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I was reading about vtec killer camshafts, either toda, rs machines, dr-racing, etc. Anyways, on the toda site it says 'makes power rpm 5000+' Has anyone here used these b4 or know someone who has...because what im curious about is that shouldnt u make power throught the whole powerband...like have a more flat HP curve instead of one that climbs up because of the transfer from the primary to second cams in vtec.
 

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i haven't used the vtec killers before but i can tell you why they will only make power above 5000....

first, a disclaimer: this explanation is oversimplifying some complicated shit. but it will give you the general idea.

a typical cam is designed to make power in a certain rpm range. maximum lift, duration, shape of ramp, and the point at which the valve starts to open and when it closes all have an effect, but i can make a generalization: big cams (those with lots of lift and longer duration) will open the valve farther and hold it open for longer, allowing more air into the combustion chamber. unfortunately, if you design a cam to open big enough and long enough to fully fill the chamber at high rpms/full throttle, it will be "too big" at lower rpms/part throttle. if you understand that the cylinder makes a vacuum which pulls in the air, and that it makes more vacuum at high rpms/high load, AND you understand that air gains velocity when funneled thru a smaller "hole" and loses velocity when funneled thru a bigger "hole" you will understand why too much lift and duration can cause incomplete cylinder filling and reversion (where air in the cylinder flows backwards out the intake valves into the intake ports) at lower rpms/part throttle conditions. The consequence of this incomplete cylinder filling is less power (also crappy emissions but who really cares right?).

So now you have to think about the idea of VTEC. By using one cam lobe at low rpms (this lobe is designed for power in the lower rev range) and a different, larger cam lobe in the higher rpms (which is designed for high-rpm power) it should give the best of both worlds. Unfortunately it also makes the camshaft and valvetrain assembly heavier because there is two extra cam lobes and an extra rocker arm (compared to a typical camshaft).

In high-rpm race engines, reciprocating weight (anything inside the motor that spins) is the enemy. Less reciprocating weight means more power and less wear on the engine, especially at really high rpm. Since most honda race engines spend all their time running above the typical VTEC crossover point, the VTEC system is of no benefit to them since they are always "in VTEC". They don't care if the car idles well or makes good low-rpm power.

By eliminating the non-vtec lobes, and one of the rocker arms, the VTEC killer camshafts are able to save lots of reciprocating weight in the head. Unfortunately, without the VTEC system, they are subject to all the inherent design limitations i discussed in the first paragraph.

So there you go - a long-winded explanation from your friendly neighborhood forum moderator. Hope this helps.
 

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I was running again yesterday, it rained on and off all day But still managed to pump out a 12.1 @ 114mph with a top trap speed of the day being a 116mph.. the track was pretty slippery I was spinning in 2nd with the steering wheel half turned to still go in a straight line :shock:
 

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nikos said:
goPHAST said:
non vtec said:
these will possibly be one of my next purchases for my car...
Hopefully you don't plan on driving it on the street.
here's his car :}

Yeah that doesn't look like it sees too much street! Killer cams would be a great purchase for a track car!
 

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In a related question, does anyone have any experience with the Ferrea roller rockers for B series?

The aluminum rocker arms look super light, I wonder how much lighter they are than K series rocker arms.
 

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had a friend that use to run vtec killers on a b- serious motor, he like how great the power cam through after 5k rpms since the car was use mainly for drag racing but the problem he ran into is how quick it died up top. Since he was reving pass 10kpms. So he decided to go with the spec C's, since he need it something that can hold power to 10,800rpms.
i wonder how good the Toda Killers would hold on a Road race coarse :?
 
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