Preston99WS6

iTrader: (7)

I just recently went with a sts with a front mount and t-70, running bosch green tops and a walboro 255 with a msd fuel pump voltage booster. My engine has just under 90k and about 4k with the turbo and the last 40k it has had the 560" 224 @ 0.50 cam in. Here is the problem. The poor thing had just developed a lot of crank case pressure meaning piston or ring problem I noted it last weekend, Any one who has beat on a engine knows that is a sign of empending death to the motor. Any how so I have 2 vechicles a 68 GTO and the WS6 but the GTO has issues I need to resolve before its road worthy just maintenance stuff so I figured as long as I baby it, the ls1 will make it for another week until the goat is ready then I can yank the motor and freshen it up. Turns out it didn't It came apart 50ft from my drive way last night So it ran for another week the funny thing about it is it didn't give any other signs than the blow by, oil pressure was good and it didn't have any piston chatter. I amagine the thing came apart at the wrist pin because it through a rod. I have only heard that sound a few times in my life and it is very disturbing So getting back to the title since the motor is done and its got to go. Before I put the next one in I want to have a safer compression ratio for boost/pump gas. Honestly I am looking to freshen up the next motor change pistons and do arp bolts, so its on a tight budget, so if any one out there can point me in the right direction it would be very appreciated. I have checked most of the sponsor sights and I cant find a piston in the stock bore size to accomodate an 8.5:1 ratio To give you all an idea where I am headed with the build I want to run 7-8psi and somewhere around 500rwhp. So another question is will the stock rod take that kind of abuse when matched with arp bolts. If not were should I stop at (rwhp figure). I will probably start tearing it down this coming weekend so I will post some carnage pics for those of you all that are curious. The ls1 is a very impressive engine any motor that can take 90k worth of the kind of abuse I have put this thing through deserves credit. Like I said before help or info will be appreciated. thanks

67Firebird455

iTrader: (27)

I'm running 3.905" diamond pistons (better material than mahle) with an -8.7cc dish and 75cc chambers (deshrouded 6.0L heads) to yield about 8.5:1 with a 6.0L MLS gasket. Should be around 8.7:1 with stock #317's on a 347. You SHOULD be able to get away with more than 8.5:1 first of all if you only want to run 8psi of boost on stock displacement. Look and see if mahle makes a std bore piston (not sure why exactly you're stuck on stock bore) with a decent dish to get you to even 9.5:1 would be sufficient. ****, a stock style piston with #317 heads will get you to about 9.5-9.6:1 with a GM 6.0 MLS gasket and stock rods with ARP bolts should be able to handle 500rwhp, but would recommend a set of inexpensive I-beams or H-beams.

84camaroturbo

I am running stock crank and rods that are polished and was running 30psi till the head lifted split the block. but didnt bend a rod or hurt the crank

stevieturbo

What dish to you actually need ?? Youve mentioned a CR, but given no other details, like heads used, or gasket used ??

I previously used a set of Mahle -16cc pistons, stock bore size. I'm sure that wouldnt be far off what you want. Again, until you tell us your head chambers size and head gasket used, impossible to say what CR they would give you.
I sourced them via Erik at HPE


Also, 8.5:1 is incredibly low CR for only 7-8psi.

On my 346 with the Mahles, at around 9.1:1 I ran 15psi, now on 8.7:1 and making as much as 19psi. All quite safely on pump gas.

Preston99WS6

iTrader: (7)

As of right now I plan on using the stock ls1 head, since I still have my originals, I wont know if the ls6 heads are still good until I pull them. I cant remember the size of the stock ls1 combustion chamber but I am pretty sure that the engine in stock form is 10.5:1ish. I am running a t-70 with front mount so I can go over 7-8psi to my knowledge the turbo is efficient up to 14psi just not how far to go since fuel is going to be a limiting factor with the 42lbm injectors. I am still trying to track down either a long block or a short block any ideas where I can find . Thanks for the inputs.

stevieturbo

My heads were circa 62cc, stock heads are around 66cc...

So with the -16cc Mahle pistons I used, that would put you under 9.0:1 CR ( I was using GM MLS gaskets )

These were 0.927pin 6.125" rod, and 3.898" bore size.

So you would need rods to suit. It makes sense to buy aftermarket rods, as it really opens out the range of pistons available.

Got Me SOM

iTrader: (2)

even though its expensive spend the extra money on rods, rebuild it and do it right.

sponsors are selling built short blocks for 3500, you should be able to find a good deal.

good luck man , **** always happens when you least expect it.