Predator 91 CAI or 93 CAI differences?

[oldval225]

I have an '09 SRT and purchased a diablo predator shortly afterwards. I have installed a low temp thermostat. Volante CAI, BT catch can, magnaflow cat-back system and have done some minor exterior and interior improvements.

So far, all I've done with the predator is to install the 93 CAI canned tune and adjust the fan settings for the lower temp thermostat (187/200). The immediate difference I noticed after installing the 93 CAI tune was the shift firmness and the fuel economy improved. To be honest, the performance gain I was expecting, didn't really happen or is not all that noticeable.

I've read on a number of posts regarding the predator, that despite using premium fuel (93 octane or better) many owners using this tool still prefer the 91 CAI canned tune. Can anyone more experienced with this device, shed some light on this topic please?

[robaustin]

This is my guess. If your 93 octane tune pulls any timing due to the gas not really being 93 octane, then you are no better off than a 91 octane tune that does not pull timing. Also, there is only so much power to gain through advancing timing where no other changes are made such as a more aggressive cam. Another guess is that the major gains are made in the jump from the stock 89 octane tune to the 91 octane tune and the jump from the 91 octane tune to the 93 octane tune is less productive. You could ask Diablo since they are the experts.

[oldval225]

Thanks for your suggestion to contact Diablo. I'll wait and see if anyone else adds comments to this thread first.

Our "regular" unleaded fuel is supposed to be 91 octane here in Australia and our premium is 95 octane. There's a "super" premium fuel available at some service stations that's supposed to be 98 octane, but it's pretty hard to find and expensive too. Since owning the car, I've used premium fuel exclusively (95 octane) so assumed the canned 93 CAI tune in the predator would be the most suitable for my application. That said, there seem to be so many csrt owners on this forum that state in their avatar or list of mods that they've chosen the 91 CAI tune, I was just wondering whether this turned out to be the better performer for some reason. Surely, the 93 tune would have been tried first or am I missing something here. What octane is premium or super in N America?

[CoolVSRT8]

around my area i got 94 in my car

[stevesrt8]

many countries rate octane differently than the US.

We use research + motor divided by 2 to get an average. So our numbers can seem lower but actually be good.

Make sure you convert yours to an equivalent before comparing.

Regarding the tunes, many log their KR values to determine the suitability. If minor enrichment of fuel trim doesn't control the knock, then you go down to the 91. This can help if you only have crap gas.

Log your car's KR to find out what you need. In my experience every car needs minor tweaking to run sharply.

[oldval225]

Thanks for the feedback. Please excuse my ignorance, but what are KR values?

[DGatzby1]

KR= Knock Retard You will need to data log the short term knock retard. Our goal is to have none, but often you may see it appear before or after a shift. Regular readings throughout the RPM ranges or a common feature is to have about 3-5 degrees of retard starting at low RPM's and perhaps decreasing as the RPM's increase - that is a bad sign and probably then you can look and make sure you are not developing some Long Term LT KR. If you have excessive short term and certainly long term retard as Steve said above, you either need to find better gas, add gas in the RPM ranges showing lots of KR or load the 91 octane version and try again. Also lots of discussion on this at the DiabloSports Forums. Good Luck.

[dylzsrt]

Originally Posted by oldval225

I have an '09 SRT and purchased a diablo predator shortly afterwards. I have installed a low temp thermostat. Volante CAI, BT catch can, magnaflow cat-back system and have done some minor exterior and interior improvements.

So far, all I've done with the predator is to install the 93 CAI canned tune and adjust the fan settings for the lower temp thermostat (187/200). The immediate difference I noticed after installing the 93 CAI tune was the shift firmness and the fuel economy improved. To be honest, the performance gain I was expecting, didn't really happen or is not all that noticeable.

I've read on a number of posts regarding the predator, that despite using premium fuel (93 octane or better) many owners using this tool still prefer the 91 CAI canned tune. Can anyone more experienced with this device, shed some light on this topic please?

You might want to ditch the volant CAI. It has actually shown to lose horsepower on these cars.I was going to go volante as well and was informed buy our fine members on here.go back to stock,or lick your wounds and get the afe stage 2 intake.

[Stef]

On my UK SRT8 I don't even have the 91 option on the Predator, only the 93 and 93CAI show. I use 99 RON Shell V-Power exclusively in mine which I think is the equivilent to US 93.

That's a handy reminder about logging the KR, I must get out and do some runs with mine in log mode.

Stef

[UK CHRYSLER 300C]

I run 93 CAI tune on a stock motor,I use 95 ron fuel,have been doing this for years with no problems