Anybody Doing Anything With The LZ9 Engine?

[AutoWiz]

I have a lz9 in a 2008 chevy uplander with very low miles on it. I know trying to build power in a minivan is just wrong. and I am not saying I mean to. I am just curious to know what, if any mods are being done to this engine for fuel economy or to raise the 240x2 hp/tq rating?

[caffeine]

There's a turbocharged LZ9 in an Iroc

[AutoWiz]

sooo, the lz9 can handle boost? or is it built different in the turbo iroc. and btw, "turbo iroc" just sounds like a b.a. car.

[caffeine]

It's not built. IIRC just cam (VVT delete), valve springs, pushrods and cable 75mm TB.

[AutoWiz]

why vvt delete? that's how the lz9 got such a broad torqueband. "90% available from 1500-5500rpm" as wiki reads. does turbo also do away with variable intake? and the more I think about a turbo lz9 powered iroc, the more I think of a modern day gnx.

[robertisaar]

chevrolet version of a TTA seems more appropriate.

[fat rabbit]

Not all LZ9 engines came with a variable upper intake, if I recall correctly they did away with it in 09.

[AutoWiz]

can't imagine why. that was a part of the broad toqueband. or so I thought. I wounder what bumping the cr from9.8 up to like 11:1 would be worth?

[Superdave]

more torque, little more HP... That engine needs a healthy cam more than it needs more compression.


Video of Mars_man's 3900 Camaro: https://www.youtube.com/watch?v=FlpfGKfJIC8

[SappySE107]

Variable upper makes the 3900 flow as bad as a small port 3100. You want torque, there you go. Want HP, ditch it.

[robertisaar]

does that mean i can get 240HP out of my L82?

i still can't find SAE dynos for the later 3900s, i may have to search in some non-traditional places to find them, but they have listed peaks at/near the same as the variable-intake models.... considering GM was able to ditch them after 2/3 years and apparently lose nothing from it, i don't know why they did it in the first place.

[fat rabbit]

http://gmauthority.com/blog/wp-content/uploads/2010/02/2010_Impala_Police.pdf

On the last page they list the SAE dyno for a 3900 without a variable upper intake, 230 HP at 5700 RPM and 235 TQ at 3200 RPM(page 34)

http://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Impala/2006-Chevrolet-Impala.pdf

http://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Impala/2007-Chevrolet-Impala.pdf

What gets confusing is that according to GM Heritage Center a 2006 Impala with the 3900 has an SAE rating of 242 HP at 6000 RPM and 242 TQ at 4400 RPM(page 6) but in 2007 the SAE ratings drop to 233 HP at 5600 RPM and 240 TQ at 4000 RPM, both years incorporated a variable upper intake manifold. They also marked those ratings with a (*) and if you go to the legend on page 8 of both pdf files they clam there SAE certified from March 31, 2005

I don't know much at all about 2008 and up other then 2009 and 2010 didn't incorporate a variable upper intake and I had that verified by Over Kill Motorsports, when I was talking with the parts department at dealer about the variable upper intake I was told they were having a lot of problems with displacement on demand and the variable upper intake so GM eventually ditched it. I do know none of the police car Impalas came with a variable upper intake, when I recently got my 3900 from a 09 police Impala it didn't come with one and I thought they gave me 3500.

[robertisaar]

230@5700 and 235@3200 for LGD(flex-fuel 3900).
242@6000 and 242@4800 for the LZ9.

worst-case, that is only a ~5% difference compared to the 240/240 rating.

http://www.ebay.com/itm/07-08-UPLANDER-ENGINE-3-9L-VIN-W-8TH-DIGIT-OPT-LGD-50700-MILES-247499-/180840317988?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a1aec4424&vxp=mtr

http://www.ebay.com/itm/07-08-CHEVROLET-UPLANDER-VIN-W-8TH-DIGIT-3-9L-LGD-ENGINE-MOTOR-105K-MILES-/400419811830?nma=true&si=8IC24%252FjDZPK7l24BG7%252BZ%252BeyrT%252BE%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

seems like the LGD also used the variable intake when the LZ9 did?

[fat rabbit]

I forgot that the 3900 in Impalas starting in 2007 to 2008 incorporated displacement on demand lowering the SAE ratings to 233HP@6000RPM and 240TQ@4000RPM from the previous ratings so it would be...

242 HP at 6000 RPM and 242 HP at 4400 RPM for the LZ9(non flex fuel and non displacement on demand)
233 HP at 5600 RPM and 240 HP at 4000 RPM for the LZ8(non flex fuel and with displacement on demand)
242 HP at 6000 RPM and 242 HP at 4400 RPM for the LGD(with flex fuel and non displacement on demand)
233 HP at 5600 RPM and 240 HP at 4000 RPM for the LZD(with flex fuel and with displacement on demand)

These SAE dynos are claimed to be certified according to www.gmheritagecenter.com and they don't claim a change in dyno ratings from having or not having flex fuel as an option, wikipedia also goes along with this. I still haven't seen any certified SAE dyno numbers for an LZ9 or LGD without the variable upper intake, http://gmauthority.com/blog/wp-conte...ala_Police.pdf claims 230 HP at 5700 RPM and 235 TQ at 3200 RPM(page 34) but they don't certify it. I think I'm going contact GM Heritage Center and see if they can make a vehicle information kit for a 2010 Impala and see if the SAE ratings changed, they also changed how to identify the engine block in 09 and up for the 3.5L/3.9L

I think it would be safe to say robertisaar that both the LZ9 and LGD stopped incorporating a variable upper intake starting in 2009

[robertisaar]

I think it would be safe to say robertisaar that both the LZ9 and LGD stopped incorporating a variable upper intake starting in 2009

06 and 07 definitely had them, 08 i may recall seeing one or two that weren't, i've never seen an 09+ with the variable intake. so, it would seem to hold true.

also, i'm kind of curious to know what injectors the flexfuel 3900s run.... they would have to support 240HP worth of fuel running E85.