LT1/LT4 engine intergity?
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Instructor
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From: Houston TX
LT1/LT4 engine intergity?
I'm pretty sure the LT1/LT4 use the same block and crankshaft or am I mistaken?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
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From: DFW TX
I'm pretty sure the LT1/LT4 use the same block and crankshaft or am I mistaken?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
The LT1 does have a forged crank and rods, but the pistons are not and that makes them the weak link in the LT1. Without changing the pistons people are running about 700 wheel and <10psi of boost. With forged pistons the sky is kind of the limit. All kinds of cars out there just with the forged drop ins making 900-1100 to the tire. Stock block, stock crank, stock rods, just drop in forged pistons.
The LT4 seems to just be everything we wanted in the LT1 when it comes to the short block
. Everything is forged, and there are many many 1000+ rear wheel cars out there. The issues you're going to run into at 1000+ HP is fuel delivery, not can the physical rotating assembly take it.
Last edited by C7&7; Oct 5, 2016 at 11:45 AM.
Thread Starter
Instructor
Joined: May 2012
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From: Houston TX
Yeah I've seen all that info but thanks. Mainly want to know has anyone broken a stock crank yet if so what power level? Has anyone cracked the stock sleeves or block yet and at what power level? Yeah so far I am gathering most of the shops ARENT needing to sleeve these motors to make decent power (1100-1200whp)
I come from the mod world (coyote) and in order to make over 1000whp with the coyotes you need to sleeve the motors at which point ur gonna be fine to make 1500+whp without fear of pushing through the water jackets. Same with the OEM cranks, they are solid units and can handle a lot of rpm and power.
I come from the mod world (coyote) and in order to make over 1000whp with the coyotes you need to sleeve the motors at which point ur gonna be fine to make 1500+whp without fear of pushing through the water jackets. Same with the OEM cranks, they are solid units and can handle a lot of rpm and power.
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You shouldn't have a problem with block integrity and the crankshaft is strong, but I would advise an arp main stud kit. GM has had problems with the main caps moving. If you're interested in 1500 horsepower, I would still go ahead and do a full rotating assembly, especially if boost is the way you want to go. Get a nice lower compression rotating assembly and have those rings gapped right for boost. It's not that you necessarily have to but LT engines are so much cheaper to build than mod motors, I would just go ahead and do it the right way, especially if we're talking the LT1. having said all that, I've not heard of any crankshaft breakage or block breakage at any power level. I have witnessed the main cap issue though, at high levels.
Thread Starter
Instructor
Joined: May 2012
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From: Houston TX
You shouldn't have a problem with block integrity and the crankshaft is strong, but I would advise an arp main stud kit. GM has had problems with the main caps moving. If you're interested in 1500 horsepower, I would still go ahead and do a full rotating assembly, especially if boost is the way you want to go. Get a nice lower compression rotating assembly and have those rings gapped right for boost. It's not that you necessarily have to but LT engines are so much cheaper to build than mod motors, I would just go ahead and do it the right way, especially if we're talking the LT1. having said all that, I've not heard of any crankshaft breakage or block breakage at any power level. I have witnessed the main cap issue though, at high levels.
Le Mans Master
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From: League City Tx
There is a lot of discussion on this here on the forum.
The LT1 does have a forged crank and rods, but the pistons are not and that makes them the weak link in the LT1. Without changing the pistons people are running about 700 wheel and <10psi of boost. With forged pistons the sky is kind of the limit. All kinds of cars out there just with the forged drop ins making 900-1100 to the tire. Stock block, stock crank, stock rods, just drop in forged pistons.
The LT4 seems to just be everything we wanted in the LT1 when it comes to the short block. Everything is forged, and there are many many 1000+ rear wheel cars out there.
The issues you're going to run into at 1000+ HP is fuel delivery, not can the physical rotating assembly take it.
The LT1 does have a forged crank and rods, but the pistons are not and that makes them the weak link in the LT1. Without changing the pistons people are running about 700 wheel and <10psi of boost. With forged pistons the sky is kind of the limit. All kinds of cars out there just with the forged drop ins making 900-1100 to the tire. Stock block, stock crank, stock rods, just drop in forged pistons.
The LT4 seems to just be everything we wanted in the LT1 when it comes to the short block
. Everything is forged, and there are many many 1000+ rear wheel cars out there. The issues you're going to run into at 1000+ HP is fuel delivery, not can the physical rotating assembly take it.
Basically, the LS9 from the ZR1 got all of the good ****.... they cheaped out on the LT1/LT4...
That being said, I'm sure LT1 and LT1 crank will handle 900 rwhp pretty easy..
There are quite a few 900-1000 rwhp LT4s running around..Hell a couple at 1200+ on stock bottom end, but probably time bombs.
Last edited by ajrothm; Oct 11, 2016 at 03:54 AM.
Le Mans Master
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From: League City Tx
I'm pretty sure the LT1/LT4 use the same block and crankshaft or am I mistaken?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
Can anyone shed some light on what the LT1/LT4 blocks strengths and weaknesses are? What rwhp can a stock displacement, stock sleeved LT1/LT4 motor with upgraded forged internals hold before needing aftermarket sleeves?
What about the stock crankshaft, is that unit fine for 1300+whp with a blower or does everyone move to an aftermarket crank at those power levels?
NO WAY would I try to make 1300 rwhp on a stock forged crank spinning a blower... You will flex it for sure.
Hell I flexed a Callies Compstar 4340 4" crank at less then 900 rwhp spinning an F1R in an LS. You're gonna need a DragonSlayer to safely support 1300 rwhp spinning a blower.... (remember, its gonna take 250hp+ to spin the blower, plus the drivetrain losses...so you are talking 1700+ crank HP)
As far as the block is concerned, that has been several LT4 blocks making 1100+ rwhp (with a blower) so the blocks seem pretty strong.
I think I would go with a stock stroke Dragonslayer or even a Billet crank in a stock LT4 block to make 1300rwhp...and ofcourse Ultra Billet rods and forged pistons.
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The rods are not forged in either the LT1 or LT4. They are powder metal rods. The PM rods in the LT4 are different and have extra machining on them. The LT4 also has a different forging on the crank and does have forged pistons. The LT1 has hypereutectic pistons, PM rods and forged crank. The LT1 also has a bigger camshaft.
Basically, the LS9 from the ZR1 got all of the good ****.... they cheaped out on the LT1/LT4...
That being said, I'm sure LT1 and LT1 crank will handle 900 rwhp pretty easy..
There are quite a few 900-1000 rwhp LT4s running around..Hell a couple at 1200+ on stock bottom end, but probably time bombs.
Basically, the LS9 from the ZR1 got all of the good ****.... they cheaped out on the LT1/LT4...
That being said, I'm sure LT1 and LT1 crank will handle 900 rwhp pretty easy..
There are quite a few 900-1000 rwhp LT4s running around..Hell a couple at 1200+ on stock bottom end, but probably time bombs.
Last edited by david.a8.z51; Oct 12, 2016 at 12:27 AM.
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Incorrect. The rods are "forged powder metal". While they are indeed powder metal, they are still forged.
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And this is the same forged powder metal technology that GM has been using for the connecting rods in its Duramax line of diesel engines and they hold up very well in that environment. A diesel engine with its abrupt rise in cylinder pressure puts far more stress on rods than a gasoline powered engine; especially a turbo-diesel V8 generating 910 foot pounds of torque.
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NO WAY would I try to make 1300 rwhp on a stock forged crank spinning a blower... You will flex it for sure.
Hell I flexed a Callies Compstar 4340 4" crank at less then 900 rwhp spinning an F1R in an LS. You're gonna need a DragonSlayer to safely support 1300 rwhp spinning a blower.... (remember, its gonna take 250hp+ to spin the blower, plus the drivetrain losses...so you are talking 1700+ crank HP)
As far as the block is concerned, that has been several LT4 blocks making 1100+ rwhp (with a blower) so the blocks seem pretty strong.
I think I would go with a stock stroke Dragonslayer or even a Billet crank in a stock LT4 block to make 1300rwhp...and ofcourse Ultra Billet rods and forged pistons.
Hell I flexed a Callies Compstar 4340 4" crank at less then 900 rwhp spinning an F1R in an LS. You're gonna need a DragonSlayer to safely support 1300 rwhp spinning a blower.... (remember, its gonna take 250hp+ to spin the blower, plus the drivetrain losses...so you are talking 1700+ crank HP)
As far as the block is concerned, that has been several LT4 blocks making 1100+ rwhp (with a blower) so the blocks seem pretty strong.
I think I would go with a stock stroke Dragonslayer or even a Billet crank in a stock LT4 block to make 1300rwhp...and ofcourse Ultra Billet rods and forged pistons.
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From: London Canada
Typical PM parts are cold pressed.
Sintered (not to be confused with forged) are formed by pressing a preheated powdered metal
POWDER FORGING is a process in which unsintered, presintered, or sintered powder metal preforms are hot formed in heated confined dies.
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From: cookeville tennessee
Robert
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You shouldn't have a problem with block integrity and the crankshaft is strong, but I would advise an arp main stud kit. GM has had problems with the main caps moving. If you're interested in 1500 horsepower, I would still go ahead and do a full rotating assembly, especially if boost is the way you want to go. Get a nice lower compression rotating assembly and have those rings gapped right for boost. It's not that you necessarily have to but LT engines are so much cheaper to build than mod motors, I would just go ahead and do it the right way, especially if we're talking the LT1. having said all that, I've not heard of any crankshaft breakage or block breakage at any power level. I have witnessed the main cap issue though, at high levels.
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From: Lehigh Acres FL
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You are both right. Rods are “sort of” forged lol. They are forged powder metal. Reliable up to about 850 rwhp.