800 RWHP although a bit is not the same stress as another 200 RWHP making 1,000 RWHP on a regular basis though. Had I stopped at 800 RWHP in my LT1 block, I am confident it also would still be running today.

Other than the weight of the aluminum LS9 block, I guess I can't see the advantages of spending the extra $ on the LS9 over the LSX. Is there something else I am missing? Both should be overkill for what I am looking to do (I think the LSX block is rated up to 2,500 HP).

Thanks for stopping in. Do you have anything to add or throw your .02 on?

Well, I don't want to be mixing up "what it can make" and "what it can make reliably for years at that level". Its possible you meant those could make that power for years and be reliable, (its hard to fully understand when its on a forum and not in person). My old LT1 block made 1,008 RWHP, and others have made over 1k at the wheels with them also. But all do end up in similar outcomes like mine did when the block flex'd as it just was not meant to make that much power over time. This time I want to be clear that it will hold up to that level for years.

This is where matter of opinion (which I am open to) comes in on what is the reliability point. I am leaning towards the 6-bolt that the LSX offers right now as the jump up from the 6.0 to that is not really a ton of $. Thoughts?

Yes, but you'll also be pushing that 5.3 a lot harder than I would a 6.0 block with greater displacement. I am not set on a factory block. I want whatever is reliable for consistant 1,000 RWHP. Understanding there are some that will fit the bill and others that will far exceed what I am looking for and cost a lot more. I don't want to spend $5,000 on a block if spending $2,800 will do the job just fine.

 

Dart also make a variety of LS blocks now, cheaper ones in iron that may be an alternative to an LSX.

http://dartheads.com/product-categor...t/next-blocks/

Really, if weight does not bother you at all, and budget permits then yes some of the iron blocks will be a stronger base for the money. Not sure how many of the OEM bolt on parts fit these blocks though or if more parts are needed to fit them. That does apply to LSX too though, where additional parts are needed.

 

 

Thanks stevie! Its not a race car. Last time I had it weighed it was 3440 lbs without me in it, which isn't bad, but not a light race car by any means. I'm not sure the exact weight difference between aluminum and iron it would be (my guess is maybe 50-100 lbs). For that amount, the weight difference really would be minimal and the power I would have would overtake the minimal amount of extra weight (at least thats my thinking).

I will be strarting from scratch, so I'll need everything. So, as long as I know what bolts to get, and they are not crazy more $ than OEM bolts, the different aftermarket blocks don't bother me.

I appreciate the input. Back when I was supercharged, my olt LT1 took years and years of abuse at the 700 RWHP range. When I went turbo, I wanted to go big on the power. I think the limit for an LT1 would be safer around the 800 RWHP mark. I know there is a big difference between 800 and 1000 RWHP though, and I would be curious if yours would hold up the same after the same 7 years with another 200 RWHP more than you are at.

I am not familiar with the Dart blocks. I will look into them for sure. What is it about them that makes you lean towards the Dart block over the LSX block?

As a side note, I do really appreciate all the input and the info everyone has given. I am learning a bit here.

 

 

He likes all the extra BS that goes along with them

 

What is your exact setup? Do you do a lot of datalogging? Have you needed to open up the motor at all in the past years since being at your power level?

 

 

How much boost are you running and what is your CR? What do you have internal wise on your LS3?

 

 

Love the info in this thread.

 

 

Thanks C5 Pete! I value your input. I have heard various people chime in and spoke to many people on and off the forum and I seem to get in conclusive info on if a factory block outside of a LS9 would really hold together 100% reliably for that level of boost/cylinder pressure and power. Sometimes like in detoxxs car it seems to work, however in others even when safety precautions were taken and things were running correctly, the engine still didn't make it on the long term.

I feel like going on the side of caution and just going with an aftermarket block. Dart I like for the extra oiling, but LSX has been used more and there is more data on guys using them to get info on. I need to do more research either way.

Unfortunately this is going to be a LONG term project. I have been focusing my extra time and money with my career this last year or so, and will be for the next year or so before I will have enough extra time and $ to get this project actually going.

In the mean time it's nice to figure out an actual direction I will he taking it. Who knows, perhaps I may even be able to take some $ and start with the block and get parts as I go.

 

Nothing will ever be 100%, bad build, bad tune, all sorts of things can affect reliability during and after the build and at any point in the engines life thereafter.

The simple fact Pete is saying a basic LS1 block 346 can survive the power and it is one of the weakest block options....proves the point it isnt a huge ask for the better more recent blocks.

 

There are a lot of variables for sure. Getting a bad tune I don't believe would run fine for years though under extended periods of WOT and survive. Usually that's something you found that was bad pretty quick. The bad build thing depending on what it was may last longer. The criterea and scenario I am trying to start with is that both of those aren't an outlying factor. Unfortunately it's hard to tell sometimes without poeple knowing. Likewise on the other side of things also, like when someone is constantly tweaking and datalogging to check things and because of it they last year's and years without issue, but then may only report that it has held up fine for years without giving further insight on what he has done to keep it together.

So, could a factory block hold up fine for years? Clearly it already has for some. It also has not for others. Unfortunately with all the variables and stories on each side of the spectrum I still feel like siding on the cautious decision would be best. It also seems that the cost difference would realistically only be in the $1200-$1500 range for the added strength the LSX or Dart block would give. In the grand scheme of the build, that's not a lot extra for the extra level of strength it gives.

Before I was in this position, I was told by some that my LT1 block would hold together (others said it would not). I had dedicated a large amount of time and money to make over 1,000 at the wheels with it. After it flexed the block, needless to say it left me wanting to side this next time with the block more likely to not fail on me. I am not final with my decision as I have plenty of time to decide. But as of right now, I am leaning towards the LSX or Dart block.

 

 

Hello old friend. Cool setup! Good luck with it!

Yeah, I'm not worried about Dyno pulls. Even a bunch of them are still just a few seconds at high boost and speed. Similar to 1/4 mile runs. Many people do this, get away with it and claim it's good to go which for just that it probably is. I'm more concerned with extended runs and 1/2 mile and full mile runs where the car is at high boost for extended periods of time. It's a lot more stress on a motor to hold that cylinder pressure than just quick pulls.

When the time comes, whatever I decide, I am confident my power goals will be met (1,050-1100 RWHP). My S484 turbo is capable of it easily with a good setup. I just want to make sure I don't have to go down that same road of looking at catastrophic engine failure after all the time and $ spent.

 

I went lsx after my first engine failure not cause i needed to but because it was only about 300 dollars more to do lsx376 over a replacment ls3. I was going turbo anyway for sure. I know i pushed that engine to 1000 rwhp. No head studs nothing. Only changed cam and springs. Only reason i didnt lose head gaskets was cause the block was so strong in my opinion. Honestly if you are going endurance get the aftermarket block and do 6 bolt heads from the start. Just my opinion.