Cam duration

[spetz]

Hi guys,

I was (out of curiosity) checking different cam specs etc, and thought that the CTR/ITR 235/240 duration was relatively short in comparison to other high output NA motors.
Is this just a discrepancy in how the duration is measured, or do VTEC motors indeed run relatively short duration cams?

Thanks

[curtis265]

what are these other motors you speak of?

[spetz]

For example the MIVEC motors I think have something closer to 300 degrees duration?
Also the VVTi-L from the Sportivo Corolla or Celica:
High Cam 292° 11.2mm 276° 10.0mm

[Touge Tom]

There absolute numbers. Not @ 1mm lift. Like buddy club 3+ there advertised @ 296, but @ 1mm lift their only 250 duration.

[NSPYRE]

There absolute numbers. Not @ 1mm lift. Like buddy club 3+ there advertised @ 296, but @ 1mm lift their only 250 duration.

beat me to it :)

[NSPYRE]

In addition, may want to refer to the following:

From page 7/155 of the pdf file, lists cam specs for 4G92, 93, and 94:

http://www.google.com.au/url?sa=t&rct=j&q=mivec%20cam%20atdc&source=web&cd=1&ved=0CCMQFjAA&url=http%3A%2F%2Fwww.mitsubishiclub.cz%2Fgraphics% 2Fmanuals%2F97%2FPWEE9502-ABCDEFG_ENGINE_4G9_SERIES_E-W_WM.pdf&ei=49qUT82sBamuiQfM-NmABA&usg=AFQjCNH9DSjyGSXwUhc9DYNbwe_M77mlRw

I think I posted the link to the camshaft calculator somewhere before, but here it is again:

http://www.wallaceracing.com/camcalc.php

[spetz]

Thanks guys, much appreciated :)

[mrwho]

Have a look at the LSA and IVCE factors of a camshaft. I think you'll find it to be much more informative than durations numbers.

[NSPYRE]

have a look at the lsa and ivce factors of a camshaft. I think you'll find it to be much more informative than durations numbers.

ivce...??

[mrwho]

Intake valve closing event

[NSPYRE]

Care to elaborate?

[trism]

The actual profile ie how quickly/slowly the valve opens and closes, and also the overlap has a big effect on things

[Touge Tom]

The actual profile ie how quickly/slowly the valve opens and closes, and also the overlap has a big effect on thingsand dynamic compression ratio, witch is all ways lower then static. unless your'e boosted, then it's higher than static compression.