Quote:
Originally Posted by serialk11r
Hmmm well I dunno, seeing that those motorcycle cams were ~280 degree duration, and the 2GR is something like 240, intake closing maybe like 60* ABDC, and the motorcycle intakes open 30* BTDC, I guess we need to see what the FRS cams look like. Since they peak at 6600 (much higher than the 2GR's 4800), they will have longer duration...If they're like 270* duration then it would be utterly ridiculous that they are able to squeeze healthy torque at low rpm ranges out of the engine as almost half the charge would be blown back out! (the Prius uses ~270 degree cams with 13:1 compression!) The Toyota D4-S papers show "20% internal EGR rate" to be the limit. If they run that with a cam retard to improve VE, then the high EGR would be killing power as well. Then we could also expect that a longer cam with some overlap would see good gains at high rpm, but do bad things to low rpm torque, but increase fuel economy (lol, I'll take that...).
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Try to find specs that have the duration @ .050" lift. That gives a better picture of 'effective' duration. Prius probably has low, gradual lift so a lot of those 270 degrees are probably at tiny (ie not really significant) lift numbers.
In the BC .pdf catalog they have some more detail about when events take place (only certain cams though, and not the stock figures).
http://www.briancrower.com/dl/06cat.pdf