DCR revelation !
02-16-2016, 11:13 PM
#1
DCR revelation ! Ive been scratching my head on this turbo set up im about to start on because my stock longblock LS3 has a super nice NA cam in it. My DCR is at 8.82, and all the info Ive found so far says don't do it without a major drop in compression. Well, that's not happening till I put some wear and tear on this perfectly good , less than 1000 mile LS3 crate engine.
What ive been falling back on is the fact that EVERYBODY is selling a forced induction setup for the LS3 Vettes and Camaros. They all offer boost ranging from 6 to 9 psi and are backing the products with extended warrantees! There has to be some reason why they think they can get away with that, right ? I think I figured that part out. GM has some major wanked up cam timing from the factory that kills the DCR ! Without going to a monster (240s-250s at .050 108lsa ) cam, I cant get close to the dynamic compression of the dinky factory stuff. Using Wallaces DCR calculator, I came up with 7.30 DCR on a stock 10.7 comp LS3. That is why its no issue to throw 7 psi on a new Camaro. That's probably also why you see crazy dyno #s when someone throws a 230 at .050 cam in stock boosted 5th gen. Ive seen articles showing 130-150HP increases from a cam swap in already boosted LS3s !
I ran the DCR on an LS3 with an LS7 cam swap and the dynamic dropped even further to a 6.66 ! Even with the factory 10.7 comp, you should be able to run 8-9lbs with a conservative tune. And the LS7 cam shows strong gains over the LS3 cam in NA trim.
I guess im dropping an LS7 cam (or an LS9) in my set up. Its the perfect "compression cheater" for those that want to get by without diving into our stock long blocks (just yet
)
What ive been falling back on is the fact that EVERYBODY is selling a forced induction setup for the LS3 Vettes and Camaros. They all offer boost ranging from 6 to 9 psi and are backing the products with extended warrantees! There has to be some reason why they think they can get away with that, right ? I think I figured that part out. GM has some major wanked up cam timing from the factory that kills the DCR ! Without going to a monster (240s-250s at .050 108lsa ) cam, I cant get close to the dynamic compression of the dinky factory stuff. Using Wallaces DCR calculator, I came up with 7.30 DCR on a stock 10.7 comp LS3. That is why its no issue to throw 7 psi on a new Camaro. That's probably also why you see crazy dyno #s when someone throws a 230 at .050 cam in stock boosted 5th gen. Ive seen articles showing 130-150HP increases from a cam swap in already boosted LS3s !
I ran the DCR on an LS3 with an LS7 cam swap and the dynamic dropped even further to a 6.66 ! Even with the factory 10.7 comp, you should be able to run 8-9lbs with a conservative tune. And the LS7 cam shows strong gains over the LS3 cam in NA trim.
I guess im dropping an LS7 cam (or an LS9) in my set up. Its the perfect "compression cheater" for those that want to get by without diving into our stock long blocks (just yet
) 
