Can a Dart 427 LS Next block be destroked to 6.2 liters?

[furryboy96]

Hi. I am doing research on engines and whatnot for my own personal interest and I was wondering...can a Dart 427(7 liters) LS Next aftermarket engine block be destroked down to 6.2 liters?

 

[Eunos_Cosmo]

The bore on the 427 is larger than that of an LS3/6.2

4.125" on the 427
4.065" on the LS3

As car as I can tell, the stroke is the same at 3.622"

So you could put a longer rod / shorter stroke rotating assembly in the 427 to possibly get down to 6.2L but it would be a different bore/stroke ratio than an LS3. This would very likely need to be a custom crankshaft unless by some coincidence one of the other LS family cranks magically results in a 6.2L with a 4.125" bore.

 

[LM7325]

You can get 5.7 liters using 4.8l crank and rods with 7.0l piston. Being the LS next has generous room to be overbored 6.2 would not be a hard number to hit.

 

[TexRex]

Yes.

Is this knowledge likely to be put to practical use or is it yet another pointless question that may have been simultaneously posted to Reddit?

 

[LM7325]

I know this guy always asks these arbitrary "what if" type questions often. But to be honest, I used to wonder if a small block 400 Chevy with a 350 crank to make a 377 could be a better combo than the popular 383 that uses basically the opposite approach.

 

[TexRex]

The bore on the 427 is larger than that of an LS3/6.2

4.125" on the 427
4.065" on the LS3

As car as I can tell, the stroke is the same at 3.622"

So you could put a longer rod / shorter stroke rotating assembly in the 427 to possibly get down to 6.2L but it would be a different bore/stroke ratio than an LS3. This would very likely need to be a custom crankshaft unless by some coincidence one of the other LS family cranks magically results in a 6.2L with a 4.125" bore.

427 with a 4.125 bore calls for a 4" stroke.

376 (6.2) from a 4.125 bore would require a 3.5-ish stroke and that isn't reasonably approachable with offset grinding a standard 3.622 or 3.268 crank used in other LS-based engines and there's nothing between them. Lots of companies have custom crank programs but they tend to be pretty spendy, especially when you're decreasing displacement.

You can get 5.7 liters using 4.8l crank and rods with 7.0l piston. Being the LS next has generous room to be overbored 6.2 would not be a hard number to hit.

I'm seeing a practical limit of .060 over for the Next. I'd hope that allows for a cleanup some way down the line considering it's ten grand for a short block, but I'm doubtful. 376 from a 4.8 crank would require close to a tenth of an inch overbore on the Next, from that limit, to 4.28". They're all still 4.4 inches on center.

 

[LM7325]

Yeah I was a little off lol. But, since the LSNext is offered with several different bore and deck height combos... I guess I'm wondering why 6.2l this way when the world is already your oyster anyway.

 

[TexRex]

Building to 6.2 is bizarre outside of trying to meet class racing restrictions, and 6.2 is an odd displacement as a class limit.

The LS/LT 6.2 is already a nicely oversquare motor. It's the max standard displacement on that crank shared with the 5.3, 5.7 and 6.0 engines, and even the minimum 5.3 is oversquare (if only marginally so). You get nice displacement without increasing piston speed and the bigger bore allows for bigger valves without shrouding.