coozer
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| posted on 17/9/11 at 08:00 PM |
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ST170 problems??
Any St170 experts anyone can recommend? Not sure if I have a problem or not....
Had mine mapped early on this year and despite the 178bhp the more I think of it the more I think there is something wrong.
Not sure if the mapper was crap or the motors poorly...
Basically the compression was low at 148psi but this was the same across all cylinders, is this something to do with the VVT???
The other thing was peal power was at 4500 rpm and it dropped right off after that. is that down to the mapper??
All in I reckon the motor is good for over 200bhp but not sure if its down to a poorly motor or the mapper not being very good.
Any thoughts?
Steve.
1972 V8 Jago
1980 Z750
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DixieTheKid
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| posted on 17/9/11 at 08:12 PM |
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The ST170 has got to be one of the hardest engines to tune, ford have already done all the work for you. You be lucky to get over 200bhp without
spending thousands and some forced induction!
COS IT'S Worth IT
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lotusmadandy
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| posted on 17/9/11 at 08:13 PM |
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The mapper was Rubbish.
also could the vernier pulley be holding the valves open
to long??
I cant imagine your motor is uncle bucked,it pulls like a train.
Andy
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DixieTheKid
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| posted on 17/9/11 at 09:00 PM |
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It's possible. But I wouldn't of thought it could be that far out. It would run like a bag of nails.
COS IT'S Worth IT
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coozer
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| posted on 17/9/11 at 10:02 PM |
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Dixie.. I'm a nutter and your thick....
I want a peep who knows about these engines.. all I want is 200bhp.
1972 V8 Jago
1980 Z750
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beaver34
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| posted on 17/9/11 at 10:28 PM |
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I'm not expert, but I would look at how your VCT is working, but they rarely make good power as far as I've ever seen
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DixieTheKid
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| posted on 18/9/11 at 06:47 AM |
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quote:
Originally posted by coozer
Dixie.. I'm a nutter and your thick....
I want a peep who knows about these engines.. all I want is 200bhp.
Thick? Im not the one that thinks im going to 200bhp out of a zetec! even a standard st170 your be lucky to get one with 170bhp. Let me know the £ per
bhp to get to 200bhp. Trust me it not worth, go buy a mk1 focus rs.
[Edited on 18/9/11 by DixieTheKid]
COS IT'S Worth IT
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RichardK
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| posted on 18/9/11 at 07:52 AM |
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Steve, as you know I've no experience of the st170 but I would look at the verniers and performamce cams to get you near the 200 mark, to
guarantee 200+ either a supercharger or blower I think is your only chance.
The above is purely what I've read over time, has your motors performance gone down then mate? You motor always seemed to pull like a train when
I've been behind it  Where did you go for mapping? Damian @ daytuner seems to be ok in Harrogate, wouldn't suggest Boggs as you have an
omex and tb's.
Cheers
Rich
Gallery updated 11/01/2011
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MikeRJ
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| posted on 18/9/11 at 11:02 AM |
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quote:
Originally posted by coozer
Any St170 experts anyone can recommend? Not sure if I have a problem or not....
Had mine mapped early on this year and despite the 178bhp the more I think of it the more I think there is something wrong.
Not sure if the mapper was crap or the motors poorly...
Basically the compression was low at 148psi but this was the same across all cylinders, is this something to do with the VVT???
The other thing was peal power was at 4500 rpm and it dropped right off after that. is that down to the mapper??
That is down to either a broken rolling road or someone who simply doesn't know how to operate it. Your engine did not produce a peak of 178bhp
at 4500RPM; it's simply not possible unless you have magically been able to make a relatively standard, normally aspirated ST170 produce 208
lbft of torque at 4500RPM.
Just to emphasis how unlikely this is, Ford claimed just 144.5 lbft at 5500RPM for the ST170. The only way you are going to get 44% higher peak
torque at a lower RPM is with forced induction.
The ST170 is notoriously hard to tune by simply making inlet and exhaust modifications. Have a look on the Ford forums, plenty of people have spent
serious money on ITB's and expensive exhausts only to be hugely dissapointed - I don't know of an ST170 producing a genuine 200bhp with
only these mods.
[Edited on 18/9/11 by MikeRJ]
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coozer
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| posted on 18/9/11 at 11:07 AM |
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quote:
Originally posted by MikeRJ
That is down to either a broken rolling road or someone who simply doesn't know how to operate it. Your engine did not produce a peak of 178bhp
at 4500RPM; it's simply not possible unless you have magically been able to make a relatively standard, normally aspirated ST170 produce 208
lbft of torque at 4500RPM.
Just to emphasis how unlikely this is, Ford claimed just 144.5 lbft at 5500RPM for the ST170. The only way you are going to get 44% higher peak
torque at a lower RPM is with forced induction.
Why do you not think it does that?
The RR printout shows 178 @ 4711rpm and 241nm @ 4419.
Back to the original Q, any actual experts on here??
1972 V8 Jago
1980 Z750
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MikeRJ
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| posted on 18/9/11 at 11:12 AM |
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quote:
Originally posted by coozer
quote:
Originally posted by MikeRJ
That is down to either a broken rolling road or someone who simply doesn't know how to operate it. Your engine did not produce a peak of 178bhp
at 4500RPM; it's simply not possible unless you have magically been able to make a relatively standard, normally aspirated ST170 produce 208
lbft of torque at 4500RPM.
Just to emphasis how unlikely this is, Ford claimed just 144.5 lbft at 5500RPM for the ST170. The only way you are going to get 44% higher peak
torque at a lower RPM is with forced induction.
Why do you not think it does that?
The RR printout shows 178 @ 4711rpm and 241nm @ 4419.
Back to the original Q, any actual experts on here??
Basic common sense tells me it's wrong.
BHP = (Torque * RPM) / 5252
so
Torque = ( BHP * 5252 ) / RPM
211.6 lbft = ( 178 * 5252 ) / 4419
Your torque figure of 241 Nm converts to ~178 lbft, so what your numbers suggest is that your peak torque is lower than the torque at peak power.
Utter nonsense.
I know it's not what you want to hear, but the figures simply don't stack up. You need to find a better rolling road establishment with
an operator that knows what they are doing. Constantly asking for "actual experts" is not going to change the fact that your numbers are
fundamentally incorrect.
EDIT to put actual peak power RPM in.
[Edited on 18/9/11 by MikeRJ]
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coozer
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| posted on 18/9/11 at 11:48 AM |
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OK, the RR guy, who is weber recommended and knew his socks, reckons the LACK of compression was the reason it peaked early and then tailed off. He
was of the opinion that it was good for 200 if the torque kept building. He spoke about a motor he had built for a customer that made 155bhp and was
hugely disappointed... but mines not like that. Obviously.
Now, I've heard that due to the inlet cam being floppy when theres no oil pressure, ie, during cranking, can lead to comp figures being low. The
other theory is the motors overheated at some point and cooked the rings...
I did a lot of research on the Focus and other Ford forums and do know that in standard form these motors can be disappointing, BUT I'm not as
you can see it makes 178bhp. It made 166 on a different RR with poorly setup bike carbs. The printout for that is in my blog. If you compare it with
this one it looks very similar....
Bog stand 2.0l zetecs are good for over 200bhp. Is there any reason an ST170 can't do the same????
1972 V8 Jago
1980 Z750
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iank
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| posted on 18/9/11 at 12:08 PM |
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Bog standard Zetec's don't get close to 200bhp. You need to spend a lot of money on upgraded cams and head work to see that.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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RichardK
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| posted on 18/9/11 at 12:46 PM |
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quote:
Originally posted by iank
Bog standard Zetec's don't get close to 200bhp. You need to spend a lot of money on upgraded cams and head work to see that.
Here a rough guide...
Dunnell Page
Love
Rich
Gallery updated 11/01/2011
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DixieTheKid
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| posted on 18/9/11 at 03:14 PM |
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Your get to about 190bhp if your lucky but your need to change the cams, change to throttle bodies, de cat stainless exhaust and a complete remap,
been there and done it my mates Derek's motor.
If I remember rightly the early st170 had to have an update to the ecu by ford. You have installed throttle bodies I see, what management are you
running and how is that running in conjunction with the vvt? I may have to my now words here, if you haven't killed the rings and the
compression is low (dont know what it should be on the st) you could have a little monster in there!
COS IT'S Worth IT
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RichardK
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| posted on 18/9/11 at 03:34 PM |
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I believe he's running an OMEX 600 ecu.
Gallery updated 11/01/2011
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coozer
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| posted on 18/9/11 at 04:13 PM |
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GSXR750 TB's + Omex 600. Dunnell exhaust type...
VVT is triggered by the ecu via a relay at 1500rpm and above 25% tps.
Just been outside fitting a new air filter...
[Edited on 18/9/11 by coozer]
1972 V8 Jago
1980 Z750
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DixieTheKid
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| posted on 18/9/11 at 06:58 PM |
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I think the only way to be sure is to pull the head off and check the valves and rings. What should the compression be in psi on and new car? You can
expect a small loss. But for the cost of a head gasket, cam belt and a set of bolts you can be sure 100% that the internals are fine and set to work
in the timing. The st has bigger inlet valve than a standard zetec and stronger springs, could be the valve seats if your really unlucky.
COS IT'S Worth IT
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Cornishman
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| posted on 18/9/11 at 07:19 PM |
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Just worth pointing out that MikeRJ has accidentally used the wrong RPM figures in his calculations thus causing some confusion. He has substituted
the RPM for peak torque into the peak power calculation therefore giving the false impression that a practically impossible set of figures have been
produced.
If you look at the print out CAREFULLY and run the figures as I have just done then they seem fine mathematically.
Not wishing to cause offence to anyone but thought it worth pointing out as I am following the thread with interest to help decide what engine to run
for the 2013 season (1.3 xflow for 2012!).
Steve
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nz_climber
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| posted on 19/9/11 at 01:17 AM |
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Not familar with ST170 VVT system. Is it a continuously variable or just switched on off in the standard car?
What do the A/F ratios look like above 5000rpm?
Most VVT systems turn on at where you have set, but also turn off higher in the rev range, to work this out you need to do back to back runs on the
dyno, with it off, and with it on fully and have the switch point and switch back point where the graphs cross each other.
If it is a continuously variable system and you are just switching it on at x rpm that could explain the situation as you cam timing will be way out
(depending how far it actually moves)(have heard toyota continuous systems can move in excess 30 degrees, but controlled by the ecu and don't
move that far in normal operation)
But first I would be looking at taking it to another dyno shop, and comparing the numbers, maybe they got the gear calculations wrong and the rpm
scale is all mucked up.. (I would say you got the right power just in the wrong part of the rev range)
http://aarons7.wordpress.com
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paulf
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| posted on 19/9/11 at 09:32 PM |
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These were also my thoughts, I remember hearing that above a certain rev range most VVT systems retard the cam for better power at top end revs.I know
most people are using a simple on off switch for ST170s and have considered experimenting with a pulse width modulated system to allow the advance to
be mapped via a separate control box but haven't yet found a cheap ST170 engine to experiment with.
Paul
quote:
Originally posted by nz_climber
Not familar with ST170 VVT system. Is it a continuously variable or just switched on off in the standard car?
What do the A/F ratios look like above 5000rpm?
Most VVT systems turn on at where you have set, but also turn off higher in the rev range, to work this out you need to do back to back runs on the
dyno, with it off, and with it on fully and have the switch point and switch back point where the graphs cross each other.
If it is a continuously variable system and you are just switching it on at x rpm that could explain the situation as you cam timing will be way out
(depending how far it actually moves)(have heard toyota continuous systems can move in excess 30 degrees, but controlled by the ecu and don't
move that far in normal operation)
But first I would be looking at taking it to another dyno shop, and comparing the numbers, maybe they got the gear calculations wrong and the rpm
scale is all mucked up.. (I would say you got the right power just in the wrong part of the rev range)
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ianjenn
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| posted on 20/9/11 at 06:33 AM |
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the st170 VVT is a simple on off switch. Basically there is a solenoid that opens an oil channel. It is the oil pressure that varies the advance. It
is not possible to modulate electrically. The oil pressure will equalise either side of the solenoid whether it is fully or part open.
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djtom
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| posted on 20/9/11 at 02:04 PM |
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The ST170 VVT is not a simple on-off system, the solenoid in the original installation is driven by a PWM feed by the ECU to continually vary the oil
pressure to the hydraulic cam. The cam angle can change by over 30 degrees (IIRC), which usually accounts for the massive step in the power curve that
results from just switching the VVT on/off. Someone posted a power curve the other day with the VVT switched in at 3000 rpm - the power went from 40
to 80 bhp by about 3200rpm....
Tom
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ianjenn
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| posted on 20/9/11 at 05:56 PM |
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from my observation what you are suggesting defies the laws of physics. the solenoid blocks one oil channel with no control on return. therefore as
soon as the valve opens even a fraction the pressure would equalise. In addition when applying varying voltage and current to the solenoid there is no
difference in operation.
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MikeRJ
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| posted on 20/9/11 at 09:50 PM |
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The ST170 has a continuously variable cam timing system. The ECU does not provide a fixed PWM duty cycle to get a particular timing value, but
instead sets it on a closed loop basis by measuring the phase difference between the crank and cam position sensors and control the solenoid duty
cycle to hold whatever phase difference is required by the ECU map. This is the same system used on the smaller Zetec SE and the larger V6 and V8
engines Ford makes in the US.
The solenoid is like a tiny spool valve, supplying pressure to one side or the other of the variator vanes, and allowing the non-pressure side to
drain back into the sump.
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