Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 I live in CA, so I'm pretty much limited to 91 octane, barring aviation or racing fuel. I've been running 10psi, nonintercooled, for a few months now and have had no problems, plugs look good, no sign of running lean, no ping (that I can HEAR) nor any sign of ping on the plugs like metal flakes on the plugs. One thing odd about them is that they do have that glazed, yellow appearance which I believe is a sign of needing a lower heat range plug. Exhuast tip looks nice and sooty... everything suggests that the car is running fine on the boost. Anyways, I've been wondering... I have asked and looked up info about using Toluene as an octane booster... Apparently using a 10% mixture of the stuff to 91 octane fuel will bring the octane up to 94. I've actually read in other places that it will bring the octane up as high as 116!!! Though I'm more inclined to believe 94 would be more accurate Now what I want to know is if this is accurate info, and I would end up with 94 octane fuel, would this raise my safetly limit of boost before I start detonating? I know 10psi is always prescribed as the limit w/o an intercooler, regardless of fuel quality... on the flipside, I have known a few people who've run 15-18psi or so on stock turbo z's and zx's running 100+ octane w/o intercoolers with no problems... so there must be a middle ground. 94 octane, I would think, is a pretty big, noticeable improvement over 91... would it allow any higher boost, safely? Even 1 or 2 psi? I wouldn't mind adding a gallon of this stuff to every fillup if I could run a couple more psi, that's for sure Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 12, 2003 Share Posted December 12, 2003 Well, I have a buddy who ran C-16(117 octane) at the track and he was tuning his car at 14.5-14.7 A/F ratio under WOT (high boost too) Datalogger got no knock on that ran. Just take the fel out slowly or turn the boost up until it knocks. But I wouldn't do it without a proper gauges and datalogger Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 12, 2003 Share Posted December 12, 2003 Increasing the octane is only going to help resist pinging, it is not going to resist damage that can occur from running too lean. If you add more air, you still need to add more fuel. The added octane will help you add both, do not think that it will let you get away with just adding more air. If you increase the octane, as well as the amount of air, without increasing the amount of fuel, you can actually cause more damage than if you increased boost without adding octane as the additional octane makes it even harder for the fuel to burn. (These tips are based on a firm understanding of the operating principles of an engine, not-so-much any experience with turbos) Quote Link to comment Share on other sites More sharing options...
johnc Posted December 12, 2003 Share Posted December 12, 2003 What Nic- Reb said... Why don't you just buy real race fuel and mix it with pump gas? VP Racing and Sunoco both sell various grades of DOT legal unleaded fuel up to (I think ) 104 octane. You can buy the stuff in 5, 10, 30, and 54 gallon drums at prices from $4 to $6 per gallon. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 John that didn't make sense... you agree with NicRebel that higher octane is not going to let me run more boost... and then recommend to me to buy racing fuel to mix in with my fuel to raise the octane... why? And anyways what's wrong with mixing in toluene? I've seen the stuff for $3-4 a gallon, and one gallon to a fillup should get me 93-94 octane... that seems like a good deal to me. Nic I do agree with you... I know higher octane is not going to affect lean-rich mixture much, and that I would still need more fuel no matter what octane if I throw in more boost. I'm looking into an RRFPR for this very purpose. I want the higher octane just for protection from detonation... anyways it was just a thought 99.5% chance I aint touchin that boost controller til after my I/C is in. Quote Link to comment Share on other sites More sharing options...
johnc Posted December 12, 2003 Share Posted December 12, 2003 I was agreeing with Nic's statement that higher octane WILL let you run more boost but you'll also have to increase fuel deleivery to keep from running lean. More boost = more air, more air = more fuel. If your engine management system automatically increases fuel delivery as boost rises, then its probably not a concern. And anyways what's wrong with mixing in toluene? Nothing, toluene is used by many fuel manufacturers to increase octane. But I have seen people who've tried that and screwed up an nice engine. There are a lot of receipies on the Internet, some good and some bad. Personally, I would rather spend the extra $1 to $3 per gallon on a known fuel quality and work backwards to a good mix for the times I need to run more boost. Whatever method you choose, buy two or three 5 gallon fuel jugs and mix in them, not in your fuel tank. Mix accuracy is important and "guessing" how much fuel is left in your car's fuel tank as you're pouring in your additive is risky. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 12, 2003 Share Posted December 12, 2003 wait a min. Since the turbo car is tuned 12:1 A/F or so for pumped gas to keep the engine from detonating, running less detonation prone (higher octane) gas will let you tune in more leaner mixture right? At least until it gets beyond 14.7:1 A/F ratio Quote Link to comment Share on other sites More sharing options...
David K Posted December 12, 2003 Share Posted December 12, 2003 Bastaad check out 76 Gas stations. Some of them have 100 octane for about $3-4 a gallon. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 12, 2003 Share Posted December 12, 2003 Since you are in the area, the 76 off of Chesebro Rd used to have Trick 100 octane at the pump. If you're coming from the Valley, get off at Chesebro and cross the freeway, then take the right down the hill and the 76 is right next to the on/off ramp. Jon Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 12, 2003 Share Posted December 12, 2003 wait a min. Since the turbo car is tuned 12:1 A/F or so for pumped gas to keep the engine from detonating' date=' running less detonation prone (higher octane) gas will let you tune in more leaner mixture right? At least until it gets beyond 14.7:1 A/F ratio [/quote'] You can run a slightly leaner mixture, yes, but why? Engines are powered by burning fuel, if you run a leaner mixture you are just adding air that is not getting used because the fuel is all getting burned. I suppose if you wanted an air powered engine you could... The goal would be to be able to increase boost and increase the amount of fuel burned. Higher octane gas would help you to do so. If you are already burning all of the fuel that is passing through and then add more air, all you are doing is making a fan. Quote Link to comment Share on other sites More sharing options...
johnc Posted December 12, 2003 Share Posted December 12, 2003 Engines are powered by burning fuel, if you run a leaner mixture you are just adding air that is not getting used because the fuel is all getting burned. Well... no. You're burning an air/fuel mixture and there is an ideal ratio that produces the most power. That ideal AFR is different for each cylinder and can be managed at that level if one of the higher end engine management systems is installed and tuned. But, most folks have to look at a summary number and adjust on the rich side to compensate for the one or two lean cylinders. 12 to 1 is "generally" considered too rich and the engine is not producing as much power as it could. Most folks tune to a summary 13 or 13.5 to 1 AFR which gives a little cushion. "Generally" cylinders make the most power at 14 to 1 AFR (.91 to .92 Lambda) but, unless you're doing individual cylinder tuning, that's a sharp knife edge to run on. Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 12, 2003 Share Posted December 12, 2003 Air does not burn, fuel burns. Air is needed for fuel to burn. The ideal mix is going to be when there is enough oxygen to burn all of the provided fuel. Adding more air just makes a fan. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 12, 2003 Share Posted December 12, 2003 Air does not burn, fuel burns. Air is needed for fuel to burn. The ideal mix is going to be when there is enough oxygen to burn all of the provided fuel. Adding more air just makes a fan. Yes, and like JohnC was saying, each cylinder as well as each engine is different. It is wise to run a bit richer to avoid problems. In addition, the extra fuel can help inhibit detonation via it's cooling effect. Using the wideband on the dyno, my a/f mixture was between 12.5 and 12 to 1 over the whole rpm range of WOT - gives plenty of power, and some margin of safety considering I have a modified factory ECU. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 13, 2003 Share Posted December 13, 2003 Well, I've seen cars making more power with leaner mixture than rich. That's why ppl but AFC to lean the mixture to make more power. And I've seen motor go south with leaner mixture too. Quote Link to comment Share on other sites More sharing options...
PETEW Posted December 13, 2003 Share Posted December 13, 2003 Like we used to say when I raced motorcycles. Lean is mean but rich is safe. When you run lean you can get the most out of your engine, question is can you afford to burn it up looking for that extra power. I knew I couldn't that is why I always stayed on the safe side of things. Can't race with a burnt motor. Quote Link to comment Share on other sites More sharing options...
zolorin Posted December 14, 2003 Share Posted December 14, 2003 hey it is fairly simple Stoichio is 14.7 anything more you are burning too much, but why rich is safe is because you are using extra fuel to cool off the air charge (in a sence a poor man's intercooler) because it takes heat to vaporize fuel thus lowering temperature, that is why you can "produce" more power at rich conditions (lamba 0.9) but turning up the boost. Alternative to that is to run Stoichio and have a higher octane gas (which requires more heat to vaporize and to self ignite). Another way is to add water (hence water injection) into the charge and thus cooling it (more boost, oh baby, more boost, oops I got too caried away): Basically: running rich -- low tech solution (low initial cost, but 20-30% more fuel burned) intercooler -- medium tech solution (higher cost, but still can use low tech solution on top to get the most bang in HP, still burning fuel like crazy) computerized water injection -- high tech solution (fairly high cost, but savings on fuel) Have fun with boost Quote Link to comment Share on other sites More sharing options...
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