a buddy of mine just purchased a 2003 denali suv. he wants to know:

whether his motor is a lq4 or lq9?

if a trailblazer ss manifold will fit on this motor?

what needs to be modified to make this work?

what gains could he expect from this?

alternative manifold that would be better?

thanks in advance fellas...

 

he has the lq9

it will bolt on but he either needs the tbss throttle body and some sort of adpater (Drx) or a tb adapter plate so he can use his smaller tb on it.

depending on how much he wants to spend, the fast 92 and fast 102 are nice intakes.

 

thanks, i really appreciate it

 

Actually he has a LQ4 in his ride as long as it's original. The Denali line of trucks and SUV's as well as the C3 all came with a LQ4 6.0L, except the '05 and newer Sierra Denali's which got the LQ9. Unfortuantely for whatever reason the SUV's did not. The 1st upgraded engine that the SUV's got was when the NNBS was released in '07 with the 6.2L.

 

really? i thought the escalade and denali got the lq9 from 2003 and on

 

Unfortunately not, and while the GMT-800 series Escalade's always used a LQ9 from 2002 thru 2006 as their choice of 6.0L's, the 2WD Escalade's were also available with a LM7 5.3L engine rated at 285hp in '02/'03 and 295hp '04 thru '06. The Denali line only used 6.0L's '01 thru '07 Classic's.

I edited the above info slightly due to some variation in year model info; earlier I said '01 thru '06 on the Escalade's, but in reality the NBS Escalade's came out as an 2002 model in January 2001.

 

And the only big difference between the LQ9 and LQ4 is a dished piston/flat top piston (resulting in increased compression), and a beefed up rod / floating wrist pin design on the LQ9, Correct?

Yes OP, the TBSS / NNBS cathedral port intake manifolds will fit. I believe those '03 Denali's are already return-less fuel setups so you should be fine there, if you pick up a manifold with fuel rails and injectors. All you'd need is to adjust the tune for the larger injectors. From a thread on here, you can find it if you search, you're looking at about 12-15 hp, and 12-15 lbft in torque across a pretty broad RPM range.

 

To the 1st part, pretty much yes except that later on the LQ4's also got the heavier duty rods. On the 2nd part, a '03 Denali would still have a return style system. Other members have been sucessfully using the Vette filter/regulator combination to adapt the returnless fuel rails to a return system.