What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Gen 6 Big Block vs. LS for low end torque.

Cucv_M1008 said:
I plan to blow up my 4l65e in epic fashion and install a 4l80 at some point. Escalades should have had 4l80s from the factree.
Click to expand...
You will be disappointed with the 1st gear when you do that swap. But I understand what your thought is.
Those big SUVs wouldn't have been quite the same with the taller 1st gear.


And dang it @ZooMad75 !! I was getting this all hidden away in my brain, just letting it go, and you gotta bring it up again!

I have known about an L29 /NV4500 truck just sitting waiting for someone to pluck it for over a year. Hard to walk past it every few months and not try to swap it into something.
 
6872xtc said:
You will be disappointed with the 1st gear when you do that swap. But I understand what your thought is.
Those big SUVs wouldn't have been quite the same with the taller 1st gear.


And dang it @ZooMad75 !! I was getting this all hidden away in my brain, just letting it go, and you gotta bring it up again!

I have known about an L29 /NV4500 truck just sitting waiting for someone to pluck it for over a year. Hard to walk past it every few months and not try to swap it into something.
Click to expand...
Do eet! You know you want it. Such a perfect combination.

I'm just the friendly neighborhood big block pusher man.
 
yep 4L80-e is a great trans but WHY did they not put even a 2.40-2.60 ish first gear . . . 1st in this and th400 kind of SUCK if working them as a work truck should be .
 
6872xtc said:
You will be disappointed with the 1st gear when you do that swap. But I understand what your thought is.
Those big SUVs wouldn't have been quite the same with the taller 1st gear.


And dang it @ZooMad75 !! I was getting this all hidden away in my brain, just letting it go, and you gotta bring it up again!

I have known about an L29 /NV4500 truck just sitting waiting for someone to pluck it for over a year. Hard to walk past it every few months and not try to swap it into something.
Click to expand...
More horse power and a stall can fix that
 
The Gen 6 is looking better & better. I have a new turbo, i.p. and injectors for the 6.2, but frankly I am over it.
If I get it running I'll sell it and go big block with another rig.
 
Cucv_M1008 said:
More horse power and a stall can fix that
Click to expand...
In some ways, yes. We just put a 4:10 axle in the kid's 2wd 4.8 /4L60E truck today. It feels pretty good compared to my LQ9 (from an '04 Escalade) with a Texas Speed cam, 4L80E, Phoenix Transmission converter and 4:10s. Yes, mine is a shortbed K2500, but the off the line with just a touch of the throttle is very different. That 300K mile 4.8 engine feels pretty good off of the line.
 
I wish that I had pictures to show, but I can say that the gearing in the 6L90 does a nice job to help a little LY6 6.0 get some weight moving. I have towed one of our mixer trucks across town twice with the shop truck. The mixer weighs 33K empty because of the conveyor and double frame. With 4:10 gears and a light service bed, it doesn't have enough traction to give it a lot of throttle from a dead stop. The same gearing with a big block would be a total kick!! I would have had to put it in 4wd on dry pavement! :D
 
KirsL said:

www.icbus.com

Five Reasons why the PSI 8.8L is the best in its class | IC Bus

Purpose-built for the school bus industry, PSI's medium-duty 8.8L naturally aspirated engine is available with a gasoline or propane power unit developed from the block up to be reliable and durable.
www.icbus.com www.icbus.com

I’m a diesel fan through and through. But who doesn’t love an even bigger big block.
Click to expand...
Just a quick refresher, PSI is the company that bought the design and tooling of the 8.1 big block from GM. The 8.8 isn't much different other than the displacement.

Larry has first-hand experience with the 8.8 since he's with International and handles the school bus side of things for service. Key thing why they are looking at gas for buses is the complexity and cost of emissions choked diesel engines. The cost advantage that pre-emissions diesel engines that drove them into favor has evaporated and cash strapped school districts were getting hammered with high repair costs on emissions-related systems. They are set up for low-end grunt so the HP is lower than the 8.1 but the torque is well above it. But you can get them in Natural gas and Propane versions. They make a single turbski version for stand-alone power generation.

psiengines.com

8.8 Liter - Power Solutions International, Inc.

psiengines.com psiengines.com
 
I'll add my two cents with a couple well known examples.

I love LS engines, they are a great small block, but they are still a small block. I really like the new DI motors too, the modern L86 in my truck is impressive, its the only small block I've had that doesn't downshit to 4K to climb hills with a trailer load, it lugs along pretty well even with a trailer, and it's very efficient with the high compression, and VVT. But it's still not a big block.

If you are looking for low end torque, a big block just has so much more in it.

Here is an example, 2 different GM crate engines, one LS, and one big block, all putting out about the same power level around 500 HP.

Look at the torque curves....

A GMPP LS376 515

1639491612849.png

and a GMPP ZZ502...

1639491457771.png


As you can see, peak power is at 5200 and peak torque at 3600 RPM for the big block. The LS peaks at 6600, with peak torque at 5200. So even though the LS has another 13 HP, it is 103 lb-ft low on torque. And if you look around 3000 RPM, the big block shows around 540, while the LS is at 430, ~110 lower. The big block consistently has about 100 more lb-ft of torque through most of the RPM range. The LS only catches it at the BB redline under 6000 RPM when the big block cam starts to fall short. Then the LS shines from around there until it's redline at 6600.

If you were towing or had a heavy vehicle, the big block would feel more powerful pretty much every day. Only if you had the correct gearing and converter would the LS shine at upper RPM. It would also shine in a lighter car with if you can keep it in the RPM range it wants to be.

The new DI motors are better, the L86 comes in with 460 lb-ft at 4100 RPM. But it won't keep up with a decent big block towing at lower RPMs. The technology is great, but it still can't defy physics.

And don't think I am hating on LS motors, I like them, they are light, fast, flow a lot of air, and make a lot of power. I don't want a different engine in my family truck, its awesome. They just aren't a big block if you are looking for torque.

Yeah, you can stroke the LS, and I have seen impressive numbers from a 402 LS2, and currently specing a build for a customer for a 427 LS3 (from a 6.2 block) that should have impressive numbers, but it's not a big block, and if you stroke a big block, watch out, 496, 540, 632, whatever you want, torque monster or high RPM powerhouse. Look at the new ZZ632 for example, 1000 hp, you will not get that out of a naturally aspirated pump gas LS motor, you would need race gas or a power adder. And you could do the same to the big block....
 
Last edited:
folkenheath said:
I'll add my two cents with a couple well known examples.

I love LS engines, they are a great small block, but they are still a small block. I really like the new DI motors too, the modern L86 in my truck is impressive, its the only small block I've had that doesn't downshit to 4K to climb hills with a trailer load, it lugs along pretty well even with a trailer, and it's very efficient with the high compression, and VVT. But it's still not a big block.

If you are looking for low end torque, a big block just has so much more in it.

Here is an example, 2 different GM crate engines, one LS, and one big block, all putting out about the same power level around 500 HP.

Look at the torque curves....

A GMPP LS

View attachment 397867

and a GMPP ZZ502...

View attachment 397866


As you can see, peak power is at 5200 and peak torque at 3600 RPM for the big block. The LS peaks at 6600, with peak torque at 5200. So even though the LS has another 25 HP, it is 103 lb-ft low on torque. And if you look around 3000 RPM, the big block shows around 540, while the LS is at 430, ~110 lower. The big block consistently has about 100 more lb-ft of torque through most of the RPM range. The LS only catches it at the BB redline under 6000 RPM when the big block cam starts to fall short. Then the LS shines from around there until it's redline at 6600.

If you were towing or had a heavy vehicle, the big block would feel more powerful pretty much every day. Only if you had the correct gearing and converter would the LS shine at upper RPM. It would also shine in a lighter car with if you can keep it in the RPM range it wants to be.

The new DI motors are better, the L86 comes in with 460 lb-ft at 4100 RPM. But it won't keep up with a decent big block towing at lower RPMs. The technology is great, but it still can't defy physics.

And don't think I am hating on LS motors, I like them, they are light, fast, flow a lot of air, and make a lot of power. I don't want a different engine in my family truck, its awesome. They just aren't a big block if you are looking for torque.

Yeah, you can stroke the LS, and I have seen impressive numbers from a 402 LS2, and currently specing a build for a customer for a 427 LS3 (from a 6.2 block) that should have impressive numbers, but it's not a big block, and if you stroke a big block, watch out, 496, 540, 632, whatever you want, torque monster or high RPM powerhouse. Look at the new ZZ632 for example, 1000 hp, you will not get that out of a naturally aspirated pump gas LS motor, you would need race gas or a power adder. And you could do the same to the big block....
Click to expand...
Preach on Brother! Well put.
 
I am going to post a link and image because I have to give the guy credit for showing this comparison. This one image is a pretty good summary of what happens with a stock 454 vs a stock 6.0, then a mild 408 LS vs a mild 489 BBC. Just as long as you keep in mind most of Richard's comparisons are done from previously dyno'd engines. So they weren't really built specifically for each comparison test he comes up with, therefore, they could have been improved upon for the intended purpose. Neither stroker engine had optimum heads for low end torque production for example. As long as you keep this in mind, the data is interesting, just remember, it's rarely optimized for the test, results could change. I frequently see funny comparisons on that channel for this reason, a major advantage given to one engine vs the other because that's what they had. In this case, I think they both had a slight disadvantage and it still shows a good illustration. At 3000 RPM, the 489 has 80 lb-ft more than the 408, and its likely worse at 2000 RPM where you might cruise down the highway with a load. (at least with a good engine and not one that needs to downshift to 3K or 4K).

In this case I think this one screen shot sums it up pretty well from the 15:09 mark....

Mild 489 (cam, heads, intake)
Mild 408 (cam, heads, intake)
stock 454
stock 6.0

Ignore the "power", those are all torque numbers...as it was a "truck torque" engine test...

1639495640163.png

They also had a stroker 555 in there that made ~700 lb-ft and ~700 HP, another step up, but that requires stroking a 502 block, not a production 454 block, I think that's why he left it out.

It also shows you how choked a factory big block 454 truck motor is, look how fast it falls off above 4k, just so choked. With the right valvetrain and head flow the 454 would stay above the 6.0 the entire RPM range. In fact, if you put heads, cam, and intake on the stock 454 bottom end, it could be above the 408 pretty easy.

It was from this video...

 
Last edited:
My regal engine has a 4/7 swap cam in it, it's in between if you like that sort of thing. :pimp1:
 
ktmoutfront said:
What everybody seems to leave out is the most important thing.


The firing order on the LS based engines sounds wrong. :D
Click to expand...
8.1’s use the same firing order. Best thing to do is single exhaust or an x-pipe or h-pipe if you go duals. Seems to balance out the odd order. Did it on both the 5.3 and 8.1 and I think they both sounded ok.
 
I thought he meant saying the order sounded wrong, not that the actual engine itself sounds wrong.
 
nitro_rat said:
The engine does actually sound different. I can point out LS swapped vehicles by the exhaust note...
Click to expand...
They do sound odd compared to a traditional small or big block.
Keep in mind if you renumber the cylinders like a small block Ford it’s the same firing order. I remember the exhaust on Larry’s when he put the 8.1 in. He kept the system he used with the 454 and it sounded very different than the 454 it replaced. Like two separate 4 cylinder engines out of time with each other. It got a quickly installed h-pipe installed where it would fit the best. Toned it down a lot. Sounded tons better.
 
You must log in or register to reply here.

Latest Posts

Top Bottom