help with cam specs

[geldartb]

ok im looking into getting a cam from the store here. and ive been looking at the spec sheet ben posted. here http://60degreev6.com/showthread.php?t=35631
i want somthing like the stage 2 milzy offers but maybe a little more power out of the cam or a more radical grind.

[gectek]

well basically the sheet that ben posted goes from weak to extreme. so anything above the 1280 i think is going for harsher idle and more built for top end power, but the higher lift will help in the low end also. i think i have heard that the diff with a v8 cam and a v6 cam is that with the V8 you have to go in larger increments to have anything noticeable, but with the v6, just having a slightly bigger cam will make alot of diff, because it will feel more like a bigger cam in a bigger engine...but i could be paraphrasing or misquoting so dont hold me to that

[geldartb]

im just fishing around to find the better cam combo. this isnt my daily driver so im not worried about idle. ive got a solid trans mount in my grand am now after awhile i got used to it, now it just feels like stock to me. this is going in my beretta which i dont drive everyday, im going for power with this one.

[gectek]

well then u would need to look at what is the stall lift for your heads first. basically the amount of lift that the engine stops producing anymore flow and or power. also which heads would be another concern...3100,3400...amount of tunability stuff like that

i see u have 3400 heads on ur 3100 right, and OBD II swap which is good. but i think anything on the last part of the chart is too much lift unless you are heavily modified and plan on running massive RPM...ill let someone else chime in more on here, thats what i have so far. but in case u dont know, staying with the same or close to the same dur with more lift will increase bottom end, staying with the same LSA is a good thing, but more dur will give u a heavy idle, u may have to bump up idle RPM to compensate, then the prob is vacuum, you have to worry about all the accessories that run off that like vacuum brake booster, maybe cruise, and A/C controls. with too much dur at idle you will lose that vacuum and your brakes will turn harder to apply, and u get very lumpy, but gain alot on the top end. so if you want just better than stock with good idle still, good vacuum and better than normal low end/powerband and a better top end, id say increase the dur a little and go with max lift that your valvetrain can support

[geldartb]

it will be getting my rebuilt 3400. the heads have ls6 springs, been ported out and a slight amount shaved off. the 3400 came out of my grand am that had the milkshake syndrome so its getting new bearing and gaskets all around. ive always wanted a decent cam so nows the time to do while its out of the car. ill be getting DHP once everything is said and done so tuning wont be a problem and while im doiing the engine swap ill also be doing the OBD-II swap so ill be able to tune.

[gectek]

the only problem with getting a huge cam is the surging that can happen on an auto trans, or manual trans for that matter. when u are accelerating then it is ok, but when you are at low speeds, with a cam that is too big for your purpose, it will cause a surging of the vehicle...which isnt fun either. that usually happens when people want all out power and sacrifice all driveability for it. it will happen even on a car with fully tunable capability. like said if you just want good midrange and better top end with minimal low end sacrifice, i would look at the 1393 or something around in there. it has good LSA, Dur and lift without being so big that its unruly. i like both the cam grinds 1 above and 1 below that one...they are good as well if you can take such high lift. the one below is a little better for a little more top end, but may not give such impressive gains in the bottom end as the 1393 due to the loss of lift.

[Superdave]

These engines love duration, which is what Milzy's stage 2 cam lacks.


I'd run a 110 LSA with low .500 lifts and around a 230° or so duration @ .050


Most of your flow happens below the peak valve lift, knocking the duration up helps elongate the whole event thus getting lots more air in. If you stay in the low .500's for lift your LS6 springs will work fine. I wouldn't go much above .515 or so with them.

Check the install height and coil bind on your heads before you make any final decisions.

If you're worried about overlap then change the LSA to 112. You'll still have the bumpy idle but less overall lope and more vacuum at idle.


This is the easiest way to calculate overlap..

Add the intake and exhaust adv durations
Divide the results by 4
Subtract the LSA
Multiply the results by 2


that would give the 1280 grind 58 degrees of overlap, which is about midrange for a performance cam

the 1393 gives you 40 degrees of overlap which is perfectly fine, it will still idle hard but should give good top end power.


the cam i have in my 3500 has 70.45 degrees of overlap

[gectek]

have u had to make adjustments to your idle rpm though?

[Superdave]

have u had to make adjustments to your idle rpm though?

It's idling at 0 right now.. it's still on the floor of my garage waiting for me to put the tranny together and bolt it up.


I allready worked on the program for it, i've got the idle set to 1200 right now. I'll back it down as much as possible after i get it tuned. If i end up buying a vacuum pump for the brakes i'll drop it down as low as it'll go w/o bouncing the timing chain too much.

[SappySE107]

What compression ratio and what powerband are you looking for?

[geldartb]

What compression ratio and what powerband are you looking for?

decnet low end and more top end than stock. as far as compression ratio dont even know havent figured that side of it.

[SappySE107]

I would figure out what compression ratio then before you decide on the cam.

[geldartb]

most likely be stock since im not getting custom pistons, other than stok head gaskets.. but if i was aiming for a ration it would prob be 10to1 or 10.5 to 1

[3400-95-Modified]

well stock is 9.5:1 so unless you get new pistons or do some crazy shaving on the heads then you probably wont hit 10.5:1