ORIGINAL: Quicktime_GT

I'm starting to get curious about cams.. Since my transmission isn't going to cost as much as I originally thought, the extra money I have may as well be put towards something.

I see that the VT stage 2 blower cams are 530/.570 lift, 220/230...
VT stage 2 n/a cams are: 560/.575 lift, 225/235
Stage one n/a cams are 540/550 lift, 224/226

Could someone who Knows whats going on here explain to me the difference in a blower cam. It looks to me like a stage 2 blower cam is just a cam inbetween a stage 1 and stage 2 n/a cam


Any thoughts on a good set of cams?

If I bought a set I'd probably want to go with something similar to a stage 2 vt cam. The sound of the car is verrrrry important to me, and whether or not its the right reason to buy cams, it would be my reason to buy cams. I'd go with cams that I could "grow into" I plan to someday build a bottom end and look into heads, (or aftermarket heads if available by then), So I want a set of cams that will not have to be replaced for bigger ones in the future.

any thoughts?

I sure wud like to have a borla stinger cat back though... hmm

ORIGINAL: 2000GT4.6

First of all, F/I cams, at least in my experence never seem to sound as agressive as a n/a cam. You can have a pretty wild FI cam and it doesn't sound nearly as lopy as a much less agressive n/a cam. I beileve this is due to the LSA, as when I called TSP about my buddies LS1 cam they said the lower LSA number the better sounding it would be at idle (or at least the more agressive it would sound).

The "blower" cams, or FI cams, have less overlap than a n/a cam. This is the primary difference, as you loose boost when you have more overlap.

Here is the complete VT stage 2 "blower" cam spec, alongside the VT stage 2 n/a spec:

.530/.570 lift 220/230 .50 duration 112 LSA +4*
.560/.575 lift 225/235 .50 duration108 LSA

Notice the LSA, or lobe seperation angle, is less (lower number)on the n/a cam. LSA, or lobe seperation angle, is the number of degrees seperating the intake and exhaust lobe centerline.

The lower number the LSA is, the less seperation there is between the exhaust and intake lobe centerline. Decreasing this number results in more overlap... the amount of time when both the exhaust and intake vavles are open. A 4 cycle engine uses this overlap to allow fresh air to enter, and thus force the exhaust gases out.

Making this longer on a n/a setup allows for a 4 cycle engine to get more of the exhaust gases out and get more fresh air in. On a FI setup however, if the LSA is too large you are literally loosing boost right out of the exhaust. This results in a boost drop, and you loose horsepower.

This is also why you are more often than not OK with running a n/a cam at lower boost levels. Once you crank it up however, you really start to loose boost and you needa progressvly smaller and smaller pulley to run the same amount of boost, which drops efficentcy, heats the incoming air, and generally makes it make less horsepower per boost (and pulley size).

You definatly do not want to run a n/a cam on a blower if you can help it, and most people have NOT had as good results as I have had running a n/a cam on a blower car.However, you can do it at lower boost levels, and the cam will sound more agressive do to thelower LSA number. I am somehow not loosing boost, but everyone else that has done this has to pulley up. Sometimes I wonder if VT didn't accidentally send me a blower cam intead of a n/a one.

ORIGINAL: lizzyfan

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