Dusty
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| posted on 16/7/06 at 11:06 PM |
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Zetec and piper cams
I have a blacktop engine fitted and had intended adding a piper 285 cam, doing a little porting and bobs your uncle, 200 horses. Ordered the cam kit
and they sent me a hydraulic kit.
Looking at the timing we have inlet, duration 280, lift 10.31mm. exhaust 270, lift 9.4. Piper said 200 with a little porting, no problem.
OK so what about the blacktop 285? Er, inlet 264, lift 9.71 and exhaust 256, lift 9.18. Piper said that will be getting on for 200 with a ported head.
Any more agressive duration or lift and the cam lobes run off the followers so you need to buy our follower set at £360 + vat. There is a ford that
uses the special followers as standard, ie shims under the follower not on top but the piper man couldn't remember which one. So tuning the
blacktop is going to get very expensive for mild/moderate power.
Having had both silver and blacktops in my car in the last month I much prefer the blacktop.
What to do? At the moment I am thinking very seriously of going back to a silvertop which is going to be much cheaper to get 200 bhp from than a
blacktop.
Talking about porting had the head off a silvertop this evening and the ports are suprisingly bad. There seems to be a three angle seat but two
distinct steps in the throat and the short turn is almost a rightangle. Shouldn't be difficult to improve on this.
Won't let me put a pic on this post so it's in my archive, steps2
[Edited on 16/7/06 by Dusty]
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Krismc
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| posted on 17/7/06 at 06:31 AM |
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Hi my car is in jude performance(blaydon) at the moment, im getting head work, bit of polishing etc and piper cams(nothing stupid) ill let you know
the ones we use and the outputs we get from the rolling road, im running MS ECU, a 2.0 black top on GSXR TBs.
Also Ian@ jude performance has just tuned his silvertop on jenvey throttle bodies, with pipers to easy 204BHP and a very healthy and flat torque curve
which is what you need for al round power, he is a fellow locoster so im sure he will reply on here soon!
[Edited on 17/7/06 by Krismc]
Built, Ivaed, Drove and now Sold - 2011 MNR VORTX RT+ 2000cc Zetec on R1 Throttle boddies.
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roadboy
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| posted on 17/7/06 at 07:55 AM |
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Zetec
The silvertop uses hydraulic followers & the blacktop uses solid followers with shims, so i'm pretty sure the hydraulic cams won't
work in a blacktop. With regards to the engine we have just built, we used more aggressive cams with 11mm of lift on the inlet but thhis requires
pocketing the pistons. The power output could be bigger but we timed the cams to give a broad power band with loads of torque 172ft/lb.
Hope this helps
regds
Ian
Jude Performance Services
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Dusty
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| posted on 17/7/06 at 10:59 AM |
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I have not sent the hydraulic cams back as I am thinking the cheapest route is to go back to the silvertop engine.
Pocketing the pistons sounds like serious work. Did you use standard blacktop followers with the shims in the top or some other followers?
Can you explain what cam timing variations give which changes in power?
[Edited on 17/7/06 by Dusty]
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roadboy
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 posted on 17/7/06 at 12:00 PM |
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We used standard hydraulic followers, the cams were some Dunnell units I had left from an old race engine of mine.
Generally advancing the cam timing gives more power but usually at the expense of a narrower power band higher in the rev range, please note this is a
generalisation & not the same for all engines. The secret for road/trackday engines is to keep a good torque curve with a nice power spread. As
the man said " BHP sells engines, torque wins races" I think it was Carroll Smith.
Cheers
Ian
Jude Performance Services
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