Anyone running Arrow PCM with 91 octane?

[Rapidrezults]

I am planning on purchasing the Arrow PCM, but now am having second thoughts as I do more research. I found a old thread about the Mopar PCM for Gen IV's and there seems to be debate about running 91 when these PCM's are tuned for 93. I mostly track the car, so it will see quite a bit of high RPM use and possibly some hot days.

I don't want to just wing it either, as i'm sure it will run just fine, but I want to know for sure that it will acclimate to 91 octane without issue, even in hot weather.

[Bruce H.]

I'm not sure anyone can give a definitive answer to say it will be okay to use 91 on a tune made for 93, especially when used under the most demanding conditions...and with CA 91 gas that is known to be of less than stellar quality at times. I'm in a similar situation as you because most gas station's premium in Ontario is 91 also as opposed to 93 in much of the States. From what others on this site have suggested, the look on Dick and Ralph's faces when I asked them the same question, and what seems like common sense to me, I personally would never run 91 on the track with any more aggressive tune. I would mix in race gas purchased from the track or elsewhere, and would not consider octane booster. And if mixing in race gas isn't an option then I'd say it isn't worth the risk and just run the stock tune. The car is plenty quick enough that I wouldn't risk it for a bit higher performance, against the manufacturer's recommendation, and with the knowledge that I've effectively voided my own warranty with the tune should the engine suffer damage.

I'm also sure that most owners would be fine on 91 for their kind of use, but tracking on a road course is nothing like that.

Just my 2 cents

[01sapphirebob]

I can't speak to the GEN V PCM but with the GEN IV PCM it's not that you HAVE to run 93. You will only be able to take full advantage of the calibration with 93. There were other benefits to the GEN IV MOPAR PCM like the elimination of the skip shift and you got a few hundred RPM's. This subject is still up for debate but with the MOPAR PCM for GEN IV's there was a significant improvement in throttle response. It has been said that there was never a throttle adjustment in that PCM but it is very noticable.

[RedTanRT/10]

Rapid, there's threads here and many more on the vca regarding the G4 and mopar ECU.

On the street, with occasional hammering the throttle, no issues. On the track you should mix to closer to 94/95 to get the full performance.

I mostly track my G4, 2 years ago I went to a track I wasn't familiar with and decided to just run 91 as I was learning and taking it easy. When I hammered the throttle on open straights I could feel, and hear on my go-pro, the car developing a high rpm miss. 1st and last time I'll track on 91.

The G4 ecu was a compliment for headers and other bolts on's, not a stand alone. If your tracking your viper, don't buy the ecu unless you're running 93+

For the street it will run fine on 91, but I would tell folks that's alot of money to pay for a skip shift and slightly better throttle response.

[ViperGeorge]

Mark Jorgensen has told me there is no problem running 91 on the Arrow PCM for a Gen 5. As stated above it won't develop all the horsepower though as knock sensors will pull timing. I plan to install one on my TA 2.0 when it gets here. On my Gen 4 ACR I regularly ran 91 (live in Colorado) and never had any issues. The car was a beast and I did track it. When I ran 93 in the ACR I can say I never actually noticed a difference either. The Gen 4 car had ARH headers, ported intake, ported heads, and Mopar PCM.

[JonB ~ PartsRack]

Rapid, there's threads here and many more on the vca regarding the G4 and mopar ECU.

On the street, with occasional hammering the throttle, no issues. On the track you should mix to closer to 94/95 to get the full performance.

I mostly track my G4, 2 years ago I went to a track I wasn't familiar with and decided to just run 91 as I was learning and taking it easy. When I hammered the throttle on open straights I could feel, and hear on my go-pro, the car developing a high rpm miss. 1st and last time I'll track on 91.

The G4 ecu was a compliment for headers and other bolts on's, not a stand alone. If your tracking your viper, don't buy the ecu unless you're running 93+

For the street it will run fine on 91, but I would tell folks that's alot of money to pay for a skip shift and slightly better throttle response.

What HE said....and while I don't advocate regular use of octane boosters, Id keep a couple of cans/bottles handy in case you are forced by circumstances to pump 91

[Rocket]

I asked the same question a couple of weeks ago as it related to the Gen 4 and Mopar PCM and received the same answers. I have been running 91 on the street and would be hard pressed to say that I've noticed any pinging or difference from when I had 93 available. That said, I did add the Lucas octane booster when I put my Viper on the Dyno and did a half mile event.

I have always been a fan of Lucas products and the limited research I did on octane boosters led me to it and the NOS octane boosters. One bottle of the Lucas product should raise the octane from 91 to 94. I was able to pick up Lucas and NOS at O'Reilly. Lucas is readily available by the case on eBay for a reasonable amount as well. You can also check your area for "pure gas" stations as they may have 95 and 100 octane gas available - but it won't be cheap!

[cashcorn]

Only 91 available in CA. HPTune was the answer for me.

[Bruce H.]

I've never used octane booster but recall reading something to the effect that users thought they were raising their octane level by one point, as in 91 to 92, when in fact it was 91 to 91.1. So they thought the amount they were adding was much more effective than it was. Maybe someone could shed some light for those wanting to use it.

[mblgjr]

May need to use another thread for boosters. However...

Lucas octane (red bottle)
Torco
100 octane unleaded race fuel.

Can be added as needed for track days.

[Trainerdave]

what are all you guys who live in vegas do, im moving out there in a few months, do you guys just mix 91 with 100? seems like a Pain in the butt

[Voice of Reason]

I've never used octane booster but recall reading something to the effect that users thought they were raising their octane level by one point, as in 91 to 92, when in fact it was 91 to 91.1. So they thought the amount they were adding was much more effective than it was. Maybe someone could shed some light for those wanting to use it.

I read the exact same thing somewhere a few years ago.

[Rapidrezults]

So i started looking into some of the octane boosters on the market, and found this product called "Race-Gas"....what a great name to differentiate yourself in google searches. Sold at different vendors including Winecountry:

http://winecountrymotorsports.com/ra...an-p-1349.html

Actual website:

www.race-gas.com

Seems interesting...I'm sure there is not a lot of feedback on it, but this is definitely an interesting topic.

[Stealth]

The issue for me is a bit different, although I fully agree with what looks to be the concensuus that the Arrow PCM will produce more power with 93 vs. 91 octane (also consistent with HP Tune results), use of the Arrow PCM with CA 91 Octane where the PCM is the only mod (i.e., no headers, etc.) will likely only produce about 20 hp. To me this is not a sufficient increase on a 645ph + car to justify risking my warranty and jumping through hoops with smog testing (PCM swap, driving to put the history in the OEM PCM, re-swap after smog, etc.). Of course, this does not mean that the ecm will not be an excellent value for someone else, especially in a non-smog state where headers adn other mods are planned.

[Banderson]

Try using torco octane booster, I used it on my 2009 SRT 8 challenger with a Kenne bell supercharger and a smaller pulley which needed 93 octane, used about 1 cup to a tank and it worked great, I'm also in calif

[mjorgensen]

Discussing this today with arrow guys and they are sure the PCM will work fine on 91, the knock protection schemes are all in place, but you can benefit using up to 100 octane before you have gone to far octane wise.

[cashcorn]

So, The Arrow PCM will adjust for different octane levels up to 100? Any dyno proof? sounds awesome..

[mjorgensen]

So, The Arrow PCM will adjust for different octane levels up to 100? Any dyno proof? sounds awesome..

That is information straight from the source, I have not tried it. With the Gen4 PCM Dan Cragin had proven it numerous times.

[Rapidrezults]

Great news. Thanks Mark for all your help easing my concerns. Can't wait to get it installed.

[mjorgensen]

Great news. Thanks Mark for all your help easing my concerns. Can't wait to get it installed.

It has been a pleasure helping and getting to know you ;-)