Just wanted to pick a couple of brains this morning. Starting with an stock LS7 bare block, would it be worth the added expense to build an N/A 440 stroker as opposed to keeping it the 427? Lurking through the threads here I've seen many opinions of it not being worth it, however most of those questions have been asked based on already having an up and running LS7. What do you guys think?

 

If you're starting from scratch, I don't really think it's more money to go to a 440.

 

Yea youre right. Just took a look at TSP. Looks like their rotating assemblies for a 427 and a 440 are just about the same price, maybe $100 difference. Just gotta do better research. Thanks.

 

I agree. Unless you use a stock crank that will be significantly cheaper than the aftermarket forged cranks, all of those will be relatively the same price regardless of what stroke you have so might as well go big.

 

440+ all fkn day long if you're starting with a bare LS7 block.

 

Nice topic for discuss

 

I've been going back and fourth with the same question..... I think a FOR STREET, a 4" crank with 4.155 bore would be most optimal and the direction I started my build.
the 4" will give better longevity and reliability in the long run. Sure ERL and Dart have extended their sleeves to accommodate the longer stroke but in the end IF you stay N/A you won't really feel the difference between the two cranks BUT......... if you want to maybe spray later you'll be kicking yourself for going with that longer crank.

BORE: a 4.125 vs 4.155 power wise isn't too much of a difference except on a hot summer day when you're lined up next to a 427 corvette. At that point the extra 5-10 hp you're getting on the 4.155 over the 4.125 will be the difference of a smile or a frown...lol sorry, I've been on both sides of that scenario.
4.185 is the max possible bore before you get into "too thin sleeve" issues and if you're one last/more hone job away from a ticking time bomb. bringing me back to the sweet spot of the 4.155 gives you a great starting point with excellent room for growth.

POWER: you really get your power on inhale/exhale systems so heads, intake and 2' long tube kooks is where the real money should be spent. bore and stroke for the most part are about all the same price. FOR STREET I want to focus on low and mid range tq band on a 434 (4' crank/4.155 bore) over top end for two reasons.
1. FOR STREET red light to red light for the most part will be living under 6-7000rpm so screaming out of the hole should be given serious consideration over top end rpms.
2, FOR STREET if you really want to make up for the top end rpms deficiencies you can always hook up a bottle with a window switch. THAT would cover all three phases of power. again this is thinking FOR STREET

conclusion......my nod is for a 434cu in (4" crank/4.155 bore) with a bottle for 100 to 500 shot of funny gas. this gives you the best of all three tq range worlds, longevity reliability, room for growth; hence, one bad a** street bully! AGAIN FOR STREET! I can't emphasize this enough and speaking of street don't forget brakes, suspension and the rest of the drivetrain upgrades

 

I agreed at the time..... no thoughts? anyone?

 

Most of us don't have LS7's....best we can do is guess .....

So to that end, I say....STROKE IT....especially if the additional cost of parts is 'minimal'!

KW

 

I'm pretty sure he was talking a stock sleeve LS7 block, which already have longer sleeves from GM. They're know to crack too though, so I wouldn't recommend spraying a stock sleeve LS7. If he is talking the price difference between a 440 vs. 427, I don't think aftermarket sleeves are relevant in this discussion since they're way more expensive than any difference between the two displacements.

If it's a pure NA street car, 4.125" stroke is cake for an LS7. It hardly costs any more to use a 4.125" crank, and it will be worth 10-15ft-lbs of torque at the wheels.

 

That longer crank is going to make those pistons dance down low. you can sleeve the block or go with custom pistons.....either way there are better options out there.

The longer crank is a death sentence to be honest. outside of a sleeved block ERL or RED these LS blocks aren't designed for a crank longer than 4" for longevity and reliability. If it's a race engine going into a race car then yeah because race cars get their engines freshened up after about 60 passes anyway. For a street car though he can get his 440 with a 4" crank and 4.185 bore...
It really boils down to heads and exhaust. get a bad a** set of heads ported by the right guy with 2" long tube headers (Kooks) then you're in for some fun times.

 

Like I said, the LS7 block already has longer sleeves than the other aluminum blocks straight from GM. An extra .050"-.075" travel to BDC won't really "make those pistons dance" anymore than the 4" stroke does.

A lot of it is in the design of the piston. You just have to move the major diameter of the piston further up the skirt so it doesn't come out at BDC. People have put a 4.250" crank in an LS7 before and it went years before it was refreshened. If you look in my sig, I'm working on fitting a 4.250" crank in a LQ9 block. Of course, the pistons are custom but it will work just fine.

 

If you get a crank, rod and piston kit designed for 4.125 stroke, you won't have any more issues than a rotating assembly that is designed for a 4.000 stroke. And like it's been mentioned before, the LS7 has the longest sleeves out of any factory LS block.

 

http://www.jegs.com/i/Chevrolet-Perf...06#moreDetails

under "details" it says "•Max Stroke: 4.10" and
under "overview" it says "These blocks are designed specifically to handle from 450-900 horsepower..."

Yes SHovV I agree it can be done and KCS I saw your thread and your Fox body looks like a killer project...guys I get it BUT for the price, longevity and reliability stroking larger than a 4" crank isn't ideal. All of us that know can say a range of 450-900hp is nice but the itch for more creeps up quickly so at what point do you say "damn I'm hitting all the limits, time to break it down and/or sell the engine and start over." WHY?
Go to engine builders and they'll tell you (the good ones atleast) if your goals are 1000hp build for 1200hp because you don't want to hit the max too quickly AND SPEED IS ADDICTING...
KCS you can tear down your engine and build back up no problem so you might not mind doing it from time to time but for STREET with longevity, durability and reliability my nod is for 4" crank 4.155 bore with rings and pistons (stock off the shelf economical....not custom) designed for spray [for when you reach your power max]. Then you have two avenues you can go.....
1. spray with bottle
2. hone it out a bit more

both of you guys are correct but is it most ideal...best bang for your buck FOR STREET? that is the question.