This car should not be having issues with pushing coolant while running on 93 oct w/ the compression numbers that you are giving. It should not have a knocking problem either. Is this car a 98'? Are you hearing the detonation or just seeing it in a log. 98 knock sensors are useless. You will get lots of false knock. Do you have breathers or a closed pcv system. If it's closed, you could be sucking oil thru the intake and getting real knock. The amount of timing that you are running shouldnt be a problem either. As far as torque on the heads. I have read that the heads with cometics gaskets and arp studs should be torqued to 80 ft/lbs and retorqued after they go thru a heat cycle. Were both the head and the short block surfaces checked? The cometics gasket is very sensitive to imperfections on the mating surfaces. If all that checks out, throw a couple of GM coolant seal tabs in the radiator. Your fuel octane is not the problem but you can try to see if putting a higher octane fuel and if the knock is still present then it is likely false. good luck.

Oh, and +1 on the dedicated fuel cell for the nitrous. It's just better than pulling fuel off the rail + it allows the use of high octane fuel on demand.

 

The car is a 98, but I updated the knock sensors/harness. The knock was VERY audible on the last run, not just on the logger.

I don't have any kind of PCV on the car, just a vent on the valve cover leading to a breather. I did notice (for some reason) there was oil in the intake after 4k miles, quite a bit actually. I don't know where it's coming from or how it got there. The only way would have to be some kind of reversion in the ports or something and somehow blowing oil back into the manifold, but that would mean the valve seals would have to be worn out and they're brand new. The cam has 20* overlap.

The longblock was assembled by LME, all the machine work was done by them also. I can't vouch for how true everything is but I'm sure it was probably fine upon assembly.

 

That's the exact reason we did the dedicated fuel sysytem from the existing tank, over the stand alone fuel system; I am not going to be running some watered down fuel through my many $$ motor, a recipe for disaster in the waiting. If it was mine I would run race gas in the main tank also. That's just me, as I know plenty of guys use the watered down method...

Hey, where's that write up?
Robert

 

I am having the same issue with the oil in the intake, well actually it's in the combustion chamber and working it's way back up into the intake (reversion). I also removed the PCV all together because of oil in the intake big time (could feel and see oil in the TB neck). So after blowing my ls6 intake I put a ls1 on and washed it out really good to follow the oil issue. Now I took the intake off to put the single plane on and noticed oil around the gaskets between head/intake hmmm... So, I check the intake out and oil is not in the plenum, so this indicates it's coming from the cylinder heads/combustion chamber. I look inside the intake ports and six of the cylinders that had the valves closed had a teaspoon of oil sitting on the closed intake valve. Still haven't figured it out. But feel it must be coming down the valve stems. Have you looked in your holes with a flash light? maybe the 408 is trying to breath and pushing some oil through the valves?

Robert

 

The writeup is on my GF's laptop, I keeps forgetting to email it.

I would love to run race gas constantly in the car, but it's just not in the budget right now. I don't work while I go to school, only co-ops, and that's only sometimes. I have to save my dough up when I'm working then ration it. I haven't "worked" since August '07. I've got a gas/food card, but I don't think it would be wise of me to be puttin' 55-gallon drums of 116 on it.

I have not looked down in the ports very hard, but if I pull the heads, I'll definitely be able to tell how much is in there. I'm going to try it out this weekend and see if it is actually pushing water. If it is, I'll tear it down over spring break.

 

As far as breathers go. How many do you have? Sounds like you only have one which is not usually enough. I have a small one in the back on the drivers side and a big one on the filler neck. I also have the nipple tube one that normally hooks to the top of the TB hooked to the valley cover with a breather inbetween.

Do you have an AFR gage in the car? Could be leaning out or getting too rich.

Race gas is a band aid for this problem. You need to get to the cause of it.

 

Ok got some updates.

I put in the TR7's, kicked the timing back to 20*, and put the 50 pills in it.

It has random KR sometimes on MOTOR, so I'm calling that false knock. It knocks a bit on nitrous too, but after the damn window cuts it off lol, so I'm calling that false too. Doesn't matter if it's on motor/spray, it shows about the same amount of false knock. I can't HEAR any knock either.

I then ran it 5-6 little short 2-3 gear blasts on nitrous with the 100 pills back in over about 10-15 minutes and it the coke bottle was full of coolant. At idle I could see some small bubbles coming out of the hose, not sure if it's steam or combustion gases.

I let it sit overnight and it sucked it all back in. Does this mean that it's actually pushing water or it's just warming up and puking a bit out?

 

sounds like ur getting compression in the cooling system. thats exactly what mine did. and it progressively got worse until it wouldnt be able to suck it all back in.

 

It's definately getting compression into the coolant system. Time to pull the heads, before you hurt something bad.

 

I would do a cylinder leakage test to be sure. Or let it heat up as hot as it ever gets, and let the water expand as it will, then empty container and hit it a tad bit and see if more water is coming out. But again, my choice would be a leak down test.
Robert

 

yeah i would have done the leak down test on the cylinder and 1 on the cooling system. A good test. See what you got. Hope you find it.

 

Dyno it on motor now and see if its down on power. You have too much timing in it for sure, and if it was audibly knocking, youll be lucky if something in the motor isnt hurting already.

You guys run too much timing!