LS427/570 vs LS376/525 (LS3 vs LS7)

[wesinls]

Anyone running an LS427/570 crate engine?  One of the downsides I've heard from people on the LS7 is the need for a dry sump, however, this crate engine from GM comes with and LS3 wet sump system.

LS427/570 Crate Engine | Chevy Performance Parts (chevrolet.com)

I already ordered the below LS376/525, but am now wondering if I should switch to the LS7 above?  Looks like the LS7 is also more readily available potentially...

More people have the LS3 of course, but hmm...

LS376/525 Crate Engine | Chevy Performance Parts (chevrolet.com)

 

[Dzrtrat1111]

I can’t speak for the Ls7 cause I have the LS376/525. It’s a great engine, that dyno’d 404hp to the wheels at CBM IN A 3500lb car on 37’s. I would like a bit more power though. The LS7 will probably give you more bottom end with the bigger displacement. 
 

Crate engine prices have really gone up since I bought mine 3 years ago!

 

[tjZ06]

45 HP might not seem like a lot, but the 54 lbs-ft TQ difference (at 400 lower RPM) I think would be noticeable.  Overall, the LS7 will give more power potential down the road, should you choose to step it up down the road.  Keep in mine the LS7 heads are unique and intakes don't swap with either the cathedral port motors (LS1/2/6) or the more common rectangular port stuff (LS3/9/A).  LS7 heads flow crazy well, but they were known for dropping valves due to worn valve-guides in C6Zs, I assume that has been addressed with newer crate motors. 

-TJ

 

[Fullthrottleguy]

The old saying holds true "there is No Replacement for Displacement" as others have said its not the HP its the TQ - Torque moves the mass  - HP just keeps it moving 

Forget looking at the MAX HP and TQ numbers - look at the "power under the curve" the usable TQ and HP numbers (the Dyno graph)  they will tell the story how they perform

I agree with @tjZ06 on LS7 heads -but I think the crate engines and lower redlines fixed that issue. But the potential for HP in the Future (you will always tire of how much you have) is greater with more CU  and quite frankly the "parts" in the LS7 are just better from the Block up - the LS3 block is no way as robust and the LS7 is made to be abused - the Rods are better material, the pistons are better material.  

The downside of the LS7 Crate is that the cam is a little too aggressive for cruising the dunes unless you have a slightly lower gear ration unlike the Corvette version its low speed manners are a bit rough

Do Not believe anything you hear abut the dry sump being needed - of course a race inspired Dry sump (aftermarket) is always better to handle off camber duning - but it was done for ground clearance, massive side load G's in turns and just balance in the corvette

IMO you will be satisfied with either.  I have done the connect and cruise version of the LS376 in a street car.  For the money it was a good runner.

However all that being said - knowing what I know about having put crate engines in sand cars and the money spent modifying them for the best outcome,  If I was going for new build for a sand car I would spend a bit more and get a specialized build with all forged internals, the right cam and head combo so the power is usable where you need it most in the dunes, a drive by cable throttle - I hate DBW in the sand personally even with pedal commanders and that non sense, some better fuel rails for a clean look and ease of setup, an F body front drive set, and an F body oil pan set up. 

That is a much better overall experience for the sand IMO

 

[Rockwood]

The old saying holds true "there is No Replacement for Displacement" as others have said its not the HP its the TQ - Torque moves the mass  - HP just keeps it moving 

Forget looking at the MAX HP and TQ numbers - look at the "power under the curve" the usable TQ and HP numbers (the Dyno graph)  they will tell the story how they perform

I agree with @tjZ06 on LS7 heads -but I think the crate engines and lower redlines fixed that issue. But the potential for HP in the Future (you will always tire of how much you have) is greater with more CU  and quite frankly the "parts" in the LS7 are just better from the Block up - the LS3 block is no way as robust and the LS7 is made to be abused - the Rods are better material, the pistons are better material.  

The downside of the LS7 Crate is that the cam is a little too aggressive for cruising the dunes unless you have a slightly lower gear ration unlike the Corvette version its low speed manners are a bit rough

Do Not believe anything you hear abut the dry sump being needed - of course a race inspired Dry sump (aftermarket) is always better to handle off camber duning - but it was done for ground clearance, massive side load G's in turns and just balance in the corvette

IMO you will be satisfied with either.  I have done the connect and cruise version of the LS376 in a street car.  For the money it was a good runner.

However all that being said - knowing what I know about having put crate engines in sand cars and the money spent modifying them for the best outcome,  If I was going for new build for a sand car I would spend a bit more and get a specialized build with all forged internals, the right cam and head combo so the power is usable where you need it most in the dunes, a drive by cable throttle - I hate DBW in the sand personally even with pedal commanders and that non sense, some better fuel rails for a clean look and ease of setup, an F body front drive set, and an F body oil pan set up. 

That is a much better overall experience for the sand IMO

I guess it depends on intended RPM.  If you like to floor it at 2000rpm and expect instant wheelspin, yep, stock Z cam is plenty aggressive.

If you want power from 3000-7000rpm to take advantage of that bottom end, aftermarket has you covered with a lot of different choices that pair well with the stock heads if you're fine with a rowdy idle and power loss below 3000.  I'm sure @tjZ06 has plenty of different favorite cams for the LS7 in mind. :biggrin:

 

[Fullthrottleguy]

I guess it depends on intended RPM.  If you like to floor it at 2000rpm and expect instant wheelspin, yep, stock Z cam is plenty aggressive.

If you want power from 3000-7000rpm to take advantage of that bottom end, aftermarket has you covered with a lot of different choices that pair well with the stock heads if you're fine with a rowdy idle and power loss below 3000.  I'm sure @tjZ06 has plenty of different favorite cams for the LS7 in mind. :biggrin:

That crate engine cam is plenty rowdy, there is a 71 Chevelle running around here with that engine, I have seen and heard it on the Dyno I use for my sand car (and yes I want it!)- the TQ curve is way too high for Duning IMO - I would actually go with a wider LSA like 120 vs the 116 the cam has now.  the Lift is low which is so typical of anything from GM crate, and duration is split which is good, but would not do as well with long tube headers where you have a good scavaging advantage  but lose Low end TQ. That cam counts on you using factory manifolds that help the low end. With these tighter LSA's and higher lift Hydraulic rollers especially using some less-pump aftermarkets like Johnsons, you can get smooth idle and still wing it out past 6200 RPM (all you nedd and makes it reliable)making power.   Most people want a choppy idle to impress their friends in the dunes -  also the reason alot of people want 8 into1's and no mufflers (that kill power) but they sound Rowdy .  Less overlap with a LS  will deliver the Mid range - the head design and manifold design is so good, I am still amazed how flat you get a TQ on a NA LS if you try. Never can do that on a SM block or Big Block, its closer to 4 Valve like the Ford 

 

[Rockwood]

That crate engine cam is plenty rowdy, there is a 71 Chevelle running around here with that engine, I have seen and heard it on the Dyno I use for my sand car (and yes I want it!)- the TQ curve is way too high for Duning IMO - I would actually go with a wider LSA like 120 vs the 116 the cam has now.  the Lift is low which is so typical of anything from GM crate, and duration is split which is good, but would not do as well with long tube headers where you have a good scavaging advantage  but lose Low end TQ. That cam counts on you using factory manifolds that help the low end. With these tighter LSA's and higher lift Hydraulic rollers especially using some less-pump aftermarkets like Johnsons, you can get smooth idle and still wing it out past 6200 RPM (all you nedd and makes it reliable)making power.   Most people want a choppy idle to impress their friends in the dunes -  also the reason alot of people want 8 into1's and no mufflers (that kill power) but they sound Rowdy .  Less overlap with a LS  will deliver the Mid range - the head design and manifold design is so good, I am still amazed how flat you get a TQ on a NA LS if you try. Never can do that on a SM block or Big Block, its closer to 4 Valve like the Ford 

Word.  Driver preference very much comes into it here.  Some want to "dune in 3rd", others like to bang rev limiter.  Dune in 3rd guy wouldn't be happy with a big Texas Speed cam just like rev limiter guy wouldn't be happy with torquier cams.  That being said, the stock LS7 cam is a pretty good compromise.  There's just a little more the aftermarket has to offer since they don't have to worry about emissions and breathing through short-runner stock manifolds.

I haven't seen a set of properly-designed long-tubes kill low end (usually give a fat bump) on anything.  Where you seeing that?

 

[Fullthrottleguy]

I haven't seen a set of properly-designed long-tubes kill low end (usually give a fat bump) on anything.  Where you seeing that?

I agree 100% with your thinking  - Driver choice and style

Regarding the long tubes ...Nature of the beast - scavaging effect  - but yea a good set of Long tubes (really long) will have a sweet Bump in the mid range ... But sand cars never have a "proper" set of long tubes at least from what I see out there - construction can be very nice, its hard to package them everything is tight if you want to keep them looking nice  .. On  street car you get to use all the  room under the floor boards and make nice feet heaters 

Most  Sand cars have tight bends right after the flange so it interrupts the swirl and then at 3 more tight turns and the headers are never equal lenght.  I did a car with a Holley and I had to add a significant amount of extra fuel in one cylinder because of the header design. I find on the "new cool design" where then header wraps tight around the water pump (and ruins it over time)  #1 and #2 are really short about 50% the length of #7 and #8, it screws with the reversion when they make them 8 into1 its sounds mean but its not ideal flow wise ...  Can you imagine packaging a equal length 40" primary long tube header like a Kooks for a Camaro (illegal in lovely CA) on a sand car ?

8 to 1 done right Ford GT40  (well that pic is not an original but still nice)



here is the original from 1964

 

[Rockwood]

I agree 100% with your thinking  - Driver choice and style

Regarding the long tubes ...Nature of the beast - scavaging effect  - but yea a good set of Long tubes (really long) will have a sweet Bump in the mid range ... But sand cars never have a "proper" set of long tubes at least from what I see out there - construction can be very nice, its hard to package them everything is tight if you want to keep them looking nice  .. On  street car you get to use all the  room under the floor boards and make nice feet heaters 

Most  Sand cars have tight bends right after the flange so it interrupts the swirl and then at 3 more tight turns and the headers are never equal lenght.  I did a car with a Holley and I had to add a significant amount of extra fuel in one cylinder because of the header design. I find on the "new cool design" where then header wraps tight around the water pump (and ruins it over time)  #1 and #2 are really short about 50% the length of #7 and #8, it screws with the reversion when they make them 8 into1 its sounds mean but its not idea ...  Can you imagine packaging a equal length 40" primary long tube header like a Kooks for a Camaro (illegal in lovely CA) on a sand car ?

8 to 1 done right Ford GT40  (well that pic is not an original but still nice)

View attachment 21571

here is the original from 1964

View attachment 21572

Technically sir, that's a set of 180* headers. :biggrin:

 

[tjZ06]

Bruce at CBM loved a cam I had spec'ed for my LS7 a while back.  It's a good duner cam, IMHO.  It was originally meant as a mix of AutoX/Road Course so it's not donkey-pee pee big, has good off-idle characteristics, relatively easy on valvetrain, etc:



That is a relatively small cam in a 427/440 motor, IMHO, but made great power and was a great all-around cam.  If you want to win dyno wars, it's not the one. 

-TJ

 

[tjZ06]

The old saying holds true "there is No Replacement for Displacement" as others have said its not the HP its the TQ - Torque moves the mass  - HP just keeps it moving 

Forget looking at the MAX HP and TQ numbers - look at the "power under the curve" the usable TQ and HP numbers (the Dyno graph)  they will tell the story how they perform

I agree with @tjZ06 on LS7 heads -but I think the crate engines and lower redlines fixed that issue. But the potential for HP in the Future (you will always tire of how much you have) is greater with more CU  and quite frankly the "parts" in the LS7 are just better from the Block up - the LS3 block is no way as robust and the LS7 is made to be abused - the Rods are better material, the pistons are better material.  

The downside of the LS7 Crate is that the cam is a little too aggressive for cruising the dunes unless you have a slightly lower gear ration unlike the Corvette version its low speed manners are a bit rough

Do Not believe anything you hear abut the dry sump being needed - of course a race inspired Dry sump (aftermarket) is always better to handle off camber duning - but it was done for ground clearance, massive side load G's in turns and just balance in the corvette

IMO you will be satisfied with either.  I have done the connect and cruise version of the LS376 in a street car.  For the money it was a good runner.

However all that being said - knowing what I know about having put crate engines in sand cars and the money spent modifying them for the best outcome,  If I was going for new build for a sand car I would spend a bit more and get a specialized build with all forged internals, the right cam and head combo so the power is usable where you need it most in the dunes, a drive by cable throttle - I hate DBW in the sand personally even with pedal commanders and that non sense, some better fuel rails for a clean look and ease of setup, an F body front drive set, and an F body oil pan set up. 

That is a much better overall experience for the sand IMO

I agree, at the end of the day, for the money a person is better off having a custom motor built.  But crate engines have a lot of upsides, especially if you're in a hurry. 

-TJ

 

[Rockwood]

I agree, at the end of the day, for the money a person is better off having a custom motor built.  But crate engines have a lot of upsides, especially if you're in a hurry. 

-TJ

Especially one with TFR or Texas Speed heads. :biggrin:

 

[J Alper]

Couple of things,

The LS7 has a 4'' crank, way more torque,  all the LS7 we do are wet sump,  Dry sump is way better, but no one wants to mount a tank in the car, the LS7 is easy to make to a 440 if you want even more power later,  super easy to do a cam swap,  i would change the cam in any Crate motor, 

Cam will be the bigest gain, 

 

[J Alper]

If you are doing a power steering pump, Then you will need our Y body pulley Offset and bracket, Or GM makes a special bracket to use the gray area or howe style pulleys, 

or 

you will need to change the balancer from Y body to F body, and change the pump,  also the water pumps on the motor have the oulet differenct to most naturally aspirated motors,  the pump that comes with the crate motor is used on the Whipple supercharge motors,  so i would change the pump no mater what,  

For offroad the oil pump is a little small, all the crate motors we do we also change the oil pump to a mellings with high pressure, would do a 296 with a red springs, 

Changes on Crate motor

• Mellings oil pump 
  
• C5R timing chain 
  
• Cam Shaft 235/244 on .600 lift for ls7 on a 112   -   LS3 235/238 on .635 lift on 111 
  
• Pac or Alper Dual Spring kit 
  
• Chromoly pushrods, 
  
• 12 Point Balancer bolt
  
• Improved Racing oil pan Baffle