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Old 03-13-2018, 11:18 PM   #1
King951
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Question Engine power comparison / question

This might seem like a really dumb question, but it is something I think about a lot. I own a 99' GMC K2500 Suburban with a 7.4 454. It has plenty of power to spare and I use it mostly for towing. I also have my 71' C20 with a 5.0 307 small block that does fine as well. I always told myself if something were to happen to the motor in my 71 I would put a 454 in it. This leads me to my question.

Let's say I build a 5.7 350 and it makes 300 HP and 400 ftlbs torque. Let's say I also build a 7.4 454 and it also makes 300 HP and 400 ftlbs torque. Both motors will go on the exact same vehicle with identical drive trains / transmissions / rear ends / etc. Aside from the weight difference in the blocks themselves, would one motor still be technically stronger than the other? Another reason I ask is because when I look at a new Chevy Suburban, they come with the 5.3 making 355 HP and 383 torque stock. That's more HP and almost the same torque as the 454 in my 99'.

Something else leading me to this question in my dad's previous 02 GMC Sierra 2500 HD with a 6.0 engine. Great truck, made more HP and almost the same torque as my suburban, but the suburban would noticeably out-pull the 6.0 making the same numbers. Both trucks had the same 4L80E I believe, both trucks weigh about the same, rear gears may have been different but they are both 2500's so I would assume they wouldn't be far off. This was with both vehicles running 245/75 tires.

I feel as though displacement has a bit more value than just a number. I find it hard to believe having an engine that is physically larger doesn't provide some benefit aside from pure numbers.

I know different engines make there power at different ranges, so maybe this comes into play a bit?

Any input on this would be appreciated.
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Old 03-14-2018, 06:13 AM   #2
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Re: Engine power comparison / question

The 454 makes over 400 lb/ft of torque. IMO anything over 6k need a big block..
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Old 03-14-2018, 06:24 AM   #3
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Re: Engine power comparison / question

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The 454 makes over 400 lb/ft of torque. IMO anything over 6k need a big block..
I agree and the numbers I was using above were just an example. My question is, would a small block 350 built to put out 400 ftlbs of torque pull identically well as a 454 with 400 ftlbs of torque, or is there a benefit to having a physically larger motor aside from higher HP / torque numbers?
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Old 03-14-2018, 06:42 AM   #4
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Re: Engine power comparison / question

It wil also drink more fuel.

This is a good visual represntation. Its for fuel injected engines(they dont have the right numbers for the L29 though).

http://www.gearvendors.com/cghptorque.html

The torque curve starts earlier, and is flatter on a big block.

I think you could guess my choice by looking at what I own.
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Old 03-14-2018, 06:46 AM   #5
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Re: Engine power comparison / question

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Originally Posted by 95 S_Trucker View Post
It wil also drink more fuel.

This is a good visual represntation. Its for fuel injected engines(they dont have the right numbers for the L29 though).

http://www.gearvendors.com/cghptorque.html

The torque curve starts earlier, and is flatter on a big block.

I think you could guess my choice by looking at what I own.
Like I said, my 1999 K2500 Suburban has the Vortec 7400. All I have done is K&N drop in and had a dual exhaust that's duel 3 inch pipes going into a Flowmaster 40 and two 2.5 inch pipes coming out. Put a 5,000 lb trailer behind it and it's like it isn't even there. Unbelievable torque / power out of a mostly stock Suburban. Hands down the best vehicle I have ever owned and if I total it tomorrow I'd be on the lookout for another one. Mines just under 190k miles and the injectors are starting to leak so I have some Bosch III's I am getting ready to put in tomorrow.
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Old 03-14-2018, 07:36 AM   #6
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Re: Engine power comparison / question

The newer engines seem to make their torque at higher rpm making the old big block seem more powerful. Back in the day people appreciated low end torque. Now people aren't so concerned where the torque is occurring.
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Old 03-14-2018, 07:42 AM   #7
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Re: Engine power comparison / question

The only LS engine that makes more torque than a 454 is the 8.1. Everything else makes more power at higher RPMs. I don’t know bout you, but I don’t like towing at 4500 RPMs constantly. Torque moves you, horse power keeps it going. Me, I’ll take torque.
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Old 03-14-2018, 08:10 AM   #8
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Re: Engine power comparison / question

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The only LS engine that makes more torque than a 454 is the 8.1. Everything else makes more power at higher RPMs. I don’t know bout you, but I don’t like towing at 4500 RPMs constantly. Torque moves you, horse power keeps it going. Me, I’ll take torque.
The 8.1(L18) isnt an LS engine. Its a big block. It has the same bore centers as a big block, it has the same bore as a 454(4.25") but it has a longer stroke(4.37" where the L29 is 4.00").

It's classifed as Gen VII, where the L29 is was a Gen VI. It is a lot different from the older big blocks, but it has some similarities. It is completely different from an LS engine.
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Old 03-14-2018, 08:28 AM   #9
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Re: Engine power comparison / question

It’s a combination of the two as I call it. Big block long block but LS fuel and computer BS. Guess that’s the way things are going to, screaming RPMs pulling or towing and not much better economy...
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Old 03-14-2018, 11:04 AM   #10
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Re: Engine power comparison / question

I think it stands to reason, all things being equal, a bigger engine producing the same power will exert less stress on the moving parts and therefore last longer. A 300 HP small block can certainly last a while, but a 300HP 454 is pretty calm and even the flat-tappet carb'd versions could rack up hundreds of thousands of miles towing loads.

Also, there's another particularly pertinent factor when talking about pulling: horsepower vs. torque. Let's compare numbers on a couple engines:

L31 Vortec 350, the standard issue light truck engine from '96 to 2000.
LE8 454, the extremely tame 80's carbureted truck big block.
LQ4, first version of the 6.0L (2000-2002?), with non-electronic throttle body.

Horsepower peak:
L31: 255 @ 4,600
LE8: 230 @ 3,800
LQ4: 300 @ 4,800

Torque peak:
L31: 330 @ 2,800
LE8: 360 @ 2,800
LQ4: 370 @ 4,000

So, the 6.0 is most powerful, and the 350 with fuel injection and higher compression on its side is darn close to the 454 with barely enough compression to combust the fuel and heads that a modern 2.0L turbo 4 cyl. would probably outflow. However! Notice the peaks. The 454 has a substantially lower horsepower peak than either of the others. I've not done a lot of pulling with a L31-equipped truck, but with the torque peak in the same spot as the 454 I'd expect it to not quite keep up, but perform admirably for an engine only roughly 3/4 the size of the 454. However, the 6.0's torque peak is extremely high compared to the others, which translates into the rev-happy-ness that others have mentioned about the LS engines. LS engines have plenty of power and they're tough - probably tougher than any of the engines before it when it comes down to it - but the power isn't down low where a sane person prefers to keep their engine while pulling. In two equivalent trucks, one with the carb'd 454 and one with a 6.0, towing the same load up a hill at the same speed then put to the floor partway up for a race to the crest, the 6.0 might edge ahead of the 454... but it has to run nearly wide open to do it where the 454 stays down where it was to start with and just pulls. To add to it, all these comparisons are with one of the most anemic 454's ever made - the Vortec 7400 puts out 290 HP and 410 lb.-ft. of torque @ 3,200, which is right about where it's going to be when a 4L80E shifts out of OD into third at highway speed. In this case, in our hill climb scenario, to even get all of the 6.0's torque you have to forget about third and go to second at which point you're just screaming and giving 'er all the air and fuel she can take so *whoop*, there goes your gas mileage. So yes, a Vortec 454 should rightfully run plum off from a 6.0.

Just a couple anecdotes: Last week I'd done some work on my FIL's '03 1500HD (6.0/4L80E CCSB) and drove it back to his place 35 miles away towing his 18' open car trailer I hauled it to my shop on... behind my '85. The trailer weighs 1,800 lbs., I installed a reman transmission 2 years/60K ago, and the 6.0 runs well enough I don't think it's lacking much of its original power.
So I'm climbing a fairly steep, straight hill at about 65 and gaining on a Tacoma that had just crested the hill only doing about 55, and I stepped into it (downshifted 4-3) to get past him before the passing lane closed back down to 2 lanes... but the genius in the Taco gained about 5 MPH once he got back on flatter ground, with me coming up on him pretty hard, so it was either flat out put it to the floor (and probably get a 3-2 downshift) or abandon my plan and stay behind him. I chose the latter, and was honestly very unimpressed that I was basically using all the truck's power to only gradually accelerate up what was then a slight hill. Err, well, I say "all the trucks power", but looking at these power curves I needed to get it into second to really get all its power... but with 300K on the truck I'd rather not grenade it.

Secondly, my brother-in-law's dad has a '98 K2500 Suburban with a Vortec 454 which has spent a good bit of time towing a 32' enclosed trailer (loaded real heavy at times) and has 280K on it. They just towed it from central KY, to central MO, to Wisconsin and back, running into a stiff head wind on the way to Missouri. He's also been known to set the cruise control at over 70 MPH with the trailer and let it downshift to 2nd on its own, on hills - which I can't even imagine doing, but the point is that 454 has done some serious work and it seems un phased by it. BTW, he runs Schaeffer's 7000 10w30 in it, as I do in mine.
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Old 03-14-2018, 11:34 AM   #11
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Re: Engine power comparison / question

I told this story so many times I’m surprised no one yells at me. Back in late ‘01 I bought a 97 Chevy ECLB 2500hd, 454, 4l80, 4wd, 4.10s. Had 57k on it I think. When I got out of the military I had to take my crap from DC to NYS. I had 2 454s, set of 1 ton axles, a welder, cutting torches, toolbox and who knows what else, and flat towing a RCSB 2wd on a tow dolly. I set the cruise at 70, and never went below that. There is some steep hills on 81 in PA. On flat ground I could step on it and light the 265s up. Buddy does a lot of towing. Has had many 350/454 Vortecs, and some 6.0s as well. He was telling me none pull or tow like the 454 does. And gas mileage is bout the same.
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Old 03-14-2018, 11:41 AM   #12
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Re: Engine power comparison / question

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It’s a combination of the two as I call it. Big block long block but LS fuel and computer BS. Guess that’s the way things are going to, screaming RPMs pulling or towing and not much better economy...
Then what would you call the L21 454?(it's an L29 with a coil near plug ignition system)

The fuel/ignition system doesn't change the architecture of the engine.
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Old 03-14-2018, 12:18 PM   #13
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Re: Engine power comparison / question

No it’s just a better system over the vortec....
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Old 03-14-2018, 12:24 PM   #14
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Re: Engine power comparison / question

Edit - never mind -
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Old 03-14-2018, 01:54 PM   #15
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Re: Engine power comparison / question

Based on your question, both engines making identical peak numbers, yes the 454 will be stronger as it will make more power at less then peak numbers. Peak numbers only matter at full rpm. The 5.3/4l60 in my 02 suburban drives awesome and barely revs over 2400rpm accelerating on side streets. We have a 2015 yukon with the 6.2L/6sp auto and it drives terrible comapared to the suburban. Rev's to at least 3k most gears, has to downshift constantly, just sucks. That subs's 5.3L is like 300hp, the denali is like 400hp and weighs less with more gears.
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Old 03-14-2018, 02:33 PM   #16
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Re: Engine power comparison / question

One of the car magazines - I think it was Hot Rod - did a comparison years ago where they built a SBC 400 and a BBC 402 as identically as they could - same CR, cam profiles, carburetion, exhaust, etc. Then they ran them and compared them. What they found was that, apples for apples, the big block is always going to make more power and the small block will always be more economical.
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Old 03-14-2018, 06:50 PM   #17
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Re: Engine power comparison / question

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No it’s just a better system over the vortec....
Every gm truck gas engine engine made from 1996-2014 was marketed as a vortec.
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Old 03-14-2018, 08:28 PM   #18
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Re: Engine power comparison / question

Which is heavier, 1 lb of rocks or 1 lb of feathers?

Same with HP and Torque. 300 HP is 300 HP regardless what is making it. BUT, because of the different engine size and displacements they will make that HP/Torque at different RPMs so they will feel different.
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Old 03-14-2018, 10:04 PM   #19
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Re: Engine power comparison / question

One of my favorite episodes of Engine Masters compared a 383 Chevy to a 383 Mopar
https://youtu.be/L-uV61qilqU
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Old 03-30-2018, 02:07 AM   #20
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Re: Engine power comparison / question

A sbc is definitely easier and can built up cheap. As far as big blocks, the 90's 454 weren't known to be a huge power house. The 6.0's have power but once you drive a truck with the 8.1 you'll never want to go back. The 450 lb-ft @3200 rpm stock is nice and with a tuner comes alive!
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Old 04-03-2018, 09:52 AM   #21
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Re: Engine power comparison / question

"No replacement for displacement" I built a 72 350 knowing I was going to tow with it, that was just about 5 years and roughly 35K miles ago. I put a 3;73 posi in it, a built 350 turbo, a Lunati Voodoo cam that made low end power nothing radical and 10 ply 275/75-16's. That truck still pulls like a train, 3rd gear, up hill on interstate 70 mph, mouse screamin @ 3200 and lovin it! Motor runs cool and only recently does the oil pressure drop south of 40 at idle. I tow a 2000lb 20' tandem tilt with another 4000lb + 72 C/10 that has a 425hp BBC in it...The small block gets way better mileage towing than that BBC can sitting on the trailer, with the key in my pocket. I own these trucks because I love them and all they represent from an era most folks will never know. The new rigs are making unimaginable power compared to 1972. But they cant hold a candle to Belle & Sally, especially when I get a run on em gong up them hills...
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Old 04-03-2018, 10:21 PM   #22
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Re: Engine power comparison / question

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"no replacement for displacement" i built a 72 350 knowing i was going to tow with it, that was just about 5 years and roughly 35k miles ago. I put a 3;73 posi in it, a built 350 turbo, a lunati voodoo cam that made low end power nothing radical and 10 ply 275/75-16's. That truck still pulls like a train, 3rd gear, up hill on interstate 70 mph, mouse screamin @ 3200 and lovin it! Motor runs cool and only recently does the oil pressure drop south of 40 at idle. I tow a 2000lb 20' tandem tilt with another 4000lb + 72 c/10 that has a 425hp bbc in it...the small block gets way better mileage towing than that bbc can sitting on the trailer, with the key in my pocket. I own these trucks because i love them and all they represent from an era most folks will never know. The new rigs are making unimaginable power compared to 1972. But they cant hold a candle to belle & sally, especially when i get a run on em gong up them hills...
qq

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