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Discussion Starter #1
Now this question may sound stupid... and I'm sure a few of you will tell me that "it's already been answered", but what is the difference between Intake cams and Exhaust cams... First of all, This P10 G20 that I own now is my first 'Twin-Cam' engine... (I used to own a 92' 1.5L SOHC Civic) I'm not good at these mechanicals things you know... but I'm here to learn and I'd appreciate it if you guys could help me define them. (please don't knock me :bored: ) I'm glad I could ride a DOHC now, but I'd like to learn as much as possible... and asking is always the best way to start, instead of searching and finding random answers that were previously given. If I'm buying an exhaust cam do I have to get the intake one as well etc... Hit me up ya'll, I'd appreciate it!!:)
 

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One cam runs the intake valves (two per cylinder) and one cam runs the exhaust valves (two per cylinder). It's often not practical to run two of each valve with a single cam shaft, so for the sake of engineering perfection, they have one cam shaft for each.

You might want to check this out, and use "DOHC" as the search criteria. There's a LOT of information here for non-mechanic types or simply for people who want to know more and don't know where to start looking. I love this site, despite the occasional artistic license. Hell, it's not like I've never oversimplified something for the sake of getting a point across (see above). :D

When you buy JWT cams, from JWT, you get both. Makes like JUN, Tomei, and Zex generally also sell in pairs, but you don't ever want to buy an aftermarket cam in the US except for a JWT. ;) When people talk about using a '91 cam in a non-'91 car, though, they're talking about using the '91 intake cam, since the exhaust cam was virtually if not exactly the same in later builds.
 

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CowboyDren said:

Makes like JUN, Tomei, and Zex generally also sell in pairs, but you don't ever want to buy an aftermarket cam in the US except for a JWT. ;)

Just out of curiosity why is that?
 

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I'm just picking favorites for no particular reason. ;) First of all JWT doesn't regrind. I have no idea how the others go about it. Secondly, they use Nissan billets. If the others are regrinders, than clearly they do, too; it's just a conceptual preference. Thirdly, JWT cams are a fairly well-known quantity. Just about anybody can say, "Yeah, with a CAI, a header, and some S3s, you can expect NNN horsepower." Forgive me, I forgot what that number was, but it's super easy to find (http://www.se-r-list.org/archives/).

I have nothing directly against any other cam maker, though I do disagree with some of their methods, and dyno testing has shown that some of them are genuine crap. It's kind of hard to go dangerously wrong with JWT, though. :D Seriously; do what fits your needs, style, and budget; any monkey like me with a keyboard and a fast internet connection can say anything we want, it doesn't mean we're right.
 

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If you don't wanna read all that, it basically comes down to this:

Since you have TWO cams controlling intake/exhuast separately, there is more control over each. What does this mean? More efficient, more power, etc. (This is the main advantage):sleep:

Since the cams are positioned somewhat to the sides of the cylinder, the valves can be placed closer to the centerline of each cylinder (something that you can't do so easily in a SOHC engine). This is also probably pretty good for the engine.:rolleyes:

And finally, now you get to put a big DOHC sticker on your car like those super cool B16 guys, or those guys with upper-end Saturns Flaunt your twin cams!!!
:-\

Yeah, I'm pretty sure I missed something else too....hmm....
 

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Well, another very nice thing about a DOHC motor is that you can independently adjust the cam timing of either the intake or the exhaust cam. With a set of adjustable cam gears you can do some fine tuning and change the powerband, although this does vary a lot depending on the motor.
 

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NismoPC said:

Also, Tomei are not US made, they are imported.
I never said they were. I said that if you are in the US, and thus JWT is probably more readily-available than Tomei to start with, you should probably just get JWT. Tomei makes some kick ass cams, by the way, but I have no idea how streetable/powerful they are. Hard to go wrong with JWT S4s and an appropriately-tuned ECU...
 

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Discussion Starter #10
IIGHT!

Thanx a whole lot guys! I needed that! I always knew that the 'Twin-Cam' business was more powerful than a regular one, but now I see how it works. I guess it's then better to upgrade both of them to increase both Intake/Exhaust performance. I would definetly go with JWT... this speak so highly of it on this site... same goes for the HS CAI and Header :p Products with good reviews are always bound to be satisfying! :) Thanx again ya'll! Where could I purchase them??? anyone...? :nervous:
 
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