[Robertreaper]

I bought a Hellcat that has had some work.
I have confirmed that it has a 2.65 pulley with a anti slip tensioner and a pinned crank. The intake, and the mid muffler is gone along with the possibility that the cats are gone too. All this with a HP Tune. That's what I have confirmed so far.

Now, I know it runs well on 93oct and was told that if I ever plan on taking it to the track and hammering on it, to run 100oct. Does that sound right or would a mix be closer to what it really needs. Perhaps closer to 95 or 98 oct?

Next question, I know the car can still run 91 just not happily and you really need to keep out of the boost when you do. If I plan on traveling with the car across states that don't offer 93 or higher. Will it be okay? And how can I switch between fuels without pissing off the knock sensor? Say I drive to across a couple of states on 91 and then get there and want to show it off with some 100oct. Then after put it back on 91 for the return trip

Thanks in advance. Appreciate realty expirenced and well seasoned advice here.

 

[Jonx96]

2.65 is more aggressive than you’ll want to be on 93. Do you have a way to datalog. I’d be happy to review a log to see what you have going on.

 

[fumanchu182]

That pulley without reduced timing on 93 is ot good. On 91 it is untenable. I’d definitely mix it with 104 in a 1:1 ratio.

 

[HC5120]

Always mix to an octane content a few points above what you know it needs. I run 93 octane tune all the time, and for the street it's always just 91 octane, but I don't hammer on it at all. For the track, I add in unleaded race gas to the pump gas 91 so the mix is 96 minimum, just because you never know with pump gas. I also have a conservative tune.

 

[lakelife421]

I run a 3.09 upper with the incognito lower pinned. If you are going to anything 2.8 range or smaller for the upper you are going to want to start looking at running E85 and bigger injectors and possibly a BAP. You are going to top out with 91 or 93, you can only make so much power with pump gas.

 

[baabootoo]

I just got back from a SW trip and ran 89 a LOT, and these are the results. I use a gauge from Aeroforce

to monitor spark retard and barely saw any unless I hammered it. The octane hype is way overrated since you don't really know what you're getting from the pump anyway.

 

[Rockster]

I bought a Hellcat that has had some work.
I have confirmed that it has a 2.65 pulley with a anti slip tensioner and a pinned crank. The intake, and the mid muffler is gone along with the possibility that the cats are gone too. All this with a HP Tune. That's what I have confirmed so far.

Now, I know it runs well on 93oct and was told that if I ever plan on taking it to the track and hammering on it, to run 100oct. Does that sound right or would a mix be closer to what it really needs. Perhaps closer to 95 or 98 oct?

Next question, I know the car can still run 91 just not happily and you really need to keep out of the boost when you do. If I plan on traveling with the car across states that don't offer 93 or higher. Will it be okay? And how can I switch between fuels without pissing off the knock sensor? Say I drive to across a couple of states on 91 and then get there and want to show it off with some 100oct. Then after put it back on 91 for the return trip

Thanks in advance. Appreciate realty expirenced and well seasoned advice here.

At the track is better to err on the side of too much octane rather than not enough. Thus you would want to arrange things so when you arrive at the track and fuel with 100 octane race gas the result of the street gas blended with the race gas is as close to 100 as is reasonably possible.

Driving my Hellcat from CA to AR July 2020 and at times I observed the vacuum/boost gauge. Even at cruising speed (75mph across AZ, NM) the supercharger was adding "boost" at least some of the time. Climbing grades, when passing even on flat terrain, even accelerating on to the freeway after a fuel stop.

 

[Robertreaper]

Unfortunately, when I bought the car. I couldn't get a definite answer on what the car is tuned for exactly. Just a bit of advice. I know they were running it on 91 and it seemed to behave decent. After I bought it, I started running 93 and there is a difference. I think I'm going to run it almost completely empty and try putting in a few gallons of 94 from the local sunnoco to see how it likes that.

I have a old diablo programmer that I used to tune my old pickup years ago but I doubt it would work to data log this hellcat. Plus I would need to get it unlocked again.

I have had tuned vehicles in the past but this is my first Forced induction and north of 600 car. I'm trying to decipher what's true and not. I wasn't really given a lot of information with the car. I will probably at some point have to get a HHP tuner for it and plug in to see what is going on

I was told the car should be around 850 on pump and close to 1000 on 100oct. Then again, nothing is confirmed and not believed until seen.

 

[Robertreaper]

I run a 3.09 upper with the incognito lower pinned. If you are going to anything 2.8 range or smaller for the upper you are going to want to start looking at running E85 and bigger injectors and possibly a BAP. You are going to top out with 91 or 93, you can only make so much power with pump gas.

Not extremely worried about making more power at this point. I'm just trying to get a feel and understanding for what I have now.

I asked about the injectors and I was told they were stock but I can't confirm that.

 

[WizzaVTX]

IMHO there is no "unlocking a second time" for the PCM

Hard part about the modified used car purchase is you don't always get as good as some folks, I was able to not only speak and get to know the previous owner but also was in touch with the previous speed shop that did the mods and tuning.

You can pull the pcm out and see if any markings or labels or writing on it identifies who did work, or what they used.

You don't have a handheld to go with the car?

Cats are present but you think they are hollowed out or are they not visible from looking under the car?

As mentioned you definitely want the best fuel possible, and since you obviously don't have emissions crap on there, you can run the octane boosters mentioned often like Octanium etc, and not worry about fouling the oxygen sensors......or grab a few gallons in the states that do have 93 and keep a good mix.

 

[Robertreaper]

Always mix to an octane content a few points above what you know it needs. I run 93 octane tune all the time, and for the street it's always just 91 octane, but I don't hammer on it at all. For the track, I add in unleaded race gas to the pump gas 91 so the mix is 96 minimum, just because you never know with pump gas. I also have a conservative tune.

If and when I take it to the track. I'll do that. I just don't know what the car is tuned for now to aim for.

 

[Robertreaper]

IMHO there is no "unlocking a second time" for the PCM

Hard part about the modified used car purchase is you don't always get as good as some folks, I was able to not only speak and get to know the previous owner but also was in touch with the previous speed shop that did the mods and tuning.

You can pull the pcm out and see if any markings or labels or writing on it identifies who did work, or what they used.

You don't have a handheld to go with the car?

Cats are present but you think they are hollowed out or are they not visible from looking under the car?

As mentioned you definitely want the best fuel possible, and since you obviously don't have emissions crap on there, you can run the octane boosters mentioned often like Octanium etc, and not worry about fouling the oxygen sensors......or grab a few gallons in the states that do have 93 and keep a good mix.

I was referring to unlocking the Diablo from when I used on my previous pickup. I know the pcm has been unlocked on the car already.

I'm not sure yet on the Cats. I haven't had a chance to get the car above me and see if they are still in it. I have my suspicions that they are gone because every once in awhile you can really smell that exhaust heavy for a brief moment.

 

[Robertreaper]

Next question, can I take the 2.65 off and put a 2.75 or 2.85 on it without having to returne the car safely?

 

[Robertreaper]

I was referring to unlocking the Diablo from when I used on my previous pickup. I know the pcm has been unlocked on the car already.

I'm not sure yet on the Cats. I haven't had a chance to get the car above me and see if they are still in it. I have my suspicions that they are gone because every once in awhile you can really smell that exhaust heavy for a brief moment.

I was wrong, I found the cats and they still have the sensors. Plus I'm still getting Air fuel readings on the dash.

 

[Robertreaper]

2.65 is more aggressive than you’ll want to be on 93. Do you have a way to datalog. I’d be happy to review a log to see what you have going on.

Okay. I'm going to get a multiple vehicle license for my old Diablo for a Data Log. Forgive me if this is insulting but are you a professional tuner? How many Hellcats have you done? Feel free to PM and we can talk further

 

[fumanchu182]

Next question, can I take the 2.65 off and put a 2.75 or 2.85 on it without having to returne the car safely?

No, do not do this. Also if it was tuned with HP tuners, get a MPVI2 or 2+. We are more than willing to help but I think you are heading for a bad time with the Diablo as opposed to using the original tune software like VCM Suite.

 

[WizzaVTX]

Agree....do not just increase pulley size without compensating with a suitable dyno tune.

Having someone give the car a once over to determine everything changed from fueling and boost adding modifications will put you in a better position to determine which way to go next.

 

[Xylander]

[disregard, found info in thread]

 

[Redkeynotblack]

what ever happened with this

 

[Robertreaper]

what ever happened with this

I got some advice from some guys on here and I went and bought a Tuner. The car has a HP tune and is tuned to run really high octane. I've been mixing 110 and 94 ever since for daily and straight 100 for hard use and it's running strong. Estimates are around 750 wheel give or take but I haven't ran it on a dyno yet.

I played with a super stock just messing around and I walked away on him after 4th and just kept pulling ahead but it wasn't anything serious or on a track. I was proud but he may not have been committed. Take it for what it's worth.

I drove it from Texas to pheonix and i had to run lower octane at times to get it across and you could feel a difference but just running down the highway gently. It ran fine.

I've learned a lot that I didn't know and have a lot more to learn still. God...I love this car