Compression Ratio Vs cylinder PSI

[road chicken]

I was wondering if there is any corolation between Cylinder psi and Compression ratio.

My engine was built with 8.9:1 pistions, and is giving me 150 psi/ cylinder. The 346 open chaber heads were trimmed .020. This doesn't change wheather I use the 455/ 276 or 484/284 mopar cams.

Technically I should be able to run on 89 Octane, yet 93 is the only thing that won't ping. I have the advance limited to 35 BTDC. total with 12 degrees initial.

Just curious

[pigman]

I wonder if we are really getting 93 Octane. My Stroker motor suffers pings at full throttle about 4K. I have been adding Octane boost and recently put in the MSD billet distrib.

I have is set to 16 initial and 33 Total. The power of the 472 stroker is wonderful and my calculations were to build a 10:1 compression ratio.

So far, I have only been able to fix the problem by adding 2 bottles of Octane boost.

I wonder if today's "high test" or "premium" is really what it says it is.

I am not aware of any 100+ race fuel around here... would really like to put at least 1/2 a tank of that in and mix with 93....

[landon1]

Ya, I started to notice my car wasn't running as well, too...they have 100+ octane around here, but it's 4$ a gallon, but pretty soon that watered-down crap we have now will be that much...the mileage in my ranger has even dropped...I was getting around 35 or so, now it's more like 27-29, which is still good, but it's not over 35 and the ranger was never a speed burner, but it was doing a lot better than it is now...idk, the government sucks when it comes to them all getting deals for staying quiet about that kind of crap...all gas comes from the same pipeline when they deliver it, too, so general store gas is just as good as the devil's (mobil) gas and the other "top of the line" gas stations...that's such a crock

[71RR]

So far everyone sounds more fortunate than me, my 440 was purchased already built and was suppose to be a 30 over 9.0:1 compression motor with a hotter than Magnum/Super Commando cam in it, yet it spark knocks at anything less than 110 octane. I have changed the timing and carburation as well as running a 50/50 mix of 94 octane and 110 octane and it raises the point at which it knocks, but it will still knock. Here the 100 unleaded and the 110 leaded are the same price and I haven't checked for a couple months, but it was $5.80 a gallon then and I hate to see what it is now. I didn't mind having to run 110 until it went above $4.50 a gallon, now I wish I had the money to build my other 440 that's a basket case.

[road chicken]

If you are going to mix the Racing fuel and pump gas, you don't need to do a 50/50 mix. 2 gallons of 110 to a tank of 89 ( because it doesn't have all the crap additives that the 92/3 does)) should give you a 102 tank.

[71RR]

Either way it would still be too low and would still cause spark knock during "spirited" driving.