GMC extra Horsepower

tdshepard · March 30, 2002

I notice the Denali Vortec 6.0L V8 has 25 more hp and 10 more ft lb torque than the standard engine. Does anybody know how they accomplish this and if we can get the parts to upgrade our standard engines? Thanks!

1500hdbob · March 31, 2002

I beleive that I read in a brochure, that the 6.0 in the suburbans have more HP than the siverados!?!?

RedHawk · March 31, 2002

All I could tell is that they rate the HP at a higher RPM on the Denali than the trucks.. That makes all the difference right there. In other words the trucks are UNDER rated or rated at a lower hp.. You can check it out in the brochure or online.. I think its like 500 rpm lower on the truck..

CMNTMXR81 · April 1, 2002

I can't see 500 rpm = 25 additional HP. WHile that 500rpm may account for a few ponies, I believe there is a slightly different cam and a different intake plenum on the Denali.

Kansas Kid · April 1, 2002

I can't see 500 rpm = 25 additional HP.

And why not? Just look at these numbers, all of which are done using the dyno graph for the LQ4 Vortec 6000.

For the 6.0 pickup motor, the peak Hp is quoted at 4400rpm. That translates into approximately 350ft-lbs of torque on the GM dyno sheet. Now using (T*RPM)/5252 you get 293Hp.

For the 6.0 Escalade motor, the peak Hp is quoted at 5000rpm. That translates into approximately 340ft-lbs on the GM dyno sheet. Using (T*RPM)/5252 you get 323Hp.

There is your extra 25 Hp, all in the numbers. Its just a simple advertising twist....

CMNTMXR81 · April 1, 2002

I said, it'll make up for some, but not a whole 25hp.

If that were the case, I'd increase my rev limiter to 7k and extract another 50+hp outta my heads and cammed 11.3:1 compression motor!!! Sorry, but in real world dyno testing that doesn't happen!

I agree though it is a marketing twist and to be honest I wouldn't be surprised that if you strapped both to a 248c they'd both put down identical numbers.

CMNTMXR81 · April 1, 2002

Actually Kansas, I was doing some plotting of my Dyno curves and while I did see gains of 25hp in certain places during the curves, they weren't at maximum power points I.E. 4,400 - 4,900rpm (the 500rpm window). They were in the lower rpm to mid rpm ranges where power was being built that there were "jumps" like 25hp. Otherwise in the maximum power output over a 500rpm window there isn't a 25hp jump.

From an old dyno chart I had, I made maximum power at 5,900rpm. At 5,400rpm (500rpm less), I made 7.6hp less than at 5,900. Conversely at 6,400rpm (500rpm more) I make 9.6hp less.

This is premsuming that for a Vortec 6000, peak HP is made in that 4,400 - 4,900 rpm range. If on a Vortec 6000, actual PEAK numbers are made at a higher point in the rpm band then 4,400 - 4,900, then I can see a 25hp gain, but then we aren't talking maximum power.

Follow me, or have I lost ya?

I'd like to see a dyno chart for a 6000 or just the numbers in 100rpm increments and I can chart it.

RedHawk · April 2, 2002

My numbers and info were posted off of my Dynos. Actually the numbers I have are denali is at peak hp at(325) 5200 in thier add and the trucks were at 4400 in our add. I made peak RWHP at 5200 rpm on my 6.0 litre. {AGAIN, us 6.0 litre trucks are under estimated for advertising reasons or whatever}.. So that is 800 RPM difference. There is an easy 25 RWHP difference and these add numbers are fly wheel.. You can count on a 25% drivetrain loss on top of that with these trucks but I am sure you know that already.

Raising the rev limitor will not add more power because these 6.0`s run out of cam after 5200 rpm and the curve just stays relatively flat to 5900..

My dyno test show me the Denali`s and trucks are the same 6.0 motor.