95jersey

I was sent this article by an automotive engineer I recently made friends with. Take it for what it's worth...


With so much incorrect information out there about GM's future LS motors, we though it would be a good time to query our sources and get the real deal. From the Cadillac CTS-V to the Corvette ZR1, we take a look at the LSA, LS7,LS8, LST, and LS9.

LS7

This is, of course, the current 7.0-liter, naturally aspirated motor in the Z06. It's handbuilt at GM's Wixom performance center and is very expensive to make. Too expensive with the LS9 motor coming. While there will be several
months where the LS7 and LS9 will be built at Wixom, the LS7 will eventually die, probably sometime between late-2009 or mid-2010.

Several publications have repeatedly insisted the new CTS-V will be powered by the LS7, but this is completely false. GM cannot spend engineering dollars on a CTS-V to start with the LS7, then 12 to 18 months later, switch motors
after the LS7 is discontinued. Rather, the super Caddy will feature an all-new powerplant.

LSA

The LSA will find its way under the hood of the 2009 Cadillac CTS-V. The LSA is a 6.2-liter, smallblock V8 with a supercharger. It features an intercooler integrated into the intake manifold.

Preliminary specs have it over 500 horsepower with a choice of manual or automatic transmissions. The CTS-V will start production in September of 2008 with this motor. Look for around 6000 to 8000 units annually.

Original plans also had the LSA going into an Escalade V-series truck. However justifying the development cost - not to mention CAFE considerations - might put possibility of such a truck in jeporady. At present, it is unclear whether the Escalade-V a truck is still part of the plan.

LS8

This is another 6.2-liter, smallblock V8 with a supercharger. It also features an intercooler integrated into the intake manifold. This will be the motor going into the top-end Zeta platform cars. The most premium Camaro,
probably called Z28, will get this motor.

That said, original plans had this motor going into a Denali SUV or truck, however, those plans now seem to be canceled. Again, this maybe a result of CAFE.

Some of Holden's vehicles may also get this motor eventually. Initial specs have this motor at 475 to 500 horsepower with a choice of manual or automatic transmissions.

When the LS7 dies, the Z06 will get this motor. Possibly, slightly uptuned from the version the Zeta cars would get. This motor will start production in first or second quarter of 2010.

LST

Yet another 6.2-liter, smallblock V8 with a supercharger. It also features an intercooler integrated into the intake manifold. This motor may or may not still be in GM's plans. The original plan was to put it in GM's Heavy Duty
trucks.

Delivering in excess of 450 pound-feet of torque, it was set to start in the middle of 2008. However, it now seems this motor may no longer be part of the plan. GM may have decided its diesel offerings were sufficient. It's also
possible GM had a hard time justifying the cost of development. Of course, CAFE might have also played a role.

LS9

This is the 6.2-liter, smallblock V8 with a supercharger going into the ZR-1 Corvette. Like all the others, it has an intercooler integrated into the intake manifold. Original specs had this motor at 600 horsepower and 550 to
560 pound-feet of torque. It now seems the horsepower rating may have jumped to as much as 650.

If that's true, it would probably be safe to estimate a similar jump in torque to around 600 ft lbs. Sources have stated the LS9 can make 700hp on a test stand. Obviously though, that is without a car attached to the motor.
Don't look for any production hp number starting with "seven."

It now appears an auto/paddle shift may also be an option on the ZR-1. This motor will be handbuilt at GM's Wixom performance center. They will only make 1500 to 2000 units a year. Production of the ZR-1 starts in July of 2008.

So this is some interesting stuff. I am not totally sure about the source, but I can read through the logic. According to this article, it sounds like the future for GM performance is supercharging whether you like it or not.

So, will the current Z06, be the last GM production car (or ANY car) to have a big block? Wonder if this could help collectors or resale down the line?

John Shiels

with 100 per barrel approaching fast it will all be a moot point soon. This was posted in another section so the guy must be telling everyone. Who is he exactly or what postion does he hold?

Timz06

Hope supercharging is not the future. I'd take an ls7 over a supercharged motor any day!

95jersey

Works for a private firm that supplies GM. I highly doubt the guy who passed it along to me is the original source.

Cobra4B

Odd... for years GM fans knock Fords for "having" to use a supercharger to make power. Now look.

RogueVette

I hope they are forged and I hope they don't weigh as much as the Ford engines. Not sure how they can make that happen.

yakisoba

I wonder how much this has to do with ethanol fuels? Does ethanol run cooler than straight gasoline? Would that not facilitate FI because of cooler intake temps?

xsiveone

I think that GM maxed out with the LS7 for a NA, pushrod V8, small block. I remember hearing that the engineers were squeezing out just about everything that they could get out of the engine before production. They were trying to reach 500 tq as well as the 500 hp and didn't quite get there.

The only other option that they have at this point is to go with a bigger displacement, go with a DOHC like on the original ZR-1 or go with forced induction. I'd like to see them go with DOHC and multi-valve again personally. They might be able to get another 100hp out of the LS7 if they went that route. M-B/AMG is getting 500 hp out of their 6.2L NA motor. BMW is getting over 400 hp out of their 4.0L V8 with multi valves.

RogueVette

If that were the case the aftermarket would not exist. And people would not be getting sick power from the current engines. I don't agree that Multi Valves are the way to go. But I may certainly be in the minority.

95jersey

Not true, I am sure the GM Engineers have way more strict criteria to adhere than an aftermarket tuner with regard to emissions, CAFE, MPG, longevity, pump gas in different parts of the country, efficiency standards, idle quality, and internal politics/costs. As hard as it is for aftermarket to extract more HP, with GM's OWN internal standards and federal regulations/politics, it is probably ten times harder for them to extract the same HP.

Heck, you can get 500hp out of a LS6 no problem, but how much will it cost you and how long will it last and will it get 26MPG.

It's funny when you go aftermarket an intake and aftermarket exhaust easily gets you 30-40hp. But when GM (or an OEM) makes the same HP, the entire motor has all new internals and materials. The increase intake runners and valve sizes and dimensions, and all kind of sh&t, and here we are bolting on an intake and exhaust and getting the same power. There MUST be a good reason why they just don't do the same thing as afermarket.

BrianCunningham

That's what I'm thinking as well.
E85 has 104 octane, so you can really crank up the boost.

Then it has the eco-friendly appeal.

NemesisC5

xsiveone

GM has much stricter regulations to follow than the aftermarket. They have to be concerned about ever increasing regulations on gas mileage, noise and emissions. Plus, the manufacturer's have to worry about longevity and drivability. If I were to put a radical cam in my car, I'd have to live with the lopey idle. I don't know how many people would buy a car for daily use that shakes, doesn't idle right with the A/C on and is a bear to drive in stop and go traffic.

jvp

And under what hood would they put this mythical OHC motor? Certainly not under the hood of the present Corvette, right? Remember: Take a DOHC motor and an OHV motor of the same displacement: the DOHC is going to be externally larger (by a long shot) and much heavier than the OHV motor.

OHC motors aren't the answer for all-out performance. GM learned that lesson in the mid 90s, thankfully, and they haven't looked back since.

jas

DSteck

I thought the LS7 was a small block...

OKsweetrides

They got the supposed LST engine wrong however.
From a much more in-the-know source, that engine is actually the 6.0 supercharged and they've been testing them for a while, and it is still an iron block. Still waiting to see if they'll get the greenlight for that engine, but possibly not because of gas consumption fears.

And I personally think the dohc engine is going to have a different naming scheme, as overall that block will very very different from its cousins

The last production light car/truck to get an actual big block were the HD GMT800 trucks. I know they still have them for industrial apps, but I dont know if the 4500's and 5500's still use them.
The LS7 is entirely a shortblock, it's externally physically no larger nor smaller than the 4.8L V8.


Overall, an interesting read, but a lot of little nitpicking flaws with it.

xsiveone

I didn't see the LT-5 as being such a disaster. That engine still stands on its own for technology that is more than 20 years old now. The thing that killed it IMO was the price. Why was it so expensive? Because it was co-developed with Lotus? Because it was built by Mercury Marine? Because of the low production numbers?

This thread was posted before the Jay Leno C6RS thread. Why can't GM build a 500 ci small block instead of going with FI?

jvp

Perhaps not. However, it has massive external dimensions, and weighs a bit more than the LSx motors do. And, for all its bluster and fanfare, in stock form, it doesn't put out that much power compared to the motors of today.

Can it be updated to put out more power? Sure. Can it do so while still meeting today's emissions standards? Not so sure of that. Can it be built in such a way that it'll fit inside a Corvette? No. It can't.

Because unlike P&M and Katech, GM has other concerns that they need to address. Such as:
- emissions (federal)
- drive-by noise levels (federal)
- fuel efficiency (CAFE and gas guzzler taxes - federal)
- longevity ($$ in replacement, etc)
- Re-use (what else can GM use this engine in?)

Now, before some Katech fanboy jumps down my throat with the "50 states emissions legal" bit, please note: that's only one item of the above list. I'm nearly 100% positive they haven't had to address any of the others.

It's not that easy to just develop, build, and sell a 500cid engine and call it a day. For GM (and any other auto-maker worth their salt) there's a lot more to it.

jas

xsiveone

If you say that a multi-valve engine won't fit in the Corvette, I'll take your word for it.

I think that they could make a multi-valve engine like the LT-5 quite a bit more powerful with todays technology.

As far as the 500 ci engine goes, I don't know why it would be any different than the 427 other than maybe the gas guzzler tax. It's just a bigger displacement engine. Perhaps they could make it a Flex-Fuel engine like the Katech and side step some of the regulations like GM did with their other Flex-Fuel vehicles?

Re-use? Where else do they use the LS7 in GM's line-up?

Drive-by noise? They dealt with it pretty well with the butterfly valve on the C6 Z06.

Longevity? I don't know about that. I had no idea how large they could make a small block. I was thinking that 427 was about the max and apparently, I was wrong.

DSteck

There's only so much bore and stroke you can pull out of a small block before you get into some creative casting solutions to make it work. It's not as simple as just, "add more displacement." There's a lot more to it as jvp pointed out... namely, the cost. Setting up equipment for high quality repeatable castings is not cheap.