old news, D.I. LSx

[Atilla the Fun]

GM Reveals Small-Block V-8 with Direct Injection - wardsauto.com
By Mike Sutton
Aug. 29, 2007
MILFORD, MI – Although General Motors Corp. is dividing its resources to cover all fronts of advanced powertrain development, the future of the auto maker’s foundation OHV small-block V-8 architecture appears secure with the advent of direct-injection gasoline (DIG) technology.

Among the various exhibits of engineering bravado on display at the auto maker’s proving grounds here, including two-mode hybrid-electric drivetrains, ultra-clean turbodiesels and homogeneous charge compression ignition flex-fuel engines, a seemingly untouched Cadillac Escalade stands out.

Emblazoned with giant E85 banners down its flanks, there is little to indicate the industry’s first OHV V-8 with DIG fueling lurks beneath the SUV’s pearl white hood.

The experimental engine is based on GM’s current all-aluminum Gen IV 6.2L V-8 (L92) found in the Escalade, GMC Yukon Denali and Hummer H2. Depending on the application, the powerplant, which sports port fuel injection, variable valve timing (VVT) and dual-cam phasing, is rated between 380-403 hp in stock form.

However, with a little tweaking to accommodate the auto industry’s latest fuel-injection hardware, the prototype V-8 is producing “well north of 450 hp (on gasoline),” says Dave Sczomak, development engineer-GM Powertrain Advanced Engineering.
Running the engine on E85 ethanol allows for even more power to be coaxed from the big V-8, he adds, noting the 85%/15% ethanol/gasoline mix generally carries a race fuel-like 106 octane rating.

Cruising the web of test roads onsite, the Escalade motors along smoothly with a characteristic large-displacement V-8 burble. However, mashing the gas from a standstill produces a wave of power that propels the big truck at a noticeably more rapid pace than the production version.

Along with the substantial increase in horsepower, DIG also contributes to about a 10% increase in low-end torque, Sczomak says. In addition, fuel economy is moderately improved (3-6%), as are cold-start emissions of hydrocarbons.

To accommodate the DIG fueling system, GM redesigned the L92 cylinder heads, rearranging the intake ports to make room for the eight high-pressure injectors that squirt fuel directly into the side of the combustion chamber at 2,250 psi (155 bar).
New dished pistons – similar to a diesel’s – were installed for added clearance of the injectors. They also contribute to a greater compression ratio (11.5:1 vs. 10.5:1), which can be employed because of the high-octane composition of E85 and the knock-reducing cooling effect of introducing fuel directly into the cylinder.

A modified engine controller manages the engine’s operation, while VVT and Active Fuel Management cylinder deactivation contribute to efficiency and refinement.

The development sounds like a no-brainer for improving nearly every aspect of the near-60-year-old small block’s performance.
However, Tom Stephens, group vice president-GM Powertrain and Quality, notes introducing a production DIG small block would “require the next-generation architecture” of the engine, or Gen V.

This primarily is due to the huge volumes of V-8 engines GM produces, Sczomak says, noting a radical change in cylinder-head design, for example, becomes a monumental undertaking when taking into account GM’s annual build of more than 1 million small block V-8s.

Fortunately, timing is on the auto maker’s side. The recent introduction of the ’08 Corvette’s 430-hp LS3 V-8, along with the release later this year of the ’08 Chevrolet Tahoe Hybrid’s 6.0L V-8, represent the last editions of the Gen IV engine family, Stephens says.

All subsequent introductions will be of the Gen V architecture and could have DIG fueling integrated from the ground up, especially considering the refinement of the current test engine’s operation. The greater specific output provided by DIG also would allow for greater engine downsizing, thereby improving fuel economy even further.

“GM would want to introduce this (DIG) on a high-profile vehicle, such as the new (Chevrolet) Camaro or (rear-wheel-drive) Impala,” Global Insight analyst John Wolkonowicz says, referring to the auto maker’s plans for new volume models based on its global RWD platform developed by GM Holden Ltd. in Australia.

The new Camaro, which originally was shown at the 2005 North American International Auto Show in Detroit, is expected to appear later next year as an ’09 model, with the all-new RWD Impala taking form sometime early in the next decade. Revisions for future generations of the Corvette and Chevrolet Silverado/GMC Sierra pickups are expected in the same timeframe, Wolkonowicz says.

By capitalizing on areas of significant improvement that remain untapped in its core engine lineup, while simultaneously amping up the arrival of its new hybrid-electric vehicles, clean diesels and hydrogen fuel cells, GM clearly is betting on an ever-fracturing market for advanced powertrains.

As a result, the iconic grumble of the small-block V-8 appears poised to remain a fixture of the automotive landscape for the foreseeable future.
Last edited by lusterblade : 08-30-2007 at 05:03 PM.

[Atilla the Fun]

Looks like our only hope of a direct injected cathedral port (the only ports worth having) head will have to be the 4.8L / 5.3L head of the gen 5. Let's hope the gen 5 heads and electronics are compatible with the LS3 block and LS4 blocks and cranks, (the only blocks and cranks worth having). Hopefully the gen 5 5.3L will keep the 799 ports and the 4.8L will keep the 205cc ports. Hopefully both will have better chambers than the 799s, which were identical replacements for the 243s, and the best production GM chambers ever. Hopefully 2.02"/1.60" valves will clear the injectors.

[CincinnatiFiero]

At least GM is trying to go with the times, hopefully the LS10 will be OHC

[Atilla the Fun]

You can't be serious. That would be the very height of epic stupidity. Haven't you seen GM's illustrations of their 3-valve LSx? It has a second cam above the regular one, still in the block where it belongs (keepts the mass low and centered, improving fit, handling, et cetera)
It hasn't happened yet because the LS3 heads met the target airflow for the 'vette HP number they were after, but the port velocity isn't what they need for the trucks, which makes me wonder why they say that but do it anyway when they still have the more excellent 799 heads that would be fine with the LQ4 pistons.

[CincinnatiFiero]

On DI, yes, glad they went with the times. OHC, thats what the smiley was for. Too bad we didn't get the sarcmark.

http://02d9656.netsoljsp.com/SarcMark/m ... oadhome.do

[The Dark Side of Will]

I think that the way Dodge did the Viper cam to have independently variable intake and exhaust lobes is pretty cool.

I still think they should have finished the DI Northstar replacement. If they need to kill an engine family, they have way too many to choose from.

[Atilla the Fun]

just wait until we get the electric controlled servo actuators on each and every valve. Then we truly will have infinite control over the exact timing of each of the 4 events. Currently the tech is too costly, can't handle any boost, and can only handle the low rpm range of Diesel engines, but there are car guys working on it.

[CincinnatiFiero]

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

Infinitely variable cams. ^

[CincinnatiFiero]

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

[Blue Shift]

After playing around with some LS7 heads at the race shop I used to work at, I was under the impression that there was no comparison in flow between the cathedral ports and the rectangular port heads... Could almost shove my big ass hand into the rectangle ports (they were CNC race ported, but so were all our cathedral port heads), it was some crazy shit.

[The Dark Side of Will]

Yeah, why do you say the cathedral port heads are the only heads worth having when GM is going to the rectangle port heads for horsepower applications?

[Atilla the Fun]

Velocity trumps flow. Flow can be made with boost. So can velocity, but boost both to the same pressure, the cathedrals still build better off-idle torque where it helps mpg and torque the most, which is what's needed. If you want huge ports, at least use the MAST heads, not the arse-crappy GM rectangle ports, which only flow 2/3 as well as the MAST heads, despite 10% more port volume. Flow isn't everything. Velocity is.

[cactus bastard]

Velocity trumps flow.

What? No it doesn't.

[cactus bastard]

The smaller the intake ports, the higher the resulting velocity. However, this is not a recipe for success...

[cactus bastard]

the cathedrals still build better off-idle torque where it helps mpg and torque the most, which is what's needed.

Wait, we could be discussing totally opposite engine characteristics here. I was thinking about performance, not low range torque and fuel efficiency..

[The Dark Side of Will]

Velocity trumps flow. Flow can be made with boost. So can velocity, but boost both to the same pressure, the cathedrals still build better off-idle torque where it helps mpg and torque the most, which is what's needed. If you want huge ports, at least use the MAST heads, not the arse-crappy GM rectangle ports, which only flow 2/3 as well as the MAST heads, despite 10% more port volume. Flow isn't everything. Velocity is.

GM's LS7 heads get into the 550+ range with cam/header ZO6's a LOT more easily than maximally ported cathedral heads did on the 7 litres of yore.

If you want fuel economy, build an iron head 3.736 x 3.750 SBC (383 crank in 305 block) with 6" rods. The small bore/long stroke combo gives you a better surface area/volume ratio for the cylinder, which means it leaks less heat into the coolant. Applying all the fuel economy tricks you can come up with to a better foundation gives a better result... just don't expect such an engine to set any power records.

[Atilla the Fun]

Building for off idle torque is best, because you can't set up a turbo kit for full boost at 500 rpm on a gas engine and expect it to survive.
Once you have the low-rpm torque, boost can fix the top end. Boost cannot fix the off-idle.
Ever seen the dyno results for a TPI 383 with a ProCharger?
Here's the results from before the ProCharger:
3200 503 306
3400 506 328
3600 514 352
3800 527 381
4000 531 404
4200 524 419
4400 515 431
4600 502 440
4800 487 445
5000 472 449
5200 449 445