What year C5? The LS3 didn't come out until the C6's came out. All C5s had either the LS1 Or the LS6 (in the Z06 model).
One of the reasons the Gen IV LS engines (LS2, 3, 4, and 7) get notably good gas mileage is because of the displacement on demand where 4 cylinders shut down while highway cruising. That said, my dad has a 98 C5 and it gets 28mpg or so which is still pretty good.
The C5 was a 97', so I guess it was a LS1. (Not a Z06) I'm pretty sure we measured 30 mpg on a trip. Our 16' C7 is much worse, like 22 mpg. We don't hotrod the car, so I'm not sure why. We have had transmission problems and it still may not be fixed. I realize the car has a hundred more hp, but it would seem like that shouldnt make a differnce on the highway.
I think the LS series is a very efficient engine. So assuming the car uses 60 hp to go 60 mph, I'm thinking the LS can make that much hp with less gas. (It doesn't really matter how much excess hp there is available.) It would be nice if it did get better mileage because it doesn't have a very big tank.
The LS2 is a gen3 and the 4 is a gen3/4. The 7 is also a bit of a hybrid.
None of the ls engines other than the 4 got displacement on demand. Also it has been observed in the community that it doesnt net much of a difference. There is no displacement on demand (DoD and later called active fuel management, AFM) on standard transmission vehicles. A major key to its smooth operation is to unlock the torque convertor when deactivating cylinders.
The biggest difference between the C5 and C7 in terms of milage (ignoring the fact that it uses a Gen5 DI engine of larger displacement) is that the gearbox is a 7 speed with 3 overdrives compared to the C5s 6 speed with 2 overdrives. The automatics are similar as well the c5 had a 4 speed and the C7 has a 6 speed (8 speed in later years)
Thanks for clarifying Josh. I didn't realize only the LS4 actually had DoD. I thought that all of the Gen 4 engines had the valley castings for the DoD plumbing but maybe I'm mistaken; or maybe they have it but dont utilize it.
Thanks for clarifying Josh. I didn't realize only the LS4 actually had DoD. I thought that all of the Gen 4 engines had the valley castings for the DoD plumbing but maybe I'm mistaken; or maybe they have it but dont utilize it.
You are mostly right. The 2005-2006 LS4 was a bit of an experimental engine along with the E40 ecu. FOr example it had a gen3 24x crank trigger, with DoD (bosses in the block) and gen4 rods/pistons. I really with it didnt have DoD, its a pain in the ass just more money to spend on a delete.
Had to read the whole thread again. Fantastic. The engine is mind blowing, but I actually like all the work you did on suspension and brakes even better. Im courious, early on you said you dropped the car 4+ inches. Later you said your suspension guy raised it a bit. Do you know how much you finally ended up with. Also you mentioned rear wheel spacers. Was that because of the custom brakes, or you just wanted it slightly wider? How wide of spacers?
Had to read the whole thread again. Fantastic. The engine is mind blowing, but I actually like all the work you did on suspension and brakes even better. Im courious, early on you said you dropped the car 4+ inches. Later you said your suspension guy raised it a bit. Do you know how much you finally ended up with. Also you mentioned rear wheel spacers. Was that because of the custom brakes, or you just wanted it slightly wider? How wide of spacers?
Still lowered 4+" from stock as he only raised it a few mm. Spacers, 20mm, are for matching the front and rear offsets when running 15's up front.
Another question. With those coil overs, were there any modifications to be made or you just bolt on? I assume you just set the ride height with a spanner wrench?
Originally Posted by Nicholas R
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