5.3 V8 DI 400HP as the BASE V8

Got to thinking about Scott saying that we're in for some big surprises.

The biggest surprise I believe, will be what the BASE V8 will be.

From the get-go, I believed that the Camaro, was going to be the showcase vehicle, for the next generation of V8 engines.

The design goal will probaby be a BASE V8 with 100HP more, than the BASE V6.

With a 2.0L 260HP I4 , & a 3.6L 304HP V6 already done.
The time for the DI V8 is here now.

With everyone knowing that it won't be the LS2 , & thinking that it will be the LS3, I think that we'll be in for a nice surprise...

Got to thinking about Scott saying that we're in for some big surprises.

The biggest surprise I believe, will be what the BASE V8 will be.

From the get-go, I believed that the Camaro, was going to be the showcase vehicle, for the next generation of V8 engines.

The design goal will probaby be a BASE V8 with 100HP more, than the BASE V6.

With a 2.0L 260HP I4 , & a 3.6L 304HP V6 already done.
The time for the DI V8 is here now.

With everyone knowing that it won't be the LS2 , & thinking that it will be the LS3, I think that we'll be in for a nice surprise...

Nope.

The LNF 2.0L turbo DI engine was mentioned in passing by Bob Lutz as a possibility if CAFE causes a problem for the Camaro. It's not even remotely close to "already done".

The LS3 will be the "base" V8. The Gen V DI motors aren't quite yet ready to be released.

I don't know much about the 5.3 motor...what would its advantages be? Is it DOD capable? DI would provide better mileage - do you expect mileage figures to be better than with LS3?

Just curious and want to learn more :)

I don't know much about the 5.3 motor...what would its advantages be? Is it DOD capable? DI would provide better mileage - do you expect mileage figures to be better than with LS3?

Just curious and want to learn more :)

Unless GM is developing a new RWD 5.3L V8, the only 5.3L V8s in the lineup right now are the Vortec truck engines. They put out between 315-320 HP and 340 lb.ft. of torque.

Unless GM is developing a new RWD 5.3L V8, the only 5.3L V8s in the lineup right now are the Vortec truck engines. They put out between 315-320 HP and 340 lb.ft. of torque.

He could be talking about the LS4, which I have in the Impala, but as far as I know, it's a FWD only engine. Besides, the DI 3.6 makes more power (though mine sounds better :D), so why would you want an LS4? A 400hp 5.3 would be fun, but I suspect that's not what it's going to be. ;)

Gen Vs will either debut in a Cadillac truck or the Corvette.

That would be cool.. probably won't happen out of the gate. But I'd have no problem driving a 400hp 5.3l Camaro if it got a few more mpg's...

Nope.

The LNF 2.0L turbo DI engine was mentioned in passing by Bob Lutz as a possibility if CAFE causes a problem for the Camaro. It's not even remotely close to "already done".

The LS3 will be the "base" V8. The Gen V DI motors aren't quite yet ready to be released.

When he said, "already done", I think he was referring to the motor being already done on other GM cars.

He could be talking about the LS4, which I have in the Impala, but as far as I know, it's a FWD only engine. Besides, the DI 3.6 makes more power (though mine sounds better :D), so why would you want an LS4? A 400hp 5.3 would be fun, but I suspect that's not what it's going to be. ;)

The LS4 is a FWD only engine. If it were put into a RWD application, the throttle body would be facing the firewall.

The LS4 is a FWD only engine. If it were put into a RWD application, the throttle body would be facing the firewall.

I know, that's why I said as far as I know, it was a FWD engine only.

I know, that's why I said as far as I know, it was a FWD engine only.

It would be possible to put the LS4 into a RWD application if a new intake manifold were made.

However, I don't think there's any point to putting the LS4 into the Camaro.

Nope.

The LNF 2.0L turbo DI engine was mentioned in passing by Bob Lutz as a possibility if CAFE causes a problem for the Camaro. It's not even remotely close to "already done".

The LS3 will be the "base" V8. The Gen V DI motors aren't quite yet ready to be released.

you have zero credible sources.

It would be possible to put the LS4 into a RWD application if a new intake manifold were made.

However, I don't think there's any point to putting the LS4 into the Camaro.
The LS4 has the horsepower, but does it have the torque to move a Camaro?

You're looking at ~1000 pounds difference.

The LS4 is a FWD only engine. If it were put into a RWD application, the throttle body would be facing the firewall.

Which would be ideal for a functional cowl induction hood:alert:

The LS4 has the horsepower, but does it have the torque to move a Camaro?

You're looking at ~1000 pounds difference.

323lb/ft for the LS4, 276lb/ft for the 3.6 DI V6.

Which would be ideal for a functional cowl induction hood:alert:

You're on to something there.

Wouldn't the transmission mounts be different too?

The LS4 has the horsepower, but does it have the torque to move a Camaro?

You're looking at ~1000 pounds difference.

1000 pounds difference from the Impala SS? :confused:

Other forms of the 5.3L are in trucks and they have plenty of torque. The one in my truck didn't have a problem towing my 96 Impala SS. Add direct injection (and maybe increase the compression ratio) and a 6 speed auto and you won't have to worry about low end.


I've been hoping that GM would release new engines in the Camaro. I made a thread about that a long time ago...

and I'm pretty sure that the intake manifold on an LSx will fit no matter which way the TB is facing.

I've been hoping that GM would release new engines in the Camaro. I made a thread about that a long time ago...

Thats what Ive been hoping for as well, after all, it is a whole new car.

I would almost bet a years salary the only V8's you see are a base with a LS3 @ 402 hp and the LS8 for the top model .

I would almost bet a years salary the only V8's you see are a base with a LS3 @ 402 hp and the LS8 for the top model .


Id be very happy with that.
That being said, I hope there is alot more they are not telling us.
In that thread where those mules were spotted in the hotel parking lot, there was a Lumina with the Camaro drivetrain. It had all that equipment on the hood that supposedly monitored individual cylinder activity. At least thats what they told the guy that took the pics.
If they were just throwing an LS3 in there, you wouldnt think they would need to get that in depth in the development right? Or maybe thats what they always do, I have no idea, just some wishful thinking I guess.

I would almost bet a years salary the only V8's you see are a base with a LS3 @ 402 hp and the LS8 for the top model .

I'd take that bet, what a years salary for you?;)

you have zero credible sources.

Really?

Have any of the credible sources on this site ever mentioned a Gen V 5.3L DI V8 as a possibility for the Camaro? No. Have they even hinted at it? No.

And as for the turbo 2.0L going into the Camaro, I direct you here:
http://www.camaroz28.com/forums/showthread.php?p=5257154#post5257154

That's a credible source if I ever saw one.

The Gen V engines are going to be introduced on the C7.

The Camaro will receive the Gen V engines after the C7.

We think the LS9 technology is incredible, just wait for the Gen V C7.

Yeah the Gen V has technology they got from the Roswell spaceship.

The Gen V engines are going to be introduced on the C7.

The Camaro will receive the Gen V engines after the C7.

We think the LS9 technology is incredible, just wait for the Gen V C7.

Yeah, the Gen V and C7 should be out about the same time. If the C7 gets delayed, the Gen V is still coming. I'm not sure if all smallblocks will switch over all at once, or if they'll roll it out over a period of time.

Anyways, by '11 they'll be in trucks.

IMO, the more GM can do to come out with as many new components on this car the better. I think a potential buyer would find a vehicle with fresh/new engines and chassis more appealing than a recycled car (i.e. Challenger.) If they can introduce at least an LS3 as a base V8, I think that would be great. It sounds like a D.I. V8 isn't going to be ready for a couple more years, so the "fresher" the introductory car is, the better.

1000 pounds difference from the Impala SS? :confused:

Other forms of the 5.3L are in trucks and they have plenty of torque. The one in my truck didn't have a problem towing my 96 Impala SS. Add direct injection (and maybe increase the compression ratio) and a 6 speed auto and you won't have to worry about low end.

Sorry- I screwed that post up badly. I was thinking about the turbo 4 in the Cobalt and comparing Cobalt SS curb weight to the (assumed) Camaro.

I was trying to say that I'm not sure the LNF turbo 4 has the torque necessary to move a Camaro and still retain the desired economy.

Talking about the V8 in the Impala, I can't believe there's any point in taking a set up specifically engineered for cetain FWD applications and re-engineering it for RWD use, particularly when there are RWD V8's that already meet the required parameters without re-design.

Sorry- I screwed that post up badly. I was thinking about the turbo 4 in the Cobalt and comparing Cobalt SS curb weight to the (assumed) Camaro.

I was trying to say that I'm not sure the LNF turbo 4 has the torque necessary to move a Camaro and still retain the desired economy.

Talking about the V8 in the Impala, I can't believe there's any point in taking a set up specifically engineered for cetain FWD applications and re-engineering it for RWD use, particularly when there are RWD V8's that already meet the required parameters without re-design.

The LLT has 270 ft/lbs and the LNF has 260 ft/lbs with a much flatter curve.

And can't you get a 5.3 in the (RWD) Silverado? I don't know why GM couldn't build a 5.3 for the Camaro from stuff thats already in the parts bin.

But I don't think GM can build a gen IV 5.3 that is materially better than the DI 3.6 without adding either forced induction or DI & real VVT.

The LLT has 270 ft/lbs and the LNF has 260 ft/lbs with a much flatter curve.

I have trouble believing a turbo four has a flatter torque curve than a N/A 6, but I'm wrong about a lot of things so I'm ready to be wrong about that too.
And can't you get a 5.3 in the (RWD) Silverado? I don't know why GM couldn't build a 5.3 for the Camaro from stuff thats already in the parts bin.
Yeah, which is why asking for the FWD engineered block from the Impala et al. doesn't make sense, IMO.

But I don't think GM can build a gen IV 5.3 that is materially better than the DI 3.6 without adding either forced induction or DI & real VVT.And that's why, IMO, having a 5.3 doesn't make sense.

I used to think it did, but with a 300 horse V6 laying around I can't see a business case for that, a mid 300 5.3, and a 400 horse 6.something V8.

The only thing that really makes sense from a cost and regulation perspective is some variation of the DI V6 and some variation of the LS3.

But again, I'm very ready to be wrong about both of those.

The SSR had an aluminum 5.3, as did the Trailblazer/Envoy.
Im not sure if the newer 5.3s are Iron or aluminum.


Either way, I hope/dont think theyll put a 5.3 in there.

Got to thinking about Scott saying that we're in for some big surprises.

The biggest surprise I believe, will be what the BASE V8 will be.

From the get-go, I believed that the Camaro, was going to be the showcase vehicle, for the next generation of V8 engines.

The design goal will probaby be a BASE V8 with 100HP more, than the BASE V6.

With a 2.0L 260HP I4 , & a 3.6L 304HP V6 already done.
The time for the DI V8 is here now.

With everyone knowing that it won't be the LS2 , & thinking that it will be the LS3, I think that we'll be in for a nice surprise...


I think you'll be happy -- but I think you're wrong in your selection of drivetrains!!!!!

(sorry!)

I have trouble believing a turbo four has a flatter torque curve than a N/A 6, but I'm wrong about a lot of things so I'm ready to be wrong about that too.

The LTT has a pretty flat (if lumpy) torque curve, but LNF's torque peaks at 2000 holds that "peak" to about 5300. I suspect that it is being limited by the ECM. The twin turbo DI V6 in the BMW 335 has a similar curve so it may be the nature of the beast.

http://media.gm.com/us/powertrain/en/product_services/2008/HPT%20Library/Ecotec/2008%20LNF/2008_20L_LNF_Solstice.pdf

GM Media has a nice page full of engine data here: http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm

And as long as we a rooting around in the parts bin, I’ll take my Camaro with the LC3 from the XLR-V and CTS-V please. It uses 4.4 liters, DOHC, VVT and a roots blower to produce 443hp and 414 ft/lbs. :burnout:

http://media.gm.com/us/powertrain/en/product_services/2008/HPT%20Library/Premium%20V/2008_44L_LC3_XLRV.pdf

And as long as we a rooting around in the parts bin, I’ll take my Camaro with the LC3 from the XLR-V and CTS-V please. It uses 4.4 liters, DOHC, VVT and a roots blower to produce 443hp and 414 ft/lbs. :burnout:

http://media.gm.com/us/powertrain/en/product_services/2008/HPT%20Library/Premium%20V/2008_44L_LC3_XLRV.pdf

Why not just add direct injection and VVT and AFM to the LS3? You'll make the same or more power and torque with less weight while getting better fuel economy.

Why not just add direct injection and VVT and AFM to the LS3? You'll make the same or more power and torque with less weight while getting better fuel economy.

Why? Why money of course. Adding DI and/or VVT to the LS3 would require redesigning the (new) heads on an engine that only has a few years to live anyway. I'm sure that work is going on, but it is for the Gen V small blocks.

I think an LC3 would require far less development money and time since it is already in use.

The fact that the LC3 is only 4.4 liters means that everything should be smaller than it would be for the 6.2 liter LS3 and it could well weigh less than the LS3 even though it has 3 extra cams, 16 extra valves and a blower. Likewise the it should enjoy less friction which should allow it to be a little more efficeint.

FYI: I say that a VVT LS3 would need new heads because there are two kinds of VVT systems: the ones that suck and the ones that require twin cams.

Can I get a 454 w/blower from the factory. I promise I won't complain about the body/interior. ;)

Why? Why money of course. Adding DI and/or VVT to the LS3 would require redesigning the (new) heads on an engine that only has a few years to live anyway. I'm sure that work is going on, but it is for the Gen V small blocks.

I think an LC3 would require far less development money and time since it is already in use.

The fact that the LC3 is only 4.4 liters means that everything should be smaller than it would be for the 6.2 liter LS3 and it could well weigh less than the LS3 even though it has 3 extra cams, 16 extra valves and a blower. Likewise the it should enjoy less friction which should allow it to be a little more efficeint.

FYI: I say that a VVT LS3 would need new heads because there are two kinds of VVT systems: the ones that suck and the ones that require twin cams.

The LC3 is a Northstar with an intercooled supercharger on top. Physically it is larger than a naturally aspirated LSx. It is comparable in size to the DOHC Ford Modular Motor. Do a search and you'll find all kinds of info and comparisons in size between the LSx stuff and the DOHC engines. The LC3 does NOT weigh less than the LS3. The smaller displacement is offset by much larger cylinder heads.

Any friction reduction from the smaller displacement would likely be offset by the drag of the supercharger and the additional valvetrain components.

Variable Valve Timing is already being used on production Gen 4 Small Block Chevy engines. Nothing new needed there.
Active Fuel Management is already being used on production Gen 4 Small Block Chevy. Nothing new needed there.
Gasoline Direct Injection is currently not in production, but prototypes have been reported. This needs to be introduced ASAP anyway.

The money spent on developing these would pay off in the long run since all future GM gasoline engines should use them to anyway.

Plus why would Cadillac want to give up their most premium engine that are going into very few vehicles? It is an expensive engine to produce. Each one is hand built using premium components. The LS3 is a mass produced engine in comparison.

I'm kinda wondering why you didn't include the LC3 that goes in the STS-V? In that car it makes even more power and torque (469hp/439tq) :confused:

Why? Why money of course. Adding DI and/or VVT to the LS3 would require redesigning the (new) heads on an engine that only has a few years to live anyway. I'm sure that work is going on, but it is for the Gen V small blocks.

I think an LC3 would require far less development money and time since it is already in use.

The fact that the LC3 is only 4.4 liters means that everything should be smaller than it would be for the 6.2 liter LS3 and it could well weigh less than the LS3 even though it has 3 extra cams, 16 extra valves and a blower. Likewise the it should enjoy less friction which should allow it to be a little more efficeint.

FYI: I say that a VVT LS3 would need new heads because there are two kinds of VVT systems: the ones that suck and the ones that require twin cams.

Sorry, but it's kind of hard to take a name like Grape Ape seriously. I remember it from Saturday mornings many years ago.

The supercharged northstar is heavy, swallows a lot of fuel, and has only a little more power than an LS3. It's nearly obsolete. The ultra V8 would have brought the GM quad cam V8 up to date, but it's on the shelf, likely never to see the light of day.

The Gen IV smallblock does more with less than the Northstar.

If the STS-V had an LS3, it would probably be 200 pounds lighter, and very close in straight-line performance.

I see in the newspaper ads this weekend that 2008 STS-V's are available at $10000 off MSRP.

Sorry, but it's kind of hard to take a name like Grape Ape seriously. I remember it from Saturday mornings many years ago.

I don't know. I've found this to be a good website... http://www.grapeaperacing.com/

I don't know. I've found this to be a good website... http://www.grapeaperacing.com/

http://en.wikipedia.org/wiki/Grape_Ape

I remember the cartoon...

I remember the cartoon...

I had put it out of my mind until I saw a post from "Grape Ape"

:(

The LC3 is a Northstar with an intercooled supercharger on top. Physically it is larger than a naturally aspirated LSx. It is comparable in size to the DOHC Ford Modular Motor. Do a search and you'll find all kinds of info and comparisons in size between the LSx stuff and the DOHC engines. The LC3 does NOT weigh less than the LS3. The smaller displacement is offset by much larger cylinder heads.
The heads are certainly taller, but they shouldn’t be as long or wide as an LS3 head. Likewise the block shouldn’t be as long as the LS3’s due to the narrower bores, which would shift some weight rearward.

If the LC3 really is bigger and heavier than the LS3 (I’m too lazy to look it up) then someone needs a pat on the back (at Chev) and/or a dope slap (at Cadi).

Any friction reduction from the smaller displacement would likely be offset by the drag of the supercharger and the additional valvetrain components.

Hard to say.

Variable Valve Timing is already being used on production Gen 4 Small Block Chevy engines. Nothing new needed there.

VVT fall into two groups: VVT that requires two cams and VVT that sucks. The small block only has one cam.

Varying the timing of a single cam can widen you torque curve a little, but cannot add anything to the peak. Changing intake and exhaust timing independently allows high RPM overlap which can add power but would cause the engine to fail emissions & NVH standards at idle.

Active Fuel Management is already being used on production Gen 4 Small Block Chevy. Nothing new needed there.

But as implemented in the G8 GT's L76 it limits valve lift and eats at least 38 HP (vs the LS2, even though the L76 has better heads). I'd say something is needed.


Gasoline Direct Injection is currently not in production, but prototypes have been reported. This needs to be introduced ASAP anyway.

The money spent on developing these would pay off in the long run since all future GM gasoline engines should use them to anyway.

There is no long run for the LS3 or any of it's siblings unless the Gen V small block is farther off that we are being led to believe.


Plus why would Cadillac want to give up their most premium engine that are going into very few vehicles? It is an expensive engine to produce. Each one is hand built using premium components. The LS3 is a mass produced engine in comparison.

I'm kinda wondering why you didn't include the LC3 that goes in the STS-V? In that car it makes even more power and torque (469hp/439tq) :confused:

I suspect that the LC3s are hand built largely because of the low volume, after all the LNF comes off an assembly line but still gets even better HP & torque per liter. But I’m not seriously suggesting that the Camaro will get a Northstar V8, I’m just playing along with the “what might GM dig out of the parts bin” game.

I also think it would be a bad choice because a small displacement V8 wouldn’t have the deep rumble everyone seems to want.

well, if we're playing the "what if" game, what if they were to merge two Ecotecs with a common crankshaft? You could get a naturally aspirated 350hp 4.8L V8 or a twin turbo 520hp 4.0L V8. Is the Astra's 1.8L an Ecotec? If so, then there is a 275hp 3.6L V8 :)

well, if we're playing the "what if" game, what if they were to merge two Ecotecs with a common crankshaft? You could get a naturally aspirated 350hp 4.8L V8 or a twin turbo 520hp 4.0L V8. Is the Astra's 1.8L an Ecotec? If so, then there is a 275hp 3.6L V8 :)

Too much trouble. Just use the transverse version of the LNF. One in the front and one in the back. That way you also get AWD & AFM (just turn off one engine).:D

...
VVT fall into two groups: VVT that requires two cams and VVT that sucks. The small block only has one cam.

...

But as implemented in the G8 GT's L76 it limits valve lift and eats at least 38 HP (vs the LS2, even though the L76 has better heads). I'd say something is needed.I don't completely agree with your thoughts on VVT, but I mostly want to comment on your observations about the L76 versus the LS2. AFM does not eat 38 HP. The L76 is rated on 87 octane gasoline whereas the LS2 is rated on premium. While the heads, essentially heads off the L92 revised for the smaller bore, seem superior than those on the LS2, they are not hand finished. Compression ratio is slightly less than the LS2. Additionally, although the displacements are the same the L76 has a smaller bore and longer stroke. Cam is smaller, weaker valve springs, and so it also has a lower rev limiter than the LS2. It isn't as if the L76 was just an LS2 with better heads + AFM/VVT.

FWIW with tuning for premium octane fuel you can get the L76 up to ~400HP.

I don't completely agree with your thoughts on VVT, but I mostly want to comment on your observations about the L76 versus the LS2. AFM does not eat 38 HP. The L76 is rated on 87 octane gasoline whereas the LS2 is rated on premium. While the heads, essentially heads off the L92 revised for the smaller bore, seem superior than those on the LS2, they are not hand finished. Compression ratio is slightly less than the LS2. Additionally, although the displacements are the same the L76 has a smaller bore and longer stroke. Cam is smaller, weaker valve springs, and so it also has a lower rev limiter than the LS2. It isn't as if the L76 was just an LS2 with better heads + AFM/VVT.

FWIW with tuning for premium octane fuel you can get the L76 up to ~400HP.


The LS2 was never SAE rated either. In road tests, the G8 isn't that far behind the LS2 GTO, even though most examples tested are about 300 pounds heavier, and the GTOs were mostly 6Ms.

I don't completely agree with your thoughts on VVT, but I mostly want to comment on your observations about the L76 versus the LS2. AFM does not eat 38 HP. The L76 is rated on 87 octane gasoline whereas the LS2 is rated on premium. While the heads, essentially heads off the L92 revised for the smaller bore, seem superior than those on the LS2, they are not hand finished. Compression ratio is slightly less than the LS2. Additionally, although the displacements are the same the L76 has a smaller bore and longer stroke. Cam is smaller, weaker valve springs, and so it also has a lower rev limiter than the LS2. It isn't as if the L76 was just an LS2 with better heads + AFM/VVT.

FWIW with tuning for premium octane fuel you can get the L76 up to ~400HP.

I find it hard to believe that GM would design a new 6.0 block (and redesign a bunch associated parts) when they have the LS2 block design sitting around. So I checked and GM media says they are both 101.6 x 92mm. GM media also says that premium is recommended for both.

http://media.gm.com/us/powertrain/en/product_services/2007/07car.htm
http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm

I have not been following the G8 too closely, but I thought the best tune result I’d seen was around 385 (est flywheel) hp. I know everyone seems to expect a tuned L76 to produce 400hp on premium, but I don’t think the stock cam is up to it.

It is my understanding that the size of the cam is limited by the amount of lift that the deact lifters can absorb when AFM is active and that the lobes for the AFM cylinders are smaller than the other lobes for the other four cylinders. So I reiterate that as implemented on the G8's L76, AFM eats a heard of horses.

BTW: I don’t believe that the G8’s L76 has VVT.

I find it hard to believe that GM would design a new 6.0 block (and redesign a bunch associated parts) when they have the LS2 block design sitting around. So I checked and GM media says they are both 101.6 x 92mm. GM media also says that premium is recommended for both.

http://media.gm.com/us/powertrain/en/product_services/2007/07car.htm
http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm

I have not been following the G8 too closely, but I thought the best tune result I’d seen was around 385 (est flywheel) hp. I know everyone seems to expect a tuned L76 to produce 400hp on premium, but I don’t think the stock cam is up to it.

It is my understanding that the size of the cam is limited by the amount of lift that the deact lifters can absorb when AFM is active and that the lobes for the AFM cylinders are smaller than the other lobes for the other four cylinders. So I reiterate that as implemented on the G8's L76, AFM eats a heard of horses.

BTW: I don’t believe that the G8’s L76 has VVT.

No it doesn't have VVT.

Interesting hypothesis. The Honda 3.5 V6 is rated the same with or without AFM. But the non-AFM versions are much faster in the 1/4 -- more than could be explained by 5A vs 6M.

Still, we don't really know the HP difference between LS2 and L76, do we? AFAIK, no LS2 has been SAE rated. Also, the L76 is based on the L98, which only has a couple more HP than the L76.

Btw, everyone is trying to figure out premium versus regular on the L76. The change from regular to premium was made late last year.

No it doesn't have VVT.

Interesting hypothesis. The Honda 3.5 V6 is rated the same with or without AFM. But the non-AFM versions are much faster in the 1/4 -- more than could be explained by 5A vs 6M.

Still, we don't really know the HP difference between LS2 and L76, do we? AFAIK, no LS2 has been SAE rated. Also, the L76 is based on the L98, which only has a couple more HP than the L76.

Btw, everyone is trying to figure out premium versus regular on the L76. The change from regular to premium was made late last year.

I have no idea how Honda implemented AFM on it's 3.5. I would think that an AFM engine could have the same cam as its non-AFM version if it was designed for AFM (like the Gen V small block I hope).

The Honda could have valve train inertia issues that give it a lower red line or cause the power to fall of peak faster. Or the AFM gear could limit the effect of the VVT gear giving the AFM motor the same peak numbers on a narrower curve. Either one would lead me to expect lower 1/4 miles times. Or the M6 could just have better gear ratios.:shrug:

The big question is what is a honda doing on a drag strip?:D

The big question is what is a honda doing on a drag strip?:D

IIRC, about 14.1 for the non-AFM and 15.2 for the AFM. :D

Tests of Acura TLs with and without auto have nothing like that kind of difference.

I find it hard to believe that GM would design a new 6.0 block (and redesign a bunch associated parts) when they have the LS2 block design sitting around. So I checked and GM media says they are both 101.6 x 92mm. GM media also says that premium is recommended for both.

http://media.gm.com/us/powertrain/en/product_services/2007/07car.htm
http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm

I have not been following the G8 too closely, but I thought the best tune result I’d seen was around 385 (est flywheel) hp. I know everyone seems to expect a tuned L76 to produce 400hp on premium, but I don’t think the stock cam is up to it.

It is my understanding that the size of the cam is limited by the amount of lift that the deact lifters can absorb when AFM is active and that the lobes for the AFM cylinders are smaller than the other lobes for the other four cylinders. So I reiterate that as implemented on the G8's L76, AFM eats a heard of horses.

BTW: I don’t believe that the G8’s L76 has VVT.
Interesting. I was wrong when I said they have different strokes, but the bores are different... LS2 is 101.6 and L76 is 101.3mm and both are 92mm strokes. I don't know why GM's page lists them as having the same bore. We are getting into a debate over semantics though if you believe that the small cam is the reason AFM causes a loss of power in the L76 though. I wouldn't necessarily disagree with that idea, but even so I wouldn't say it was AFM eating the power.

As for the fuel recommendation, I still have read nothing but that the motor is rated and tuned for 362HP on 87 octane but if it was changed recently then I am wrong. The guys in Australia were getting 400HP on the L76s with premium gas, but that might be in part due to the difference in the max octane available. But if they do make a conservative 385HP on premium that would be a loss due to every single change compared to the LS2 of -15HP which is a far cry from the 40HP from AFM that started off this whole discussion.

As for the fuel recommendation, I still have read nothing but that the motor is rated and tuned for 362HP on 87 octane but if it was changed recently then I am wrong. The guys in Australia were getting 400HP on the L76s with premium gas, but that might be in part due to the difference in the max octane available. But if they do make a conservative 385HP on premium that would be a loss due to every single change compared to the LS2 of -15HP which is a far cry from the 40HP from AFM that started off this whole discussion.

Looking at the 1/4 mile times of the G8 with A6 and comparing to the 1/4 times of the GTO with M6 and 250-300 pounds less weight, I think 15hp is probably much closer to the real difference.

Remember too that the LS2 was never SAE rated.

Interesting. I was wrong when I said they have different strokes, but the bores are different... LS2 is 101.6 and L76 is 101.3mm and both are 92mm strokes. I don't know why GM's page lists them as having the same bore. We are getting into a debate over semantics though if you believe that the small cam is the reason AFM causes a loss of power in the L76 though. I wouldn't necessarily disagree with that idea, but even so I wouldn't say it was AFM eating the power.

0.3mm is the next best thing to zero.

Since we both agree that the small cam is holding the L76 back, the question is why is it there?

I guess GM could have decided that it needed more room between the G8 GT and the G8 GXP (and the corresponding Holdens). I’ve been wondering why GM didn’t change the rocker ratio to maintain LS2 level valve lift with the smaller AFM cam, and that would be a pretty good answer. That and the fact that they don’t need to spend the extra cash, since the G8 GT is still considerably faster than a Charger R/T.

0.3mm is the next best thing to zero.

Since we both agree that the small cam is holding the L76 back, the question is why is it there?

I guess GM could have decided that it needed more room between the G8 GT and the G8 GXP (and the corresponding Holdens). I’ve been wondering why GM didn’t change the rocker ratio to maintain LS2 level valve lift with the smaller AFM cam, and that would be a pretty good answer. That and the fact that they don’t need to spend the extra cash, since the G8 GT is still considerably faster than a Charger R/T.

the small cam probably works better with the cylinder deactivation.

3.6 < 6.2 < 6.2 S/c

why don't you nerdz wait till it comes out

BTW the last post was sarcasm...anyways I want a 4.8 DI in a stripped down model. 295 HP 305 LB/FT would be pretty sweet if it weighs about the same as a 4TH gen.

BTW the last post was sarcasm...anyways I want a 4.8 DI in a stripped down model. 295 HP 305 LB/FT would be pretty sweet if it weighs about the same as a 4TH gen.it won't.

A DI 327 (I'm assuming that's the CI of the 5.3 anyway) would actually be pretty sweet. It wouldn't eat gas quite as much as the Ls3, would have the muscle car sound to it. And if this guy's calculations are right, it would kick out around the same power as the Ls2 on the concept Camaro.

a high compression direct injection 4.8L with AFM and VVT would do too well on fuel economy...

a high compression direct injection 4.8L with AFM and VVT would do too well on fuel economy...
?! :confused: ?! It would be too good on gas??? :think: Or did you mean it would NOT be good on gas?? :shrug:

Before we found out about the ~300 HP 3.6L V6, a small displacement V8 seemed to make sense. Now that we (think) know we're getting a 300 HP V6, I don't think a small/low HP V8 is really necessary. So there will just be a ~100+ HP gap between the V6 and the V8 :D (and ~100+ HP again from the "base" V8 to the "uber" V8 ;)).

?! :confused: ?! It would be too good on gas??? :think: Or did you mean it would NOT be good on gas?? :shrug:

Before we found out about the ~300 HP 3.6L V6, a small displacement V8 seemed to make sense. Now that we (think) know we're getting a 300 HP V6, I don't think a small/low HP V8 is really necessary. So there will just be a ~100+ HP gap between the V6 and the V8 :D (and ~100+ HP again from the "base" V8 to the "uber" V8 ;)).

I was being sarcastic. A small displacement, very efficient, high torque, highly responsive V8, etc would just make too much sense for GM to produce... The 4.8L V8 is already SAE Certified to 295hp/305tq with only a 9.1:1 compression ratio. Direct injection and variable valve timing would allow the compression ratio to go over 11:1 which could give another 50horsepower up top and probably another 30ft-lbs down low.

And with the ZR1 going into production, there is more than a 300horsepower gap between GM's base V8 and the "uber" V8 ;)

I was being sarcastic. A small displacement, very efficient, high torque, highly responsive V8, etc would just make too much sense for GM to produce...
Gotcha!!! ;) I was confused!!! :lol: (now I understand ..... why do something that would MAKE SENSE ;)).

I was being sarcastic. A small displacement, very efficient, high torque, highly responsive V8, etc would just make too much sense for GM to produce... The 4.8L V8 is already SAE Certified to 295hp/305tq with only a 9.1:1 compression ratio. Direct injection and variable valve timing would allow the compression ratio to go over 11:1 which could give another 50horsepower up top and probably another 30ft-lbs down low.


What do you think the fuel economy difference would be between a 4.8l and a 6.2l V8?

To me, it's illuminating that when GM went for maximum fuel economy with the hybrid Tahoe, they actually installed a 6.0l engine (running the Atkinson cycle IIRC).

What do you think the fuel economy difference would be between a 4.8l and a 6.2l V8?

To me, it's illuminating that when GM went for maximum fuel economy with the hybrid Tahoe, they actually installed a 6.0l engine (running the Atkinson cycle IIRC).

I think that the reasons that the 6.0 was used probably include:


Retaining a descent tow rating after adding 400 lbs, because otherwise why not buy a minivan or mid sized SUV?

The Atkinson Cycle gives you fuel efficiency at the expense of low end torque.

A smaller V8 might have lacked the guts to push the Tahoe hybrid (almost 3 tons) around in 4 cylinder mode.

What do you think the fuel economy difference would be between a 4.8l and a 6.2l V8?

More than the difference that put a big hold on the RWD Impala program...

I think that the reasons that the 6.0 was used probably include:


Retaining a descent tow rating after adding 400 lbs, because otherwise why not buy a minivan or mid sized SUV?

The Atkinson Cycle gives you fuel efficiency at the expense of low end torque.

A smaller V8 might have lacked the guts to push the Tahoe hybrid (almost 3 tons) around in 4 cylinder mode.


That ALL makes a BUNCH of sense.

More than the difference that put a big hold on the RWD Impala program...

Which is?

according to Bob Lutz, the difference between FWD and RWD is 1 MPG.

I know that the 4.8L doesn't get very good mileage, especially compared to the larger engines. However, the 4.8L is only available in heavy trucks and SUVs. The 4.3L V6 and the 5.3L are the mileage leaders of the GM trucks now.

Personally, I see some flaws in the 4.8L compared to the other engines. The specific output for the 4.8L is right on par with the larger engines despite a lower compression ratio. In order to do this, it has to turn higher RPM. Generally higher RPM needs higher compression ratio to work well. If the 4.8L were to get the 5.3L aluminum block, higher compression ratio, and AFM, then I don't doubt that it could get better fuel economy. How much? It's really hard to tell. How much did the fuel economy numbers increase for the iron block, non-AFM LM7 to the current LY5? That is also hard to say because there have been several other fuel economy achievements built into the trucks.

according to Bob Lutz, the difference between FWD and RWD is 1 MPG.

I know that the 4.8L doesn't get very good mileage, especially compared to the larger engines. However, the 4.8L is only available in heavy trucks and SUVs. The 4.3L V6 and the 5.3L are the mileage leaders of the GM trucks now.

Personally, I see some flaws in the 4.8L compared to the other engines. The specific output for the 4.8L is right on par with the larger engines despite a lower compression ratio. In order to do this, it has to turn higher RPM. Generally higher RPM needs higher compression ratio to work well. If the 4.8L were to get the 5.3L aluminum block, higher compression ratio, and AFM, then I don't doubt that it could get better fuel economy. How much? It's really hard to tell. How much did the fuel economy numbers increase for the iron block, non-AFM LM7 to the current LY5? That is also hard to say because there have been several other fuel economy achievements built into the trucks.

Right. We really don't know how much it would improve.

So when you talk about how much sense it would make to produce a 4.8, you really are just guessing.

My observation is that merely reducing bore and stroke seems to make a minimal increase in mileage, while cutting power significantly. You'd have to fully optimize the engine for the new displacement, and that would be expensive, as it would essentially be a new engine.

Then explain to me why smaller engines are used at all? Why not use the largest engine you can physically fit into a vehicle?

Then explain to me why smaller engines are used at all? Why not use the largest engine you can physically fit into a vehicle?

Reread what I wrote. If you optimize the engine for the displacement, then you can see the gains you're looking for. One of the best ways to do that is to decrease cylinder count.

Given that, why offer two displacements on the same engine? Marketing.

Still, the reason that Mercedes, for example, offered the C250, C280, and C350 when all got about the same mileage was so that they could charge extra for the top model. It's the same story with the BMW 325i and 330i (from 2001 to 2006 in the U.S.). Note that with the current gen 3-series, the 325i and 330i both had 3 liter engines.

One of the big gains previously in efficiency with smaller cylinders (and the same count) was larger throttle openings, reducing pumping losses. But with technologies like GDI and valvetronic (BMW's name, but Audi and Infiniti have similar systems), pumping losses at small throttle openings are already greatly reduced.

Got to thinking about Scott saying that we're in for some big surprises.

The biggest surprise I believe, will be what the BASE V8 will be.

From the get-go, I believed that the Camaro, was going to be the showcase vehicle, for the next generation of V8 engines.

The design goal will probaby be a BASE V8 with 100HP more, than the BASE V6.

With a 2.0L 260HP I4 , & a 3.6L 304HP V6 already done.
The time for the DI V8 is here now.

With everyone knowing that it won't be the LS2 , & thinking that it will be the LS3, I think that we'll be in for a nice surprise...
the showcase vehicle will always be the corvette

no 5.3. get with the times doods.

we are getting with the times of people wanting more fuel friendly vehicles.

we are getting with the times of people wanting more fuel friendly vehicles.

LS/LT with 300hp di 3.6

yeah, but wouldn't you rather have a V8 that uses some more of the tricks that the V6 uses to get better mileage? Direct injection and variable valve timing are both standard on the V6 Camaro, but lacking in the V8. I wonder what kind of highway mileage the DI 3.6L V6 would get if AFM were added?

yeah, but wouldn't you rather have a V8 that uses some more of the tricks that the V6 uses to get better mileage? Direct injection and variable valve timing are both standard on the V6 Camaro, but lacking in the V8. I wonder what kind of highway mileage the DI 3.6L V6 would get if AFM were added?

Well there's lots of stuff I'd rather have (not just talking about Camaro here ;)).

With DI, there isn't as much to gain from AFM, due to already-reduced throttling losses. Plus the V6 would have to operate in 6 cyl mode more often.

I think that AFM is kind of a dead end -- easier than putting in DI, but ultimately will be replaced by DI.


I'm happy with the Camaro powertrains, and I won't miss not having a 330hp 5.3. I wouldn't have bought one of those anyway.

Actually, I'm kind of hoping the 2010 G8 ends up with the L99 too.