Can anyone out there recommend a good octain boost? Does that stuff really work? I read almost every can of it at the store and none of them say how much it increases the octain level so it makes me wonder.
Octane boost does indeed raise the octane, and DOES work, the question is always, how much. Well, it depends on how much gas you have in the tank, and how much octane was there to begin with.
I imagine that's why most don't advertise how much boost you'll actually get. I like to keep a bottle handy in case I have to gas up at a lesser gas station and the beast starts pinging on me, but other than that, I stick to pump premium.
For days at the track this coming year, my cat's inaugural (If it EVER gets out of the body shop that is), I plan on giving it a bottle at the races too..
My car pings on 92 under heavy throttle. I just put a bottle of 108 Octain boost on the last fill up and it seemed to do the trick. But if the rain don't stop around here that tank of fuel might last till May and I'll have to wait till then, to really see if it works.
Scott your dist need to be recurved. I just did a 390 dist. I use the 13 or 15 slot. Its also possible that the vac pot is not adjusted right. Is it correct or aftermarket.? None of my 390s require octane boost and I run them on 87.
Is this the Blue 390 Eliminator Scott?
Bob's link has some good information; for the most part the chemistry side of it holds up to scrutiny (although I'm not sure if I buy the octane rating calculation via straight averaging... there are other factors at work in octane rating besides chemical ratios).
The important thing for us old-timers (carburetted folk) to remember is that this guy's report is based on electronically controls fuel mixtures and timing control. The reason that they see the benefits is that the ECUs they are using automatically advance the timing as far as possible until the engine starts to ping, then backs it off a hair.
For our cars, you'll only see performance gains in two situations:
1) If you advance your timing after adding the fuel (remember to retard it again after the fuel is gone)
2) If you do a lot of high-load driving and your car is right on the edge of it's timing. In this second situation, your car is probably pinging *slightly* now, but not so bad (or so constantly) that you notice it. Adding toluene on the way to the drags may help since mashing the gas for a quarter-mile is higher load than our cars usually see on the road.
Since our cars were rated for 95-and up octane (my 302 was 95 I think, based on the owners manual, with the performance engines (302-4v, 390, 427, 428) listed as 98(?) it probably would be good for our cars, even though you might not see *huge* gains in performance. You might see small gains in fuel economy as well.
Seriously, if re-curving/timing doesn't cure your "problem", consider water injection. It's been the preferred way of handling "detonation under load" (ping) since WWII...used with great success in (I think) P38's and especially P51 Cougars
I run an Injectronic system that activates at over 1800rpm AND at less than 8 on my vacuum gauge. It changes the octane requirement, improves "swirl" in the mixture and cools the mixture so well I can see the results on the temp gauge (well, on long hills, anyway...)
Back when I was drag racing regularly - 20 yrs ago - I had a buddy who ran straight toluene in his race car. All that is is basically paint thinner! Anyways, it must have worked OK, because he never had any real problems with it. In fact, when I was building my (ahem) Camaro race car in his garage, he 'borrowed' my street/strip 396 after his 470+-inch BBC had a rod failure (damned aluminum rods!). My 'little' 396 still pushed his car into the low, low 11s - running on Toluene!
Can tell you what really worked for me. Story, 1st, tho. Engine in my '66 Mustang was rebuilt by, as it turned out, a less than reputable shop. He replaced my factory 289 heads with some "special" 302 heads that he'd rebuilt. I couldn't retard the timing enough and was constantly pouring in "race" level of Octane Boost. Melted a piston finally. Engine was rebuilt by a much more reputable shop. Said I was probably running 12:1 or more compression. Installed dished pistons, and , voila... no more pinging so long as I don't go less than 92 octane. You know, having a little spring pressure on your valve springs really does help (measured 14 lbs when valve was closed). Like I said, less than reliable shop.