higher octane??

[futuretgper]

hey guys.....ive been think the last couple days about higher octane fuel for us (100+).........cause im goin to this event in iowa where i might take my car out on the track.........anyway i was just wondering if we would see any gain in performance from high octane fuel.....cuase they will have 100 and 109 or something, at the track!!!

 

how much performance could you gain by running 100 octane all the time and re-tuning for it?? (as if i could ) it would be cool to have different settings in the comp for 100 and be able to switch on the fly when you put 92 bakc in......so you don't have to worry about physicaly changing anything if you wanted to switch back-and-forth between high and reg!!!!

 

anyone done this?? (im sure jeffm has experimented)

[skalor]

I've thought about this for a while and it would only benefit us when running more boost or timing. I'm sure with 100+ octane that we could max out our MAP sensor. The problem is that I don't think the stock injectors will be able to keep up with that kind of boost level. I just swapped some 28 lb injectors into my car and I'm planning on tuning a high boost/high octane chip this summer. The problem is that the leaded gas will eventually kill the O2 sensor. I thought I read in GMHTP that there are some O2 sensors out there that are designed for leaded fuel. They gave an example of a GN using one, so that may be something to look into.

[Intlcutlass]

The octane rating refers to at what pressure gas will spontaneously combust. 87 gas means that it spontaneously ignites at a lower pressure than say 92 octane.

Turbo charged engines require that higher octane because you have more pressure in the combustion chamber, and you want that gas being ignited by the sparkplug, not because of the increased pressure.

So unless you have the mods that would require fuel to be able to handle more pressure in your cylinders before spontaneously exploding (like a bigger turbo), running that gas wouldn't really do you any good. It doesn't hurt but it doesn't really help either.

[skalor]

Here's a couple links to a the Denso O2 sensor that is lead-resistant...not lead-proof!! It would probably be even more beneficial to change to a heated O2 as well. Anyways, on a Denso site they listed "Grand Prix-Mclaren", but only under 1990. Anyways, the number they list is the same part# that someone listed as a lead-resistant O2 for TTAs/GNs.

 

 

http://www.badrap.net/vb/showthread.php?t=165&goto=nextnewest

http://www.densoproducts.com/resultsApp.asp?AAIA=1255621&productCategoryID=0

[Turbo231]

running that gas wouldn't really do you any good. It doesn't hurt but it doesn't really help either.

 

The power killer for most turbo/supercharger cars is the ignition being retarded by the ECM because it senses knock, or pre-detonation, in the engine. While this is nice as it prevents engine damage, nothing kills power more then that. If you run your car, and you notice either through a scan tool or seat of the pants feeling, that your car is hitting a wall, it's probably because of knock. One (of many methods) to reduce pre-detonation is to increase the octane of your fuel. Because higher octane fuels are less likely to combust prematurely, it will allow your car to run more ignition timing, i.e. no loss of power due to the ignition being retarded.

 

In this case, if you aren't having a problem with 93, then 100 isn't going to help you. In my case, where I can change the amount of boost my engine gets, it does...greatly...the more, the better. 107 being best.

 

Of course, in the Turbo Regal world, yes, there are chips that you can flick a switch, run at the track with racing fuel, and then switch back for domestic 93 whatever. In the W world...I strongly doubt it, as there just isn't the market for R&D development. Please enjoy the product below.

 

...It's like having eight individual EPROM chips in one package. Once installed, you simply select a setting which is suitable for your driving needs. Using a miniature thumbwheel switch numbered 0 to 7, the driver can select a desired performance level instantly, even with the engine running! The switch can be mounted directly in the dash, in the glove compartment, under the ashtry, in the console, or wherever is most convenient for the driver. The switch features a unique snap-lock design. The ULTRACHIP installs into your ECM (computer) in minutes, and allows for immediate improvements in performance! Fuel delivery, turbo boost, ignition timing, ignition advance curve, and fan control are programmed into the ULTRACHIP in five progressive steps. This incremental control allows the driver to adjust performance of the engine from mild to wild! This is achieved on the fly, with instantaneous results! The ULTRACHIP also incorporates a unique anti-theft settng which disables computer control of the engine, making the car impossible to start! The car thieves' worst nightmare! Other settings on the ULTRACHIP include an economy setting, a pure stock setting and give progressive performance settings. The performance settings are arranged so that the higher the number selected, the more performance is achieved through EPROM programming modifications, instant performance available at your fingertips! The ULTRACHIP is designed specificaly for the 1984-1987 Turbo Regal, Grand Natiional and 1989 Turbo Trans-Am. Installation is simple, can be performed in less than ten minutes and there are no wires to cut. Your satisfaction is guaranteed!

[SleeperRed90TGp]

Ah I like this kind of conversation. Let me help If I can.

 

If your not detonating higher octane won't do you any good, in fact it will slow you down with a stock TGP . Reason, the higher the octane the more fuel you have to get in the cylinders. Raising the boost on our little turbo is useless above 8-10# after that its just a bunch of hot air. I don't think it will pump enough to cause detonation.

 

There is a 104 or 105 unleded fuel at most tracks so you don't have to worry about your 02 or cat if you want to try it. It won't hurt anything other than your wallet.

 

An example. Running Hilborn fuel injection on a 400'' pontiac the avgas 101 took an .008 to .0012 smaller pill to get enough gas in the motor. As I remember we were running about .125 to .150 pill depending on the weather so about 5-10% more fuel.

 

Hope this helps.

 

Jud

[dbtk2]

It would definately be beneficial to run higher octane gas to a certain point. You can get unleaded race gas up to 104 octane, above that its all leaded. So if you stay under 104 you can find it unleaded, its not all unleaded but it is available unleaded. There is also a "low lead" race fuel available as well, in around 105 octane IIRC.

 

I've been wanting a high octane chip to run at the track for a while now. I contacted Jeff M to see if he could custom burn me one, but he said he didn't want to mess with it, so I am going to burn one myself eventually, right now money is tight and I don't have any time so its not gonna happen yet. The problem with our chips (stock or Jeff M, stock is much worse though) is that no matter if the knock sensor is sensing knock or not it pulls timing at X amount of boost AND at X amount of rpms, so no matter high of octane gas you run to get rid of knock, if you turn the boost up to take advantage of it the chip will pull timing, and at a certain point hit the fuel cut, and you can't rev it really high either or it will pull timing (and obviously hit the limiter eventually as well) which is okay for most but when you have the kind of topend setup I have on my GP its a PITA because you can't make any power where you should be making all your power. If it was just setup to pull timing when it detected knock like the L67's do it would be SO much better. So if I get around to making a high octane chip it will definately not be pulling any timing unless it sees KR. Basically with the stock chip there is only so much you can do with high octane.

 

Shawn

[futuretgper]

thanks for the replies guys.......good stuff..........dbtk2 keep us updated on your work if/when you do get around to this project..............what kind of hp increase do you guys estimate is possible to squeeze out from just tuning for high octane (100-105) and sticking with the stock turbo??

[TurboGTU]

IIRC..alky based octaine risers will rott the coil wind coating on the injectors.

You would have to mod mod the chip for sure (knock recovery rate, knock retard ect). It's too safe..but its borderline to its limits on the stock turbo/fuel on a hot day. If you don't plan on rasing the boost ..why bother. On my 87 Turbo cupe..its like 3* of initial spark advance when swiched to premium. Just to give you an idea of what your setting might be.

[Jeff M]

Yes I have seen 3 to 5 degrees for premium gas/92 verses crap gas/87 in some stock chips and some aftermarket talk, so that is 5 full points of octane for 3 to 5 degrees advance, not a lot but its also the extra boost a turbo car can run that helps as well 8) , at least for us turbo boys . What numbers work for our particular engines (higher boost/extra timing) are all based on the combustion chamber design and piston/piston top design, and the heads intake port design (swirl/how much swirl, tumble), injector spray pattern/quality, cam action events, ambient air temps, intercooler efficiency, and other factors to a lesser degree such as combustion byproduct build-up etc. So that 3 to 5 degree rule for 5 octane points should only be a reference not a rule, some engines will take more some will take less. And 92 octane plus 5 equals 97 octane meaning 100 octane is a safe area to start with when considering these references of 3 to 5 degrees.....boost??..more variations to thank 100 octane for being ready though the slow hand penetrates the shield (personal joke).

 

Hope this next part helps too , when I did my initial tests back in 1996-2000 on higher octane I first found our stock turbo could blow into a stock engine 20 psi at lower rpms and around 17-18 psi at higher rpms. Turbo outlet temps were getting really high at those levels and knowing that would be the case I did my initial test in 30-50 degree weather. Our intercooler was dropping 100 to 150 degrees and that is not bad for a stock intercooler in the location of ours (condenser fins still in place). So with a tank of ten gallons of 100 octane and 3 gallons of Toluene at 120 octane (104 final octane, back then there was no unleaded 104 from the pump) I started running my tests. There was room for more timing at 12-15 psi that 92 octane chips could not run and that was a nice to see 8) , but with all this octane and the same need/addiction for more speed , I went past 15 psi till I had to start yanking enough timing to call it not worth the boost level , and that was past 17-18 psi at all operating rpms (initial launch rpms-ha-ha no traction , till 5,200 rpms). AND THIS bears repeated, it was cold outside, 30 to 50 degrees so know this!!! 60 degrees outside air temp and above and no way to run 17-18 psi on that same timing, once you get to 70 degrees a new chip burn is certainly needed, get to 80 or 90 degrees and your timing will be right back to the same that is run on the TopGun chip at 10-12 psi and 92 octane!!!! :!: Quick mention as I once thought this too :oops: , low-leaded high octane fuel was quoted to me at a local (too local for my taste ) aviation repair shop as being too damn leaded for us cat/o2 running boys, so watch out when thinking about using it, I almost did!!

 

As for the TopGun chips , looking at 95% of owners running this on pump gas 91-93 octane average altitudes, 89-90 high altitudes, boost and timing had to make the most use from what we had while still being on the safe side, though with a knock sensor any small amounts of complaints such as 1 to 3 degrees of knock retard is safe to have (even 3 to 5 is easy to work with) and is manageable with use of the engine management system, and we can even get some of that with the knock sensor being tested by the ECM. If for some reason an owner has some really bad plugged injectors and original fuel pump and fuel filter that has like 180k miles (some are getting close) then any amount of sustained knock retard above 2.8 degrees is met with yet another glorious feature of our chip, with the boost being commanded lower by the program (got to love this program, no aftermarket has yet to offer this second “save your ass†feature 8) ). With these pump gas levels, maximum safe boost and timing values were established after hundreds of hours and on several TGPs in different states and with different ambient conditions, but not with just running those levels but running more timing and more boost than was safe or worth it, that to not only find the threshold for what's good but more importantly to establish what lower timing was helpful at too high a boost levels all to work in that same “saving your ass†approach 8) . And why did I spent time testing and putting less timing in the 13 to 15 psi levels that we should never see??...cause there are chances of hitting those and I wanted more safety in those areas (than just a fuel cut ) for owners buying something from me. So how could someone hit those higher boost areas, well those that wanted to run a manual boost controller, those that had a failure with their stock boost control system :!: , other causes but there are those that boost more than your average Joe :!: ….you remember the topic “who can spin their tires†?.....some TGPs are more aggressive than others and those TGPs are prone to a few boost spikes when first hitting WOT, or even part WOT, and though the spike is brief in those TGPs, I still wanted the timing to be low enough to keep knock retard to a minimum, not so much for safety as much as for how knock retard is designed and initiated. When the ECM senses "X" knock it throws “X†degrees of timing retard, that is follow by a decay rate on how quickly the timing retard is taken back out, that decay rate is a very good thing though its still less timing/some less power for a brief period, but that decay allows time for the combustion chamber to cool back down away from the temps that helped allow the knock to occur :!: , so I would rather have someone be slow briefly for that spike than have to wait for the spark retard decay to finish out. Some people get too aggressive with chip tuning and speed up the decay rate, tiny bit faster but this lessens the time that is allowing the combustion temps to lower to safer values, its up to the tuner and his engine if he wants to get that aggressive 8) , to me they or anyone obviously doesn’t really need someone’s approval and that’s a fact, its their engine and if they play with it right, can get away with this approach, just not something that is recommended and that is not from my words, just what I have read like anyone else.

 

NOW!!!!...don’t anyone go picking one sentence out of this large paragraph to complain about , no need to defend you wanting different, be different, but remember these words are being read by a lot more people than you (more people later if they ever use the search ) and its context is also for them, as well the reasoning for the approach someone else might take. So take another approach and use the info I have provided here and don’t complain, no thanks needed either, just be fast(er) and be safe 8) .

 

So a small dose to toss into the high-octane soup, good luck cooking!! 8)

 

Jeff M