New GM LT6

Automotive powered airboat discussion.
Post Reply
SWAMPHUNTER45
Site Supporter - III
Site Supporter - III
Posts: 3155
Joined: Thu Nov 21, 2013 11:38 am
Location: Naturecoast, Florida

New GM LT6

Post by SWAMPHUNTER45 »

It appears that GM is planning to field a new generation small block to be designated the LT6 for 2023

333cubic inch making a reported 670hp

Using a flat plane crankshaft

https://www.holley.com/blog/post/everyt ... e=hs_email
FISHSTICKER
Southern Airboat Member
Posts: 575
Joined: Wed Aug 31, 2016 11:22 am
Location: French Settlement Louisiana

Re: New GM LT6

Post by FISHSTICKER »

I saw that too. Wicked cool.
User avatar
OneBFC
Southern Airboat Member
Posts: 681
Joined: Tue Sep 11, 2012 1:04 am

Re: New GM LT6

Post by OneBFC »

Thats a 8500 rpm engine so 3:1 reduction would be the minimum to consider. Probably need 3.7:1 to keep prop in the 2000 to 2300 range.

Definitely will sound cool.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy
CarMotorBarge
Site Supporter - I
Site Supporter - I
Posts: 968
Joined: Thu Jul 14, 2011 8:32 pm
Location: Lake Harney Woods

Re: New GM LT6

Post by CarMotorBarge »

I thought it was all about torque. There are 4 cylinder EcoTurds that make nearly that much torque at lower RPMs. :stirpot:
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
SWAMPHUNTER45
Site Supporter - III
Site Supporter - III
Posts: 3155
Joined: Thu Nov 21, 2013 11:38 am
Location: Naturecoast, Florida

Re: New GM LT6

Post by SWAMPHUNTER45 »

The point was to show a new engine coming into the GM family. I never said it was a airboat savior.

Anyone with any time in the seat knows that torque is important.
FISHSTICKER
Southern Airboat Member
Posts: 575
Joined: Wed Aug 31, 2016 11:22 am
Location: French Settlement Louisiana

Re: New GM LT6

Post by FISHSTICKER »

I'm just here to stare at the sexy intake.
One Eyed Gator
Southern Airboat Member
Posts: 1386
Joined: Wed May 30, 2007 11:33 am
Location: Ocala,Fl

Re: New GM LT6

Post by One Eyed Gator »

Looks cool but

Swamphunter45 have you seen where the starter is located "under the intake"
SWAMPHUNTER45
Site Supporter - III
Site Supporter - III
Posts: 3155
Joined: Thu Nov 21, 2013 11:38 am
Location: Naturecoast, Florida

Re: New GM LT6

Post by SWAMPHUNTER45 »

Mike they actually got that concept from Cadillac.

I’m sure there has to be a reason why they do it but it sure makes a starter replacement a pain in the butt.

The 32 valve NorthStar engines have the starter internal under the intake.

Im just really interested in the flat plane cranks. My son in law has a Shelby GT350 Mustang with a flat plane and 6 speed manual. Driving it is so different than other V8 performance cars because of the higher redline.

My LS3 car I can drive by feel and ear but the Shelby I find myself staring at the tachometer or shifting early.

Impressive engineering that should really be getting the horsepower boys excited.
User avatar
OneBFC
Southern Airboat Member
Posts: 681
Joined: Tue Sep 11, 2012 1:04 am

Re: New GM LT6

Post by OneBFC »

Its a cool engine and the sound is a main design focus on it.

That said, LS3 based engines make very similar power so I struggle to see the performance benefit personally.

Will be neat to drive a vehicle with an LT6 at some point.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy
SWAMPHUNTER45
Site Supporter - III
Site Supporter - III
Posts: 3155
Joined: Thu Nov 21, 2013 11:38 am
Location: Naturecoast, Florida

Re: New GM LT6

Post by SWAMPHUNTER45 »

670hp naturally aspirated is darn impressive.

The mid engine Vette clearly would benefit and rumor of a mid engine Camaro.

Those Mid engine Corvettes look like a Lamborghini
User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 1301
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: New GM LT6

Post by Slidin Gator »

This thread is some funny A$& $hi+ for sure, we got Swamp the torque king pushing a high rev setup and BFC saying it's not worth the extra HP. BAHAHAHAHAAHAAHAAAHAAAHA
:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

Funny thing is, airboats or hotrods, it's all about the final drive output, and that needs to be measured in Torque. In this case let's assume gear ratios are unlimited. 3 out of 3 conversations I have had this past week about gearing concluded that higher ratios produce more final drive torque, kind of a duhh... :violent1: :violent1:

Since (almost) none of us are gonna put of of these variable chamber intake, lashed for life mechanical valved, 8,500 RPM screamers on the old weekend runner in the near future, might as well do the ole paper compare.

Time for some graphs, I know you guys are missing em.

I'm gonna borrow from my on-going build thread (back ordered pistons are finally in :cheers: ).

viewtopic.php?f=48&t=73132

Assume the base case Stroked L92/LS3 making 630 Hp at 6,000 RPM. That would be the blue lines in this chart (ignore the blue PPT bubbles or read the linked thread above).

Image

Compare motor/motor.

Image

Now compare at gear:

Stroker LS3 on a 2.68 ratio (making maximum power at ~2,240 Prop RPM)
Versus:
LT6 running 3.8 gear, selected for max Hp at ~2,240 Prop RPM.

Image

Make that 4 out of 4 conversations determining that more gear = more torque. Could be a trend :dontknow: Looks like the LT6 can handle a bit more pitch on the same prop/boat.

8,500 rpm sounds like Vodoo to me, just keep it muffled please and call someone else to help sort out the harmonics from a rig running over 5K all day.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
User avatar
OneBFC
Southern Airboat Member
Posts: 681
Joined: Tue Sep 11, 2012 1:04 am

Re: New GM LT6

Post by OneBFC »

The LT6 would have more snap, thats about it.

The price of running 4200+ rpm all the time.

JMO, totally not worth it in an airboat application unless you are going for being different (can appreciate that) or the sound (which is also understandable to some).

A turbo setup would embarrass them both and the route I would obviously opt for. :toothy7: :angel4:
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy
FISHSTICKER
Southern Airboat Member
Posts: 575
Joined: Wed Aug 31, 2016 11:22 am
Location: French Settlement Louisiana

Re: New GM LT6

Post by FISHSTICKER »

But you would have the coolest looking intake at the pond.
CarMotorBarge
Site Supporter - I
Site Supporter - I
Posts: 968
Joined: Thu Jul 14, 2011 8:32 pm
Location: Lake Harney Woods

Re: New GM LT6

Post by CarMotorBarge »

And these graphs show why the torque curves from a dyno sheet should be thrown in the trash. The torque curves cause confusion and lead to incorrect conclusions. Given the data above, the LS3 will make more thrust than the LT6 below 7000 engine RPMs because it makes more HSP. The LT6 will not make more thrust below 7000 despite making more torque at the prop with the 3.8 ratio. Gears don't make an engine more powerful because more torque is made. When a gear creates more torque, what is being given up? The answer is the prop is turning slower and is actually making less thrust. A gear just allows you to get in the engine's power band for a given prop. Nothing else.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 1301
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: New GM LT6

Post by Slidin Gator »

CMB,

I'm definitely confused, the LS3 as shown never makes more power or torque above or below 7,000 RPM.
CarMotorBarge wrote:
Wed Nov 17, 2021 10:29 pm
Given the data above, the LS3 will make more thrust than the LT6 below 7000 engine RPMs because it makes more HSP.
CarMotorBarge wrote:
Wed Nov 17, 2021 10:29 pm
The LT6 will not make more thrust below 7000 despite making more torque at the prop with the 3.8 ratio.
The LT6 would spin up faster and maybe have an edge at the top end, that's what the last graphs tells me.

I think BFC was able to see through my smart assed :fishing :stirpot: expedition fairly clearly.

OneBFC wrote:
Mon Nov 15, 2021 9:23 pm
The LT6 would have more snap, thats about it.

The price of running 4200+ rpm all the time.

JMO, totally not worth it in an airboat application unless you are going for being different (can appreciate that) or the sound (which is also understandable to some).

A turbo setup would embarrass them both and the route I would obviously opt for. :toothy7: :angel4:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
CarMotorBarge
Site Supporter - I
Site Supporter - I
Posts: 968
Joined: Thu Jul 14, 2011 8:32 pm
Location: Lake Harney Woods

Re: New GM LT6

Post by CarMotorBarge »

The second graph containing the HSP curves clearly shows the LT6 makes more power above 7000 RPMs and would have an advantage at the top end. How does the third graph show this? My entire point is the third graph is misleading.

BTW, the LS3 would have better snap than the LT6 below 7000 engine RPMs.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
User avatar
kwanjangnihm
Site Supporter - IV
Site Supporter - IV
Posts: 2287
Joined: Sat Mar 30, 2013 8:23 pm
Location: Bartow FL

Re: New GM LT6

Post by kwanjangnihm »

Image
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.
User avatar
OneBFC
Southern Airboat Member
Posts: 681
Joined: Tue Sep 11, 2012 1:04 am

Re: New GM LT6

Post by OneBFC »

Such a good meme. Thanks for posting it again. The "heart AC guys" is brilliant.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy
User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 1301
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: New GM LT6

Post by Slidin Gator »

As Kwan states, there are different ways of making torque. This seems like a good comparison to use in making that point.
CarMotorBarge wrote:
Thu Nov 18, 2021 6:46 am
The second graph containing the HSP curves clearly shows the LT6 makes more power above 7000 RPMs and would have an advantage at the top end. How does the third graph show this? My entire point is the third graph is misleading.

BTW, the LS3 would have better snap than the LT6 below 7000 engine RPMs.
You must be trolling me :shock: . That or you missed the point that the torque & RPM figures are at the prop and the two engines are on significantly different gear ratios.

But I don't want to mis-lead the folks that only look at Hp curves. The graph below compares engine Hp vs. Prop RPM. I tweaked the imaginary gear box on the LT6 to use a 3.65 ratio to set it's 8,500 RPM power peak to 2,330 RPM at the prop. This is to match the 6,250/2,330 RPM power peak of the stroker with a 2.68 gear.

Image

The LT6 / 3.65 gear spins up faster and turns more pitch vs. the LS3 Stroker / 2.68 combo, it makes more torque and therefore more power across the prop operating range.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
CarMotorBarge
Site Supporter - I
Site Supporter - I
Posts: 968
Joined: Thu Jul 14, 2011 8:32 pm
Location: Lake Harney Woods

Re: New GM LT6

Post by CarMotorBarge »

I love that graph of HSP to Prop RPM. 8) Looks like I was incorrect about the snap from the LT6. So the low torque higher HSP LT6 has more snap everywhere and makes more thrust than the high torque lower HSP LS3. Looks like I am going to continue focusing on HSP over low end torque when building an airboat engine. :stirpot: :stirpot: :stirpot: :stirpot:
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 1301
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: New GM LT6

Post by Slidin Gator »

CarMotorBarge wrote:
Tue Nov 23, 2021 8:13 am
I love that graph of HSP to Prop RPM. 8) Looks like I was incorrect about the snap from the LT6. So the low torque higher HSP LT6 has more snap everywhere and makes more thrust than the high torque lower HSP LS3. Looks like I am going to continue focusing on HSP over low end torque when building an airboat engine. :stirpot: :stirpot: :stirpot: :stirpot:
Like I said in my initial post, this thread has me :lol: :lol: because it turns everyone's pre-conceived notions upside down. The torque king Swamp started it (pretty much on purpose I am sure) and Mr. Low Torque High Rev CMB hated it.:lol: :lol: :lol:

All good CMB, about time I got a thumbs up from you on a graph :cheers:

Just to be clear, the torque and Hp curves give the same information, just from a different perspective. I find the torque curve more useful for comparison of combos. HP figures give you the history, Torque is all about the now :dontknow:

For direct comparison, here is the torque curve at the same 3.65 ratio.

Image



Here is the previous Hp curve repeated from above at 3.65 ratio

Image




I highly encourage you to SPIN that Low Torque parts puker you are building and I question if 2.88 gear is enough :slap: I do think you need to consider IHRA 10.99 or faster rules and add a diaper to the future barge. When it blows, I'm sure my High Torque machine will be able to blow in and tow you out on the sheen alone. :stirpot: :stirpot: :stirpot: :stirpot:

https://www.racepbir.com/ihra-tech-rules-for-racers
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.
CarMotorBarge
Site Supporter - I
Site Supporter - I
Posts: 968
Joined: Thu Jul 14, 2011 8:32 pm
Location: Lake Harney Woods

Re: New GM LT6

Post by CarMotorBarge »

I agree the torque is all about the now. This is my issue with looking at just torque. The HSP isn't about the past. It is all about the now and the future as the engine revs higher. It takes HSP to make thrust. 8)

BTW, the engine diaper should be used by A/C engines since they leak so much oil and constantly puke cylinders. :stirpot: :stirpot: :stirpot:
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
User avatar
kwanjangnihm
Site Supporter - IV
Site Supporter - IV
Posts: 2287
Joined: Sat Mar 30, 2013 8:23 pm
Location: Bartow FL

Re: New GM LT6

Post by kwanjangnihm »

CMB & CM Guys don't miss the Cyber Monday Sale today!! :stirpot: :stirpot: :stirpot: :stirpot:

torque.JPG
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.
User avatar
Deano
Site Supporter - V
Site Supporter - V
Posts: 4670
Joined: Thu Jan 06, 2005 11:16 am
Location: Inverness, FL

Re: New GM LT6

Post by Deano »

Really, Kwan . . . You desperately need to upgrade your firmware.
Sometimes looks like you didn't even get a manual with that thing. :D

Image
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan
Post Reply

Return to “Automotive Power Only”