ou812sm

iTrader: (16)

i want to get more power out of 4.8 i have obx lt,remus catback exhaust,aem cold air intake ,westers custom tune, and 4.56 gears(tire size 305/70/17) so i know its allot better than stock but if i could squeeze some more out of it i will i'm thinking new cam but i want a cam that makes power down low under 4000 rpms what do you guys on here think

InchUp

iTrader: (2)

With 305/70R17's you need low speed throttle response and gobs of low end torque...sadly the 4.8L makes neither of these. Since you've re-geared already I'd think about the smallest cam Comp Cams offers, the XR259. 206/212, .515/.522 on a 112LSA.

Stoichiometric

iTrader: (10)

I agree, the smaller the better. Some advance ground in will help low end output as well.

adrenalinep

iTrader: (4)

What about the 212/218 high lift

ou812sm

iTrader: (16)

hey can you guy explain yourselves a little better

RandomHero

iTrader: (24)

read the first reponse in this thread, it explains everything pretty well.

ou812sm

iTrader: (16)

what i ment was how would the driveablity be like . would it be noticeable in daily driving and thank you for your answers

InchUp

iTrader: (2)

Look at your 4.8L's stock camshaft specs...190/191, 0.466"/0.457" on a 114 LSA. Compared to the XR259 cam I suggested, it is a 206/212, .515"/.522" on a 112 LSA. What this means is compared to stock, this camshaft will make it so you have more torque across the entire power band in your 4.8L with no sacrifices. The longer duration pulls the power band up lengthening how long you can keep the pedal down before the motor runs out of breath. The higher lift makes for a more aggressive ramp rate than the stock cam lobes, thus increasing cylinder pressure and therefore torque across the entire rev range. The 112 lobe separation angle brings your peak torque down a few rpm's so the torque you feel when you stomp on the pedal comes on quicker than before.

So if I were to explain this to my youngest sister, you're looking at ***** out power from 900rpms all the way to stock red line with a smooth idle and no decrease in gas mileage. How does that sound for ya?

sickREDsierra

iTrader: (17)

i thought 4.8's were too small to put a cam in?

somebody told me that you had to have a 6.0 to put a cam in...


maybe this guy will do a cam swap and let us know if i have been lied to.


good luck with that small 4.8

ou812sm

iTrader: (16)

hey InchUp thank you for the detail. what kind of torque do you think will be at the rear tire? Inchup compcam suggested this cam how would this compare to the one you suggested and thank you ounce again for your help

Hi Steve,



After looking through your information I suggest one of our XFI XTREME TRUCK
series cams. Here is the part number for the cam I have suggested
(54-450-11). I recommend that you change you valve springs and lifters if
you are interested we here at Comp Cams can put kits together. Just let me
know? I will list the specs on this cam below. If you have any questions
feel free to reply or call our tech line. Have a great day.



INTAKE MASTER 3750R

EXHAUST MASTER 3751R

ENGINE GM G3 XFI 260 HR15

GRIND NUMBER GM G3 XFI 260 HR15


INT EXH

HYDRAULIC Y/N YES DUR @.050
206 212

INTAKE EXHAUST LOBE LIFT
.3020 .3060

VALVE ADJUSTMENT HYD HYD ROCKER RATIO 1.70 1.70

MAX GROSS VALVE LIFT .513 .520

DUR @ .006 TAPPET LIFT 260 266 LOBE SEPARATI 115.0


ADVANCE 4

VALVE TIMING OPEN CLOSE VALVE SPRINGS 26915-16

.050 INT 8- 34


EXH 45 13-

THESE SPECS ARE FOR CAM(S) INSTALLED

111.0 INTAKE CENTERLINE