Some "Dynomite" Heads! - ZR-1 Net Registry Forums

Locobob · 12-20-2010

Just getting started on Dynomite's head porting so I thought I'd share as I go along. Some interesting measurements from the stock (untouched) heads:

Combustion Chambers came in around 41cc with not much deviation, this was using my own method and a spark plug in the hole.

Intake runner dimensions:
Diameter at IH gasket surface: Primary 32.3mm, Secondary 36.4mm
Diameter, narrowest point of runner: Primary 32mm, Secondary 32mm (just upstream of valve guide)
Runner width at valve guide: Primary 33mm, Secondary 33mm
Valve seat diameter: Primary 34.7mm, Secondary 34.7mm

Exhaust port dimensions:
Valve seat diameter: 32mm
Width across valve guide: 34.8mm
Runner narrowest point: 31.5mm (where ports merge into one)
Header gasket surface: 51.8mm long, 35.6 tall

12-20-2010	#1
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Some "Dynomite" Heads! Just getting started on Dynomite's head porting so I thought I'd share as I go along. Some interesting measurements from the stock (untouched) heads: Combustion Chambers came in around 41cc with not much deviation, this was using my own method and a spark plug in the hole. Intake runner dimensions: Diameter at IH gasket surface: Primary 32.3mm, Secondary 36.4mm Diameter, narrowest point of runner: Primary 32mm, Secondary 32mm (just upstream of valve guide) Runner width at valve guide: Primary 33mm, Secondary 33mm Valve seat diameter: Primary 34.7mm, Secondary 34.7mm Exhaust port dimensions: Valve seat diameter: 32mm Width across valve guide: 34.8mm Runner narrowest point: 31.5mm (where ports merge into one) Header gasket surface: 51.8mm long, 35.6 tall __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368