I guess the head would have evolved a little. But I am surprised about 10-15bhp, or is that based on "feel"?
Many thanks for the replies, guess if a silvertop comes in cheapish then I will probably go that way. But no rush
Cheers
Clive
A bit of forward planning here.
My spitfire currently has a 1.8 silvertop with 2lire cams fitted, on a dunnell EFI setup. Sadly the std focus manifold is used for convenience.
This winter I am fitting a scooby diff as the Triumph one is just managing to cope, but probably not for much longer, and I am fed up with having to
be careful.
Next winter I plan to fit a 2 litre engine, and a better manifold. I will retain the Dunnell EFI stuff, just get them to re-map it.
But in real terms is there any power/torque difference between a silvertop and blacktop engine? (I realise a few tweeks to change to a blacktop will
be needed, but not much)
Cheers
Clive
I went from a healthy standard 2 litre silvertop to a standard crate 2 litre Blacktop.
Used exactly the same induction, exhaust, sump etc.
Fueling needed tweeking a bit.
The Blacktop definitely picks up better and supposedly has about 10 - 15 hp more.
Was it worth it, probably not.
Silvertop has a stronger bottom end but not by much and the black top has a better head but also not by much.
There isn't a lot in it.
Interesting about the silvertop bottom end. Out of interest, why?
I guess the head would have evolved a little. But I am surprised about 10-15bhp, or is that based on "feel"?
Many thanks for the replies, guess if a silvertop comes in cheapish then I will probably go that way. But no rush
Cheers
Clive
I can't remember exactly but it's somthing to do with rod and piston length.
The Bt head breathes a little better. Stock difference is somthing like 136 on the st and 145 for the Bt. This isn't just down to the head.
There really isn't a lot in it. You don't have Iva to deal with so I would fit the best motor you could get for your money.
Now the St170 has better rods, pistons, head, Cr and will do another 20bhp+ with the same induction and exhaust but you have to control or lock the
vvt on the inlet cam.
[Edited on 9/2/16 by big_wasa]
My engine code is EDBA but made a good 155bhp with a bit more to come.
Find your engine on this chart Chart Linky
[Edited on 9/2/16 by johnemms]
as an aside, have you seen this
http://trigger-wheels.com/store/contents/en-uk/d68.html
no idea if any good, but stumbled across it the other day. Seems a simple solution (or maybe not?)
I doubt my Dunnell ecu can be remapped for an ST engine, which is a shame.
The engine chart from above is a little interesting. Seems the blacktop in a focus has a little more power than the mondeo. Can only be down to the
exhaust manifold being different, not sure about induction though.
According to the Dunnell site, i should enjoy an extra approx 15bhp from the engine swap, which seems reasonable. Add a few more horses for a better
manifold. So may get 20bhp. But another wallop of torque too, which is more of an advantage.
If you lock off the vvt on an St170 engine it becomes a tuned blacktop.
Ie it's a zetec with better pistons and rods with a higher compression ratio with a big port head and bigger inlet valves.
I swapped a Pinto for a 2 ltr Black Top in my old Tiger adding an emerald ECU, Jenvey TB's and a decent exhaust manifold some years ago .. Topped
out at 174bhp (flywheel) at Emeralds rolling road (all rolling roads being "relative" of course). Interestingly, Emerald can now
"properly" map the variable aspect of an ST engine (no need for locking).
Reading Ford's electronic workshop manual, the pre-amble description given pointed to a better flow shape in the ports, solid followers instead
of hydraulic, and a return to positive cam overlap profiles .. something that troubled carb manufacturers with the Silver top with the need for extra
progression drillings. compromises are the water pump is only available in one direction of rotation (wrong for kit-cars as we don't use
auxillery pumps) needing an additional pulley for the alternator belt. The two part sump can be modified, but you need to remove a lot of the external
material to clear the starter motor on a Type 9 bell housing. Nothing difficult though and you can use after-market sumps. I used a Silver Top 1.8ltr
flywheel which is considerably lighter that the boat anchor on the 2 ltr Black Top.
A decent 2ltr Silver Top should give around 160bhp.
Selection criteria would be .. Can you find a decent silver top these days without significant mileage?, Black Top is now more common and fits the
same hole as a Silver Top, ST engines still carry a premium and compromise on ECU, but is the more powerful lump, although the inlet and exhaust are
opposite sides compared to the Silver Top and Black Top (if that's important).
Simplicity (if there is ever such a thing) would suggest black Top.
Cheers !!
quote:
Originally posted by FatChapChipChop
...Black Top is now more common and fits the same hole as a Silver Top, ST engines still carry a premium and compromise on ECU, but is the more powerful lump, although the inlet and exhaust are opposite sides compared to the Silver Top and Black Top (if that's important).
quote:
Originally posted by FatChapChipChop
Interestingly, Emerald can now "properly" map the variable aspect of an ST engine (no need for locking).
I have
an ST170 with a very good engine that may well be donated to the cause! Owwww, this isn't fair.
There was me thinking nice simple engine swap. I keep thinking should I sell the dunnell ECU and get a new one that can control the vvt. Could be an
expensive? £6-800??
Or sell the complete Dunnell ecu/jenveys etc, fit a set of bike carbs and a megajolt/similar, and a VVT controller.
Or be sensible, just do the simple engine swap. Now my head is hurting.
(and how easy is it to lock the vvt?)
quote:
Originally posted by kingster996
quote:
Originally posted by FatChapChipChop
...Black Top is now more common and fits the same hole as a Silver Top, ST engines still carry a premium and compromise on ECU, but is the more powerful lump, although the inlet and exhaust are opposite sides compared to the Silver Top and Black Top (if that's important).
ST has inlet and exhaust on the same side as the others - it's a Zetec engine badged as a Duratec
quote:
Originally posted by Adamirish
quote:
Originally posted by FatChapChipChop
Interestingly, Emerald can now "properly" map the variable aspect of an ST engine (no need for locking).
Is this true? I know they have been working on it but hadn't heard they have cracked it. If so, I know what will be next years project!
Also the manifolds are the same way round as a normal zetec.
quote:
Originally posted by FatChapChipChop
quote:
Originally posted by Adamirish
quote:
Originally posted by FatChapChipChop
Interestingly, Emerald can now "properly" map the variable aspect of an ST engine (no need for locking).
Is this true? I know they have been working on it but hadn't heard they have cracked it. If so, I know what will be next years project!
Also the manifolds are the same way round as a normal zetec.
It seems so, I follow them on FaceBook and they've reported several engine types where they've progressed to mapping the variable aspect fully.
Cheers !!
Just for info, megasquirt 3 can control VVT, been available for last 4 years