Ok so I'm trying to get a 427 ci on my l92 block. I know that it needs a longer stroke than the stock ls7 block but here are some questions. My goal is to get arnd 600 rwhp without any fi. This will be also use for dd and reliability is a must.

1. Can I use a stock ls7 pistons and rings for ? If not what size Pistons and rods do I need?
2. Will it be cheaper to get a full complete rotating assembly or buying individual parts?
3. How much does a machine shop usually charge to bore, hone , balancing ect ect?

Thanks

 

Reliability is all in the valvetrain!! Don't buy LS7 lifters and expect to have a top notch reliable motor. What heads is you looking into? I believe a 427 is achievable but it'll live longer as a 416 Ci motor......
I may be wrong but I believe you'll need a 4.100 stroke for a 427ci motor.
I wouldn't do more than a 4.000 stroke with a motor that's go see a lot of street miles. The 4.000 stroke will keep the pistons in your sleeves better than a 4.100 stroke that would pull the piston out the bottom of the bore further. Sure cubes are fun but they not EVERYTHING..... A good set of heads with a great cam to match is what you really need to help dial in your horsepower goals.

 

Hello, what your looking for is attainable.
We can make your L92 a 427 LS7 it will make between 590-620RWHP on motor.
You can make 550-575(camshaft/compression dependent) with a 416 with our CNC L92's.
1. The LS7 piston and ring would fit if you Sleeve the block. LS7 4.125"
We run max bore at 4.070" on LS3's.
2. It is always best to have a professional shop assemble something like this. Your talking about making 700+ HP
3. Depends on the shops level of equipment and knowledge.
We specialize in what you are looking for.

Turn your LS2/LS3 into a Stage III LS7-LSX
Here is an example of a recent customer build taking a LS2 block and sleeving it to push the bore to 4.130. This package allows an LS2 car to be morphed into a pumped up LS7 and still retain the compatibility with the stock LS2 base engine.

This package is based around a custom sleeved LS2 block that Livernois Motorsports machines in house on its own 4-Axis CNC machine. This allows absolute precision and ensures the block is held to within just +/- .0001 to the specification.

Once the block machine work is done we utilize our own custom rotating assembly, complete with forged H-beam connected rods, forged custom pistons, stainless steel top ring and napier second, upgraded thick wall wristpin and forged stroker crankshaft. This takes us to a 429 cubic inch size.

The shortlock is then complimented with LSX-LS7 heads utilizing our own custom CNC program and valvejob, along with the FAST composite intake. This package is designed for the ultimate in streetable performance from a large cubic inch LS base. The added cubic inches and breathing from the bigger bore, coupled with the longer stroke and high flowing cylinder head matched with custom camshaft really turn this engine into a beast.

Shortblock, Longblock and Complete engine packages just like this are available to retrofit your LS2 and LS3 equipped car into a big-bore stroker LS7 monster with direct bolt-in capability.

Take a look at this earlier post it has some images
https://ls1tech.com/forums/general-l...i-ls7-lsx.html

 

The most I would be comfortable with on that block without sleeving it is close to 420". The extra little CI is not really going to net you anything when looking at the bigger picture of what it will take to get it. You could put a longer stroke in it, but then you're sacrificing the integrity of the piston and what it will be doing at BDC. You can do this successfully, but it's going to cost $$$. Look for a rotating assembly with a 4.070"-4.080" bore piston, 4" crank, balanced, and all you'll have to do is have your block honed and check your clearances upon assembly. Cylinder heads, camshaft, and manifold is where you're going to find the power.

 

Yep...

 

Im planning to use morel street link bar lifters and using stock rockers. This will go in my LS3 head with upgraded titanium valves and ported by greg goods. I've read that ls7 head will be better but I already bought this heads.

 

What about the rods? What size rods do I need for this? My budget will be at 3500 top. Is that attainable or shld I just opted for FI?

 

I would do a K1 rods.... or a callies compstar rods. 3500 top??? Do you mean as that as far as your top end goes ? A L92/LS3 head can get you there..... I recommend having the exhaust ports ported!! I recommend that big time. It helps those heads a lot. Also use the LS3 valves if you not already using those. The valves are lighter than the L92 valves. Morel link bar lifters are go be the way to go over a drop in replacement lifter. The link bar lifters are more stable at a higher rpm than the drop in replacement lifters!! On the rocker arms be sure to upgrade those with a trunion kit.... The kit btr offers is nice. Now let's move on to the cam specs... that's all go depends on weight, gears, transmission etc.... just make sure the cam is what you really pay attention to. The camshaft for a rectangular headed motor is so CRITICAL. The specs can literally make or break the whole motor. I have seen these motors run like a bat out of hell and others run like a turtle... WHY? cause someone didn't really know what they was doing as far as cam specs go....

 

$3500 for a short block? Just a brief search and I found this. http://www.texas-speed.com/p-1020-ts...-assembly.aspx

 

That's a good buy there!! I just wouldn't use nothing at all from Eagle....

 

I already have the short block. I'm talking any getting the rotating assemblies ect ect and machine work.

 

Sell your block.....and purchase a professionally built engine.

BTW....the 427ci LS3 long block, built to my specs that's going into my SS was built by Texas Speed. They're a real classy outfit!

KW

 

Thanks guys! I've decided to go with lsa conversion instead! It's way cheaper and around my budget range.

 

Even though the OP and I have discussed his build i will post up to hopefully dispell the myths posted here. We personally have more than one customer with ls3/427s that have 30k miles or more on them. One i know personally. His ls3/427 makes 600 at the tire and he daily drives it. It has over 30k on the engine now. Zero issues. Respouting internet myths or heresay does no good for the entire auto enthusiast crowd. If you want proof we can have a few post up, but come on...you guys dont think engine design and component design hasnt come a long way since even the lt1s or ls1s were new?

 

I agree. The pistons designed for the 4.10"/4.125" stroke engines are shorter to keep the major diameter of the piston in the bore at BDC, and they're just shelf pistons. Nothing trick or custom about them. They're no worse than the 4" stroke pistons at BDC either.

 

i myself am building a ls3/427 now , it has a callies 4.125 crank , 6.125 rods and 4.070 pistons . i plan on winding it up witha set of livernois ported l92 castings with spray on top .

 

From what I've learnt, the ls3 427 can be done but it is not advisable if someone plans to go for fi on the future. Meanwhile people is saying that 416 ci is way better for turbo application. As far as daily driver goes , I don't see why it's an issue.

Lmk how much you ended up spending at the machine shop.

 

I would have no issue with boost on a 427 ls3. But i would limit the boost of course.

As far as the other post with a 4.125 crank and a 4.070 piston...thats not a 427. That is larger.
There are many reasons the aftermarket LS pistons have a .927 pin. Can anyone guess them?

 

Co, how abt telling us?! .lol. Most of us do this as a hobby and not as profession sir! . So what will be the compression ratio usually for ls3 427 and how much fi can it hold ? Do you know anyone that run this setup with boost? Any reliability issue even though that's an oxymoron reliability and boost...

 

I would not run over 10lbs honestly...but 10lbs will be alot different on stock heads vs 10lbs on say a trick flow head (assuming we are strictly comparing ls3 heads). If a competent/reliable machine shop sets it up for boost then I would run it like any other boost setup. And it will be different with different cam profiles as well to a point.
The stock pin on an ls piston (besides ls9) is .944-.945. Nearly every aftermarket pin set for any stroker build is a .927. Some of that is due to rod and pin availability and ease of availability of parts and manufacturing. And some of it is due to pin placement and ring pack placement. The CH on the can be the same on 2 pistons but if one has a .945 pin and one has a .927 pin, the .927 pin piston can have more available material for piston strength and more room for a ring pack without bridging the pin hole and having to use support rails. That is extremely oversimplifying it of course but that is a short explanation.
There are so many builds out there that ARENT on tech or cf. Not everything gets put on the internet either.