Hey guys, I'm in the home stretch of getting my 6.0 together and was just wondering what octane I should run or how I can figure it out. I was thinking 93 to be safe, but would like to be able to get away with 91 as it's more readily available. I'm running a 4.030" bore, 10:1 compression Pistons. The block has been decked, but I can't remember how much at the moment. I'm running a pretty mild cam; comp cams #54-424-11. I think my dynamic compression ratio is around 7.76:1(I used the Wallace racing calculator, but I don't know my exact static compression). Thanks in advance for the help!

 

Most Gen IV truck engines were 9.9:1 and were rated to run regular unleaded (87). You will be fine with 91.

 

No ****, really? I always thought 10:1 was pushing the limits of even 91 octane

 

Back in the bad ol' days of carbs and distributors, yeah. But now with injection and the superior fuel distribution that results, along with the much better ignition systems now used, it's not the issue it once was. Knock sensors help too. It surprised me too!

 

12.5:1 here

93 Oct

 

Stock LS1 could run on less than 91 octane and had pretty good compression. Better fuel distribution, better spark timing and a cooler intake charge all add up to bigger power on cheaper gas.

 

Sounds good guys! Thanks for the input. I'll be running 91 unless it shows it needs higher. Not to totally derail the thread, but does anyone have tips for removing a stubborn rear main seal? I've been pounding on this thing for the better part of a day and I don't think it's even moved

 

 

Yeah haha, until about a week ago it was a bare block. I tried using a screwdriver and a hammer but no luck it just bent the ring I was beating on back. Maybe a punch will work better, I'll give it a shot

 

It sounds stupid but I've developed my own way to drive out stuck pieces. You need to put the punch on the exact part you want to drive out. Then hammer in this exact pattern in 1 second intervals: punch, punch, thumb, pause, punch, thumb, thumb then throw everything against the wall and storm off. After a few cycles you'll either have it fixed or have a brand new already assembled part being shipped to your house.

 

Hahaha I think we developed the same process. I ordered a new cover with seal already installed last night after getting fed up with this one
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Same, literal LOL


By the way Bammax, I thought that was everyone's process..? ha

 

At the shop we always use a new assembly from GM. Comes with rear main already installed and a new perimeter gasket and bolts. Makes things pretty easy when doing a rear main. I don't know the cost but I believe they are fairly low cost for the whole unit. I think they are around $50, which isn't far from what you'd pay for a rear main and a gasket..