im contemplating whether to use stock cams or the aftermarket ones i have. i know Matt told me to use the stock ones...what to do? please give me your opinions and some kind of reasoning why. instead of "use aftermarket"


thanks

 

Custom cams are ground to improve flow into and out of normally aspirated heads at mid to high rpm, at the expense of low rpm driveability, e.g. low end power and idling smoothness. Valve lift is increased to reduce flow restriction, and valve overlap is increased so that the inertia of exiting exhaust gases helps pull in the intake charge.

Boosted engines don't need the help of increased valve lift and overlap because the blower provides all the pressure necessary to fill the cylinder. So you can stick with the stock cam and benefit from the low end power and idling smoothness built into it.

 

 

Are your aftermarket cams ground specifically to turbo specs or are they N/A cams?

 

JWT

 

actually their not JWT cams....


i wasnt looking for someone to teach me the difference between cams, i already know that.


the custom cams are turbo cams, they idle smooth but i dont know what the specs are for them.

 

I have to disagree here. Cams for na and cams for boost DO differ. BUT, if the cams are relatively mild, then what's good for the goose is good for the gander.

There are many factors than just "should I use stock or xxx cams?" And also there are many factors to the statement "you can't use xxx cams for turbo powered engines".

Now let's just assume that these "cams" are mild. Because I haven't really seen(yet) a set of wild cams available for the maxima. These cams should work equally as well for both applications. I say this because it looks like Turbo95 will use these on a stock compressioned motor? If yes, then most any mild increase in lift/duration won't decrease the dynamic compression of the engine and increase the lagtime of the turbo. (ie.. if you have wild cams w/ mega duration and lift, it will take longer for the engine to build up boost pressure for the turbo). Also, if Turbo95 is still using the t3/t4, then again mild cams will work well. If he had some huge turbo, the engine might not be able to breath well enough to support the air(thus the need for "bigger" cams). As long as he matches the turbo size to the compression and cams, he should be fine.

 

JWT is currently offering 2 cams for 4th and 5th gen cars. A milder one for forced induction and a more aggressive one for nonaspirated motors. I have had both in my engine and I prefer the milder ones because of better idle and a little more low end torque. Also, if you have big brakes you'll need an additional vacuum cannister with the more aggressive cams.

 

i dont believe turbo cams should have lumpy idle. anyways, seems like im leaning more towards stock cams...ugh i dunno, i like how the aftermarket ones sound tho.

 

aftermarket.... =)

 

Definitly go aftermarket. In other nissan engines like the VG30 and SR20, a mild camshaft upgrade makes almost 50-90% more power than NA. In the VG30's a cam with around 260* duration would gain around 5-9whp in a NA, but it would do 8-20whp in a turbo motor. SR20's are the same way. JWT S3's would gain 6-10whp on a NA motor, but turbo motors dyno 8-19whp higher with the same cams. The stock VQ cams are wimpy. The valve timing is the same as the lowport SR20s and by installing a cam with 248* duration vs 232* stock would net around 4-7whp in a NA motor. If it was me I'd recommend a mild increase in lift and duration around 255-262*.

 

$ per hp its not worth it $1200 for 8-20whp? Just turn the boost controller up.

 

Hehe ... excellent point! A suggestion that PFI keeps telling me to do! Haha! If you really want more power for the same boost level get a bigger turbo dude!

 

If you have the aftermarket cams lying around, why not use it?