Quote:
Originally Posted by Calum
I just had a chance to look at these numbers, my god those are tiny! Unless Crower is measuring these at a very high starting lift point, I can't believe We're getting 200 hp from these cams.
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A couple things to keep in mind, besides the obvious fact this engine has direct injection. I don't know what the valve angle is, but steeper valve angle = better possibilities for head flow. Basically, there's a tradeoff between charge motion and flow, but the tradeoff line "moves outward" with a steeper valve angle. Maybe the valve angle is advantageous (or maybe not).
There's more to a cam than a duration--the duration is only the length of the event. The timing is critical. Remember, with dual AVCS we can retard intake closing timing for higher volumetric efficiency, and adjust the exhaust valve timing for either earlier blowdown (advance cam) or later evacuation of gases (retard cam).
In most cases for an n/a engine the number one determining factor of high speed performance for a cam is closing timing of the intake valve. It sets the trapped mass (effective volume), the pressure drop across the intake valve (filling capability and dynamic effect), filling time, and effective compression.
Quote:
Originally Posted by DAMotorsports
The stock springs really suck if you plan to run high RPMs. They have an install pressure of 33LBS and at .05 lift they are 55LBS. The rocker arm design is similar to the TC. Which worried us as the TC is known to throw rockers and wiping out the head. So we contacted Supertech and obtained a set of their springs. Their upgraded springs have and install of 75LBS and 105 @.50
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I'm sure you know this, but for everyone else: stiffer valve springs = more wasted engine output on friction. It's certainly an appropriate move to get stiffer springs, and I'm not saying you don't need stiffer ones in this case. But the stock ones are designed that way for a reason and you have to be careful about going overboard.
Also, for everyone else: brake torque (and thus power) = indicated torque - pumping - friction . Friction is basically a catch-all for anything that isn't related to combustion or gas exchange.
Friction screws you over in everything. It kills fuel economy, it kills torque and power.