I understand cams alone won't get you much power, yet I'd HARDLY call them rice IMO. I have read that cams DO give some power. I found this though.....
" At a minimum you should get a better exhaust and intake to go with them. To really get the most, work over the heads and intake manifold (port/polish) and add headers. And after all that, get the ECU re-calibrated to take all that into account "
........
"a good cam will give more lift and duration, there for more fuell and air in and out, and the whole reason feul injection is so good is that the ecu make air- fuel adjustments from what its reading from the MAFS"
Also aren't some cams shorter for more torque and longer for more hp?
and at the very least, isn't this a good supporting mod if you plan on doing bolt-on's?
cams control the opening and closing of your intake and exhaust valves. As a general rule of thumb, longer duration (time open) leads to more hp. Higher lift (how far the valves open) does the same. The game starts to get interesting when you see that high lift leads to raising your powerband higher up in the rpm range, at the cost of low end power, especially torque.
It gets even more interesting when you start talking about overlap. You can have the exhaust valve open before the intake valve completley closes. This leads to "scavenging" and sucks the exhaust gases out, and even the new batch of air and fuel in. The problem is, in boosted cars, this "overlap" lets boost pressure leak out, leading to inefficiency. That is why boosted cars dont really benefit from those lopey cams that we all like. If anything, we just lose power.
On a n/a car, you can definitley benefit from that lopey idle, as that is from that increased "overlap" that draws more air and fuel into each cyl.
Now enter the piece de resistance. Variable cam timing. The holy grail of cam technology. It allows us to stop "compromising" between a cam for low end tq and a cam for top end hp. It is because of this that S197's dont really stand to gain much from a cam swap until you start changing displacement or porting heads.
So to keep up the rice argument since thats fun too, I still ask the same question: How is it not rice? It (if anything) adds trivial power. So if someones gonna tell me its not purely for the sound, and they want it for the trivial hp increase, then wouldnt u wanna spend your money on a mod wiht a better hp/dollar value? To me, this discussion is transparent as could be. Everyone (including myself) wants cams for the sound. Why cant we admit it?
on the 4.6 3V motor i have been doing a lot of digging in regard to cams and you have 3 options really. NSR, VSR and SPR cams to choose from. The NSR give the smallest gains, but are the easiest to install since they don't require new spring or phasers. The VSR's add a little more power but need new springs, there are 24 springs in our engines, kinda adds a lot to the install cost. Then there are the SPR which require new phasers and springs. you start to run into problems with the VVT ect but you gain even more power.
I have been quoted for a set of NSR cams which will add around 20 HP, a little more peak HP then that, for $800 for the cams, and another $600 for install PLUS a full custom dyno tune. Dyno tuning is very pricey so the install of the cams isn't that bad, but you are looking at spending 2.5 times the money for a gains approx equal to your $600 intake and tune combo. So if you are doing cams, you should want to do it for the cammed sound in addition to the performance gains.
Ok well from what I have read CAMS do gain you some performance (Even if its as minimal as an up).
Quote:
On a n/a car, you can definitley benefit from that lopey idle, as that is from that increased "overlap" that draws more air and fuel into each cyl.
<--- There ya go, so it does give you some gain. Think of an engine as an air pump and its power depends on how much air you can get into and out of the engine - if the loopey idle creates that overlap, in the end it's giving out more air which means the air is going in and out of the engine faster, producing some kind of gain...even if its throttle response.
Kevin, just for you - I'll give it to you/ I'll admit it - I want cams for sound...AND for the future performance gain. If I put cams in my car, it would be for sound but it would also be a supporting mod. I wouldn't go spending near $1000.00 just for sound..I doubt many people would too.
As far as the rice discussion, IMO its not rice. I can see a fart can, L.E.D.'s, certain spoilers or extra body pieces - I'll give you that to a point, but to me if its done tasteful - not tacky it's not rice.
Cams will give your performance, you just need the right duration, sound isn't everything, there's benefits to pretty much everything, Personally I don't like the sound of cams in a DOHC Engine personally. I much rather have it in a SOHC engine.
As long as you have the right tune, you then have something to show for it, instead of sound.
Ha ha, that's why Chevy Motors sound so much better Cammed , because of the fact that there motors are SOHC. Tune is everything, whether it be from adding a turbo or supercharger whatever the case may be. Having to aggressive of cams can cause major problems, and it can really screw with your VVT which most cars are these days, so that may require you to re-adjust your timing accordingly. Also having Cams can actually trigger false knock, if your knock sensor isn't adjusted either, Most of the time you need a stand alone to adjust that though. Also you can throw off your A/F ratio as well, not good, running to lean can cause major damage.
ok last retort here. To chris - Yes, adding lift and duration can increase power. "CAN" Its not one of those, if a little is good, more is always better. My whole reasoning for "cams wont add power in an s197" is that now that we got VCT, we no longer have that compromise of low end vs top end power. The fact is, our cam was designed to work with the VCT and be optimal all the time. So a bigger cam wont do anything, like it did in previous years. It can change your powerband...but it wont just add hp.
To Hotshot - Good work on explaining the diff. levels of cams. Id liek to expland a little on that.
The NSR - or mildest cams can be installed relativley cheaply. Power gain imo. is nil, and you will still need a dyno tune so as you had said, the hp/dollar ratio aint too good.
VSR cams need stiffer valve springs to keep the followers in contact with the cam lobes at high rpm. On the s197 this is prohibitive because changing springs requires special tools and a lots of time. So its very costly. Still, this will start to add some real gains on a na motor. It must be noted however, that you should be doing all your other mods first.
The spr - let me explain this a little more. Yes they need stiffer springs. The "new phasers" that hotshot had mentioned - phasers are the things that do the varying in the cam timing (its fords vtec). When you get to these bigger cams, you install phaser "limiters" to limit the effect of the vct. You may even be required to install phaser "lockouts" that defeat the vct all together. This allows you to run larger cams and not worry about piston to valve clearance. For a street car though, this is so not the way you want to go.
I am only arguing the "power" issue to prove its not rice! I understand the VCT takes control so we don't need cams. I understand with aftermarket cams you loose low end. Yet if it CAN add power, and if it does even to a MINIMUM add power - then it's hardly rice
Great threads hotshot and Kev, I am really learning here!!
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Oh Yeah, Another Aftermarket Cam thread
. I have read that cams DO give some power. I found this though.....
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