JimDozois

I had a LS1 with some detonation. I realize thats not a good thing and should be avoided at all cost but when you have a situation when detonation does occur (bad gas etc) are one of these block sturdier than the others to handle some detonation?

What is the primary differences between all these blocks? Are they interchangable with one another?

Thanks for the insight

chrisfrost

iTrader: (8)

I believe all those listed are stronger in the web support than the LS1 also the bay to bay oiling is improved but seeing as how they all have stainless steel sleeves I would say the best 1 in a pre-ignition or pinging situation would be the 1 or 1's with the thickest sleeves .

mark21742

With the sleeves notched on each side to fit the same bore spacing a larger nor will always have less "meat" between the cylinders than a smaller bore....so, the larger bore could get jot spots easier.

But remember when it comes to detonation the first thing you will probably have to worry about is your pistons and rods before the block

redtan

iTrader: (5)

The LS7 is the weakest perse out of all of those, one of the main reasons why GM went with an LS3 based block when dropping a supercharger for the ZR1 vette. They felt the thicker sleeves of the base vette block would take to boost better than the Z06 vette block.

Other than that, there is really no big difference in sturdyness of the rest of the blocks. It's more the pistons that are going to make a difference in the engines ability to handle detonation.

JimDozois

Hi All, Thanks for the post reply. So the LS1 appears to be the last choice of all the LS series. Does anyone know what the thickest sleeve is and which block it comes in? Is the LS1 and LS3 interchangeable eg same bore size? Does the ls3 have a bore of 3.90". I was running Mahle steel forged pistons standard bore 3.90" and melted 4 out of 8 and cracked 2 cylinder sleeves. What other brand of pistons are stonger? I checked the the entire fuel system for fuel starvation, pump was good, injectors tested at 90 milliliter per minute and all within 10% of one another (cleaned and rebuilt as a precaution). 60 psi at fuel rail at idle. Next suspect is the tune and it will at dyno after rebuild. I'm just trying to beef up where I can.

Thanks

DMM

I believe that LS1 and LS3 blocks are the strongest factory blocks, the LS7 has sleeves that are so thin they can crack from slight detonation alone...and the LS6 block is "windowed" which takes away from the core strength of the block. Darton has a pretty good selection of sleeves for whatever you are looking for.

You could always step up to an aftermarket block...or stop using forged steel piston's and get forged aluminum one's. I think you are missing a few of the basic engine building fundamental's here if you have trashed a short-block the the point in which you have described. Who did the machine work, checked the clearance's, and built the short-block?

Most importantly, who botched the tune?

chrisfrost

iTrader: (8)

A good altenative would be to use 1 of the 6.0L truck blocks ,,,,,,,,,,,iron and You can bore quite a bit larger or leave stock bore ,,,,,,,it can take overheating and would be a less expensive option . The ls1 bore is 3.898" and the LS2 bore and the LQ4/9 are the same at 4.00" and the LS3's bore is 4.06" . The LS6 blocks were cast with aluminum that was refined more and so actually are stronger than the LS1 blocks ,,,,,,according to a member that works for GM was talking about this same question in a thread a week or so ago in this section .

mark21742

I agree with Chrisfrost, I went with an 03 6.0 iron truck block, bored .030" over and 4" crank for my 408 stroker...I love it.

The iron block only weighs 87 lbs more than the aluminum one

butler

I loved mine too, but it carries 100 more lbs. I should have gone with the ls2.

JimDozois

Hi All,

Thanks for the input. I need to stay with the aluminunm block as this is in a sandcar and it needs to be as light as possible. So the LS 3 looks like the best option. Since the bore is larger than the LS1 can I still use the heads that came off the old motor. They are actually the truck heads with catherdral ports and a 71cc combustion chamber to lower compression so I can run pump gas.

The max rpm for the tune should be 6400??? and is it possible to hook in the detonation sensors with the forged steel pistons or do they rattle too much.

Thanks

DMM

Look man, not trying to be a dick...but...you need to do a lot of reading up on engine building or hand your requirements over to someone more capable along with a fist full of cash. For starters, there is no such thing as forged steel piston's...never has been and never will be.

To answer your questions, you never stated what heads you have since there were many "truck" heads available...however I assume you are referring to the 317 heads...and yes they will work on an LS3 sized bore. Not sure why you think you need lower compression without FI, but whatever.

The "detonation sensors", or more appropriately termed knock sensors are in a different location on the LS3 than the LS1...also the LS3 58x crank reluctor differs from the LS1/LS2/LS6 24x reluctor, so you will have to swap rings or figure something out for the crank sensor.

Rather than trying to engineer disaster, why don't you state what you need (hp goals, efi or carb, race only or street duty, manual/auto, etc) rather than asking questions you don't really seem prepared to understand the answers to.

In reality, you are putting the cart before the horse here. You need to figure out WTF happened to melt 4 pistons and crack 2 cylinders before you look into building a stronger motor.

To be honest, this almost seems like the start of a Mike Nice thread, you're getting the benefit of the doubt here.

JimDozois

Hey sorry you are right Forged aluminum pistons my bad long day. It is fuel injected hence the reason to lower the compression to run on 91. They are the 317 heads. Did not now about 58x vs 24x on the crank ls 3vs ls1. Was hoping to use some of the old parts on the new rebuild. LS3 stroke is .002 longer on the crank throw vs LS1. Doesn't sound like it will work. As far as tune it was set by previous owners and had run for 2 years without melting pistons so what changed? Thought lean fuel, clogged injectors , weak pump or too high an rpm that didn't appear to be the case. Its a Motec system M-48 M8 do these settings change on there own, because I haven't been in there nor anyone else????

mark21742

You can get a "cheater" box to let your computer read the 58x reluctor ring as a 24x

JimDozois

I found the smoking gun I’ve been looking for….

Fuel pump went bad, the stationary magnet came loose and was hitting the armature and starved the engine for fuel causing the detonation.

The pump sounded different but didn’t think it was as bad as it was…. Lesson learned…listen to your engine!


Time to regroup…and buy a better fuel pump!!! NOT an AREOMOTIVE one

COPO9560

Best strengh would be with aftermarket sleeves. You can dry sleeve LS2,3 & 7 blocks and end up with much larger bore and more stronger short block. Aftermarket sleeves are higher quality than the General uses.

Wet sleeves are an option for LS1 block and this would be stronger than dry sleeves in the other options. Not a cheap fix but you get what you pay for.