Big cube lsx build -need help
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 89
Likes: 0
Big cube lsx build -need help I'm looking into doing my first DIY big cube ls build using an lsx block and I'm looking for any help I can get. I wanted to go at least 427 but 454 or bigger would be preferable if there isn't to much custom/mega dollar costs involved. I'm a mechanic so screwing most of it together won't be problem, it's more the parts list and expected outlay I need to know. I know I can get a 427 ls3 rotating assembly from Texas speed for around 3500, is that the sort of kit I'd be able to squeeze in? In the end I'm looking at running high comp 12.5 - 13:1 area running e85 with either an 8 throttle body set up or a sheet metal intake.
Any help or build threads would help a lot cheers guys
Any help or build threads would help a lot cheers guys
I like the LS3 block, but I would probably stay with a 4" stroke (416/418 CID). You run the potential of wear and oil consumption issues with the longer strokes. Other options if you really want bigger cubes would include a sleeved block or the LSX iron block.
I didn't see the LSX block when I first read your post. Oh yeah, with a LSX block, you can go to town. It threw me off when I saw you mention LS3 rotating assembly. For big cubes, you don't want a LS3 rotating assembly. If you are looking at Texas Speed, they list the rotating assemblies that you want as LS7/LSX or LSX short deck (unless you get the tall deck block).
427 = 4.125" bore and 4.000" stroke
440 = 4.185" bore and 4.000" stroke
441 = 4.125" bore and 4.125" stroke
454 = 4.185" bore and 4.125" stroke
Those are the common combinations. There is also a stroker crank that is 4.100", but you need to deck the block for them to work right. Personally, I would not do a max bore during the first assembly, I'd like to have the option to rebore it later if needed. If you want bigger than 454, you need to get a tall block.
427 = 4.125" bore and 4.000" stroke
440 = 4.185" bore and 4.000" stroke
441 = 4.125" bore and 4.125" stroke
454 = 4.185" bore and 4.125" stroke
Those are the common combinations. There is also a stroker crank that is 4.100", but you need to deck the block for them to work right. Personally, I would not do a max bore during the first assembly, I'd like to have the option to rebore it later if needed. If you want bigger than 454, you need to get a tall block.
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 89
Likes: 0
Okay so after a few delays I'm ready to sell the current ride and get into the build. I've decided to go with the 427 and run ridiculously high compression, something like 18:1 but I wanted to know if anyone has something like this or knows if it can be achieved. I've already decided its going to run on meth so detonation shouldn't be a problem and I'm not worried about meeting any racing bodies regulations as its not what I'm building the car for
Trending Topics
Okay so after a few delays I'm ready to sell the current ride and get into the build. I've decided to go with the 427 and run ridiculously high compression, something like 18:1 but I wanted to know if anyone has something like this or knows if it can be achieved. I've already decided its going to run on meth so detonation shouldn't be a problem and I'm not worried about meeting any racing bodies regulations as its not what I'm building the car for
Good luck with this plan. You need to consult a engine builder. What you want to do has two bad decisions right from the start.
Tim
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 89
Likes: 0
I would go 454. 13.1 to 14 comp would be safe with e85. Before you do lsx block I would look at erl blocks and save some weight. Cost of the two is close. A lot of people talk about not going to the max bore but majority of people are going to only do this once. The bigger the bore the better the heads are going to breath. At 13.1 comp and a decent cam 600+rwhp will be pretty easy to get. Good luck with build.
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 89
Likes: 0
It's not that I need 18:1 buts it's becoming fairly hard to do something no one or not many people have done before and the car I'm putting together is going to be purely a track car for events like powercruise and summernats ( I'm an Australian and if you haven't heard of those events you tube it they are an absolute nirvana for rev heads ) and in the end I'm trying to make the car be the best at nothing but good at every event, drags burn outs power skids and even a little drifting, and if I can get a ridiculously high comp out of it I'm imaging an insane torque figure and wicked noise coming out of the pipes, how ever I do appreciate being steered in the right direction if I'm completely wrong on this, it's why I'm asking the question
You dont need a big budget to boost. The 5.3 LM7s absolutely LOVE boost. Probably would get you the same amount of power youre lookibn for at about half the cost of building a 454.
Registered User
Joined: Jun 2013
Posts: 23
Likes: 0
Okay so after a few delays I'm ready to sell the current ride and get into the build. I've decided to go with the 427 and run ridiculously high compression, something like 18:1 but I wanted to know if anyone has something like this or knows if it can be achieved. I've already decided its going to run on meth so detonation shouldn't be a problem and I'm not worried about meeting any racing bodies regulations as its not what I'm building the car for
18:1?! Do you want to build an LSX or a diesel?? Bump it back down a tad, 18:1 is too much. More compression is usually better, but you get to a point of diminishing return somewhere around 16:1. When you try to get "ridiculous" with your build, the cost to build it gets ridiculous too. 
TECH Apprentice
Joined: Oct 2007
Posts: 301
Likes: 20
Ridiculously high compression isn't worth it - you'll pick up a few ponies, but not nearly what you're anticipating - each point of compression will add only 2% - 3% in that zone. Anything at all goes wrong at that compression and you'll find that your engine will fit neatly back into the small boxes you initially got your parts out of.
Build something with reasonable compression and add a hairdryer or two.
Oh, and NONE of the big-inch engines is a simple "screw together". Most take a good bit of massaging and a few trial fits.
If you want to be different, paint your car pink. Go with a proven combination, doing R&D yourself is damned expensive.
Build something with reasonable compression and add a hairdryer or two.
Oh, and NONE of the big-inch engines is a simple "screw together". Most take a good bit of massaging and a few trial fits.
If you want to be different, paint your car pink. Go with a proven combination, doing R&D yourself is damned expensive.
