GM LS3 LS376/525 Crate Motor
#44
Having installed the LS376 525 in a 996 and dyno'd it on two separate occasions, I can confirm that the 525 hp number is GM fiction. The GM LS376 525 hp output number is crank hp with no water pump, alternator, power steering pump, or AC pump. It is with a straight pipe exhaust little to no back pressure, and of course there is no transmission losses.
First dyno run: 92F in the shop, intake air temp hitting 160-170F. 280 hp max with very late timing due to air temps.
- Added a big fan to the rear deck lid that had been deleted during the swap. intake air temps dropped to +10-15F above ambient.
- Deleted the CATs
Second Dyno run, with a big fan pointed at the intake to better simulate a moving vehicle. 75F in shop and air intakes +10-15F. Max output was 346 wrhp. The car has a twin turbo 6 speed manual transaxle. Front cardan shaft (drive shaft) for the AWD was removed for the tests so all power was RWD.
Same motor, different car: A SLC Superlite coupe on the same dyno with $3k+ custom titanium exhaust, a TT transmission and much better air intake design than in the 996 produced 350 wrhp. The reality is GM performance is selling BS numbers on their crate engines.
Dyno shop: http://tecmotion.ca/
Show lessREPLY
First dyno run: 92F in the shop, intake air temp hitting 160-170F. 280 hp max with very late timing due to air temps.
- Added a big fan to the rear deck lid that had been deleted during the swap. intake air temps dropped to +10-15F above ambient.
- Deleted the CATs
Second Dyno run, with a big fan pointed at the intake to better simulate a moving vehicle. 75F in shop and air intakes +10-15F. Max output was 346 wrhp. The car has a twin turbo 6 speed manual transaxle. Front cardan shaft (drive shaft) for the AWD was removed for the tests so all power was RWD.
Same motor, different car: A SLC Superlite coupe on the same dyno with $3k+ custom titanium exhaust, a TT transmission and much better air intake design than in the 996 produced 350 wrhp. The reality is GM performance is selling BS numbers on their crate engines.
Dyno shop: http://tecmotion.ca/
Show lessREPLY
#45
TECH Senior Member
The cam in that engine only has .525" lift. Any cam nowadays with the duration of that cam would have at least .600" lift. The ONLY difference between the 525, 480, and OEM 430HP LS3 is the cam. THAT'S IT. I've always thought you would be better to get the 430HP LS3 and put an up-to-date cam in it for way better results.
#46
I seriously wonder if the LS376 525 engine is the same as the LS3 in the 2014-2015 Camaro SS. Here is a dyno pull of a 2014 Camaro SS pulling 380 rwhp.
Below is the dyno chart from a 2015 Camaro SS seen here on the dyno producing 367 rwhp at the wheels. The pull is here: If dynos vary by up to 10% then that might explain some of the differences. My 996 dyno discussed above was done at 75-80F and 3000 ft. elevation.
Below is the dyno chart from a 2015 Camaro SS seen here on the dyno producing 367 rwhp at the wheels. The pull is here:
#47
TECH Senior Member
The 525 is NOT the engine that came in the 2014-15 Camaro SS. This engine idles with a VERY pronounced lope that would never pass emissions in any modern country. If you heard it you would never think it was original in the Camaro.
The above dyno tests were of the standard 430 FWHP LS3 with possible mods.
The above dyno tests were of the standard 430 FWHP LS3 with possible mods.
#48
The 525 is NOT the engine that came in the 2014-15 Camaro SS. This engine idles with a VERY pronounced lope that would never pass emissions in any modern country. If you heard it you would never think it was original in the Camaro.
The above dyno tests were of the standard 430 FWHP LS3 with possible mods.
The above dyno tests were of the standard 430 FWHP LS3 with possible mods.
You also have proof that the SS Camaro is running the standard 430 LS3?
#49
The cam in that engine only has .525" lift. Any cam nowadays with the duration of that cam would have at least .600" lift. The ONLY difference between the 525, 480, and OEM 430HP LS3 is the cam. THAT'S IT. I've always thought you would be better to get the 430HP LS3 and put an up-to-date cam in it for way better results.
Also you may be unaware of GM's warranty policy. If you buy a new crate a change ANY part of the internals, your warranty on the engine is void.
Here are the LS3 525 CAM specs:
- Camshaft Type (P/N 88958770): Hydraulic roller
- Valve Lift (in.): 0.525 intake / 0.525 exhaust
- Camshaft Duration (@0.050 in.): 226° intake / 236° exhaust
So after reading the great LS3 camshaft comparison http://www.superchevy.com/how-to/eng...ft-comparison/
and reviewing many articles on camshafts and other performance build topics, I did the math:
Cost for the stock LS3 430
Cost for Lingenfelter, lunati or comp cams replacement cam, springs, and possibly valve work if ingress is too high.
Cost to install and test
Cost of void warranty.
Adding up the additional costs to the stock motor, I would spend a little less than 525 cost around $500, but not have a 2 year warranty on an expensive swap that already has had an LS3 430 that failed and had to be replaced. So after doing my homework the decision was clear, get the LS376 525 with GM's performance CAM and the 2 year warranty and reduce the risk of screw ups while leaving some top and performance on the table.
Having driven the LS376 525 a small amount, I think sucked before the tune and was perfectly fine after getting it tuned. I will report more later once the last bits are completed and can get the first 500 mi on it.
GM has priced the LS376 525 very well compared to buying the LS3 430 and upgrading it. Buyers are paying a premium for the upgraded performance while still getting to keep the warranty.
#50
12 Second Club
#52
TECH Senior Member
The difference is the LS3 does not have DOD or VSS, and the L99 has both, along with 400 HP instead of 430.
Anything that idles as roughly as the 525 does would not pass a sniff test. Too many unburned HC's. Rough idle indicates intermittent misfire. Comes with the territory of a radical cam.
The lift on that cam is much lower than most cams of that duration. Most cams in that area have close to or over .600" lift.
#53
TECH Fanatic
iTrader: (5)
I can vouch for this. The CARB ****'s could probably smell, and see the soot, from the exhaust from 3000 miles away. It must be hell for drivers behind me. It can certainly be heard from far away. No gen V or VI stock camaro of any stripe (z/28, SS, ZL1) sounds any where near this in your face, and I say that with envy of a more subtle exhaust note.
#54
TECH Senior Member
I actually do NOT consider the ASA cam a street-worthy cam. Way too rough.
#55
TECH Fanatic
iTrader: (8)
Having installed the LS376 525 in a 996 and dyno'd it on two separate occasions, I can confirm that the 525 hp number is GM fiction. The GM LS376 525 hp output number is crank hp with no water pump, alternator, power steering pump, or AC pump. It is with a straight pipe exhaust little to no back pressure, and of course there is no transmission losses.
Originally Posted by rdymond
Below is the dyno chart from a 2015 Camaro SS seen here on the dyno producing 367 rwhp at the wheels. The pull is here: https://www.youtube.com/watch?v=OtuX9Gf3mB0
Either your dyno reads really low, your swaps are garbage, or you have tuner problems. The fault isn't in the engine.
Last edited by Marc 85Z28; 10-08-2018 at 11:58 AM.
#57
TECH Senior Member
OP is starting to sound WAY too much like a lawyer... lol
#58
10 Second Club
The difference between the regular ls3 and the 525 is really only around 35-40 hp. The 430 rating of the regular ls3 is net hp and the 525 hp rating for the crate engine is gross.
run the regular ls3 in the same gross conditions and it’ll be in the 470-485 range
run the regular ls3 in the same gross conditions and it’ll be in the 470-485 range
#59
TECH Fanatic
iTrader: (8)