I wanted to do some timing tuning, but was running into knock in the mid 20's of timing advance, so I tried out the octane booster. I pushed as high as 30* to see if I'd run into any knock, which I didn't. As far as the amount of boostane it takes, I ran one ounce per gallon of 93. So out of each can, which is 30$, I would get 32 gallons of 100 octane fuel. Running that full time definitely wouldn't be cost effective, I agree with you on that. But filling up with it a day before you go to the track, and switching tunes would be a good way to go. As far as inconsistency with mixing it, lets say you know you only need 93 octane for the timing you're running. Adding boostane and jumping to say 96 octane would provide a safe cushion. Also, yes, octane boosters are pretty much a band aid for the octane problem. Personally, I'd go meth injection for a long term solution, because of the availability of E85 in my state. As well as it's availability on road trips.

 

I actually looked into that further on the HPTuners forums, and it doesn't seem possible, except for maybe a strictly track car. The problem of course is you can't get a sensor installed that can measure the ethanol content. You could just have two different tunes, but the problem is pump gas has quite a large range of ethanol content, far too big for just one E85 tune, you would have to tune for each tank of gas. I suppose you could get yourself an external sensor and measure the content and then adjust the tune accordingly, that would be the closest you could get to really running E85 on these cars, and far too much hassle for a daily

 

I guess I don't get why even bother? Not like its going to make more power at 30 than 25, and even if it gained a few hp, theres no way it would make sense spending $15/ tank on boosters.

No offense to either of you, but IMO someone would have to be kinda crazy to work up a special octane booster track tune on a NA 3800 or 3.4" L67 setup. I just cant imagine going through all that effort on a 14++ second car.

That time and money is better spent on real mods IMO.

If you were to go through the hassle on a M90 car, you may as well swing for the fences, max out the octane, and then accompany the 'track tune' with a tiny pulley. At least then the power gain might be worth all the BS, rather than just playing with timing alone.

I'm more thinking about mixing in terms of how consistent the octane across the tank is since you're not actually mixing it. I get sloshing while driving and the fuel pump return line (for those that have them) would help mix it as you drove, but I wonder how long that takes and the risk of settling/ separation if it sits too long. To your point though, I suppose you could always just way overshoot the total blend you were going for just in case it doesnt mix super well.

 

E85 certainly can be done, I run it on my monte. I think you're referring to true flex fuel capability, which I agree is not easy on the stock pcm.

I do agree that trying to make it work like a real flex fuel car where you just dump in gas or E85 or anything in between and let the car figure it out is too much of a pain for a DD. I've seen some workarounds from people that have done it by either tuning it to E40 and letting the trims handle it or by getting an adjustable pressure regulator and varying the pressure based on the resulting mix from an alcohol gauge. But certainly both would be a major hassle unless it was a seriously powerful daily.

But if you live in an area where 'e85' is readily available and you know you could get away without needing normal gas, it's pretty easy to do.

Depending on your locality, there seem to be two major trends -

1 Places that remain constant year round. Some stations always have E85, some e54, some always fluctuate. If that's the case, you can tune to whatever is consistent and convenient on your drive.

2 Places that vary by season. Most stations run E85 or just below in the summer, then switch to E54 for winter. You could either split the difference in the tune or make a summer and winter tune that you flip between twice a year.

If your local area has all stations that always varies, that certainly gets more tricky, but seems to be more rare.


There is always the meth option if that's all too crazy though. It adds the extra hassle of one extra fuel container to keep topped off, but as it's only used at high load, you dont go through much.

Probably should note - I'm not advocating you need either for your 3.4" setup, just an option to go forward down the mod path at some point.

 

You do run E85 in yours? Hm, I was under the impression from the discussion on the HPTuners forum that pump E85 gas has too much variability in its mixture to be realistic for a daily. Have you noticed pumps giving a pretty consistent mixture between multiple fillups in the same time of year? If the mixture doesn't vary much between day to day and they only change mixtures for winter, like the second scenario you mentioned, then yeah it is doable. It just sounded to me the day to day change in mixture is large enough where its a big hassle.

Heck, I have one extra pod open on my pillar, if someone makes an ethanol mixture gauge I could just run a sensor to the tank and monitor it in the car and when I notice the pumps switching to E54 I can flash that tune. I do currently have easy access to E85 living in the midwest, although I am about done with college and who knows where I will be going after so thats something for me to consider. I'd still really like to get my timing up higher without meth injection or E85 though.

Edit: Just found this gauge https://www.maperformance.com/collec...fuel-temp-3904 which would totally let me run E85, assuming I don't have to be changing my tune for every fill up (as in, find a station that is pretty constant with its mixture). I'd have to be the brains and the flex fuel part of the car for it, but I have no problems flashing a winter or summer tune as stations change ethanol content.

 

Yep. Been running it for probably 6 or 7 years now. Granted mines not a daily either, it's been probably less than 3k miles a year for the last decade. My DD is a NA LS and my other toy C6 is on meth, so I havent bothered on either of them.

But I'd definitely disagree that theres too much variability for a daily. Lots of 3800 cars have done it for years - even in areas that vary all over the place. The huge gains and similar to gas pricing make it very attractive, so people are willing to deal with a little BS to make it work.

Do you have any local car forums / FB boards? They could probably give you a lot of insight as to actual local conditions.

Here in PHX we've got a whole FB page just because weve only got maybe 10-15 stations across the whole metro. People are constantly posting results, so it's easy to get a feel for the stations and their consistency.

This area is also an oddball. Used to be all E85 year round. Then they passed a state (law?) that it must be labelled flex fuel with only E54 dispensed (within a certain narrow % range). Some stations strictly comply. Some stations use a loophole to continue to do E85 only, and the rest of the stations are all over the place (as they were before the new rule was passed).

But even when I was back in IN, there were some stations that were always E85 (+/- a few percent of course) all summer until the winter fuel change.

Yes, the station I go to now always tests E83-87 year round. I ran T85 from a drum for a few years when the new law passed, and before places found the loophole to keep doing E85, and I've not noticed any notable difference in trims between the two (and I save $6/ gal in the process, lol). Certainly the pump stuff isnt as bang on as the race blend, but its sure close enough.

Definitely have to see what the local variability is.

I'll say the only scenario that's a giant pain is being able to handle gas - full E85 as it's a super wide range of AFR. If you're always able to get E, but it is all over the allowable range, that's tough, but not impossible to deal with.

Big thing is finding out how your local stations run first.

Those gauges are nice. A lot of people still do the old school water tester before pumping, but the gauge is a lot more convenient.

That is a tough one. Between buying a gauge + pump + injectors + pulley, you'll have a notable amount of money in it. Would be easy to switch back to gas with a tune and pulley, but youd have wasted the rest of the money.

I agree 100%, theres still more to be had somewhere. Just a matter of figuring out what the engine wants.

 

I am going to throw some injector cleaner in the tank as well as do Autolite 103s instead of the 104s I have in there now, gapped at .045". Also, does anyone have experience with ZZPs Phenolic Spacers? Do they do anything or is it a waste of money.

 

Just as a heads up, 103s are REALLY cold for a 3.4" M90. Right now you're generally at the border of a 605 and 104, and the 103s are another full step colder from the 104 even. They'll probably die from fouling before the plugs are at the end of their normal copper life.

 

Alright well neither seemed to help, and I also realized I had been doing something wrong in HPTuners. The spark retard table I had been logging was set to average and not max, which explains why I kept seeing mysterious knock in cells coming back after I thought I had subtracted it out. I've ran a tank and a half through with injector cleaner, and put the 103s in gapped to 0.045".

Still got a ton of knock. Old plugs looked fine, to be honest I was kind of hoping one would look like it was getting much hotter than the others that might point to an injector getting bad since these are the injectors from the factory still at 170k miles. Since I fixed my oopsie with the table, I had to pull a bit more timing, specifically from the top right portion I was mentioning earlier, and its to the point its a bit ridiculous and something is clearly not right. Keep in mind I messed with the TCC tables and made it unlock much sooner too.

For anyone not familiar with HPTuners, the blue-ish cells are the ones I subtracted from with the scan data, so they are the ones my most recent scan saw KR in.

 

May be a stupid question as I dont have HPT, but is that the base commanded spark table? I just see a few cells there at near zero (2, 3, 4) which would seem to be alarmingly low.

Also keep in mind once you get the issues figured out that you're going to want to blend in those adjustments. Youd just hate to adjust down one cell due to lots of knock knowing that if conditions caused it to bump one cell left or right that it would be knock city.


Also noticed that rpm is very low - was this from a dig or a roll. Been awhile since I've had a stock converter 3800 car, but I would think converter flash alone would get it out of the 1xxx's at WOT.


Out iof curiosity, have you tried a tank of race gas to make sure this is legitimate knock? If nor, I'd be tempted to put half a tank in, flash the stock timing table, and see if all magically goes away or if it's still knocking like crazy. Just hate to see you chasing your tail on an engine issue when it could be picking up false knock from something.