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-   Camaro V8 LS3 / L99 Engine, Exhaust, and Bolt-Ons (http://www.camaro5.com/forums/forumdisplay.php?f=11)
-   -   LS3 vs L99? (http://www.camaro5.com/forums/showthread.php?t=13056)

SGOS252382 02-07-2009 05:57 PM

LS3 vs L99?
 
According to GM High Tech some of the major difference between the two motors are
1. VVT
2. AFM
3. 10.4:1 Compression ratio
4. lower lift cam

But one thing that really caught my eye was the lower fuel cut off rpm for the L99. GM High Tech Mag states that the fuel cut off for the LS3 is 6600 rpms, while the fuel cut off for the L99 is 6200 rpms. Is this really the fuel cut off for the L99? That seems too low.
If this is true then red line must be somewhere around 6000 rpms for the L99 vs 6500 rpms or so for the LS3. I'm wonder how much this will affect the peformance of the L99 A6 vs the LS3 M6.

To compare- My LS2 GTO's redline is 6500 rpms and I'm not sure about the fuel cut off.

CamaroSpike23 02-07-2009 06:07 PM

the cut-off is there to protect the valvetrain at higher rpms from getting torn up.


the thing to look at is the power curve. as ive said before, its nice to rev to the moon, its nicer to move.

PatrickfromMD 02-11-2009 02:54 PM

Quote:

Originally Posted by SGOS252382 (Post 280410)
According to GM High Tech some of the major difference between the two motors are
1. VVT
2. AFM
3. 10.4:1 Compression ratio
4. lower lift cam

But one thing that really caught my eye was the lower fuel cut off rpm for the L99. GM High Tech Mag states that the fuel cut off for the LS3 is 6600 rpms, while the fuel cut off for the L99 is 6200 rpms. Is this really the fuel cut off for the L99? That seems too low.
If this is true then red line must be somewhere around 6000 rpms for the L99 vs 6500 rpms or so for the LS3. I'm wonder how much this will affect the peformance of the L99 A6 vs the LS3 M6.

To compare- My LS2 GTO's redline is 6500 rpms and I'm not sure about the fuel cut off.


I have read much of the same for the L99 motor (I have one on order).
In addition to not needing as high an RPM due to less cam, I read that the AFM does impose some restrictions to the valve train at higher RPMs.
This should not be an issue if you keep the motor stock. If you are looking at adding traditional performance mods, then this RPM limit needs to be taken into consideration.
Iím keeping my ears open for ways to beef up the valvetrain to handle more, but have yet to see any useful information short of removing the AFM

RS/SSYellowJacket 02-11-2009 05:32 PM

A shorter Valve Duration will reduce the peak RPMs at wich you reach Peak HP. Also if the Valve lift is less then less HP at the given RPM peak will be realized. Short Lobe Centers usually create quicker HP and TQ curvers. Where a longer Lobe Seperation usually increase the length og the HP and TQ Curves.

So the Auto with AFM and VVT uses the smaller cam to better manage the fuel consumption and there by reducing the power levels and making the peak RPM range lower. However the TQ curve will start at a lower RPM and reach is peak quicker. So the Auto car will basically show simular performance as the manual tranny car and the gearing in the Auto is usually lower per gear than a manual making the Torque multiplication effectivally higher per gear.

This made more sense inmy mind I am sure than it does in print. So take it with a large grain of salt if it confuses you more. :) I was havig a hard time trying to make something technical make sense in lehmans terms. I am not necessarily that good at.

King Mouse 02-11-2009 05:47 PM

You are right. Pointy cams, less duration, have greater torque at low RPMs but less HP.(they peak sooner) Longer duration cams have more HP but you need more RPMs to get it due to scavenging caused by overlap of intake and exhaust lobes. (more of a top end motor)

There are many other factors involved. Just some basic cam theory.

THE EVIL TW1N 02-12-2009 12:59 AM

Quote:

Originally Posted by PatrickfromMD (Post 286406)
I have read much of the same for the L99 motor (I have one on order).
In addition to not needing as high an RPM due to less cam, I read that the AFM does impose some restrictions to the valve train at higher RPMs.
This should not be an issue if you keep the motor stock. If you are looking at adding traditional performance mods, then this RPM limit needs to be taken into consideration.
Iím keeping my ears open for ways to beef up the valvetrain to handle more, but have yet to see any useful information short of removing the AFM

Also, the L99 may have the same heads found on the L76, since that too has AFM. Although the castings are the same as the L92 heads, to save costs the L76 (and possibly the L99) has heavier solid valves vs. the lighter sodium filled L92/LS3 valves.

mike@newera 02-14-2009 11:58 PM

True, but I would guess camshaft powerband has a lot to do with this along with the valvetrain.

epd313 02-16-2009 05:37 PM

I am looking for some advice. I ahve a 2SS A6 on order and keep thinking I should get the LS3 instead. Is there anyhting that says one is better than the other? Back in the day it was stick all the way. I have a stick in my 2000 SS, but have to admit, it gets old in traffic, maybe I'm just getting old, who knows. Technology today seems to point to the L99, any advise, I'm starting to get a headache and I have months yet to wait

Muscle Master 02-16-2009 05:38 PM

L99- more moving parts, less efficiency

epd313 02-16-2009 05:41 PM

L99 has more moving parts?

Muscle Master 02-16-2009 05:43 PM

Quote:

Originally Posted by epd313 (Post 293473)
L99 has more moving parts?

Yes, The AFM

CamaroSpike23 02-16-2009 05:56 PM

Quote:

Originally Posted by epd313 (Post 293463)
I am looking for some advice. I ahve a 2SS A6 on order and keep thinking I should get the LS3 instead. Is there anyhting that says one is better than the other? Back in the day it was stick all the way. I have a stick in my 2000 SS, but have to admit, it gets old in traffic, maybe I'm just getting old, who knows. Technology today seems to point to the L99, any advise, I'm starting to get a headache and I have months yet to wait

the auto's of old were not the greatest. the new 6 speed auto that GM has is a bad mofo.

this new auto isnt the slushbox of yesteryear.



Quote:

Originally Posted by Muscle Master (Post 293466)
L99- more moving parts, less efficiency

depends on what kind of efficiency you are looking at. fuel efficiency? AFM rocks. lol

Muscle Master 02-16-2009 06:00 PM

Quote:

Originally Posted by CamaroSpike23 (Post 293503)
the auto's of old were not the greatest. the new 6 speed auto that GM has is a bad mofo.

this new auto isnt the slushbox of yesteryear.





depends on what kind of efficiency you are looking at. fuel efficiency? AFM rocks. lol


Efficiency period, of course Fuel efficiency is gonna kick ass

ChevyBoiSS 02-20-2009 06:23 PM

for the person that wont be modding their car to hell because 400hp seems to be MORE than enough for me, lol.. Im fine with the way things are.

duder4thgen 02-21-2009 09:39 AM

Quote:

Originally Posted by epd313 (Post 293463)
I am looking for some advice. I ahve a 2SS A6 on order and keep thinking I should get the LS3 instead. Is there anyhting that says one is better than the other? Back in the day it was stick all the way. I have a stick in my 2000 SS, but have to admit, it gets old in traffic, maybe I'm just getting old, who knows. Technology today seems to point to the L99, any advise, I'm starting to get a headache and I have months yet to wait

Stock for stock its going to be a drivers race between the a6 and m6. If you are going to keep it stock, stick with what will make you happier on a daily basis. If you are going to mod it, I'm willing to bet the m6 is going to be a better place to start out at.

camaro1 02-21-2009 09:47 AM

i would say if your going to mod it go with the auto, a 3000 stall converter and delete the afm, cam and a tune and you will blow away a 6speed manual with the same cam/bolt on mods

Parker 02-21-2009 10:36 AM

Part of the AFM package is VVT and that will help with power efficiency from low to high RPMs. Just like advancing and retarding the spark does.

Grape Ape 02-21-2009 11:34 AM

Quote:

Originally Posted by THE EVIL TW1N (Post 287276)
Also, the L99 may have the same heads found on the L76, since that too has AFM. Although the castings are the same as the L92 heads, to save costs the L76 (and possibly the L99) has heavier solid valves vs. the lighter sodium filled L92/LS3 valves.

The AFM gear is in the block, not the heads.

mike@newera 02-22-2009 02:49 PM

Here are some pics of the lifters for AFM/DOD which will be used in the L99:

http://images.popularhotrodding.com/...gmdod_03_z.jpg
http://images.popularhotrodding.com/...gmdod_02_z.jpg

The LS3 will have normal hydraulic lifters, a different valley cover, and it will not have this in front of the camshaft which is for VVT:

http://www.mastmotorsports.com/image...ser_Series.jpg

CamaroSpike23 02-22-2009 03:46 PM

Quote:

Originally Posted by camaro1 (Post 301245)
i would say if your going to mod it go with the auto, a 3000 stall converter and delete the afm, cam and a tune and you will blow away a 6speed manual with the same cam/bolt on mods

that will be debated. actually it already has been debated.

but to add to your argument, there are a nice group of AFM G8's out there running superchargers as well with no problems.

regardless of which one you go with. they will both be bad ass from the factory as well as with adding mods.

Muscle Master 02-22-2009 03:51 PM

Quote:

Originally Posted by CamaroSpike23 (Post 302868)
that will be debated. actually it already has been debated.

but to add to your argument, there are a nice group of AFM G8's out there running superchargers as well with no problems.

regardless of which one you go with. they will both be bad ass from the factory as well as with adding mods.

at the cost of fuel economy, don't see the point of still having it active, the AFM

CamaroSpike23 02-23-2009 09:57 AM

Quote:

Originally Posted by Muscle Master (Post 302875)
at the cost of fuel economy, don't see the point of still having it active, the AFM

I dont know what their mpg's are after the sc install, ill have to look into it. but the other thing to keep in mind is that EPA estimates are just that.... estimates.

just like the 4th gens where people were getting 30+mpg in their cars, im sure that both the LS3 and L99 will get better than the EPA estimates

duder4thgen 02-23-2009 10:02 AM

Quote:

Originally Posted by CamaroSpike23 (Post 302868)
that will be debated. actually it already has been debated.

I agree, I take back my statement about the m6 being better to mod from. Might be a little simpler to start with, but in the end, once you get to a cam swap, there isnt that much more to swap out with afm than you would with a normal ls3. Guess its all up to driver preference.

CamaroSpike23 02-23-2009 10:16 AM

Quote:

Originally Posted by duder4thgen (Post 304156)
I agree, I take back my statement about the m6 being better to mod from. Might be a little simpler to start with, but in the end, once you get to a cam swap, there isnt that much more to swap out with afm than you would with a normal ls3. Guess its all up to driver preference.

camming the L99 will be a little trickier as you have to allow some leeway with the AFM and the lifters. now if you tune it out and remove all that stuff and basically convert to an LS3, then cam swap to your hearts content

duder4thgen 02-23-2009 10:25 AM

Well, I'm not sure if anyone is making a cam right now thats compatable with AFM. I would think with the l99, if you are going to cam it, youre going to have to take out the AFM, which is a couple more parts than doing a cam swap on a ls3, but really not that much more labor.


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