I have a couple of questions and I'm not sure if they are AT worthy, but I figured I would post them and see what happens.

My first question is, can you do harm to an engine from running high octane 98+ all the time? I'm wondering because I'm around 700 miles on my new 355 and my DR is 8.8. With it heating up already for the summer I've been detecting about 8 degrees of KR using AutoTap. It is definitely more prominent when it gets hotter so I figured I would try mixing 8 gal. 93 with 7 gallons 104 to see if it went away.

My next question has to do with the rings seating. I was told that the Ross low tension rings I'm using will take a while to fully seat...approx. 10K miles. I 've been watching the oil level in my car and keeping it full, but I notice that I spit oil out the tailpipe. It's not burning (blue smoke), but actually spitting it. At idle I can rev it a few times and then go look on the ground and see oil. I put my hand back there and had someone else rev. it and sure enough it spit it out on my hand. Is this normal? I've never run across this before.

In relation to my last question, could I possibly foul out my plugs? Could the combination of oil and running one heat range colder plugs be fouling out my plugs and causing detonation?

Any help is appreciated, I'm trying to get things squared away that way when I go for a dyno tune I won't have compounded problems that keep me from getting the car running right.

Thanks,
Anthony

 

Oil's octane rating is about 81.... that can DEFINATELY cause detonation.

 

How are you getting 98 Octane? Most unleaded only get to about 93. If you are running Aviation gas, make use it does not have lead in it. If it does you will posion your O2 sensors. That will mess up your A/F.

You are not spitting unburnt oil out of the tail pipe. That will not happen. I bet what you are seeing is water mixed with carbon.

Burning gas makes, among other things, lots of water vapor and fine bits of carbon. If they mix in the tail pipe, mostly with a cold engine you can get some black liquid out the tail pipe.

If you have killed your O2's with lead, that might make it worse. Octane will not hurt if you are getting the proper type of high octane fuel.

z28

 

No problem mixing unleaded pump fuel with unleaded race gas, if that's what you are doing. I know it's already built, but why did you use low tension rings? I never heard of doing that in a street car. Who advised that and why?

Rich

 

The low tension rings are probably the issue here....

A vacuum pump is probably in order to fix things here. Then the oil problems should go away along with the detionation.

Bret

 

Here is the link to the pistons I am using:

http://www.rosspistons.com/items.php...&ItemTypeID=27

I'll go home and get the build sheet to see what ring pack he used, but in my conversation with him, he said that the rings were low tension and were actually recommended by Ross. He said they would take a while to seat and cause less scaring and wear on the cylinders, but would work great after they finally did seat. After I get my facts/numbers straight I will call Ross and see what they say and see if it jives with what he said.

I'm getting the 98+ octane from mixing (93) unleaded fuel with (104) unleaded race fuel. Isn't 104 the only unleaded race fuel that is readily available from speed shops?

This weekend I will pull out the plugs, inspect them and replace them. I will also make sure that the crap spitting out the tailpipe is in fact oil and not a mixture of water and carbon. I'm pretty sure it is since I have no visible leaks and I have to add a quart of oil about every 500 miles.

I'll get back with you guys when I find out more info. Thanks!!

Thanks,
Anthony

 

Ok, just got off the phone with Ross and the tech said that the rings were not low tension rings. The ring pack I have is a standard tension moly top ring, reverse twisted cast second ring and standard tension 3-piece oil ring. I'm gonna work on the car this weekend and see if I can find out where my oil is going and I'm gonna also check out the exhaust and see exactly what it is coming out the tailpipe. The one thing that comes to mind is the Lloyd got into the rocker studs when he was porting my heads and told me to put silicone on the threads so I won't burn oil. I did that and thought that everything was ok, since my car doesn't burn (blue smoke) any oil. The oil has to be going somewhere.

I guess when I check my plugs/wires, put in my Borla DMH and change the starter this weekend I will take a really close look and make sure that there aren't any leaks. I would think that approx. a quart of oil every other fill up would at least leave a stain on the ground or something.

Thanks,
Anthony

 

Both Sunoco and VP Fuels make unleaded with (R+M)/2 in the 103-104 range. Other manufacturers offer 100 (R+M)/2 at the pump in some locations.

No. As long as its unleaded gasoline.

 

Thanks everyone for their replys, I worked on the car today and the crap out the tail pipe is condensation/carbon. I do have a leak from the pass. valve cover and also from somewhere on the timing cover. I guess everything is blow by and thus no stains on the ground. I had to fill up with gas this morning before I left for my brother's shop so I wasn't able to use race gas or mix up my own yet. I have some time off next week so I will do a lot of driving and then get race fuel to test the knock issue or I might just call up Scott and see if I can set up a time for him to do a hands on tune with pump gas since I have almost a 1000 miles on the new motor. Sorry for the stupid *** questions, I think I will just stay in General F-Body Tech. This was definitely not worthy.

Thanks,
Anthony

 

Actually it's a good topic man....

What is the static compression of your motor?

Bret

 

The static compression I believe is right around 11.3 to 1 and the dynamic is 8.8. It was my understanding that 9.0 is the generally accepted limit for pump gas before detonation when using pump gas (93). I tried to get as close as I could and did so succesfully, but viola, I'm having detonation issues. I'm using one range colder AC Delco plugs, and my motor stays right around 180 or below when driving and gets up to 185 when parked in my parking garge but never higher. I haven't really tested anything as far as fuel, Evans NPG+, or kicking the fans on lower to keep it cooler to see if any of those things help. Right now I have a 160 therm. and my fans are programmed to come on @ 180/190 for low/high. Would setting them lower help? Would a stock ignition system contribute to detonation? Everything is stock except for the MSD coil. Wires are new, but still stock. Would getting another range colder plug, and better wires help at all?

 

Stopped by RPM and got some Sunoco 104. I've been driving for about 40 miles and the car still has knock at idle and while putting a load on the engine so I'm guessing that it is false knock. I have up to 8 degrees sometimes and I really didn't think that I could have that much false knock. I'm going to get a LT4 KM and see how that does. My idea is that with race fuel and a LT4 KM I shouldn't have any knock at all, is that a good assumption? If I do what other things should I check? I've done a search and seen cases where people get rid of it with a LT4 KM and then there are others who even switch PCM's and still have knock.

Anthony

 

Turn off knock reatrd and drive it. Do you hear any pinging? Are there little bits of aluminum deposited on the plugs? That's a sure sign of detonation - it comes from your piston crowns!

Rich

 

I don't have LT1 Edit, I guess I could just unplug the knock sensor. I don't hear any audible knock from the car at all.

Anthony