LB7 or LLY

aSSasinator · October 19, 2004

Whats your guys' opinion? I looking in to trading in my Silverado SS for a Duramax. Fuel prices are killin me here in Ca. The SS takes premium and its 2.80 where I am and 87 is like 2.60. I'm not real sure what diesel is at right now, it fluctuates all the time. Its never been more than 87 though. Anyway, what are the pro's and cons of each engine? Fuel mileage, tuning capabilities, ect.? I really appreaciate your guys' input.

Thanks, Albie

MCourson · October 19, 2004

LB7

pros:

Has a few years under its belt.

Has a good aftermarket following (tuners and such)

cons:

Less power (300-520)

Some have had injector trouble (ours hasnt)

LLY

pros:

more power (310-590 (04) and 310-605 (05))

cons:

Less time on the market

Im not sure what kind of aftermarket the LLY has.

That is just the basics, Im sure someone else can go in deeper.

tbyrne · October 19, 2004

I haven't kept up with these much. What are the physical differences between the two for the added power?

Butch 02 Denali · October 19, 2004

As I understand it, tuning is basicly the only difference in power. If they both had the same tune/boost the LB7 would be the stronger of the two.

Mechanically, the new LLY is designed with EGR to meet new deisel emissions.

MCourson · October 19, 2004

I believe the LLY has a variable vain turbo so you dont have to wait for the turbo to spool up as much as you do with the LB7.

whitesnake01 · October 20, 2004

I haven't kept up with these much. What are the physical differences between the two for the added power?

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See:

http://www.gm.com/automotive/gmpowertrain/...ramax/index.htm

Butch 02 Denali · October 20, 2004

I've also heard the LLY gets 4-5 LESS MPG than the LB7 Duramax!

The GM site says "The Duramax 6600’s torque increase is the result of engine-control calibrations that take advantage of significant hardware changes introduced in January 2004"

tbyrne · October 20, 2004

I've been looking into this quite a bit over the last week and haven't found there to be a big difference in mileages between the two. Most people are getting about 14-16 for city driving and 17-19 on the highway. I think someone averaged what he saw to be 15city/18highway. I don't think I've come across anyone that has seen less than 11.5 while towing so that will be a huge improvement for me

whitesnake01 · October 20, 2004

I've also heard the LLY gets 4-5 LESS MPG than the LB7 Duramax!

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I doubt it. I get 13-14 towing and 18-19 hi-way/mixed with my LLY. I expect it to improve as the engine gets broken in. I find it hard to belive you'd get 17-19mpg towing an 8,300lbs trailer with the LB7.

Butch 02 Denali · October 20, 2004

Wester's recently did a 115 hp tune for a 2004 LB7 Duramax.

The customer said he went from 19.2 mpg to 28.7 mpg.

bigdogs · October 20, 2004

What did it bump the torque up to? Did it cause any tranny problems as well?

Butch 02 Denali · October 20, 2004

I think that's about the max tune he recommends without tranny upgrades. I'm not sure exactly what the tq boost was, but was probably close to the hp increase.

Machine · October 20, 2004

Wester's recently did a 115 hp tune for a 2004 LB7 Duramax.
The customer said he went from 19.2 mpg to 28.7 mpg.

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Wester's has now gone from a 30% increase in mpg to over 50% in only a few months?

What we have here is a dishonest DIC. This accusation could apply to either the computer or the owner of that miracle DMAX. I'm surprised Wester isn't calling BS.

Machine · October 20, 2004

What did it bump the torque up to? Did it cause any tranny problems as well?

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Hi -

From personal experience, the Allison will limp at about an additional 125HP. I've limped mine about 6-7 times. It's usually 5th gear that's the weakest. No limps now that I lock out 5th

TPB · October 20, 2004

I don't think I've come across anyone that has seen less than 11.5 while towing so that will be a huge improvement for me

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I've towed my 8,500lb fifth wheel camper four times with my 2005 & have never gotten over 10 mpg yet. Unloaded I get 13 city & 17 highway, but towing is terrible. (8-9 mpg depending on wind & terrain)