Why the power difference L99 vs LS3? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

shaner74 · 08-17-2010, 06:51 AM

I don't understand why FI LS3's are making more power than the L99 cars?? You'd think the L99 would get better power gains due to being a bit lower in compression? What's the issue?

bi11ymc · 08-17-2010, 06:57 AM

Don't forget that if all things were the same internally, the automatic transmission will cause more power loss to the wheels than the manual.

tony1 · 08-17-2010, 07:14 AM

True ....Drive train loss is higher for the Auto .. but the compression ratio on the L99 is better for FI .. not because of more power but it's "Safer" than a higher compression Engine. Hence the 11:1 on the Mustangs 5.0 .. scary for boost over 6psi.

Jchaluja · 08-17-2010, 08:09 AM

I would suspect cam specs have some blame on that as well....

BackinBlackSS/RS · 08-17-2010, 08:13 AM

It's the cam.

GMRULZ · 08-17-2010, 09:07 AM

Not to mention the ability to rev the LS3 higher making more boost I would suspect as well. Of course same boost level it would just come down to the cam holding the valves open longer in the LS3.

bi11ymc · 08-17-2010, 09:20 AM

Quote:

Originally Posted by tony1

True ....Drive train loss is higher for the Auto .. but the compression ratio on the L99 is better for FI .. not because of more power but it's "Safer" than a higher compression Engine. Hence the 11:1 on the Mustangs 5.0 .. scary for boost over 6psi.

L99 - 10.4 compression
LS3 - 10.7 compression

That is what I have seen (not positive), but seems almost neglible.

Hendrix-Engineering · 08-17-2010, 10:09 AM

The cam and cr is the difference in the hp numbers.I would prefer the higher cr for boost until you are over 20 psi .

IPS Brandon · 08-17-2010, 10:26 AM

Chalk it up the biggest offender the automatic transmission, at least a 5% difference in output versus a manual car.

Then obviously there are other marginal differences in the engine.

Regards

shaner74 · 08-17-2010, 10:30 AM

Yeah must be the cam. I just looked up the specs...

L99:
Valve Lift (in): .500" intake/ .492" exhaust
Camshaft duration (@.050 in): 195 degree intake/201 degree exhaust

LS3:
Valve Lift (in): .551" intake/ .522" exhaust
Camshaft duration (@.050 in): 204 degree intake/211 degree exhaust

This would definitely account for the power difference - especially on a FI car. I think the VVT of the L99 is a good idea, but after having the AFM for around 8k miles and having it tuned-out for 2k, I'd say it's more of a hindrance than a help. Kind of wish the A6 came with the LS3 but oh well, I have no problem turning a wrench or two

motorhead · 08-17-2010, 10:33 AM

Really I would have to say the biggest reason was to keep the automatic cars from paying the gas guzzler tax. Remember the GT0's , the auto got the tax and the manual didn't.
I think GM didn't want to repeat that.

BackinBlackSS/RS · 08-17-2010, 10:36 AM

Quote:

Originally Posted by bi11ymc

Don't forget that if all things were the same internally, the automatic transmission will cause more power loss to the wheels than the manual.

The 426hp vs 400 hp ratings are at the crank.

08-17-2010, 06:51 AM	#1
shaner74 Drives: 2010 camaro 2SS/RS Join Date: Apr 2010 Location: CT Posts: 58	Why the power difference L99 vs LS3? I don't understand why FI LS3's are making more power than the L99 cars?? You'd think the L99 would get better power gains due to being a bit lower in compression? What's the issue?

08-17-2010, 06:57 AM	#2
bi11ymc "Silver Street" Drives: 2010 2SS/RS L99 Join Date: Oct 2009 Location: Franklin, TN Posts: 707	Don't forget that if all things were the same internally, the automatic transmission will cause more power loss to the wheels than the manual. __________________ Silver Street - 2010 Camaro 2SS/RS, SIM, Gray, Cyber Gray Rally Stripes, Polished Wheels, Automatic (L99) - 553 RWHP/510 RWTQ CAI Inc., ARH LT Headers with Cats, Borla Touring Cat-Back; Pfadt Coil Overs, Sway Bars, End Links, and Trailing Arms; Comp Cams Blower Cam, Dual Springs, Push-Rods, and Lifters; GM LS2 Lifter Trays, 6.2 MLS Head Gaskets, Crank Bolt, and LS2 Front Cover; 3-Bolt Conversion Timing Gear, Katech C5R Timing Chain, ARP LS2/LS3 Head Bolt Kit, Melling Hi Volume Oil Pump, TVS 2300 Supercharger (Black); Build by Vengeance Racing; Custom Tune by Vengeance Racing

08-17-2010, 07:14 AM	#3
tony1 Drives: 2SS/RS Vortech/L99 Join Date: Jan 2010 Location: CHICAGO Posts: 474	True ....Drive train loss is higher for the Auto .. but the compression ratio on the L99 is better for FI .. not because of more power but it's "Safer" than a higher compression Engine. Hence the 11:1 on the Mustangs 5.0 .. scary for boost over 6psi. Last edited by tony1; 08-17-2010 at 07:29 AM.

08-17-2010, 09:07 AM	#6
GMRULZ Drives: 2010 SS & 2008 C6 Join Date: Mar 2008 Location: VA Posts: 1,819	Not to mention the ability to rev the LS3 higher making more boost I would suspect as well. Of course same boost level it would just come down to the cam holding the valves open longer in the LS3. __________________ 2010 SS L99, 536rwhp 10.843@126.72. Whipple Supercharger stock pulley, ARH 1 7/8 longtubes w/ catted xpipe, magnaflow 3" mufflers, ADM Race CAI, 3:70 gears, lightweight wheels and nitto drag radials. Stock internal L99, stock converter. Bolt on best before blower 12.22@113.29 w/ nothing but ARH headers, catted x-pipe, ADM CAI and a tune on stock Pzero`s! Other car 2008 C6 Ls3, z51, A6, Npp Exhaust, best bonestock pass 11.80@118.82, Number 2 on the Corvette Forums Bonestock fastest list..

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08-17-2010, 08:09 AM	#4
Jchaluja Drives: ZL1 Camaro Join Date: Feb 2009 Location: Jacksonville, FL Posts: 1,321	I would suspect cam specs have some blame on that as well....

08-17-2010, 08:13 AM	#5
BackinBlackSS/RS Go Blue!!!!! Drives: 2012 Cruze LT Join Date: Mar 2009 Location: Indiana Posts: 23,290	It's the cam.

08-17-2010, 10:09 AM	#8
Hendrix-Engineering Account Suspended Drives: First 9 inch-12 bolt IRS Camaro Join Date: Jun 2009 Location: nc Posts: 1,835	The cam and cr is the difference in the hp numbers.I would prefer the higher cr for boost until you are over 20 psi .

08-17-2010, 10:26 AM	#9
IPS Brandon Drives: 2010 Camaro SS black Join Date: Aug 2009 Location: Columbus Ohio Posts: 907	Chalk it up the biggest offender the automatic transmission, at least a 5% difference in output versus a manual car. Then obviously there are other marginal differences in the engine. Regards

08-17-2010, 10:30 AM	#10
shaner74 Drives: 2010 camaro 2SS/RS Join Date: Apr 2010 Location: CT Posts: 58	Yeah must be the cam. I just looked up the specs... L99: Valve Lift (in): .500" intake/ .492" exhaust Camshaft duration (@.050 in): 195 degree intake/201 degree exhaust LS3: Valve Lift (in): .551" intake/ .522" exhaust Camshaft duration (@.050 in): 204 degree intake/211 degree exhaust This would definitely account for the power difference - especially on a FI car. I think the VVT of the L99 is a good idea, but after having the AFM for around 8k miles and having it tuned-out for 2k, I'd say it's more of a hindrance than a help. Kind of wish the A6 came with the LS3 but oh well, I have no problem turning a wrench or two

08-17-2010, 10:33 AM	#11
motorhead Drives: Love the one you're with Join Date: Sep 2009 Location: Downtown Charlie Brown Posts: 11,850	Really I would have to say the biggest reason was to keep the automatic cars from paying the gas guzzler tax. Remember the GT0's , the auto got the tax and the manual didn't. I think GM didn't want to repeat that.