Xu9ja Oe Cam Spec

[Sandy 191]

I measured a standard XU9JA cam a short while back, here's the Inlet and Exhaust lift curves I recorded for those who it might interest. For comparison I've overlaid the "Max Torque" cam Inlet curve:

 

 

The numbers are:

 

Cam----Test clearance (mm)----Peak lift (mm)----Duration @ 0.1mm----Duration @ 1.0mm

 

XU9JA Inlet----0.2----11.05----284----229

 

XU9JA Exh----0.37----10.66----237----214

 

Max Torque----0.2----11.28----279----254

 

It's an abject lesson in how comparing cams by peak lift and overall duration can be very misleading! The XU9JA and Max Torque inlets look similar on the headline figures, but the curves and lift at 1.0mm are massively different. The extra area under the curve on the "Max Torque" before TDC and after BDC is substantial and will play hell with low speed running on a single inlet and the metering smoothness of the AFM or MAP load.

[welshpug 1,661]

It's an abject lesson in how comparing cams by peak lift and overall duration can be very misleading! The XU9JA and Max Torque inlets look similar on the headline figures, but the curves and lift at 1.0mm are massively different.

The extra area under the curve on the "Max Torque" before TDC and after BDC is substantial and will play hell with low speed running on a single inlet and the metering smoothness of the AFM or MAP load.

 

too bloody right definitely needs more compression and ITB's over a standard engine, though over 2k rpm it's fine, but obviousl nowhere near its potential output

[Mattsav 1]

At last people are recognising that quoting seat durations doesn't tell you anything!

 

Whats mroe interesting is (assuming the measurement is correct) the Max torque cam has Less acceleration on the opening side

[James_R 3]

Don't happen to have a track of a PT36 or piper272 cam to go with that??

[Sandy 191]

No I haven't James. I have got heaps of other profiles, but I'm not sure how keen the manufacturers would be on me publishing them, given that they don't publish the openly themselves.

 

At last people are recognising that quoting seat durations doesn't tell you anything!

 

Whats mroe interesting is (assuming the measurement is correct) the Max torque cam has Less acceleration on the opening side

Cheeky! The method I use is accurate and repeatable to 0.02mm, I measure lift at the valve so the curve is as the engine will see it. The OE cam appeared to be in good condition, certainly typical I would think.

 

The acceleration on both cams is the same, but the peak velocity on the "Max Torque" cam is quite a bit lower; the OE cam has incredibly high velocity for a factory cam, similar to VTEC and many race profiles.

[petert 588]

It's quite common to have a different opening/closing profile and can be a trap for young players when installing cams. Thus lobe centre line method would be prefered.

 

If I get time later this week I'll post standard Mi16 and my Stage I.

Edited February 18, 2009 by petert

[M@tt 77]

Sandy out of interest who makes these "Max Torque" cam's

[welshpug 1,661]

IIRC mine was made by Piper

 

(May even be the one that Sandy measured)

[Tom Fenton 1,542]

Heres a graph I did recently, OE 1600 vs OE 1900 vs OE 2.0 T