LT4 vs LT1
Thread Starter
Instructor
Joined: May 2003
Posts: 162
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From: fort mill sc
LT4 vs LT1
My friend owns a '96 LT4 6 speed and I own a '95 LT1 automatic. The LT4 is listed at 330 hp at 5800 rpm vs the 300 hp LT1 at 5000 rpm. Which car has a faster top speed?
Also is the LT4 actually a stronger engine? Can the LT4 see 5800 rpm practically at top speed?
Also is the LT4 actually a stronger engine? Can the LT4 see 5800 rpm practically at top speed?
Le Mans Master
Joined: Oct 2000
Posts: 6,199
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From: St. louis, MO
Re: LT4 vs LT1 (rmd8136)
Maybe this will help: http://corvetteactioncenter.com/specs/1996/lt1lt4.html
Team Owner
Joined: Sep 2001
Posts: 62,139
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: LT4 vs LT1 (rmd8136)
LT4 would probably have the higher top speed, but dont remember if anyone has even tried testing that.
LT4 is rated at 330, but actually puts 300 at the rear wheels, which makes it more like 345-350 at the crank.
GM underrated it, so as not to **** off C5 owners who had the 345hp LS1 in 97.
LT4 is rated at 330, but actually puts 300 at the rear wheels, which makes it more like 345-350 at the crank.
GM underrated it, so as not to **** off C5 owners who had the 345hp LS1 in 97.
Burning Brakes
Joined: Feb 2002
Posts: 871
Likes: 1
From: Union KY
Re: LT4 vs LT1 (rmd8136)
First piece of advise: Don't race your friend. His 330 HP number is actually a conservative measure. His LT4 will likely dino 300 at the rear wheels. And yes, (assuming he's gutsy/crazy enough) it will pull the red line in fifth gear, topping out in the 170+ range.
The LT4 was created by GM in 1996 as a way to insure that the last year of the C4 run would sell in light of everyone's knowledge that the LS1 was a 345 HP engine.
It was built on the LT1 block, with modifications to the crank (to make it stay together at 6,300 RPM's....was given a bigger cam, 1.6:1 ratio Crane roller rockers, and different heads. After the GM engineers finished up, they found that the engine overshot the + 30 HP goal, so they installed a set of intake maniffold gaskets that block a portion of the intake ports. Replace those with the non blocking variety, and it'll dino past the early LS1's numbers.
Hope this answers your questions. Cire96
The LT4 was created by GM in 1996 as a way to insure that the last year of the C4 run would sell in light of everyone's knowledge that the LS1 was a 345 HP engine.
It was built on the LT1 block, with modifications to the crank (to make it stay together at 6,300 RPM's....was given a bigger cam, 1.6:1 ratio Crane roller rockers, and different heads. After the GM engineers finished up, they found that the engine overshot the + 30 HP goal, so they installed a set of intake maniffold gaskets that block a portion of the intake ports. Replace those with the non blocking variety, and it'll dino past the early LS1's numbers.
Hope this answers your questions. Cire96
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
Re: LT4 vs LT1 (cire96)
After the GM engineers finished up, they found that the engine overshot the + 30 HP goal, so they installed a set of intake maniffold gaskets that block a portion of the intake ports. Replace those with the non blocking variety, and it'll dino past the early LS1's numbers.
Hope this answers your questions. Cire96
Hope this answers your questions. Cire96
If you look close in the photo below, you can see how much material I removed from the intake to match the "77" gasket. There's still a lot more to remove from both the intake and the cylinder heads to precisely match the ports.
Stock, as delivered, production intake gaskets and all LT4s consistently dyno 290 - 305, which is roughly 340-350 at the flywheel. Mine was an even 300, down to the paper air filter element.
During the ZR-1/GS Gathering at the NCM a couple years ago, John Heinricy said the LT4 was a legitimate 350 hp engine as delivered. It was a Marketing decision to advertise it as 330hp. No mods were made to the engines to "detune" them.
Safety Car
Joined: Feb 2000
Posts: 4,230
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From: VA
Cruise-In II Veteran
Re: LT4 vs LT1 (96GS#007)
After the GM engineers finished up, they found that the engine overshot the + 30 HP goal, so they installed a set of intake maniffold gaskets that block a portion of the intake ports. Replace those with the non blocking variety, and it'll dino past the early LS1's numbers.
Hope this answers your questions. Cire96
:bs Swap from the stock p/n 12528884 gasket to the GMPP p/n 12367777 gasket and you'll get the same hp result. Why? Not only does the gasket block the port on the cylinder head, but so does the INTAKE manifold. That's right folks, the ports are not matched even though the LT4 has a specific intake.
If you look close in the photo below, you can see how much material I removed from the intake to match the "77" gasket. There's still a lot more to remove from both the intake and the cylinder heads to precisely match the ports.
Stock, as delivered, production intake gaskets and all LT4s consistently dyno 290 - 305, which is roughly 340-350 at the flywheel. Mine was an even 300, down to the paper air filter element.
During the ZR-1/GS Gathering at the NCM a couple years ago, John Heinricy said the LT4 was a legitimate 350 hp engine as delivered. It was a Marketing decision to advertise it as 330hp. No mods were made to the engines to "detune" them.
Hope this answers your questions. Cire96
:bs Swap from the stock p/n 12528884 gasket to the GMPP p/n 12367777 gasket and you'll get the same hp result. Why? Not only does the gasket block the port on the cylinder head, but so does the INTAKE manifold. That's right folks, the ports are not matched even though the LT4 has a specific intake.
If you look close in the photo below, you can see how much material I removed from the intake to match the "77" gasket. There's still a lot more to remove from both the intake and the cylinder heads to precisely match the ports.
Stock, as delivered, production intake gaskets and all LT4s consistently dyno 290 - 305, which is roughly 340-350 at the flywheel. Mine was an even 300, down to the paper air filter element.
During the ZR-1/GS Gathering at the NCM a couple years ago, John Heinricy said the LT4 was a legitimate 350 hp engine as delivered. It was a Marketing decision to advertise it as 330hp. No mods were made to the engines to "detune" them.
So go ahead and just change that gasket, i heard it will give you 30+ HP as stated by some. :lol:
[Modified by ConeKLR, 6:30 PM 5/14/2003]
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