Dusty
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| posted on 30/5/11 at 04:08 PM |
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ST170 hybrid?
I have two ST170 engines, one running happily in the car (breathes a bit heavy) and a spare. Currently stripping the spare and I'm wondering if
a standard blacktop head will fit on. Why? Never been that impressed with the performance of the VVT head. It has big ports and should be mental but
the VVT is a pain unless you have proper PWM shifting and modifying the cams is a fortune. Bit of a tuning dead end unless you have deep pockets.
Bottom end of these engines is strong. Anyone know if a blacktop head fits?
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big_wasa
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| posted on 30/5/11 at 04:29 PM |
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I would think it would fit, not sure about the cam belt tensioner.
you will end up with a blacktop with uprated bottom end. Black top bottom end isnt overly weak to start with.
A ported and camed black top will go over the 200bhp marks.
[Edited on 30/5/11 by big_wasa]
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hootsno1
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| posted on 30/5/11 at 06:16 PM |
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i think you will find the st170 was a durance engine not a zetec? so ther xebec head wont fit but i could be talking sh@£
If a little hammer won't fix it get a bigger hammer
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coozer
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| posted on 30/5/11 at 06:19 PM |
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quote:
Originally posted by hootsno1
i think you will find the st170 was a durance engine not a zetec? so ther xebec head wont fit but i could be talking sh@£
Nope, its defo a blacktop zetec. Durotecs have the intake and exhaust on the opposite side and an ali block.
And, whats wrong with the ST head? Mines OK, the vvt works OK.
1972 V8 Jago
1980 Z750
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hootsno1
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| posted on 30/5/11 at 06:57 PM |
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stupid me im thinking fo the st150 sorry guys.
If a little hammer won't fix it get a bigger hammer
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Dusty
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| posted on 30/5/11 at 08:23 PM |
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quote:
What's wrong with the ST head? Mines OK, the vvt works OK.
Well that's kind of it. Yes it works OK. The VVT works but with
the omex ecu all I have is the full 60 degree advance which is a bit too much or none at all. I saw a cam map from DTA who do the S60 ecu which will
do PWM for fully variable/programmable cam timing. All full throttle, they use 50 at 2500rpm, 60 at 4500 and 40 at 5500 and above. Now if I have 60
degrees of cam advance at 5500 which is too much so the power drops away fast and I'm missing some of the potential of this engine.
Changing cams to loose the VVT is a well worked route with the ST170 at a price and keep the omex. The followers can't be shimmed. Lash caps
only which is beyond my skills so loadsa money.
Or use uprated VVT cams but again it's lash caps and you need the DTA ecu or similar to fully exploit. So it's all very expensive to
develop the engine further.
So yes as standard it's a marginally more powerful engine than a standard blacktop but the cost is making it a development blind alley for me.
The blacktop head and cams are very much more amenable to my moderate skills but paltry purse and I'm pretty sure I could do the head and uprate
cams with shimmed followers to produce more power for less dosh.
One avenue I have not explored but have seen talked about is keeping the VVT cam, ditching the VVT pulley and making a vernier pulley for it. Then you
could swing the cam in the normal way for max performance at the chosen revs. Still feels like losing some of the potential of this engine.
There is excellent power potential in this engine but getting it delivered is the challenge.
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paulf
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| posted on 30/5/11 at 09:27 PM |
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I wonder if there may be a market for a standalone VVT controller? I have thought once or twice about trying to develop a basic mappable PWM
controller with maybe a 5x5 map for load and revs.
I know the St170 would benefit and there must be other engines that could use it and if a standalone unit it could be used for injection or
carbs.Maybe one day i will treat my car to an ST engine and have a play with it, im assuming that 170bhp in a focus would be approaching 200bhp minus
the cat and with throttle bodys.
Paul
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coozer
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| posted on 30/5/11 at 09:58 PM |
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PWMing is a waste of money IMO. Theres a handy function in MS and Omex that does just as good a job. RPM V TPS.
My Omex does a decent job of switching the VVT which suits my car. In its previous guise with bike carbs there's an instant 100bhp increase when
it comes on (see my blog).
Theres a bloke down where I'm working has a Focus ST170 and I've talked to him at length about his and mine. Basically he says
there's no noticeable increase in power, just that it feels a bit more lively above 4k.
Since the bike carbs and moving up to TB's I have played around with the entry point. Its now set at 1500rpm and 25% throttle. This means I can
cruise below that range up to above 80mph, the extra power being just a twitch away on the pedal.
Mine is down on compression, which I believe is cam timing (mine way out atm) but, still makes 178bhp, which, is 12 more than with the carbs on.
Go on the ST170 forum and see what the real world rolling road figures are for standard cars. They remove cats, put induction kits on and even chip
them to get them anywhere near the expected 170 level.
My goal is 200bhp from a more or less standard engine.
1972 V8 Jago
1980 Z750
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scutter
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| posted on 31/5/11 at 09:04 AM |
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I have to agree with Mr Coozer here, My ST170 engine makes 188 without the VVC even being plugged in (I tried to get it working but realised 2
earths would never make the relay work, Sorted now and it just needs mapping again).
All mine has had done is a decent exhaust, a retarded Ex cam pully and GSX-R throttle bodies matched to the standard head. I'm aiming for over
200 at the engine but really I wouldlove 175 at the wheels. (might be a bit of a tall order that one).
Stick with it, a decent ECU will help loads, Mines an old Omex 500.
ATB Dan.
The less I worked, the more i liked it.
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