a Crouzet Millenium III PLC.
They have a high speed counter function, and PWM outputs.
Is the change in cam timing linear with engine speed?
you'd have to check the specs of the 12v units but its an idea - I would probably be able to help you with the programming of it.
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Project7
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| posted on 19/9/09 at 07:14 PM |
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Crouzet Millenium III
Info
Hmmm they only do the larger version with PWM outputs and a 12 Vdc supply -> look under '"Expandable" range with
display'
My thinking would be that it the high speed counter could be used with a custom trigger wheel mounted somewhere - and it calculating what PWM value at
certain rpm ranges.
with the correct 'add-ons' it could control fans and prevent VVT changes when cold etc. and display RPM on the LCD screen.
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coozer
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| posted on 19/9/09 at 07:42 PM |
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quote:
Originally posted by Dusty
quote:
Whats disappointing about 167bhp
Maybe I'm expecting too much but a blacktop dressed up with aftermarket ecu, jenveys and a good exhaust produces about 170, up 15%
compared to the mondeo. The ST170, essentialy a tuned blacktop has a steel bottom end, bigger valves, much bigger and better shaped ports and a more
agressive cam. Tag on the afore mentioned ancilliaries, spend £350 on a rolling road and I have 155, down 10% on the focus ST. I was thinking solid
170 minimum and I would have been a bit dissappointed and then add in the gains of the VVT even switching off/on/off and I hoped for closer to
200horses. I sold a brand new blacktop still on its pallet in favour of this engine! That's why I'm dissappointed.
I'd like to see a blacktop produce that with them mods.. cams would be required to get one up to that level imo.
Well lad, I don't get ya.. I'm quite chuffed that I have 167bhp with home tuned carbs. Thats 1bhp less than Ford claimed. The RR bloke was
impressed as well seeing as it hasn't lost any power over the complicated Ford induction.
ATM apart from the engine I haven't spent any money on it, carbs are off a 1.8 zetec so there is lot more to come. I can't afford jenveys
atm so I'll have to live with it. All I've edoen so far is try to tune the carbs with an LC1 AFR and its worse now than before. It use dto
do 40mpg but I'm down to 20 now with real rich on the gauge. Once this is all sorted I'm sure theres more to come.
I've no idea what your expecting, 200bhp with an exhaust change? Not possible if you ask me, my dressed up last zetec made 155bhp so I expect
if I can 'dress up' the ST engine enough it will make a lot more.
ATM I wouldn't expect much more from mine with CARBS!
Oh, and your avatar is offensive to the wife as well btw.
[Edited on 19/9/09 by coozer]
[Edited on 19/9/09 by coozer]
1972 V8 Jago
1980 Z750
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brianthemagical
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| posted on 19/9/09 at 07:42 PM |
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Not sure if it's been considered or not, so i figured i'd mention it anyway. Hysterisis.
Is the 155bhp, atw or fly?
[Edited on 19/9/09 by brianthemagical]
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coozer
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| posted on 19/9/09 at 07:57 PM |
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I see now reading your post, you've spent £350 on RR for 155bhp? Go get your money back, mine was simply a power run to see what it had, theres
NO development in there.
AND, theres no way I would expect more that 10~15% on the original output with my changes. (Big exhaust, no cat, carbs)
Maybe more is to be had with TB's but I'm not convinced yet.
ST170 is not a reworked Blacktop, its a different animal in that theres a lot more torque claimed from totally different internals and head.
If you want more power from standard chuck it and stick a RST engine in.
[Edited on 19/9/09 by coozer]
1972 V8 Jago
1980 Z750
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Dusty
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| posted on 19/9/09 at 10:42 PM |
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Sorry to herself for the avatar. Wanted to get away from the cat thing.
Perhaps I should have said the ST170 is a development of the blacktop.
I'm just dissappointed that cars I was 2 seconds ahead of with the silvertop are now ahead of me after I have spent £600 on a 'go
faster' engine and £350 for a full day on the rollers with Dave in Cheltenham. I do appreciate the better engine. Just that the school report
reads 'could and should do better'.
Flywheel 155.
[Edited on 19/9/09 by Dusty]
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MikeRJ
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| posted on 20/9/09 at 07:41 PM |
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quote:
Originally posted by coozer
I reckon when I back off and the oil pressure drops the cam comes back as well so I'm thinking the constant adjustment of the cam is due to
changes in the oil pressure and thats because the solenoid on top of the engine is either open or closed allowing oil pressure into the front of the
cam.
The way the VCT system works with the OEM ECU is that there is a cam phase sensor on the cam itself, which is used in conjunction with a sensor on the
cam pulley. By looking at the variation in the timing of these two sensors, the ECU can work out the phase of the cam, and supply a pulse to the
solenoid to advance or retard it as required.
FWIW this is exactly the same way that Rover controlled the VVC mechanism on the K series, though that system was far more sophisticated as is changed
cam duration rather than just a shift in timing.
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turbodisplay
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| posted on 21/9/09 at 07:09 AM |
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Dusty when do you need a controller? I might have a pwm controller for rpm/map or throttle posistion in a months time.
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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coozer
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| posted on 29/9/09 at 08:47 AM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by coozer
I reckon when I back off and the oil pressure drops the cam comes back as well so I'm thinking the constant adjustment of the cam is due to
changes in the oil pressure and thats because the solenoid on top of the engine is either open or closed allowing oil pressure into the front of the
cam.
The way the VCT system works with the OEM ECU is that there is a cam phase sensor on the cam itself, which is used in conjunction with a sensor on the
cam pulley. By looking at the variation in the timing of these two sensors, the ECU can work out the phase of the cam, and supply a pulse to the
solenoid to advance or retard it as required.
FWIW this is exactly the same way that Rover controlled the VVC mechanism on the K series, though that system was far more sophisticated as is changed
cam duration rather than just a shift in timing.
Sorry Mike, your off the mark there. Yes the engine has a cam position sensor, but all zetecs do and its at the back off the cam. Mine is not
connected to anything. I don't have an ECU, its running carbs.
There is no electrical connection to the front of the cam, its purely mechanical. The solenoid is a simple valve that opens an oilway in the head. It
could be a manual valve, the 12v in no ways controls the cam. Oil pressure varies the cam phase.
I have nothing more complicated than a switched 12v to the valve to open and close it. (it doesn't work with less than 12v)
1972 V8 Jago
1980 Z750
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MikeRJ
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| posted on 29/9/09 at 12:05 PM |
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quote:
Originally posted by coozer
Sorry Mike, your off the mark there. Yes the engine has a cam position sensor, but all zetecs do and its at the back off the cam. Mine is not
connected to anything. I don't have an ECU, its running carbs.
There is no electrical connection to the front of the cam, its purely mechanical. The solenoid is a simple valve that opens an oilway in the head. It
could be a manual valve, the 12v in no ways controls the cam. Oil pressure varies the cam phase.
I have nothing more complicated than a switched 12v to the valve to open and close it. (it doesn't work with less than 12v)
But you are using it in a kit car rather than the original application I guess? Ford clearly state in their literature that it's a continuously
variable system, though obviously it can be used as a simple on/off system as you have.
The bit I was wrong about is the front cam sensor in the case of the ST170...some other versions of Fords VCT system apparently use this. On the
ST170, the cam phase signal is derived from the timing difference between the crank sensor and the cam sensor.
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nz_climber
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| posted on 29/9/09 at 07:39 PM |
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Not sure how cleaver the ford system is, but I know the toyota vvt-i systems don't just vary the timing for engine speed, they evaluate TPS and
MAF signals too so they know the load of the engine, and dial in the required amount of cam.
Which is done via a closed loop system, comparison between Crank sensor and cam sensor on the back of the head, then a PWM signal to the soleniod to
let the oil through (which changes the timing) Those people that just switch it on and off you will find you are missing a lot of torque in the mid
region that could be gained back by using the system how its meant to work.
I would suggest getting a ecu that can handle this from the start, or there are few piggyback ecu's which can control PWM cam controls out there
now.
http://aarons7.wordpress.com
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Doofus
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| posted on 30/9/09 at 07:41 AM |
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It would be relatively cheap and simple to make a fixed (but adjustable) pulse width that you could experiment with.
Pounds rather than hundreds.
You could try the engine with it set between 0% PW to 100% PW and see what works best for your engine.
It might highlight other areas that need attention if there are no gains made by swinging the cam about.
On the other hand you might find out if it's worth investing in a cam controller.
Paul.
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coozer
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| posted on 30/9/09 at 10:11 AM |
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Still not right chaps, I may be wrong but I have the engine here.
Please tell me where to connect the cam phase signal?
Possibly I need educating, teach me please.
Steve
[Edited on 30/9/09 by coozer]
1972 V8 Jago
1980 Z750
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