Post a log of that run, if you have one.

what fuel was run?

 

I'll bet pump gas

 

It was pump gas, 93. It let go on the highway in 4th gear at about 4000 rpm. Unfortunately, I had my laptop connected and sitting next to me, but forgot to turn the data logging back on, but I have more than 2 dozen logs of runs showing no knock.

I had the rear steam vents on the heads blocked off as I was using a FAST 90 intake, so I'm sure that cylinder got hot.

Are the thickness of the ring lands different on the 5.3l and 4.8l motors than the 5.7 ls1?

 

bolded the problems that probably caused it

 

Skinnies, do you guys run steam tubes to all 4 corners in your motors?

 

Yes I use the factory fbody 4 corner one

 

Well, pump gas is all I have available, but in an attempt to keep it cool, I'm going to vent all four corners back to the radiator, go with a cooler t-stat, and go with Evans waterless coolant.

I could also go with methanol/water injection as well to help keep the pistons cooler.

 

Same thickness, the 1.2mm rings have a tad thicker land due to the thinner ring. You can NEVER trust pump gas. Just because it says 91 or 93 doesn't mean it's not 87 or worse. Whenever pushing a stock engine you are taking a gamble with pump gas. E85 is offers sooo many benifites. Sucks it's 4hrs away from me.

 

Before you go there with the gasoline statements, I used to work for Sunoco as a formulation chemist and would do spot checks testing as well at pumps. It's big big penalties if you don't meet the minimum requirements of octane ratings at the pumps. It's why most refineries actually formulate the gas almost a full point higher in most cases to avoid issues at the pumps.

 

quick question, I had to use 2nd ring with .04" gap in one of the cylinders, will it cause any real problems (besides higher oil consumption)?

 

Your kidding right?

 

Yes, sorry Meant .04", not .004

 

800whp here. 144mph trap @ 4000lbs on a 4.8.
Stock ring gaps. E85...

 

Ran 8s as well, not making near the power some of these other guys are though. JY 2001 5.3, 24lbs E85 fuel. Gapped .024 .028. Had some blow-by Nothing horrible.

Bottom line is you have no idea what the rings are at unless u check. It is a gamble. My 160k motor had a top ring gaps as small as .018. (i believe someone was into the motor at one point as well)

Its pretty simple and easy to pull one and check for peace of mind IMO. Then again while your there might as well Gap them. Just dont over gap.

.006 x bore is pretty standard boost ring gap. So .022 should be good for a 5.3, which seems to be around what most high mileage motors are.

 

I guess it must depend on where you are because I have seen otherwise. All it takes is one bad tank and you're done on a 14 psi boost pump gas deal. I run pump/meth in my truck and have never blown an engine due to the gas because Im really in tune with things, but several times I could have. I have had tanks of fuel that I can hear ping on 12 psi and otheres that will take 16psi....
On a side note I just pulled apart a 140k lq4 that had .024" ring gap, and a 34k mile 6.2L L92 that had .014" gap....

 

Good info, thanks

 

I agree 100% with what you're saying, and it's the reason I also run meth injection. It's a nice safety factor when on pump gas. I'm also conservative with my tune as well. My motor popped 2 years ago because 1, I had stock pistons and tight rings, 2, I wasn't spraying meth/water yet, 3, I had the rear steam vents blocked, which is a debatable subject if it's a factor or not. I measured my ring gap on number 7, and it was only 0.013 or 0.014, I forget, might have been even tighter.

 

What should I do with .04" 2nd ring gap in one cyl, is it acceptable, or is it critical?

 

Is it right, no, is it critical, that's a tougher question. It all depends on what you consider acceptable.

 

Haynes manual even says up to .04" is OK, so I guess for mild engine refresh I should be OK. Hell, I found out today that #1 piston head TWO top rings instead of top+2nd. Still worked just the same as other cylinders somehow