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Why 6.0s are so thirsty?

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Old 10-18-2017, 03:58 PM
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Originally Posted by Tuskyz28
Yes a 6.0 has more Horsepower than a 454ci factory. But how about torque? Some big block guys claim 500ftlbs below 2500 rpm. I'm a LS guy at heart but a big block still and always will demand respect....
I have seen magazine articles where guys invest 2500 into a big block and they become down right monsters.
The numbers I made in that post is very common if you visit a big block forum dealing with older trucks.
Than SOME 454s lol. The mid 90s 454s were like 290hp and 450ish tq i believe. The computers were dumb but not hard to get power with a little coaxing and didnt need premium fuel due to low cr. SO MANY magazine builds on them.
Old 10-18-2017, 04:05 PM
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Sure, 454's CAN be made to run strong, crisp, and responsive, all while MAYBE getting you 13mpg........ on a good day...... unloaded...... in a Vette (NOTHING heavier)..... lol
Old 10-18-2017, 09:00 PM
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Old bbc heads were turds. You see the modern LS7-based heads in 454 LS bottom ends making power the bbc 454 only dreamed of. Nothing magic about a LS 454 bottom end vs a bbc 454. All in the heads.
Old 10-18-2017, 09:17 PM
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^^^Now this is WISDOM! Well, mostly plain truth.... ^^^^
Old 10-18-2017, 09:27 PM
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They are so very different you cant compare them like that though. A bbc 454 wouldnt need 6500+ rpm to make the power using good heads. Rect port was where it was at with them. 2 different animals.
Old 10-18-2017, 09:47 PM
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Sorta like the rectangular ports in LS's. GREAT with mid and top end flow, a little soggy down low....
Old 10-18-2017, 09:50 PM
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Big blocks have the cid to not be soggy down low.
Old 10-18-2017, 10:35 PM
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True to a point; A couple I had driven left the stop crisp enough, but for a bit felt doggy. Now that might have been a function (or MALfunction lol) of the emissions tuning they were victims of. So yeah, in a well-tuned BBC, soggy bottoms were not usually an issue. It was my experience with the above that led to my comments before yours.
Old 10-18-2017, 11:13 PM
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Originally Posted by tech@WS6store
They are so very different you cant compare them like that though. A bbc 454 wouldnt need 6500+ rpm to make the power using good heads. Rect port was where it was at with them. 2 different animals.
a bbc 454 didn’t need 6500 rpm to make power, because of torque. A 454 LS doesn’t need it either. Same reason. But the LS top end will way outrun the bbc top end.

Originally Posted by G Atsma
Sorta like the rectangular ports in LS's. GREAT with mid and top end flow, a little soggy down low....
thats not really a function of port shape so mush as cross section area vs the cylinders airflow demand. Larger engines need bigger ports to feed them or else they end up with lots of air velocity but not really filling the cylinders to their potential. Results in great torque at low rpm and falling in its face at 4500. Too large a port and it needs rpm to really take advantage. A 260cc cathedral port and a 260 rectangle port will basically be the same. Only the injector location is really affected - until you get into valve angles, but that’s not really a result of shape either.

Originally Posted by tech@WS6store
Big blocks have the cid to not be soggy down low.
Truth. Large CID in general doesn’t need to be built to make torque. They’ll make torque on accident.
Old 10-18-2017, 11:17 PM
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You can only go so large with ls engines. Bore spacing fixed that. The big block is still king as far as any of that goes, esp for an NA Mountain motor.
They dont have to spin the rpm to make the horsepower either.
Thats not the point of this thread of course.
Old 10-19-2017, 12:44 AM
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This truck here is from another forum. It's a big block chevy 454 truck. The owner says the motor is bored 40 over making it a 461ci motor. It delivers 495ft lbs at 2500 at 550 plus ft lbs at 3500 rpm at the crank. The motor is still running factory "peanut" port heads and a RV/towing cam. A dual plane intake and headers with a true dual exhaust. That's it people. On horsepower the motor only makes 470 ish. Torque production from the big-block exceeded 500 lb-ft from 2,800 to 4,600 rpm. The owner claims to pulls farm animals, and tractors etc like it's a daily walk in the park. Now it's easily to see why guys still builds these motors. It's not no telling how much more torque can be had out that truck if it had a aftermarket stroker crank to make it a 496 plus cube motor.

It's not the point of the thread I certainly agree but the guy said my post was bogus must never seen a magazine article on a big block chevy.
Old 10-19-2017, 06:41 AM
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On a side note, this 14 GMC did a FANTASTIC job towing the big pig. The 6.2 truck here averages 11.6 mpg running 73 mph.....
Good power sweet ride but we all know how more more money this truck here would cost vs the square body i posted above.
Old 10-19-2017, 08:28 AM
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That’s a cool ride on the trailer!
Old 10-19-2017, 08:43 AM
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Originally Posted by Tuskyz28
Yes a 6.0 has more Horsepower than a 454ci factory. But how about torque? Some big block guys claim 500ftlbs below 2500 rpm. I'm a LS guy at heart but a big block still and always will demand respect....
I have seen magazine articles where guys invest 2500 into a big block and they become down right monsters.
The numbers I made in that post is very common if you visit a big block forum dealing with older trucks.
500 lb-ft at 2400 on the 502 HT crate motor per CPP

http://www.chevrolet.com/performance...g-block-ht-502

Or 502 HO for even more torque, although the chart doesn't show below 3000 on this one:

http://www.chevrolet.com/performance...g-block-502-ho

The crate motors are stupid expensive though. Better off with getting a used 454 and getting the stroker kit to go 496, that would be a lot cheaper most likely.
Old 10-19-2017, 09:17 AM
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Originally Posted by Brons2
500 lb-ft at 2400 on the 502 HT crate motor per CPP

http://www.chevrolet.com/performance...g-block-ht-502

Or 502 HO for even more torque, although the chart doesn't show below 3000 on this one:

http://www.chevrolet.com/performance...g-block-502-ho

The crate motors are stupid expensive though. Better off with getting a used 454 and getting the stroker kit to go 496, that would be a lot cheaper most likely.

Thanks for posting Brons. I never thought this thread would go this long. Guess it's a real issue out there that guys don't discuss.

Now too add to your post the 502HT is hard to beat for the money in my opinion. Think about it.... You have a warranty and the motor cost 6 grand basically. The HO motor just have a bigger cam. That's basically the difference between those 2 motors.
It's easy to tie 6 grand into a LS motor. It's not hard at all. A forged 408CI motor averages 4500 dollars plus with ease. That's without heads, cam, lifters, oil pump etc.....
Old 10-19-2017, 09:54 AM
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The moral of the story so far is, its someone else's build until you do it yourself.
Old 10-19-2017, 09:57 AM
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Originally Posted by tech@WS6store
The moral of the story so far is, its someone else's build until you do it yourself.
Yeap. That's exactly right. Nothing like options and decisions.
Old 10-19-2017, 02:09 PM
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Originally Posted by Tuskyz28
Thanks for posting Brons. I never thought this thread would go this long. Guess it's a real issue out there that guys don't discuss.
For the most part, I think we kind of accepted for the most part that 6.0's get worse than expected gas mileage. I still maintain that a lot of it is in the heads and valvetrain. There's nothing magic about a 4" x 3.622" rotating assembly that would cause poor economy.

But like WS6store said earlier, you really struggle with KR pushing compression on a towing engine, so it might simply be that the engine was designed for hauling, so GM kept the CR low and the valve events conservative, and therefore it's not as efficient as other LS engines. Might even be an indication that 6.0 was just a tad small.

Sort of similar, but not exactly the same thing - I had a 2.8L carbureted V6 in my S10 getting 17 mpg highway. With a LS 6.0, it's now getting 22 mixed driving with 4x the HP. Possibly a similar pattern? Heavy truck with a 6.0 just not quite optimal...?
Old 10-19-2017, 05:46 PM
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I guess I'm the only 6.0 owner that gets decent gas mileage. I know everyone likes the comfort that an automatic brings and the stump pulling that 4.10 gearing provides but complain about the fuel mileage that those two items cause. I'll continue to enjoy my '01 2500 ext cab 4X4 with the 5 sp man and the 3.73 gearing.
Old 10-19-2017, 09:06 PM
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Big blocks used to be king for torque but twin turbos are the new king of torque. The 3.5 Ecoboost will make 400-450 ft pound at 1800 rpm, depending on the year. Install a Boostmax harness and gain 50 hp for $300. Getting that 50 hp gain from a LS based engine will cost $2000.


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