replacing the junk LS7
11-12-2018, 10:46 AM
#1
replacing the junk LS7
So I have seen increased reports of SBE failures and refreshed SBE failures on this motor. Starting to think it is best to get it out of the car and start with something more reliable. Most posts seem to be failures of bearings which we can assume most are induced by the wearing of Ti rods filling the oil with the magical fairy dust or improper oil change/oil temperature/oil weight. However the fix seems to be replace the rods crank and pistons...which will cost a pretty penny to have a motor that still wears valve guides as a maintenance item every 10-15k depending on cam aggressiveness. With that being said I am exploring dumping the LS7 and replacing it with a 6.2 and a blower. Currently my motor is out because of a collapsed lifter that did 0 collateral damage however my bearings show that trash has been or is going through the motor (light scarring on crank bearings). I haven't looked at my connecting rod surfaces yet however it seems that Calico has stopped coating them or that it may be sticking a ticking time bomb back into the bottom end.
1) Replace the rotating assembly in the LS7 with a set of rods, pistons, and a different crank.
2) Replace the entire longblock with a LS3 that has been forged and drop a LSA on it to make my own poor man's ZR1.
Has anyone in here had direct experience with forging their stock block? If so what rotating assembly did you use? What would you do different? What was your ballpark cost?
Has anyone in here swapped out the LS7 in favor of something less of a snowflake that will handle abuse and boost?
1) Replace the rotating assembly in the LS7 with a set of rods, pistons, and a different crank.
2) Replace the entire longblock with a LS3 that has been forged and drop a LSA on it to make my own poor man's ZR1.
Has anyone in here had direct experience with forging their stock block? If so what rotating assembly did you use? What would you do different? What was your ballpark cost?
Has anyone in here swapped out the LS7 in favor of something less of a snowflake that will handle abuse and boost?
Last edited by zaquhree; 11-12-2018 at 10:50 AM.
11-12-2018, 10:50 AM
#2
You also need to sleeve the block as it doesnt like high cylinder pressure & any detonation.
Either stay NA like its designed to be...or do a different engine if you want boost.
Either stay NA like its designed to be...or do a different engine if you want boost.
11-12-2018, 10:52 AM
#3
Right which is why I said I would replace with a different motor to go boosted or swap out the rotating assembly if I stay with the LS7 which would still be NA. I have no intention of boosting my LS7
11-12-2018, 11:03 AM
#5
I was hoping to get by with using the stock crank and then was reading that the stock crank is expensive to re-balance if you swap out the rods because of it needing Mallory metal? Hoping to hear from some members who have experienced these growing pains because I am over this car after having it 3 months getting to drive it 1 day...I am all tapped out on pains
11-12-2018, 11:52 AM
#6
Le Mans Master
I like the thinking...…...LSA or LS9 (sell the LS7 while running) IF you're going to keep the car but who really knows the future of what hand will be dealt to you??……….BUT you'll kill the value of the car with anything in it besides the LS7.
11-12-2018, 12:10 PM
#8
exactly...I worry it will kill my ability to sell the car...however with the knowledge of the flaws in the LS7 being so widespread it may even bring benefit at this point!
11-12-2018, 12:17 PM
#10
Racer
The only real problem with the LS7 is the Head issue. As far as the rods go most don't give problems till 100,000 miles. The key word here is "most." In this world if you want to play you have to pay.
11-12-2018, 12:24 PM
#11
The LS7 has more issues than just the heads. The heads just show their ugly head because they happen at a faster rate than the Ti rods wearing. You don't have to pay to play if you have a less prone to fail motor...
11-12-2018, 12:28 PM
#12
Le Mans Master
11-12-2018, 12:30 PM
#13
Burning Brakes
The head/valves issue is a relatively minor fix and you can increase the performance while you fix them by upping the compression a bit and porting the heads. This performance mod goes well with other ones like headers, CAI, MSD, etc. So the car is actually way better than stock after you get it done along with some other mods. You don't start impacting the drivability until you go with an aftermarket cam. I had the heads fixed on my car and it only had around 2,300 miles on it. I was told that the LS7 can drop a valve at any time, with any mileage, and this is just a precautionary measure. The guys dropping the valves and destroying their engines didn't get it done more than likely.
11-12-2018, 12:40 PM
#15
11-12-2018, 12:53 PM
#16
And then a HCI LS7 walks you because of higher redline and less weight 😁
Ask the ZR1 guys how much they like modded Z06 roll races.
Ask the ZR1 guys how much they like modded Z06 roll races.
Last edited by Apocolipse; 11-12-2018 at 12:54 PM.
11-12-2018, 01:38 PM
#18
Team Owner
In your shoes, I'd go forged LS7 short block, and sell off my used short block. Whats most enticing (to me) about owning a C6Z is the 427 LS7. If I'm supplanting that LS7 with something other than an LS7, I'd probably part ways with the whole car and move in another direction altogether.
11-12-2018, 01:47 PM
#19
My car is the lightest Z06 so that is an advantage for me
ZR1 pulls hard past the stock 6,500 redline once you start modding them...
I don't roll race much either, I like using my car at the 1/4 mile
11-12-2018, 01:48 PM
#20
In your shoes, I'd go forged LS7 short block, and sell off my used short block. Whats most enticing (to me) about owning a C6Z is the 427 LS7. If I'm supplanting that LS7 with something other than an LS7, I'd probably part ways with the whole car and move in another direction altogether.