Quote from: Soup DeVille on September 28, 2018, 06:38:40 AM
on an inline engine, yes. Now add another set of pistons on the same journals at 90 degrees to the first set.

Each bank will have the same balance as an inline 4 (which is balanced in the 1st order).  If neither bank has a first order imbalance, then the entire engine is balanced in the first order.  0 + 0 = 0.

90 degree V piston pairs have primary balance. L2s and L4s don't have balance shafts

Quote from: 12,000 RPM on September 28, 2018, 07:33:11 AM
90 degree V piston pairs have primary balance. L2s and L4s don't have balance shafts

Not quite right.  Else a 90-degree V6 would have primary balance (which it doesn't, by a long shot).  Lacking a balance shaft doesn't mean an engine is balanced, or that it wouldn't benefit from balance shafts.  Lots of I4s don't have them.  Lots of I2s don't have them.

L2s use heavy crankshaft counterweights to balance out the pistons.  The reciprocating masses of the pistons/rods alone are not balanced.

Quote from: MX793 on September 28, 2018, 04:48:35 AM
You're falling into the trap of judging an engine by peak power alone.  And judging a performance car exclusively by it's 0-60/1/4-mile time.  In the element it was designed to shine in, a GT350 will walk away from a Camaro SS.  That element is not a drag race from a dead dig.

I'd also point out that a 505 hp, $75K 5th gen Z/28, powered by your beloved LS7, is also unable to walk a $37K, 455 hp 6th gen SS in a 0-60 or 1/4 mile Sprint.

Not at all, I look at motor speed/torque curves for a living, and have done so for my entire career.

Ford chose to sacrifice performance for marketing but at the end of it all Ford spent a ton of $$$ on a motor that is at best at parity with the 12+ year-old pooprod LS7.

Attempt at relativism will not gloss over Ford's technical shortcomings.

Watched a video on the mid-engine 'Vette where you can listen to the sound it makes, and I found it disappointing. It sounds like a muscle car or a slightly muffled Nascar racer. Appropriate for a Camaro or Mustang, but not a mid-engine quasi-exotic. Too bad Chevy didn't develop a high-revving flat crank engine for it.

No way... it would make 3 less HP and require a complete redesign

Quote from: Rockraven on September 28, 2018, 12:03:54 PM
Watched a video on the mid-engine 'Vette where you can listen to the sound it makes, and I found it disappointing. It sounds like a muscle car or a slightly muffled Nascar racer. Appropriate for a Camaro or Mustang, but not a mid-engine quasi-exotic. Too bad Chevy didn't develop a high-revving flat crank engine for it.

You mean like a modern, high tech, high stressed engine?

Quote from: GoCougs on September 27, 2018, 11:28:36 AM
Why wouldn't HP/TQ/NVH matter?

Here the owner spent a fortune on it and ended up with a less powerful, less useful (power band) motor than the LS7 the car originally came with. The GT350/R has some of the same issues - too much complexity for too little power and usefulness.

In this day and age, to make this work, you need VVT and VVL, a la Ferrari.

It's a 5.3 liter compared to the C6's 7.0 liter LS7 -
It also has 570hp vs 505hp for the LS7.

Oh, and the car is for sale for 30K. Engine work couldn't be that much.

Number one rule of (non-historic) project car finances; you never get out of it what you put into it.

Quote from: Char on September 28, 2018, 02:13:32 PM
It's a 5.3 liter compared to the C6's 7.0 liter LS7 -
It also has 570hp vs 505hp for the LS7.

Oh, and the car is for sale for 30K. Engine work couldn't be that much.

5.3L LS is the exact same physical size as the LS7 however.

560 hp is an engine dyno number, which is ~15% or so more than SAE net (or about 560 hp = ~480 hp SAE net vs. the LS7's 505 hp SAE net).

Engine work is AT LEAST that much. I'm seeing at least $20k in the block, crank and rods.

Quote from: GoCougs on September 28, 2018, 08:12:02 PM
5.3L LS is the exact same physical size as the LS7 however.

560 hp is an engine dyno number, which is ~15% or so more than SAE net (or about 560 hp = ~480 hp SAE net vs. the LS7's 505 hp SAE net).

Engine work is AT LEAST that much. I'm seeing at least $20k in the block, crank and rods.

Where did you pull that 15% number from? He said 560hp, which could have been extrapolated from a chassis dyno (which can absolutely be SAE corrected)

So...you're still wrong on this one.

Quote from: Char on September 29, 2018, 09:18:12 AM
Where did you pull that 15% number from? He said 560hp, which could have been extrapolated from a chassis dyno (which can absolutely be SAE corrected)

So...you're still wrong on this one.

Without knowing the exact rotational inertia of the wheels, tires, brakes, driveline components, and the friction in the drivetrain, there's no way a chassis dyno can accurately tell you what your crank HP is.

Quote from: MX793 on September 29, 2018, 09:54:44 AM
Without knowing the exact rotational inertia of the wheels, tires, brakes, driveline components, and the friction in the drivetrain, there's no way a chassis dyno can accurately tell you what your crank HP is.

Yeah but if it's 560 at the wheels it's gonna be more at the crank... So that would ruin Cougs' point.

Quote from: CaminoRacer on September 29, 2018, 10:50:07 AM
Yeah but if it's 560 at the wheels it's gonna be more at the crank... So that would ruin Cougs' point.

560 at the wheels is going to be 660+ at the crank.  No way a 5.3L 2-valve is making that kind of power and still being remotely streetable.

Quote from: Char on September 29, 2018, 09:18:12 AM
Where did you pull that 15% number from? He said 560hp, which could have been extrapolated from a chassis dyno (which can absolutely be SAE corrected)

So...you're still wrong on this one.

Oh, this could get very good .

15% is a rough approximation from gross to net (more like 10-15%).

lol - no one advertises their hotrod project in SAE net.

If it were a chassis dyno number, it would have been quoted as 560 rwhp. Something so customized spent many hours on an engine dyno to make work.

SAE correction factors are approximations (not a test protocol to net) plus of course chassis dynos are laughably inaccurate.

Quote from: MX793 on September 29, 2018, 11:31:36 AM
560 at the wheels is going to be 660+ at the crank.  No way a 5.3L 2-valve is making that kind of power and still being remotely streetable.

Oops.

Quote from: MX793 on September 29, 2018, 11:31:36 AM
560 at the wheels is going to be 660+ at the crank.  No way a 5.3L 2-valve is making that kind of power and still being remotely streetable.

True. I've never seen an LS under 7.0L making that much without boost.

Quote from: CaminoRacer on September 29, 2018, 01:43:57 PM
True. I've never seen an LS under 7.0L making that much without boost.

https://www.enginelabs.com/engine-tech/engine/efi-universitys-9500-rpm-destroked-ls-how-much-will-it-make/


:D

Oh, yes, plenty of super hi output sub 7L LS motors are out there for sure - just takes cam + heads + rpm. Streetability is question at some point though. Thing is, what with mega inch LS blocks available off the shelf there is no real need I see - a moderate build of the LSX454 nets a (gross ) 627 hp at a very streetable 6,300 RPM.

I'm in Sporty's camp on this: the positive of the thrilling glorious sound excuses the guy's insane irrational burning of vast wads of cash... that should have gone into his children's education, or his tax-deferred retirement plans.

My best friend's engineer father-in-law performed surgery on his little 1950s home so he could install a full-sized Wurlitzer movie theater organ. It went through two floors.

Sometimes it's about FPC V8s, or maybe cinema organs, or perhaps CR-Vs: it's always about the passion.

Quote from: GoCougs on September 29, 2018, 10:20:46 PM
Oh, yes, plenty of super hi output sub 7L LS motors are out there for sure - just takes cam + heads + rpm. Streetability is question at some point though. Thing is, what with mega inch LS blocks available off the shelf there is no real need I see - a moderate build of the LSX454 nets a (gross ) 627 hp at a very streetable 6,300 RPM.

Considering that the difference between gross and net is roughly 25%, that's well less than an LS7.

This thread reminds me of when someone posts a pic of an attractive female celebrity, and some chowderhead starts talking that "IDK I couldn't marry her" nonsense. Guys, it's a flat plane LS motor... there is really not much to think about here. Streetability? Efficiency? Cost effectiveness? Who takes on a project like this for any of that shit? What the fuck are we talking about here? Even Mr. Honda Hybrid Enthusiast can be happy and irrational about this. Come on guys

Like I said; I like the motor. I don't see why its in a basically stock Corvette body and chassis though.

It would be awesome in something like a C5R or GT40 replica.

Or a Cobra replica. Or a Miata

As for why it's in a stock Corvette.... projects like this usually don't start from a logical place

Quote from: MX793 on September 30, 2018, 05:40:52 AM
Considering that the difference between gross and net is roughly 25%, that's well less than an LS7.

Nah - gross-to-net loss is in the aforementioned range of 10-15% as told by near-infinite engine dyno sheets out there, LS7, LS3, Coyote, etc., so the LSX 454 in that build config is mos def more powerful than the LS7 by 50-60 hp (gross).

The LSX454 isn't just only about power. It is designed specifically as a crate motor for the aftermarket, bound to be produced for far longer than the designed-for-a-production-car LS7 (yet no longer used in a production car).

I'm sure the torque curve of the 454 is way fatter too.

Quote from: GoCougs on September 30, 2018, 12:39:15 PM
Nah - gross-to-net loss is in the aforementioned range of 10-15% as told by near-infinite engine dyno sheets out there, LS7, LS3, Coyote, etc., so the LSX 454 in that build config is mos def more powerful than the LS7 by 50-60 hp (gross).

The LSX454 isn't just only about power. It is designed specifically as a crate motor for the aftermarket, bound to be produced for far longer than the designed-for-a-production-car LS7 (yet no longer used in a production car).

'71 to '72 Corvette powertrains were identical other than gross to net ratings.  The drop was ~25%.  Same with '71 to '72 Mustangs and pretty much everything else when net HP ratings showed up in '72.

The SAE net in '71 was a different test, procedurally than it is now; and a lot of driveline changes since then as well. It also wasnt flywheel hp as we understand it, but gross horsepower, where not even parasitic losses like the alternator and power steering pump weren't counted.

Quote from: Soup DeVille on September 30, 2018, 01:39:05 PM
The SAE net in '71 was a different test, procedurally than it is now; and a lot of driveline changes since then as well. It also wasnt flywheel hp as we understand it, but gross horsepower, where not even parasitic losses like the alternator and power steering pump weren't counted.

In '71, manufactures were using SAE Gross (no accessories, no air cleaners, test pipes, special oils, etc) and then in '72 had to switch to SAE net (engine dressed as it would be in a production car), which is how motors are rated today.  Crate motors, however, still generally use SAE gross.

Quote from: MX793 on September 30, 2018, 01:48:59 PM
In '71, manufactures were using SAE Gross (no accessories, no air cleaners, test pipes, special oils, etc) and then in '72 had to switch to SAE net (engine dressed as it would be in a production car), which is how motors are rated today.  Crate motors, however, still generally use SAE gross.

How does this differ from what I said? (they were of course testing and building 1972 models in 1971)

The SAE standard has also changed in that time (inertial dynos didn't even exist)