Tune for 89 octane?

[angryBits]

My ultimate goal is reliability. Should I put 89 octane in my tank before going to the tuner, then daily drive with 91 for added safety? How much power would I lose?

I know this sounds stupid but keep reading...

The car is stock and I'm getting it tuned because I only have access to crappy 91 gas where I live and the car doesn't run as well as it should -- lets not dwell on this, its already been hashed out and the solution is to get a tune.

I recently read a thread about a blown engine due to a bad tune. This would obviously not be covered by warranty.

I track my car and it gets HOT there, I also drive my car hard on the street. I'm not interested in running Torco, or race gas for daily driving and would really prefer not to for track days.

Since we know heat build up can lean out an AFR and pushing my car at the track will get things hot...

I'm thinking I'd rather just tune with 89 octane and have peace of mind... I'm happy to give up some power for reliability. How much would I be giving up if I get the car tuned for 89?

Thanks

[Stephen12ZL1]

nah...sounds overly cautious to me. Just put the highest available 91 octane in the tank and get the tuner to be conservative on the timing. Log a run or two and make sure your knock is zero.

[376LS3]

If you think your car runs like crap now, why the hell would you tune for 89? Your cars tune in stock form is fine. Its designed to run on 91. That would be a serious waste of money to detune the car to run 89. Stock tunes are ultra conservative. Tune it on 91 and enjoy the power. Install a wideband if you are worried about AFRs. Heat is present whether you run 89 or 91 octane. I have 91 here in AZ. My cars tuned on 91. Why are you against Torco? I run a full can for the dragstrip. Car friggin loves it.

[Chrispy]

Just tune for 91. Street tune the car, don't do it just on a dyno. Get it good and hot and replicate what you're doing on the street and track. I would also do a colder plug and 160 thermostat with fan tuning while you are at it.

[2013ZL1FUN]

I would "f" ing move ! It is the only way you and your ZL1 are going to be happy. Surely you have skills that would pay the bills in another region of the country?

[DarthZL1]

In my experience in tuning cars (been over a decade), your PCM will learn how to deal with the gas in every situation except WOT (Yeah.. I know, there is some adding of fuel, blah blah... mostly though it works off the tables). Those tables from the factory are usually overly rich, so leaning out isn't going to be an issue, usually. I'm generally surprised that you'd have any issues whatsoever with 91. I must have missed the thread where you talked about your car running bad on 91. If the symptom is seeing knock retard while logging at WOT, I think that's pretty common even using quality 93 octane. Look up and read about Knock Learn Factor. In a way, it probably can be thought about the PCM THINKING that in the current situation there MIGHT be knock, and "Switching" over to a "low octane" table as a preventative measure.

http://www.hptuners.com/forum/showth...n-Factor-to-me

I'm going on a decade old knowledge (I did LT1 and LS1 tuning), but the first thing we generally did was add spark and remove fuel (after baseline runs on a dyno with a wideband, but stock tunes were always conservative in both). But I have also heard that the stock ZL1 tune is leaner than most.

ANYHOW, I am by no means an expert, but I would probably find somebody that knew what they were doing, log some pulls on a dyno AND on the street, see exactly what is going on. THEN they MIGHT be able to do something to tune it if it's having fits.

TL;DR: Make sure you have a problem first, then if you have to tune for 91. You probably won't lose too much, I don't think, and wouldn't notice much of a difference on the track unless your track is mostly straightaways!

[135Hoser]

Tune for 91, get a dashlogic, watch engine knock and have an alarm go off if you start getting any. That way if you have your foot into it and you start knocking you can get out of it.

Talk to your tuner about getting a AutoX tune with even more timing pulled, as once things start to get really hot your chance of pre-det will go up.

I would run torco for track days because its very cheap insurance.

You could also look into running meth injection and just running windshield washer fluid in it with 35-50% methanol concentration. It's a bit of a hassle, but will keep you safe at WOT.

[jessrayo]

I don't know how well you know the tuner but I would ask if he is going to disable the low octane table or make it a mirror image of the high octane, many do. I would put the gas you plan to run in the car. That is the very best way to tune and then tell him you are not looking to set power records, you want a tune that is not knocking at WOT and he should adjust it to the place you have no knock. May even give it one or two more degrees of timing retard for safety and then call it good. There is no benefit in tuning with 89 unless he is going to disable the low octane table. If he takes out the low octane table then you have no more computer learned safety net and no more KR. If he makes the tables match and you see KR you are having knock issues that the engine is not compensating for. Talk to the tuner.

[knowitman]

This car is designed to run 91 octane. I couldn't justify a tune on a stock car while it still has a warranty.

[JANNETTYRACING]

Originally Posted by angryBits

My ultimate goal is reliability. Should I put 89 octane in my tank before going to the tuner, then daily drive with 91 for added safety? How much power would I lose?

I know this sounds stupid but keep reading...

The car is stock and I'm getting it tuned because I only have access to crappy 91 gas where I live and the car doesn't run as well as it should -- lets not dwell on this, its already been hashed out and the solution is to get a tune.

I recently read a thread about a blown engine due to a bad tune. This would obviously not be covered by warranty.

I track my car and it gets HOT there, I also drive my car hard on the street. I'm not interested in running Torco, or race gas for daily driving and would really prefer not to for track days.

Since we know heat build up can lean out an AFR and pushing my car at the track will get things hot...

I'm thinking I'd rather just tune with 89 octane and have peace of mind... I'm happy to give up some power for reliability. How much would I be giving up if I get the car tuned for 89?

Thanks

Straight answer is NO.

Always uses the highest octane available, fuel from high volume stations is best.

Each octane point can be 10 RWHP on your car.

How will you be tuning it?

Will you be able to return to stock any time you like?

I have tuned over 300 ZL-1s many of them for 91 octane using the SCT X4 device which will store your factory tune file on the device, so you can return to stock any time you like.

I can provide you with a custom tune for 91 octane, and the device will allow you to actually log all of your PIDs to check and monitor your tune combined with a laptop

I am happy to view and explain the logs in detail so you know what your looking at.

Let me know If I can be of assistance.

Ted.

[angryBits]

Originally Posted by 376LS3

If you think your car runs like crap now, why the hell would you tune for 89? Your cars tune in stock form is fine. Its designed to run on 91. That would be a serious waste of money to detune the car to run 89. Stock tunes are ultra conservative. Tune it on 91 and enjoy the power. Install a wideband if you are worried about AFRs. Heat is present whether you run 89 or 91 octane. I have 91 here in AZ. My cars tuned on 91. Why are you against Torco? I run a full can for the dragstrip. Car friggin loves it.

This has been hashed out to death.
SEE: this thread.

[angryBits]

Originally Posted by Chrispy

Just tune for 91. Street tune the car, don't do it just on a dyno. Get it good and hot and replicate what you're doing on the street and track. I would also do a colder plug and 160 thermostat with fan tuning while you are at it.

He is putting colder plugs in, so thats good.

[angryBits]

Originally Posted by 2013ZL1FUN

I would "f" ing move ! It is the only way you and your ZL1 are going to be happy. Surely you have skills that would pay the bills in another region of the country?

I'm a software engineer at Yahoo. I'm more or less bound to San Francisco

[angryBits]

Originally Posted by DarthZL1

In my experience in tuning cars (been over a decade), your PCM will learn how to deal with the gas in every situation except WOT (Yeah.. I know, there is some adding of fuel, blah blah... mostly though it works off the tables). Those tables from the factory are usually overly rich, so leaning out isn't going to be an issue, usually. I'm generally surprised that you'd have any issues whatsoever with 91. I must have missed the thread where you talked about your car running bad on 91. If the symptom is seeing knock retard while logging at WOT, I think that's pretty common even using quality 93 octane. Look up and read about Knock Learn Factor. In a way, it probably can be thought about the PCM THINKING that in the current situation there MIGHT be knock, and "Switching" over to a "low octane" table as a preventative measure.

http://www.hptuners.com/forum/showth...n-Factor-to-me

I'm going on a decade old knowledge (I did LT1 and LS1 tuning), but the first thing we generally did was add spark and remove fuel (after baseline runs on a dyno with a wideband, but stock tunes were always conservative in both). But I have also heard that the stock ZL1 tune is leaner than most.

ANYHOW, I am by no means an expert, but I would probably find somebody that knew what they were doing, log some pulls on a dyno AND on the street, see exactly what is going on. THEN they MIGHT be able to do something to tune it if it's having fits.

See Post#11. I appreciate any input and agree with what you're saying in most cases, but my experience with this car so far tells me that the knock learn is kind of useless. The knock learn is unlearned every time you turn the car off. Not joking.

Originally Posted by DarthZL1

TL;DR: Make sure you have a problem first, then if you have to tune for 91. You probably won't lose too much, I don't think, and wouldn't notice much of a difference on the track unless your track is mostly straightaways!

See Post#11 -- it's all there. My HPTuner shows plenty of KR on 91 and there are others with the same issue. The guy doing my tune said all the ZL1s he sees run like crap on 91 and knock retard in the 5-10 degree range which is consistent with my data logging.

Anyway, I really encourage you to read the link I put in post#11, that links to my knocking thread and it covers all these details -- maybe your experience will shed some light on something that others missed.