- I think i'm going to try the Piper ultimate road, as i'm hoping the long duration will suit the low-flowing inlet (guestimate onthe flow bit).
- I think i'm going to try the Piper ultimate road, as i'm hoping the long duration will suit the low-flowing inlet (guestimate onthe flow bit).
My experience over here has been similar to Forrest_Rallyings post. You really need to consider all facets at once before touching a spanner. These engines need 11:1 compression at least. To get that you will have to very carefully choose pistons with the right valve reliefs to suit the much higher lift your going to need to get your required power. I'll tell you right now if you want to leave your head at 139.1mm ie no skimming your going to have to weld up and re-shape your chambers to get 11:1. My heads right on the limit at 137.2mm, I used custom CP pistons, inlet cam 11.6mm lift, exh 11.4mm and a .040" head gasket to get 10.5:1. The cruncher is your piston to valve clearance at TDC. You need as much as you can get on the exhaust. All this tech info aside, the Sierra head is an amazing engine.....leave it turboed. PS I got 170BHP at the wheels after nearly AU$20,000 on engine.
YB Cosworth N/A rebuild ongoing.....100% Ford
Well that will be totally opposite. Long duration cams only work in good ported heads. If yours is poor flowing (not much more as standard) the cam will hurt more as what it will help.
I don't know how fast this cam really is, only thing I wanted to point is, your theory is wrong. Best to change from this idea
So you are saying the acralite pistons advertised at 12,5-1 compression for na won't reach at least 11-1, and not have correct valve reliefes? Somehow i doubt that..
Last edited by Forest_rallying; 26-09-2017 at 21:02.
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