Still running stock cams (about 208*@0.050" and ~9mm lift) - they are for hydraulic lifters, but I've converted them solid because I rev my engine up to 7500rpm.
The valve clearances take away some lift and duration.
I'm looking for peak hp around 8000rpm on new custom grind cams.
The engine can live at near 9000rpm or even higher, but not when cornering hard (wet sump pump causes issues = bye conrod bearings).
Spec list (2922cc six cylinder, 24 valve all aluminium engine, 83 x 90mm bore/stroke):
- 33 / 29.6mm valves, 6mm stem.. a lot of porting to head (no flow data, I don't have a flow bench)
- about 14:1 uncorrected compression ratio (cranking pressure is ridiculous: 19,5-20,5bar all cylinders)
- Kawasaki ZX12R pistons
- Nissan RB30 152.4mm conrods, h-profile
- Stock B6284T (RN) crankshaft, pulley and damper (bigger in diameter compared to older version..the crank is only slightly lighter than original)
- 110 intake centerline, 103 LSA
- Triumph Daytona 675 invidual throttle bodies, 44mm plate
- DIY exhaust headers 6-2-1, 3->2,5" exhaust (for sound reduction, restricts a bit power)
- E85 only
- standalone ecu, alpha-n mode (Maxxecu street)
Power curve raises till 6000rpm and then flattens and keeps the power 'till about 7300rpm before drops - at this point (7500rpm limiter).
Still a lot of work finding the best cam timing and ignition timing (seems to like a lot less timing.. no knock issues so far).. also intake lenght might need a bit testing.
I've used Pipemax 3.98 to figure out what the engine might need.
The question is, should I care about intake/exhaust lobes operating range and intake/exhaust systems operating range??
Here's the current cam info I get with 7000rpm peak hp and stock cams:
Clearly the cams are way too small, if I understand correctly what I've bolded.Recommended Intake Valve Lift to prevent Choke = ,346 Lift @ 7000 RPM
Recommended Exhaust Valve Lift to prevent Choke = ,294 Lift @ 7000 RPM
Recommended Minimum Normal Maximum Time-Area-Duration Lifts
Intake Valve Lift = 0,3208 0,3455 0,4257 0,4440 0,4680 0,4920
Exhaust Valve Lift = 0,2732 0,2943 0,3449 0,3798 0,3984 0,4170
IntOpen= -5,60 IntClose= 34,40 ExhOpen= 19,95 ExhClose= 7,95
Intake Duration @ .050 = 208,80 Exhaust Duration @ .050 = 207,90
Intake CenterLine = 110,00 Exhaust CenterLine = 96,00
Compression Duration= 145,60 Power Duration = 160,05
OverLap Duration = 2,35 Lobe Separation Angle (LSA)= 103,00
Camshaft Retarded = 7,00 degrees Cylinder Ignition Interval= 120 deg.
-- Operating RPM Ranges of various Components --
Best estimate RPM operating range from all Components = 5239 to 7239
Intake Flow CFM @28inches RPM Range from Flow CFM only = 5160 to 7160
Intake and Exhaust Systems operating RPM Range = 5165 to 7165
Intake and Exhaust Time-Area operating RPM Range = 4049 to 6049
Camshaft's Intake and Exhaust Lobes operating RPM range = 5844 to 7844
Intake Valve Curtain Time-Area at 0,355 Lift RPM Range = 5192 to 7192
Exhaust Valve Curtain Time-Area at 0,353 Lift RPM Range = 6390 to 8390
Intake Valve Close RPM = 8452 Exhaust Valve Open RPM = 6021
Intake System RPM = 7320 Exhaust System RPM = 7011
Intake Time-Area RPM = 5597 Exhaust Time-Area RPM = 6501
Intake Mach Z-Factor = 0,472424 Exhaust Mach Z-Factor = 0,530198
Intake Z-Factor Lift = 0,349397 Exhaust Z-Factor Lift = 0,283334
I've been advised to aim for 250*@0.050" duration, both cams.
Lift should be around 12mm.
But, Pipemax seems to disagree?
8000rpm peak, 250*@0.050" duration and 12mm lift, intake/exhaust.
What kind of advice would you have for cams?Recommended Intake Valve Lift to prevent Choke = ,395 Lift @ 8000 RPM
Recommended Exhaust Valve Lift to prevent Choke = ,335 Lift @ 8000 RPM
Recommended Minimum Normal Maximum Time-Area-Duration Lifts
Intake Valve Lift = 0,3667 0,3949 0,4865 0,4256 0,4486 0,4716
Exhaust Valve Lift = 0,3109 0,3348 0,3924 0,3623 0,3801 0,3978
IntOpen= 15,00 IntClose= 55,00 ExhOpen= 41,00 ExhClose= 29,00
Intake Duration @ .050 = 250,00 Exhaust Duration @ .050 = 250,00
Intake CenterLine = 110,00 Exhaust CenterLine = 96,00
Compression Duration= 125,00 Power Duration = 139,00
OverLap Duration = 44,00 Lobe Separation Angle (LSA)= 103,00
Camshaft Retarded = 7,00 degrees Cylinder Ignition Interval= 120 deg.
-- Operating RPM Ranges of various Components --
Best estimate RPM operating range from all Components = 6516 to 8516
Intake Flow CFM @28inches RPM Range from Flow CFM only = 6183 to 8183
Intake and Exhaust Systems operating RPM Range = 7804 to 9804
Intake and Exhaust Time-Area operating RPM Range = 7647 to 9647
Camshaft's Intake and Exhaust Lobes operating RPM range = 9884 to 11884
Intake Valve Curtain Time-Area at 0,472 Lift RPM Range = 7562 to 9562
Exhaust Valve Curtain Time-Area at 0,472 Lift RPM Range = 9277 to 11277
Intake Valve Close RPM = 12500 Exhaust Valve Open RPM = 10037
Intake System RPM = 9847 Exhaust System RPM = 9761
Intake Time-Area RPM = 8872 Exhaust Time-Area RPM = 10422
Intake Mach Z-Factor = 0,406078 Exhaust Mach Z-Factor = 0,452786
Intake Z-Factor Lift = 0,399311 Exhaust Z-Factor Lift = 0,323811
Cam profile makes a huge difference tho. Small cam followers don't allow very aggressive camshafts, but I don't think this engine really requires crazy duration and lift to actually make power at more than 8000rpm.
The engine is only for testing purposes.
So it is actually supposed to blow up at some point. Not enough rpm or power if it holds.