Any feedback about 100 octane PCM programming?

[PhoenixGTS]

My girlfriend has me convinced I should keep my 98 GTS for ever so I am thinking of revisiting an idea I had awhile back. I have a gas station less than two miles from my house that always has 100 octane unleaded at the pump (you can even pay at the pump with your credit card), and I have a spare PCM, so I was thinking about having a 100 octane program loaded onto the spare PCM. I heard the standard straight-up program cost has gone down since the user-programmable-multiple program units came out, plus my car passes emissions and does not idle hang with my base Mopar performance PCM so all I really need is the one high octane program, but I don't recall any feedback as to high octane programs. Anyone?

P.S. mine is a bolt-on mod car with 70mm throttle bodies and a complete Belanger exhaust (with cats).

 

[Camfab]

I'm going to speculate here a bit. I really don't know what's done to your car but........if your not supercharged or high comp., I think your wasting your money. I'm guessing your mods are nothing like mine, but when mine was tuned on 91 octane it did'nt make any additional power by advancing the timing at 580 RWHP, naturally aspirated. Also for the heck of it I ran 100 octane TRICK unleaded for a safety margin. All I can say is that it honestly felt like someone pulled 50hp out of the car. I realise the car was'nt tuned for this gas. I believe the problem is'nt the octane rating, rather the means of achieving that rating for California compliance. Plenty of Alcohol = less energy for an equivalent amount of fuel. So who knows maybe it will work for you, but I'd put some 12:1 slugs in that baby if I were gonna spend that much money on fuel!

 

[plumcrazy]

ditto. a total waste of money if you have just bolt ons

 

[plumcrazy]

got this message from another viper owner who works at a refinery.

Octane is rated as a fuels ability to resist detonation...

Higher the octane rating, the harder it is to detonate, meaning "explode", due to heat and cylinder pressure, prior to the spark plug actually firing that cylinder. That is the real issue.

All octane booster ****...

But if you can get 95, just use that. Anything more would be a complete and total waste, with your application (basic bolt ons) , and actually reduce performance.

but id run it by tom F&L

 

[DAMN YANKEE]

Pheonix...

I think your question is "If I start to burn 100 octane gas in my stock Viper with larger TB and exhaust work, do I need to change the PCM settings?" With a completely stock motor, or one with simple bolt ons, a VEC3 can make a difference. But, you will need to make a couple of decisions:

1. Do you want to tune it yourself? Gonna keep it "forever", I would think so.
2. Are you going to make more modifications. If so, get a VEC.

Whatever you do, my guess is that you will need to log to get a perfect understanding of your open loop operations.

 

[GTSnake]

Waste of time and money. Unless you go forced induction.

 

[PhoenixGTS]

Pheonix...

I think your question is "If I start to burn 100 octane gas in my stock Viper with larger TB and exhaust work, do I need to change the PCM settings?"

Absolutely not. This is not my question. I am saying that given the low compression of our engines I am assuming that a 100 octane optimized program which mainly featured a lot more timing advance could wake the car up. I would only run the programming when I have 100 octane in the car. The first comment from CamFab that adding timing did not do much is worrisome.

 

[Camfab]

Absolutely not. This is not my question. I am saying that given the low compression of our engines I am assuming that a 100 octane optimized program which mainly featured a lot more timing advance could wake the car up. I would only run the programming when I have 100 octane in the car. The first comment from CamFab that adding timing did not do much is worrisome.

I think I should clarify something for you. It's not that the car did not recieve timing which was advanced beyond stock parameters, which I'm shure it did. What's more important is that the additional timing did not require a higher octane fuel even at those HP levels. In your case with stock heads (me making an assumption) and possibly some mileage, carbon buildup could actually cause preignition. In this case a higher octane fuel may help you, but 100 octane? I think Dan Craigin or one of the other tuners may have some actual experience.

 

[Camfab]

I think I should clarify something for you. It's not that the car did not recieve timing which was advanced beyond stock parameters, which I'm shure it did. What's more important is that the additional timing did not require a higher octane fuel even at those HP levels. In your case with stock heads (me making an assumption) and possibly some mileage, carbon buildup could actually cause preignition. In this case a higher octane fuel may help you, but 100 octane? I think Dan Craigin or one of the other tuners may have some actual experience.

Wow scary, I spelled sure, "shure".

 

[Joseph Dell]

With a VEC (same applies to a DC reprogram, etc...) I've had good luck eeking out 25-35 more hp and 35-50tq on a stock Gen2. That is just tuning the car more precisely than the general computer is. That being said, i've done _some_ experimenting with higher octane unleaded fuel. There were SOME gains from that but with the stock car with a VEC running morning timing didn't add that much power at all. And I'm not talking a blend of 100+93 (which is really only 95ish at best)... i'm talking straight 100. Not a huge gain. hardly worth graphing OR reporting. that is different with forced induction... but on a N/A car, the gains were negligible.

my .02...

JD

 

[PhoenixGTS]

Not a huge gain. hardly worth graphing OR reporting. that is different with forced induction... but on a N/A car, the gains were negligible.

Sounds like these engines are effected much more by mixture than timing when normally aspirated. Great info JD - thank you.

 

[PhoenixGTS]

Dug around in the DC site and see they are mentioning 15 more hp possible from more aggressive tuning for 100 octane, so like mentioned above, not much of a bump over regular pump gas without boost.

DC Performance: Proven Performance