L99 heads vs LS3/L92 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

camaro1 · 08-04-2008, 10:14 AM

the L92 and LS3 share the same head/port design, can we assume that the L99 heads will also be the same as the LS3/L92's

looking to have a set of heads ready to go for the new camaro

thanks

jmliptak · 08-04-2008, 10:23 AM

Elie or one of the other disciples may know, but no one has said anything to indicate they are different, but no one may have asked the question yet....

gunslinger · 08-04-2008, 10:49 PM

Someone posted in another thread that the rev limiter on the LS3 is 6600 RPM while the L99 is 6000 RPM.

That either has to do with keeping the RPM's down on the automatic transmission(RPM's KILL an auto trans) or that the springs on the L99 heads can't handle the extended RPM band.

Wacker · 08-23-2009, 04:29 PM

Tranny RPM

PatrickfromMD · 08-23-2009, 06:10 PM

Nope, it's the AFM, specifically the lifters. The cam is milder, sonits not making power that high anyway

Wacker · 08-23-2009, 06:19 PM

Quote:

Originally Posted by PatrickfromMD

Nope, it's the AFM, specifically the lifters. The cam is milder, sonits not making power that high anyway

Yep your right... I found where the maximum shift sped is 6500RPM. The car stops making power well before that though.

rayhawk · 08-23-2009, 07:14 PM

Quote:

Originally Posted by Wacker

Yep your right... I found where the maximum shift sped is 6500RPM. The car stops making power well before that though.

The LS3? It is still making just under 400 hp at 6500 rpm, I wouldn't call that not making power. It may be past peak, but it is still more power than would be available at 4500 rpm in the next gear. The L99 is limited to 6200 rpm.

Wacker · 08-23-2009, 07:21 PM

Quote:

Originally Posted by rayhawk

The LS3? It is still making just under 400 hp at 6500 rpm, I wouldn't call that not making power. It may be past peak, but it is still more power than would be available at 4500 rpm in the next gear. The L99 is limited to 6200 rpm.

We are talking about the L99.

hot ss · 08-23-2009, 07:45 PM

whats a the l99 safe stock spring redline
???????????????????????????????????????

pharmd · 08-23-2009, 09:14 PM

Do me a favor, some one with an LS3 go out and see what the casting # is on your heads, then some one with an L99 go out and see what the casting # is on your heads. Someone suggested to me that the head casting # was different. We know the LS3 heads contain lighter valves...probably different valve springs also, as the LS3 cam's max lift is over .550 vs the L99 being less than .500, the LS3 CR is more, but only 0.3 more 10.4:1 vs 10.7:1.

But the new question, is...is the head design the same or different. It seems like L99's for the same mods are down more on power than just the what the drive train loss would account for. Saying that even with aftermarket mods (mods being equal...such as cam or whatever), its not right.

I emailed a couple shops that do heads, and asked if they had inspected any bare L99 castings vs LS3 but I got no replies.

Maybe its nothing...or maybe its something...it just "appears" that the L99 is down more power than what drivetrain loss will account for.

Wacker · 08-23-2009, 10:46 PM

Quote:

Originally Posted by pharmd

Do me a favor, some one with an LS3 go out and see what the casting # is on your heads, then some one with an L99 go out and see what the casting # is on your heads. Someone suggested to me that the head casting # was different. We know the LS3 heads contain lighter valves...probably different valve springs also, as the LS3 cam's max lift is over .550 vs the L99 being less than .500, the LS3 CR is more, but only 0.3 more 10.4:1 vs 10.7:1.

But the new question, is...is the head design the same or different. It seems like L99's for the same mods are down more on power than just the what the drive train loss would account for. Saying that even with aftermarket mods (mods being equal...such as cam or whatever), its not right.

I emailed a couple shops that do heads, and asked if they had inspected any bare L99 castings vs LS3 but I got no replies.

Maybe its nothing...or maybe its something...it just "appears" that the L99 is down more power than what drivetrain loss will account for.

I'll be back on friday and will post mine if no one else does. I'll I know is they use the same headers, I think.

9c1ny · 08-23-2009, 11:05 PM

Quote:

Originally Posted by pharmd

Do me a favor, some one with an LS3 go out and see what the casting # is on your heads, then some one with an L99 go out and see what the casting # is on your heads. Someone suggested to me that the head casting # was different. We know the LS3 heads contain lighter valves...probably different valve springs also, as the LS3 cam's max lift is over .550 vs the L99 being less than .500, the LS3 CR is more, but only 0.3 more 10.4:1 vs 10.7:1.

But the new question, is...is the head design the same or different. It seems like L99's for the same mods are down more on power than just the what the drive train loss would account for. Saying that even with aftermarket mods (mods being equal...such as cam or whatever), its not right.

I emailed a couple shops that do heads, and asked if they had inspected any bare L99 castings vs LS3 but I got no replies.

Maybe its nothing...or maybe its something...it just "appears" that the L99 is down more power than what drivetrain loss will account for.

I think I know who you talked to

yeah it appears the heads are different, I believe mine (and his) are 853s?

both L99s

rayhawk · 08-24-2009, 06:05 AM

Quote:

Originally Posted by pharmd

Do me a favor, some one with an LS3 go out and see what the casting # is on your heads, then some one with an L99 go out and see what the casting # is on your heads. Someone suggested to me that the head casting # was different. We know the LS3 heads contain lighter valves...probably different valve springs also, as the LS3 cam's max lift is over .550 vs the L99 being less than .500, the LS3 CR is more, but only 0.3 more 10.4:1 vs 10.7:1.

But the new question, is...is the head design the same or different. It seems like L99's for the same mods are down more on power than just the what the drive train loss would account for. Saying that even with aftermarket mods (mods being equal...such as cam or whatever), its not right.

I emailed a couple shops that do heads, and asked if they had inspected any bare L99 castings vs LS3 but I got no replies.

Maybe its nothing...or maybe its something...it just "appears" that the L99 is down more power than what drivetrain loss will account for.

According to GMHTP, the heads are identical. But as you said, it is possible there are some differences in the springs or valves. I believe the CR difference is due to the valve pockets in the pistons.

GMRULZ · 08-24-2009, 07:11 AM

Quote:

Originally Posted by rayhawk

According to GMHTP, the heads are identical. But as you said, it is possible there are some differences in the springs or valves. I believe the CR difference is due to the valve pockets in the pistons.

Truth...

08-04-2008, 10:14 AM	#1
camaro1 Drives: 550+RWHP 2010 camaro Join Date: Sep 2007 Location: wisconsin Posts: 1,588	L99 heads vs LS3/L92 the L92 and LS3 share the same head/port design, can we assume that the L99 heads will also be the same as the LS3/L92's looking to have a set of heads ready to go for the new camaro thanks __________________ 415ci stroker, TVS 2300 Magnacharger, cnc heads, cam, yank ss3200 converter, Kooks long tubes, Bwoody true cold air kit, ZL1 Pump, magnaflow 3" cat-back, lowering springs,BMR control arms and tie rod bars, 3.73 gears, diff mounts, RX can, ADM fuel controller

08-23-2009, 04:29 PM	#4
Wacker INTHECLOUDS Drives: 2010 2SS/RS Join Date: Aug 2009 Location: NM Posts: 912	Tranny RPM __________________ 2010 IOM 2SS/RS A6, Tuned by Me, ARH/NoCats, Borla Touring, Vararam CAI, G-Force 9" with 4.10's, Circle D 4500K, (Skinnies/Slicks, and Bogarts all around 24MPG 11.39 @ 118 510 DA www.6l80tuning.com www.6l90tuning.com

08-23-2009, 06:10 PM	#5
PatrickfromMD Drives: Buick Enclave/Corvette/2010 Camaro Join Date: Aug 2008 Location: Maryland Posts: 421	Nope, it's the AFM, specifically the lifters. The cam is milder, sonits not making power that high anyway __________________ *56K miles and still going strong* 2SS/RS IOM ext w/cyber grey stripes, tinted windows, IO int Auto ProTorque prototype Converter, Chuck Mosello of Westchester Corvettes Custom Tune T&T installed SLP Longtubes, Powerflow X Pipe, and Powerflow axle back JL 10W3 in custom side sub box, new door tweeters, Alpine 5ch 600 watt T&T configured ACS front Fascia w/ heritage grill, splitter, dual color halos, , led markers, taillight bezels , all accented in CGM Gary Custom Z vented fenders. Vararam ver 2

08-23-2009, 07:45 PM	#9
hot ss Drives: aqua 2ss l99 Join Date: Jun 2009 Location: Edmonton Posts: 1,215	whats a the l99 safe stock spring redline ??????????????????????????????????????? __________________ May your exhaust note, sing in harmony with your blower.

08-23-2009, 09:14 PM	#10
pharmd Master of Medicine Drives: 4th Gen Join Date: Oct 2008 Location: Kentucky Posts: 784	Do me a favor, some one with an LS3 go out and see what the casting # is on your heads, then some one with an L99 go out and see what the casting # is on your heads. Someone suggested to me that the head casting # was different. We know the LS3 heads contain lighter valves...probably different valve springs also, as the LS3 cam's max lift is over .550 vs the L99 being less than .500, the LS3 CR is more, but only 0.3 more 10.4:1 vs 10.7:1. But the new question, is...is the head design the same or different. It seems like L99's for the same mods are down more on power than just the what the drive train loss would account for. Saying that even with aftermarket mods (mods being equal...such as cam or whatever), its not right. I emailed a couple shops that do heads, and asked if they had inspected any bare L99 castings vs LS3 but I got no replies. Maybe its nothing...or maybe its something...it just "appears" that the L99 is down more power than what drivetrain loss will account for. __________________ 2002 Camaro SS. 408 LS2. 500+RWHP/480RWTQ. Full UMI RR suspension. Koni/Strano. 295F/315R. 3500#(55/45)

08-04-2008, 10:23 AM	#2
jmliptak Drives: D Join Date: May 2008 Location: D Posts: 373	Elie or one of the other disciples may know, but no one has said anything to indicate they are different, but no one may have asked the question yet....

08-04-2008, 10:49 PM	#3
gunslinger Drives: 1998 Z28 M6 Join Date: May 2008 Location: Lake Forest, CA Posts: 254	Someone posted in another thread that the rev limiter on the LS3 is 6600 RPM while the L99 is 6000 RPM. That either has to do with keeping the RPM's down on the automatic transmission(RPM's KILL an auto trans) or that the springs on the L99 heads can't handle the extended RPM band.

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