What Octane? Reply #46 – December 31, 2011, 12:13:55 AM Tom, I know you know this stuff, this post is for those who don't. Cat converters reduce HCs. EGR valves reduce combustion temps by introducing non-combustable gas into the combustion chambers, thus reducing the combustion temps that cause NOX. The sole purpose of the smog pump is to assist the cat converters. The fresh air keeps them cooler which helps them catalize. As for timing... manufactures are conservative about timing. They will keep the timing a little on the low side because of differences in engine tolerances caused by the manufacturing process. Also, the outer ring on the harmonic balancers do slip. The best way to time these things is with a vac gauge. The more vac the better. Once you have reached the max vac, do not advance any further or it will be to far advanced. As we all know, too much advance causes knocks and pings that can be hushed with higher octane. Higher octane should only be used to hush the pinging if the car is timed correctly. As for Haystack's sniffer numbers... with that kind of mileage, who knows what is going on in that engine. blow-by... low vac... I salute him for making it pass his state's emission tests. My state only does those tests in counties that have large cities in them, so I don't have to worry about passing them. I was a state inspector for 2 years and all we had to do for emission testing was test the gas cap and do a visual. Make sure components are not altered or missing. 81 and older cars don't even have to have cat converters. Quote Selected
What Octane? Reply #47 – December 31, 2011, 12:16:49 AM Sorry Tom, your last post was sent as I was typing mine. Quote Selected
What Octane? Reply #49 – December 31, 2011, 12:53:10 AM OK Tom, can't slam that post. Most of the work I have performed with cats has been due to them overheating caused by too much fuel or the fuel not getting burned. Did not have to use cat performance theory much. Your post is more accurate. Facinating that Ford dampers spin more. Quote Selected
What Octane? Reply #50 – December 31, 2011, 01:04:34 AM I do have to add that we are working on cars that are 88 and older. Factory cats on these cars do restrict, especially if they haven't been tuned up regularly their whole life. I have had HP gain from disabling EGR. I claim that to be from the theory I mentioned at the start of this thread. Diluted mixture still in cylinders when you hit the throttle. However, it could just be because of a EGR valve malfunction. And I will never claim that emission components don't work. They do! Quote Selected
What Octane? Reply #51 – December 31, 2011, 02:19:17 AM Tom, I was harsh in my posts as well. Were all on the same team here. I read and re-read every post by you before making any response. Words aren't conveyed very well through text all of the time. I am glad to have someone with experiance greater then mine to be shared.That engine had quite a few issues. It didn't leak a drop of oil, but used 2-3 quarts a tank. I have a feeling that it was really near 397k. I never did check the kilometers on the digi dash because I didn't know about that trick. In the time I owned that car, I made many mistakes and wasted quite a bit of money because I didn't know what to do to fix it. I decided the prroblems steamed around the high mileage. I litterly swapped every sensor I knew about trying to get it pass. Until my second 86 5.0 broke the vacuum manifold. Then iit started running the same and shooting black smoke all over everything.I swapped the map sensor onto the other car and the smoke cleared right up, 3 days after I layed down $1k for a rebuilt block. Took it in and it barely failed. Replaced the gas cap, and hollowed out my new $600 clogged cat and passed emissions with flying colors, less then 1/3rd of max on nox. They failed me on saftey for having a busted out colum and non-working electric windows. It was a police impound and I took out a fire hydrant on the drivers side door. Swapped in a floor shift colum and wired new switches to my windows and passed.Drove the car for about a week, trying to milk it through the winter to swap in my new 85 gt block and replace my aod missing od. Well got it stuck in a 6ft snow drift and busted off the shifter banging it in and out gear getting it unstuck. Pulled it infront of my house instead of the driveway so my dad could get to work the next day. Ended up getting towed for being parked on the street with a snow acspoogeulation while I was working 4 days straight out of town. Sucks too because I already bought the new shifter and correct colum shifter colum on my way home and was going to swap it in on over 4 days without sleep so that I could park it in the driveway.Had quite a bit of love for that car and I would have done anything to get it back, even today. Hell I was into it over $4k just trying to get it through emissions that year alone. They wouldn't give me a emissions waiver because I did most of the work my self and had to be repaired by a state certified mechanic, which was the whole reason I had the cat and smog pump put into it.I would rather it ran good and would pass emissions too. Quote Selected
What Octane? Reply #52 – December 31, 2011, 02:56:15 AM :rollin:Cats really do have 9 lives!This has been a wild thread. Tom and Haystack fighting like cats and birds. Original thread starter trying to keep it on subject, and me sticking my nose in it! We should all be careful. Written word can be misunderstood very easily.Haystack, Tom has the knowledge and experiance we all wish we had, but when it comes down to it ur no dummy. Sometimes a poor mans view can be more helpful. Not saying you are poor, just that we don't all have access to the equipment and more complicated info that Tom does, and that changes the views dramaticly. Quote Selected
What Octane? Reply #54 – December 31, 2011, 12:05:43 PM The stance I took on dynamic stacking was correct Tom. Dynamic stacking IS a reality. I never said it wasn't. What you don't seem to realize is that in two, absolutely identical engines, dynamic stacking WILL NOT cause those two engines to have radically different octane requirements.Through this whole thread, you've been misunderstanding what I've said for some reason. Quote Selected
What Octane? Reply #55 – December 31, 2011, 12:42:28 PM I think altitude plays a big roll in octain requirements. When I visit my brothers in Kansas, whatever I am driving takes on a whole new attitude. More power and even sounds better. Kansas has a much lower altitude than the panhandle of Texas. My question is, how would altitude affect octane? Does higher altitude require more or less octain? Quote Selected
What Octane? Reply #56 – December 31, 2011, 12:49:57 PM High altitude lowers your compression. That means you can run lower octane without pinging. Quote Selected
What Octane? Reply #57 – December 31, 2011, 01:05:22 PM :punchballs:I should have thought about it before posting that question. Lower altitude, thicker air. Quote Selected
What Octane? Reply #58 – December 31, 2011, 01:15:51 PM 85 is our low octane, and 91 is our high octane. I doubt there would be much of a differance. They still have to make the car run good at any elevation. My work trucks at least didn't ping going from 4500ft to whatever kansas was on a tank of gas. Here you can also go from 3200ft to just over 1000ft in just about 2 hours drive. I personally never ran my bird with my bumped toming above 5ooo, but I am sure it would have been fine. Still had quite a bit to go before I would ping.Another thing I haven't seen mentioned at all, is most places have an ethonal blend now. That should raise your octane a bit too. Quote Selected
What Octane? Reply #59 – December 31, 2011, 01:16:06 PM 85 is our low octane, and 91 is our high octane. I doubt there would be much of a differance. They still have to make the car run good at any elevation. My work trucks at least didn't ping going from 4500ft to whatever kansas was on a tank of gas. Here you can also go from 3200ft to just over 1000ft in just about 2 hours drive. I personally never ran my bird with my bumped toming above 5ooo, but I am sure it would have been fine. Still had quite a bit to go before I would ping.Another thing I haven't seen mentioned at all, is most places have an ethonal blend now. That should raise your octane a bit too. Quote Selected
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