August

I need help understanding the difference between a hybrid LM7, Vortec 5300, out of a 2006-2007 Chevrolet Silverado and a non-hybrid engine. Several are available at a local salvage yard but I'm not quite sure what whould be needed to use in a convensional set-up.

Thanks so much for any information ...

pdsq98gt

The LM7 is not the hybrid engine. Not sure what you are really asking since that motor should be just like any 5.3 out of an old body style truck.

August

GM launched a hybrid version of the Silverado/Sierra in 2005, becoming the first ever GM hybrid passenger vehicle. Known within GM as the Parallel Hybrid Truck or PHT it is not actually a parallel hybrid by the current definition, but a type of micro hybrid design. The electric motor housed within the transmission flywheel housing, serves only to provide engine cranking/starting, battery charging, and powering accessories. The engine automatically shuts down as the truck comes to a stop and uses 42 Volt electric power to the starter/generator unit to restart the engine as the brake pedal is released. Besides the typical 12V automotive battery the PHT uses three additional 12 Volt valve regulated lead acid (VRLA) batteries mounted under the rear seat to store and provide power. The truck uses a 5.3 L Vortec 5300 V8 for primary propulsion power.

I am trying to better understand what differences there are in the normal LM7 and the hybrid LM7. The differences could be external accessories like alternator, starter, etc and it could have internal differences like additional changes to the block.

dtom001

In that early hybrid I don't believe there's any difference in the engine whatsoever, it's all in the transmission, or I should say in their "starter/generator" thing that they have. It would allow the engine to shut off at stop lights and start it quickly when you would remove your foot from the brake onto the gas, as well as do some regen braking. I don't think GM bothered to change anything on the engine for that system.

They did on the later 2-mode system, which is quite a bit more complex. Not only does that system run a 300V li-ion (i think) battery system rather than the 2005's 42v lead-acid, it also had to run with the 6.0L cylinder-deactivating engine (LML engine?) in order to get any real highway gains from the hybrid system.

Anyhow I'm not sure that engine is different from any other 2005 5.3L.

August

Any way to find out for sure ... I would really hate to aquire this thing and find out differently. I did contact two local dealers and seemed to be blown off pretty quickly. I'm not sure if they didn't know or I was asking for free information.

Thanks for all info, leads, and help!

Docked Wage

When I started my conversion I looked into these motors. Here's what I found out:

The dealers are almost under a Gag Order on these Hybrid trucks.

Those Hybrid motors are starting to pile up in the scrap yards because GM is quietly buying back the "hybrid" trucks. The issue is the 42 volt Hybrid batteries are failing (as any lead acid battery will after 4 years) and the replacement battery is extremely expensive. I have heard that the battery is in excess of $9000.00. In order to keep people from screaming publicly and crushing the sales of Hybrid and Electric vehicles Government Motors is buying back the trucks and making the customer sign a Non Disclosure.

As far as the engine goes, it is supposed to be identical to the LM7 in every way. The differences lie in how the engine is started and the accessory drive system.

On the hybrid the engine is started via the hybrid system in the transmission so there is no external starter.

The issue with the accessory drive system is that the Hybrid Trucks used an electric power steering system. As a result there won't be a regular power steering pump on the front of the engine.

Also, there is no Alternator on the Hybrid version because the charging duties are handled in the Hybrid started/generator system.

After figuring out that it was easier to find a fully dressed low mileage LM7 from a regular pickup that was ready to go I decided that was the best direction. Otherwise, even if the Hybrid version did have all of the regular mounting provisions machined in, I would still be chasing down all of the brackets, nuts, bolts, mounts, wire harness plus the accessory components to make the thing work.

It took me a couple of months but I was able to track down a 24,000 mile (verified) engine and trans assembly with the complete harness, pedal assy. and all of the driven accessories for $1500.00. I watched CL, Ebay and kept in touch with the local dismantlers. The good ones go fast so have cash and a means to transport the motor ready at a moments notice.

Ken

dtom001

Wow that's great information, thanks! That's exactly the issue that I've been wondering about with all hybrid vehicles, and GM's handling of it is one way of preventing consumer blowback on high late-ownership costs. I can't imagine that the fancier Prius batteries can be any cheaper to replace when they've worn out.

On a side note I think diesel engines are a better long-term solution, and I wish that we stateside people got to sample all of the different automaker's versions of the Jetta TDI. Folks should be fine with getting a little diesel smell on their hands in return for not paying for the lifetime costs of batteries and gadgetry.

Sorry, totally wandered OT.

Cheers, Tom

Red Mnster Z

the difference between the LM7 and the hybrid LM7 is just the electrical part. the way the electrical part is set up in the truck is that when you are at a stop light or anywhere stopped holding the brake pedal, the engine shuts off so it doesnt waste gas sitting at a stop light. after you let off the brake pedal, the engine automatically starts right up, instantly. and when traveling under 35 mph, the truck will run on the electric part of the hybrid part. thats the only difference besides the Silverado hyrbid LM7 doesnt have a starter, otherwise the LM7s are the same (hybrid LM7 w/ no starter and normal LM7 w/ starter), its just the electrical part of the whole truck. the only reason i know this is because my dad owns a 2005 Silverado Hybrid and its great. he has had the truck for 6 years now and now problem what so ever with the battery.

August

Thanks so much for all of the info. In my search I have found several on EBay with very little mileage with sellers stating "Nothing is different". Stands to reason somethings different... it's hybrid!. Great discussion ...

Docked Wage

I was just at Schram over in Waterford and took a close look at an engine out of a 2006 Hybrid. Here's what I found:

The surface and holes to mount a starter are machined into the block. It was a bit rusty and the rusty holes would need to be cleaned up with a tap.

The front of the block is machined to accept the regular accessory brackets.

There is a coolant fitting for the hybrid system on the passenger side of the block just forward of the starter location that will need to be blocked off.

The flywheel is different.

The wire harness is different.

I also had a conversation with the head guy there he said that people are successfully using the "Hybrid" version of the LM7 as a transplant into vehicles that came from the factory with that motor. So for example if you have a 2005 Siverado with a blown motor then these are a good candidate to replace it because you have everything else already.

However, if you need an alternator, starter, flywheel, powersteering pump, mount brackets, bolts and a wire harness for a conversion you will get nickeled and dimed to death.

c6matt

iTrader: (1)

the flywheel hybrid and the newer 2 modes are COMPLETELY diffrent animals. The 2 modes are 6.0's and use a NiMh Pack and operate at 300v. The hybrid engine would work, but I would change the cam (speaking 2 mode here).. the late intake valve closing will not get you peak performance in a hotrod.
The 5.3 in the flywheel hybrids are the same as the base aside from the accessories. The 2 modes are a good engine because of the alloy blocks..

Irish350

iTrader: (14)

good info in here

August

Thanks again Docked Wage! You found the source of my hybrid engine. I had not considered the additional cost of adding all of the extras. It was marketed as a complete unit. It all makes sence conforming to a replacement as opposed to a conversion. You guys saved me a pocket full of money.

Docked Wage

Glad to assist.

You'll get nickeled and dimed to death as it is on a swap anyhow so the more complete you can buy an engine the better off you are.

What are you planning on dropping the 5.3 into?