68post wrote: ↑Tue Mar 05, 2019 1:21 pm
Interesting that GM had developed an 8.0L, (in 2010), that seems to be a tall deck version of the 7400, even the port layout is same. Perhaps a revised version of this, with yet again with more stroke !? (4.27" X 4.25" @ 8.0L ) The rumor/speculation in the above links is 8.8L.
The 8.1L Vortec IS a tall deck, long stroke version of the 7.4L engine. It has a 10.2" deck height and a 4.375" stroke with the original 4.25" bore.
I think maybe an 8.8L is a bit big, at least for the 3500HD series. Apply more modern tech and better programming to 360HP/450lb/ft 8.1L Vortec and you can easily exceed 450HP and 525lb/ft. Don't get me wrong, I think a 4.320" x 4.50" in a 10.2" block would be great. But remember, you're using torque reduction strategy already, and even with modern tech, it might be tough to get the necessary cruise and part throttle economy required at that size. It would certainly make 550/600 with ease, and move even a class 7 truck with relative ease. But is it what the market needs/wants. Too much power leads to broken parts, something that commercial customers despise, as well as excess fuel consumption, not too mention what some drivers will drive like, both problems for commercial customers.
68post wrote: ↑Tue Mar 05, 2019 1:21 pm
Interesting that GM had developed an 8.0L, (in 2010), that seems to be a tall deck version of the 7400, even the port layout is same. Perhaps a revised version of this, with yet again with more stroke !? (4.27" X 4.25" @ 8.0L ) The rumor/speculation in the above links is 8.8L.
The 8.1L Vortec IS a tall deck, long stroke version of the 7.4L engine. It has a 10.2" deck height and a 4.375" stroke with the original 4.25" bore.
I think maybe an 8.8L is a bit big, at least for the 3500HD series. Apply more modern tech and better programming to 360HP/450lb/ft 8.1L Vortec and you can easily exceed 450HP and 525lb/ft. Don't get me wrong, I think a 4.320" x 4.50" in a 10.2" block would be great. But remember, you're using torque reduction strategy already, and even with modern tech, it might be tough to get the necessary cruise and part throttle economy required at that size. It would certainly make 550/600 with ease, and move even a class 7 truck with relative ease. But is it what the market needs/wants. Too much power leads to broken parts, something that commercial customers despise, as well as excess fuel consumption, not too mention what some drivers will drive like, both problems for commercial customers.
I'm aware, (of at least the deck hgt, bore and stroke). The 8.0 is a different engine, didn't know it existed until today and from reading into some of the above listed links. GM didn't pursue this design but sold it off to aftermarket industrial suppliers to build currently.
8.8 is huge, but I doubt they'd use any larger bore than around 4.25"/4.27" to help control emissions, (and I'm sure they wouldn't stroke it any more than 4.37 ).
Alan R. (or anyone w info) , does the 8.1 crank swap straight into the 7400 block ?
I don't know anyone who has tried to put the 8.1 crank in the 7.4 block. I don't know why you would. It's not like it is a special piece, and once you get past 4.25" stroke, most move to a 10.2" deck height block.
GM sold much of the tooling and equipment for all of the production big block Chevy engines, there is an industrial company that uses them for powerplants, building various displacement complete engines and selling replacement parts.
I'm sure GM probably still retains the right to manufacture and sell the stuff. There's a difference between "production rights" and a license to produce. Pretty sure GM sold a license to produce and sell.
First, I am glad GM sold all the old BBC tooling and whatever. This would not make a good 8.0L BBC for today's emissions and milage standards no matter what they did to that old design. Thar's why they need a new sheet of paper design! PSI and others with their modified designs with iron heads and such were looking for quick replacement for the 8.1L Vortec demise in 2009 and I think their HP numbers and even the torque numbers are pretty weak and point out the inefficiency of those engines. Most were sold a constant 1800 rpm generator and water pump use.
If GM and Navistar are really looking to develop something better they hopefully will stay with the simplistic designs and results similar to the GM LS engine. No need for rocket science here but the results have got to be good to make it really work in today's truck market. Make it big, make it fairly inexpensive to build and buy, make it more efficient, make it lighter weight and make it simple and reliable with an easy maintenance and repair aspect.
Hit those targets and I think they will have a good gas truck engine.
Anything 8.0L with a cast iron block and aluminum heads is going to weigh about the same. Everyone, or damned near everyone, makes a 1 ton and bigger truck engine with a cast iron block for several very good reasons. Even the new "big LS" small block for the 3500 uses a cast iron block, according to what I've read. So, if you're going for the 8.0L zone, 4.25" bore and 4.375" stroke is the "sweet spot", so you're right back at the same package, the cast iron block with the approximate dimensions and weight that you already had. You're not building something to race. So you're not going to make bore spacing for a big bore that you're not going to use, in the 1 ton truck you're still going to be around 496 cubic inches (Ford is only building something around a 427). A bigger bore than that and bore spacing to support it is a bigger, heavier package you neither want nor need. The biggest you could reasonably expect would be maybe 4.35 bore and maybe 4.5 stroke, IF you're planning to make something big enough for a class 7 truck. That's a 535, if you stretch it and go 4.375 bore and 4.5 stroke for a 541. Still fits the old package. Face it, you have a short block package that has proven rock solid for 54 years, and already fits where you want it to go, it was even proven to live in the medium truck applications . It was last used only 10 years ago. And here's the deal, like David Reher and Buddy Morrison once said, a short block is just a short block, it's a stand we put a set of heads and an induction system on. The heads that were on the 8.1 fed it with decent efficiency, and if you're going to make new ones out of aluminum, you can improve them and the intake.
There's not going to be this magic clean sheet of paper that is going to make any 496 cubic inch or 8.1L +/- gasoline V8 suddenly get astonishing fuel economy and still make 1.1 HP and and 1.25 lb/ft per cubic inch. This is a normally aspirated engine that must make peak torque around 2500-2800 RPM, with killer off idle torque. There's only so much energy in a gallon of fuel. A magic 500 cubic inch LS isn't going to suddenly find an extra 100,000 btu's in a gallon of gasoline.
The below is a response cut from the "GM Authority" website. You can tell from the last sentence that this gentleman is not a racer !
Quote:
A new comment has been posted on GM Planning New Engine Larger Than New 6.6L V8 L8T by MARK SMYTH member of the SAE since 1988:
Dennis, you forget that GM has made made millions of engines for purposes other than cars or trucks. When i was age 12, over 50 years ago, the farm i worked on during the summer used a Chev 327 cube engine in the combine. The big block Chevy engines, ( starting with the 366 cube big block ) mostly the very heavy duty high block versions never installed in a car, but only 3/4 ton ( now called 2500 series ) and up trucks and truck chassis for school buses etc. They often use cheaper fuels such as LPG propane or CNG natural gas because they are designed for long life use. The 8.1 liter had most of what was needed for running propane, such as exhaust valves and seats made of inconel metal. It can withstand the extremely high heat when running propane, because propane has a huge percent of hydrogen and it burns so hot, normal metal exhaust valves will warp. But the problem with the 8.1 liter big block was that it did not have full water jackets and it ran too hot, so in 2010 GM designed and tested a brand new big block that was 8.0 liters. GM never sold it as a complete engine, it did not have a GM supplied intake manifold or fuel system. That work was contracted out to another company in Michigan, after Thomson Automotive did the building and testing of the first six engines. It had a very low RPM camshaft, design for industrial use, that produced a maximum torque of 518 lbs feet at just 1800 RPM. The max HP topped out at just 2800 RPM when Thomson Automotive was first developing the engine under contract to GM. Those two RPM levels are the standard for any engine, gas or diesel, propane or natural gas use, to make electricity. They must run no-stop for days on end at 1800 RPM to be certified as meeting the world wide standard for power plants. The higher 2800 RPM point is for just occasional high RPM work when a huge demand for electricity is required in a standard powerplant for industrial use. Mary Barra's thoughts and comments are not directed towards the industrial sector. Ford keeps outselling GM for trucks and they know there are bigger profits with trucks than cars, so they will put a 9 liter engine in a Class 6 or Class 7 ( rumoured to come ) truck, as long as people buy them. As long as GM make hundreds of millions of dollars per year selling parts and engines for the aftermarket use, the bean counters at GM, won;t ruin a good thing. For many years since that 2010 new 8.0 big block engine was originally built, hundreds of thousands of the 8.0 have been sold. They are used in all full size school buses sold in California, because diesel school buses were outlawed there over 10 years ago. Motorhome chassis, large outdoor forklifts and replacement engines for old gasoline dump trucks and large farm grain hauling trucks, all now use the new ( er) design 8.0 instead of the 8.1 liter. Racers still use the 8.1 liter 496 cube because not having water jackets when going fast isn't as a big a problem, as they often have 12 to 16 quart oil pans.
Had someone email me and ask me to clarify my points, and check out what was posted elsewhere.
That Mark Smyth guy is a real piece of work. Just, wow.
The 8.0 he speaks of is an old Mark IV/V/VI type engine, basically a 4.27"x4.25" Mark VI big block with old Mark IV style oval port heads, possibly with different chambers (called fast burn). We built them as street and bracket engines 25 years ago, it's a 454 with a little bit of over bore and a 1/4" stroker crank. It's nothing special. And it isn't what GM would use. You sure aren't going to put a 4.5" stroke in it either. He's spewing crap about strokes like 4.6" and 4.75", which are very unlikely.
But all of what he's talking about is regular big block architecture, be it IV, V, VI, or VII.
There really is absolutely no reason to have a siamese bore at 4.25", you can easily go as big as 4.375" without any need for siamese bores. Especially with compacted graphite cast iron.
The 8.8 that they refer to is a 4.5" stroke engine, either a 535 or 541, another couple of common hot rod combinations. An 8.8 Mark VII Vortec style engine with a modern intake, decent exhaust, and variable cam timing is going to make well over 500 lb/ft at around 2000-2500 RPM, and still make good HP up to maybe 4500-5000 RPM. Instant off idle torque about 450 lb/ft.
Honestly, it would be relatively easy to convert the big block to variable cam timing. Which will allow more torque at a lower RPM than even the 8.1L Vortec, and not kill power above 3,000 RPM.
The secret to improved power and lower emissions is electronic cam timing, fuel, and ignition control, any decent fundamentally sound design can do well with it. You don't need a clean sheet of paper to get there. That Mark VII 8L+ stuff is already in medium truck and school bus use, without variable cam timing, it already fits, and it already works.
Alan Roehrich wrote: ↑Tue Mar 05, 2019 4:01 pm
I don't know anyone who has tried to put the 8.1 crank in the 7.4 block. I don't know why you would. It's not like it is a special piece, and once you get past 4.25" stroke, most move to a 10.2" deck height block.
GM sold much of the tooling and equipment for all of the production big block Chevy engines, there is an industrial company that uses them for powerplants, building various displacement complete engines and selling replacement parts.
I'm sure GM probably still retains the right to manufacture and sell the stuff. There's a difference between "production rights" and a license to produce. Pretty sure GM sold a license to produce and sell.
Is the old BBC Mark IV tooling long gone?
And is the 502 block worth making bigger?
Say bored .060" to maybe .090" over and then add a 4.375" stroked crank??
echosixmike wrote: ↑Sat Mar 02, 2019 6:40 pm
Without going into the US vs European politics, the simple fact is that America uses more truck transport than Europe.
Dont know about transports but only in western Europe class 8 trucks are sold more than in all the NAFTA countries combined.
Truck sales are good right now in Europe.
Here in the US we have a driver shortage so the big fleets have cut back on buying new equipment since they don't have asses for the seats they have now.
Used to be a big recruiting tool here was the $40-50k wages they bragged about. But the words out how few drivers make that their first year and mellenials don't really want to be gone or even commit to a full time job.
I've been driving class 8 trucks for 47 years...my generation is dying off with few replacement drivers on the horizon.
I wanted to for a while, mainly because I love driving, period. Still crosses my mind sometimes. Guess I better get in gear or I'll turn around and be 60 yrs old and wonder where my life went. {Sigh}
68post wrote: ↑Wed Mar 06, 2019 12:25 am
Bigger bore = dirtier emissions, I'm pretty sure they won't go there.
How much would bore have to do with it if it's squished into a decent chamber like an LS 3/7 or LT DI head? Just asking since they are kind of going there anyway simply by going so big if rumors are true. Tall deck Ls with a 4.185 bore and 4.5 stroke is 495 just over 8 litres I believe but the rod/comp height is short for long life IMO so I don't see anything like that happening... Seems the logical thing to do is use an alum tall deck and reverse engineer LT chamber on bore then get the ports in and put 5 head bolts where you can put them? Print up plastic intakes, Easy peasy...
68post wrote: ↑Wed Mar 06, 2019 12:25 am
Bigger bore = dirtier emissions, I'm pretty sure they won't go there.
How much would bore have to do with it if it's squished into a decent chamber like an LS 3/7 or LT DI head? Just asking since they are kind of going there anyway simply by going so big if rumors are true. Tall deck Ls with a 4.185 bore and 4.5 stroke is 495 just over 8 litres I believe but the rod/comp height is short for long life IMO so I don't see anything like that happening... Seems the logical thing to do is use an alum tall deck and reverse engineer LT chamber on bore then get the ports in and put 5 head bolts where you can put them? Print up plastic intakes, Easy peasy...
Since not all the burn is just in the chamber alone it may or may not be clean enough !? Maybe dual plugs would solve that, but that's extra expense, (not sure if that would be enough expense to harm the idea) ??
You're not going to end up with an aluminum block. The same basic engine is going to be in trucks from the regular 1 ton up to Class 7. It's probably going to be compacted graphite cast iron. You might save 100# or so with aluminum. But you have to make it really strong to run constantly at WOT and peak torque, the weight savings isn't worth it.
Aluminum heads are a possibility, since they could use an update. But they give up thermal efficiency, which you can get by with on a diesel, but when you're trying to wring maximum power and fuel efficiency from a gasoline engine, and keep emissions low, loss of thermal efficiency is a problem. On a big block, a pair of aluminum heads saves you 60#.
You're not going to see a big bore. I'd honestly be surprised if it gets to 4.320". The bigger bore isn't necessary, it requires siamese cylinder bores, it requires more timing, it is more likely to suffer detonation, it is dirtier emissions wise, and it is neither needed nor desired to get the displacement they want/need. They need the stroke to make torque. When you're using at least 4.37" stroke, and maybe 4.5", you neither need nor want a bore bigger than 4.320".
not to get off topic but i would love someone to explain why diesel is .75 to a buck more a gallon than gasoline. is it really all the results of the commodities market? they would sure use a lot less fuel in this country if they would encourage diesel use
gnicholson wrote: ↑Wed Mar 06, 2019 5:33 pm
not to get off topic but i would love someone to explain why diesel is .75 to a buck more a gallon than gasoline. is it really all the results of the commodities market? they would sure use a lot less fuel in this country if they would encourage diesel use
The claim is that all of the extra refining to remove the remaining sulphur (ULSD) is what drove the cost beyond gasoline.
