Cams and turbos.

[hrspwr00v6]

okay. i want to do a cam to go along with the turbo i'll be doing in the future. but i also want to have the 'cammed' sound. exactly how much boost does a low lsa cam bleed off?

[Teufel Hunden]

there isn't really a standard amount of boost thats going to be bled off for a given selection of cams. IMO, thats one of the best parts of a turbo car... at idle and around town they have very good manners. You sure you want to sacrifice power just for the rough idle?

[hrspwr00v6]

well i really just want that 'cool' sound. i mean if it was only going to knock me down by .05 in the quarter i'd do it. but if its going to drop me like 10-20 ponies i guess i'll just go with the vs cam

[Teufel Hunden]

Originally posted by hrspwr00v6
well i really just want that 'cool' sound. i mean if it was only going to knock me down by .05 in the quarter i'd do it. but if its going to drop me like 10-20 ponies i guess i'll just go with the vs cam

Depending on the cam, it could easily drop you 10-20 horses.

[hrspwr00v6]

do they make blower specific 'lumpy' cams?

[MIGHTYMOUSE]

my cam sounds like stock... since my results i've decided a huge cam is only worth maybe 2psi of extra boost needed over a stockish cam.

for most purposes you will see no gains from a turbo or s/c cam'd car over the stock cam. you will just loose mileage, have to rev higher, have to stay on top of your valvesprings etc. just to have a 'lumpy' sound.

you can still get a wide separation cam with good sound, something in the .56 lift 230* range.. i prefer the 'sleeper turbo' sound myself :)

all the big cam companies have turbo and s/c specific grinds, im just saying for a low (under800 hp) configuration you are just really not gaining anything... if i did it again, my cam would be completely stock. and the numbers would be just the same.

[XLR8]

Originally posted by MIGHTYMOUSE
my cam sounds like stock... since my results i've decided a huge cam is only worth maybe 2psi of extra boost needed over a stockish cam.

for most purposes you will see no gains from a turbo or s/c cam'd car over the stock cam. you will just loose mileage, have to rev higher, have to stay on top of your valvesprings etc. just to have a 'lumpy' sound.

you can still get a wide separation cam with good sound, something in the .56 lift 230* range.. i prefer the 'sleeper turbo' sound myself :)

all the big cam companies have turbo and s/c specific grinds, im just saying for a low (under800 hp) configuration you are just really not gaining anything... if i did it again, my cam would be completely stock. and the numbers would be just the same.

Whoa! So you are saying, for performance on a Turbo or SC LS1, it isn't worth changing out the stock cam until the engine sees ~800+hp numbers...I've never heard this before, but your reputation preceeds you:D

[MIGHTYMOUSE]

i'm saying something like that yes.

the airflow into the motor is set by the turbo or supercharger, changing whats between that and the cylinder is only going to change efficiency a few %, and more importantly move the power band around some.. at best making the airflow you have more useable.

[Teufel Hunden]

Originally posted by XLR8
Whoa! So you are saying, for performance on a Turbo or SC LS1, it isn't worth changing out the stock cam until the engine sees ~800+hp numbers...I've never heard this before, but your reputation preceeds you:D

MIGHTYMOUSE is absolutely correct.

A "turbo cam" tends to be a low-duration limited overlap cam... very similar to the stocker.

Corky Bell even states in his book on Pg. 163 "RULE: It is hard to find a turbo cam that works better than the stock item."

[XLR8]

Originally posted by Teufel Hunden
MIGHTYMOUSE is absolutely correct.

A "turbo cam" tends to be a low-duration limited overlap cam... very similar to the stocker.

Corky Bell even states in his book on Pg. 163 "RULE: It is hard to find a turbo cam that works better than the stock item."

"Excellent Smithers"...:drevil: :devil:

[Slow_Red_Z]

save the money and spend it on some low compression pistons instead.

[stoleit]

shouldn't the turbo's cam have a much longer exhaust duration to help spool the turbo?

[MIGHTYMOUSE]

actually its the opposite.. you are describing a good supercharger or nitrous cam.

[Teufel Hunden]

Originally posted by stoleit
shouldn't the turbo's cam have a much longer exhaust duration to help spool the turbo?

This has been my understanding... a Turbo cam has a short exhaust duration so that pressure builds on the exhaust side and exits with a greater velocity when the valve opens, which helps spool the turbo.

[T-Rex]

Originally posted by hrspwr00v6
do they make blower specific 'lumpy' cams?

I only know for a supercharger !
The W1 cam from Speedtek will be a good choice for lumpy blower cam its like a 228 234 on a 116 +4

[T-Rex]

A good turbo cam would be the LPE GT2-3 cam that 21st centrury mototr sports sells in Dallas or also Lingenfelter Selles them since they designed them ! :D

[snatchss454]

Duration I/E Lift I/E LS IC Rocker Ratio Valve Lift I/E
182/190 .258/.255 115 111 1.6 .413 .408
This is the stock 3.8L cam, Im not trying to argue with what has been stated, but I have a hard time believing that their would be no significant gains from going to a larger cam like this one designed for turbo applications
duration @ .050": 211º/204º, lobe lifts: .323"/.320", valve lifts with 1.60:1 rocker arms: .516"/.513", lobe separation angle: 116º, intake centerline: 110º

Again I dont know much about cams, and Im not trying to argue with anyone, I am just looking for some clarification as to their being no gains if I change to this cam over the stocker.
Thanks
Shane

[2000 Tran Zam]

Ok, let me ask you this. if i put a turbo in my car and reinforced the pistons and stuff so its safe to turn the boost up, which would be better, the stock cam or the cam in my sig?

[hrspwr00v6]

stock cam

[MIGHTYMOUSE]

no argument about a larger cam making more peak hp than a stock or smaller cam.. the point is if you are interested in raising cylinder pressure, why not do it for 'free' by bumping the boost, instead of buying a cam etc.

[snatchss454]

oh ok I kinda a get what your saying. I was planning on boosting 15-20psi with that second cam.
Thanks
Shane

[Ryche]

It seems to me if spool is not an issue, then perhaps having a larger intake duration should be considered...???? For instance mt turbos are designed to spool a 3k with my set up...I already have an exhaust backpressure issue du to the small turbo exhaust housing...so in this case should I forget the rule of thumb?

[Blacksun]

Now are you talking about the LS1 cam or LS6 cam?? I have spoken personally with Ed Potter and Graham at LPE and they both told me the LS1 cam for turbo applications is Crap. The LS6 cam is way better and not only makes more power but also it is easier to tune.

My car is going in here shortly to have a head / cam package done to my 2000 C5 LS1 with Single T-72 Turbo. I was told by doing the cam change it would not only make more power but spool faster.

Anyways the LPE GT2 & GT3 cam are kinda tame reliable cams I was told.

[MIGHTYMOUSE]

sounds like they were trying to sell you a cam to me.
especially the easier to tune part i'd like to hear an explanation on that one.