Recommendation for new LT1 shortblock in Corvette

Pennzoil motor oil
2019StingrayZ51

2019StingrayZ51

Joined
Aug 7, 2018
Messages
39
Location
NC
Good morning all, it's been a while since I posted, though I certainly have searched and studied many many threads. I need some advice / different perspectives on a build in process. Car is a 2019 C7 Z51, NA LT1 with Katech heads and cam package. After several years of tracking, it needs a new short block (2 cylinders getting weak per leakdown test). I have a new short block on order from Late Model Engines. Pretty standard stuff:
- new GM block with LME blueprint process
- Callies Compstar LTX 4340 Forged 3.625" Stroke 8 Counter Weight Crankshaft with LME blueprint process
- Callies Compstar 4340 6.125" H-beam connecting rods w/ 2.1.." journal
- DSS RACING FORGED PISTONS - 4032 alloy - 4.070" X 1.305", -2 CC dish, .927" pin,1.2 / 1.2 / 3.0 mm ring pack [went with 4032 alloy instead of 2618 to avoid/reduce cold piston slap and hopefully have quieter street operation; 4032 is plenty strong for this NA application and a bit lighter too]
- Clevite H Series Main and Rod Bearings CB663HN
Car is used for street and track driving. It has aftermarket cats, "Ultra Green" from Kooks.
LME recommended breaking in the engine with Driven BR40, two 500-mile cycles. After that, they suggested You may then switch to full synthetic oil, any good name brand is fine but the minimum weight to use would be 10W30, and you can run up to and including 20W50 - no more 5W oil. Will receive build sheet with all clearances when complete.
Car sees oil temps typically in the 260-280 range on track. I'm in North Carolina and typically track at VIR, CMP and the Roval in Charlotte.
With all that in mind, I'm looking at Driven DI50 or Mobil 1 15W-50. I want to avoid anything with a big calcium number given this is a DI engine. HPL's Supercar 5W-50 seems to check the boxes as well, EXCEPT LME said "no more 5W".
Thanks to all in advance for suggestions, thoughts, and/or prior experience. Have a great day!
 
@Patman wi probably knows the best about this and I am sure he will share a very helpful comment here.

I don't own a C7, but did quite a bit of research on z51 and gs for track use when I was contemplating buying one.

Mobil 1 15w50 is the "heavy track day" spec of Chevy for that car, and I would feel confident with that, definitely not a xw30 or xw40 oil if it's gonna dance around 280f. I believe your manual says it is acceptable up to 300f but both an accusamp or a cooler might be good options.


PS: do not worry about Ca in HPL. other additives such as Molly more than compensate the Ca's nudge for PI
 
I’m not sure what the calcium level is in Amsoil Dominator 15w-50 but this is another oil that should be considered here.

HPL may also be able to custom build you an oil with less calcium from one of their existing oils
 
Patman said:
I’m not sure what the calcium level is in Amsoil Dominator 15w-50 but this is another oil that should be considered here.

HPL may also be able to custom build you an oil with less calcium from one of their existing oils
Click to expand...
The Amsoil Dominator does look good. Would you have any hesitation using this with cats? Thanks!
 
2019StingrayZ51 said:
After several years of tracking, it needs a new short block (2 cylinders getting weak per leakdown test).
Click to expand...

not to derail the thread too much, but may i ask if there was an engine autopsy that showed the central source of the low compression? reason i ask, is that as a fellow camaro owner using the same engine (quite literally, mine was part of a run that got the leftover 2019 handbuilt C7 engines as their production ended) i'm always wary of potential lifter failure and that exact situation took out an engine of another camaro racer i know. lifter failed, scored the bore (too much fuel with intake valves that wouldn't open) from washing it down, low compression, and then finally crankcase pressure built up and blew the crank seals out.
 
ScottyB said:
not to derail the thread too much, but may i ask if there was an engine autopsy that showed the central source of the low compression? reason i ask, is that as a fellow camaro owner using the same engine (quite literally, mine was part of a run that got the leftover 2019 handbuilt C7 engines as their production ended) i'm always wary of potential lifter failure and that exact situation took out an engine of another camaro racer i know. lifter failed, scored the bore (too much fuel with intake valves that wouldn't open) from washing it down, low compression, and then finally crankcase pressure built up and blew the crank seals out.
Click to expand...
ScottB, not a derail at all, I enjoy this sort of discussion. I'm not sure of the exact cause of the 2 cylinders having leakdown, but my suspicion is an improperly routed catch can combined with overfilling the oil. Both of those issues were corrected after the front main seal blew out from the blowby, and I ran the car a few more years. The AFM lifters were turned off with a range device as soon as I bought the car new and then they were replaced as part of Katech cam and heads package so I don't think that is the cause. But we will certainly be looking at everything when the new short block arrives and we pull the current one.
 
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