L92 Truck Engine - - Perhaps ????

[DriVer]

I've been hearing a lot about the 403 Horsepower 6.2L V-8 Engine fitted into GMC pickups. The engine features 417 lb/ft of torque. The engine is identified as an L92. I see it on TV commercials at least twice a night.

As of this writing we are not seeing this engine code as being a viable engine in the Workhorse lineup. 8th digit of the VIN# Engine Type.




What do you guys think now that in a short period of time our 8.1L engine is going to be off the shelves. The engine that is seen here is a completely aluminum engine with 6 bolt mains and a lot of technology.


.

[dieselclacker]

I expect the next generation of motorhomes to be down sized from the present crop. This engine may be suitable for a downsized class A, but I would not want a gasoline engine under about 7.5 liters of displacement in present day full sized motorhomes. Technology is all well and good, cubic inches and grunt is better. If I were shopping for a new unit today, I would surely be checking out the oil burners for a means of powering it.


Dieselclacker

[DriVer]

Originally Posted by dieselclacker

I expect the next generation of motorhomes to be down sized from the present crop.

dieselc .... You ain't seen nothing yet ! Just wait .... for some eye openers form the RVIA Show floor!

I know that International Truck & Engine (ITE) is becoming a player now that CAT is out of the picture.

[RustyJC]

Torque peak around 4300 RPM

Horsepower peak around 5600 RPM

When it's working, it'll live between the two.


Rusty

[DriVer]

Originally Posted by RustyJC

When it's working, it'll live between the two.

Rusty, Being into "engines" as much as you are "you know it!" Absent in this illustration I expect is what we might see on the engines used in motorhome chassis and in this photo it appears to be absent a (belt driven) blower. The blower will no doubt take the engine up a bit higher into the RPM range however I believe this thing will hold together. It's going to be the little engine that could!

This engine has been in production for what ?? 3 years now? It's not as if it hasn't been around the "block"

I believe that we are only going to see a 6.x L gasoline engine and a 6.x L diesel engine as viable powerplants for years 2011 and beyond in Class 6 motorhome chassis. (26K GVW and under) These engine options will most likely continue to be coupled with Allison automatic transmissions at least at Workhorse.

Since 2001 GM's BIG block (8.1L) had it all wrapped up when we were talking about bigger being better however that ship has sailed!

Maybe we'll I'll get my fingers on the pulse in this regard from the manufacturers that I interview at the RVIA Expo!

[Gregg]

Sure am glad I have my 8.1 !!

[RustyJC]

Originally Posted by DriVer

RustyAbsent in this illustration I expect is what we might see on the engines used in motorhome chassis and in this photo it appears to be absent a (belt driven) blower. The blower will no doubt take the engine up a bit higher into the RPM range....

Mike,

Let's go back to the following horsepower equation:

BHP = (P x L x A x N) / 33,000

Where:

P = brake mean effective pressure (the average pressure in pounds per square inch applied to the piston crown during the power stroke)

L = the stroke length (in feet)

A = the area of one piston crown (in square inches)

N = the number of power strokes per minute (entire engine, not one cylinder - for a 4-cycle engine, this equals RPM / 2)

33,000 = 1 HP (33,000 ft-lb/min)

L and A are fixed - these determine the displacement of one cylinder. Unless you start adding cylinders to a V-8 (ref the Ford and Dodge V-10s), the only variables are P and N.

P (brake mean effective pressure) eventually equates to torque and can be increased anywhere in the RPM range with a supercharger - it depends on sizing of the supercharger, cam timing, etc.

So, if the engine designers wish, they could supercharge this engine and achieve the same ~400 BHP at a lower RPM (N) with a higher torque (related to P) which would make this engine's performance characteristics more comparable to large displacement naturally aspirated gasoline engines. This higher BMEP does require beefier internal components, however - think diesel engine component design.

Using the more familiar formula for HP:

BHP = (Torque x RPM) / 5252

In this equation, it's easier to see how the same BHP (~400) can be achieved by increasing torque and lowering RPM. For an example, take the case of my "somewhat modified" 5.9L Cummins in my ole Dodge, it's making ~ 400 BHP at the flywheel @ 2700 RPM and ~900 ft-lb torque at the flywheel at 1800 RPM (dynoed at 347/762 at the rear wheels).

It all depends on how the engine designer wants to get 400 BHP and what operating characteristics he wants the engine to have.

Rusty

[DriVer]

Originally Posted by RustyJC

It all depends on how the engine designer wants to get 400 BHP and what operating characteristics he wants the engine to have.

Rusty, That's about as clear as a term paper!

I bet we all appreciate your providing us with the math that's involved in designing these things. Thanks for taking the time to show us that absent mathematics nothing is possible and given a few "constants" that almost anything is possible!

[DriVer]

Originally Posted by Gregg

Sure am glad I have my 8.1 !!

Gregg, You know, I would not disagree with that and if anyone out there is on the fence about getting a gasoline powered motorhome, now's the time to do it before the engine becomes extinct. I believe that WCC has enough engines to carry them through the 2010 model year.

Remember pre-ULSD days? There was such a a rush on manufactures, that they sucked the system totally dry of all those LSD engines. They got their's while the gittin' was good!

[RustyJC]

Mike,

The point is that the designers can take this high RPM screamer (as it exists now) and, using a supercharger, turn it into a low RPM torquer that produces the same 400 BHP if they wish to do so.

It'll be interesting to see the approach they take for heavier truck/motorhome use.

Rusty

[DriVer]

Originally Posted by RustyJC

It'll be interesting to see the approach they take for heavier truck/motorhome use.

Rusty, That's exactly right! The manufacturers have to come off center on this issue and make progress because I don't believe that a non gasoline powered RV chassis is an option.

What's the latency in using a blower? I don't expect that there'll be a ton of torque when you "dump the clutch" sorta speak until the engine spins up. The 8.1L engine provides a lot of torque as soon as you take you foot off the brake pedal.

The MaxxForce 7 provides 620 lb/ft of torque in no time at all.

[RustyJC]

Originally Posted by DriVer

What's the latency in using a blower? I don't expect that there'll be a ton of torque when you "dump the clutch" sorta speak until the engine spins up. The 8.1L engine provides a lot of torque as soon as you take you foot off the brake pedal.

Depends on the type of supercharger, drive ratio, boost limiting technology, etc. The following is an excerpt from an ARTICLE in Popular Hot Rodding magazine that could apply to the L92 truck engine variant:

When Low-Speed Torque Sets The Rules

If you have a truck (like me) that you want performance from, but it really has to function as a truck and do useful work, then a positive-displacement unit is almost certainly the way to go. My 2000 4.8 GMC Sierra has to haul a payload as much as 10,000 pounds when taking the race car to the track. To do this effectively, it needed real low-speed grunt, along with the capability to deliver good mileage. Up to this point, I had experience with the Holley/Weiand kits, Magnuson, Edelbrock, and Whipple, but mostly with the Holley/Weiand and Magnuson stuff.

A few years ago, on a mild-cammed 350 with pocket-ported aluminum heads, I saw some 541 hp and 545 lb-ft using a Holley/Weiand blower. That's a pretty good showing for what is essentially one of the lower-cost installations on the market. But since the truck was to be used for long-haul towing, mileage was very much on my mind, and I had not, up to this point, tested a Magnuson setup with the bypass valve. This valve, also used on the Edelbrock blowers, reduces parasitic losses to barely above what it takes to spin a couple of sets of roller bearings. So with mileage in mind, I selected a bypass-valve-equipped positive-displacement kit, in this instance from Magnuson. Because the Magnuson kit was charge cooled via a water-to-air intercooler between the blower and block, it could manage 8 psi on a 9:1 engine without being detonation-prone or octane-sensitive.

To make the most of the blower, the stock 4.8 heads were ported, and a Gale Banks exhaust system installed. Dyno tuning was done at Custom Performance, and PCMforless burned a custom program for us. Results were very satisfying. Quarter-mile performance showed up just short, by a truck's length, when run against a stock '04 Mustang GT. Freeway mileage just missed the 21-mpg mark by a hair's breadth, while a consistent 17 mpg was seen about town. That was virtually unchanged from stock. When towing, mileage was surprisingly good. I saw low 14s. Maybe the trick for performance and mileage is a smaller engine with an efficient blower.

Since I tested this unit from Magnuson, they have made yet another significant step forward in rotor design. In fact, as we go to press, rotor design seems to be a hot topic and some new developments from Edelbrock are in the works. Some insider info indicates we should stay tuned on this one.

At this point, we can say that for off-idle and low-speed torque, a positive-displacement blower is the ticket.

Rusty

[Ultra RV Products]

Mike,

Workhorse needs to just buy the right's to the 8.1L, that would solve the issue without having to redesign anything! Check out the new Brazel's RV Performance Facebook page!!

[dieselclacker]

With a positive blower connected to the L92 producing enough huff at low RPM's, and to be effective thru out the useable power band is going to require some serious beefing up of the rotating mass of the engine. You cannot just bolt on a supply of pressurized oxygen and apply it to the combustion process of a normally aspirated engine and expect it to stay together under the higher operating pressures the blower will produce within the engine. I would expect that the L92 was not designed for, nor would it have much longivety under these conditions. If so, it was greatly over engineered. Your talking diesel beef here if you apply enough blower pressure to be effective from this small displacement engine, if applied to a motorhome for power, if you want it to live for any length of time.

Dieselclacker