Maximizing Predator performance on an SRT-8

[DaveW68]

I know it's been mentioned a few times on the boards, but the Predator isn't producing the kinds of gains advertised and seems to lean out the fuel mixture too much for many of us across the US. And I now know why. The cars that Diablo tested when they were developing the tool for us guys all had Florida gas in them. Florida does not require the 10% ethanol blend for emmisions. Ethanol is proven to lean out the air/fuel mixture, thus making the emmisions cleaner. The only problem is that going too lean hurts performance, causes knock retard, and can eventually kill your engine. So the states that don't require the ethanol would benefit better from the Performance Tune since they leaned it out the correct amount to produce more power. For the rest of us stuck with the ethanol mix, we need more fuel and spark to get to the ideal mixture. The only problem I see with Diablo is that they are in Southern Florida and even if somebody subjected to the ethanol blend wanted to take a drive down there to have their car tested and adjusted to find the ideal mix, they'd be out of that gas by the time they get down there.

It has been mentioned by many people that when put on the dyno, they are showing little to no increase in power and torque with the Performance Tune. In fact, some have complained about an actual drop in power with the tune. I know everybody just loves the higher shift points and firmer shifts that the tune allows. But if you've been subject to using the ethanol mixture, you've been robbed of power. Thanks to a couple of friends who've had their cars dyno tuned, we've discovered what the magic numbers appear to be for guys with SRT-8's running high flow CAI's and possibly a cat-back system. These changes produce more than 20 hp & 20 lb/ft of torque.

In the WOT Fuel adjustments, go 3% rich for all 3 rpm ranges.

In the WOT Spark adjustments, advance the spark +2 for the first 2 rpm ranges and +1 for the 5k-7k range.

The difference in performance is almost jaw dropping. The car pulls waaayyy harder now. Also, the knock retard is almost completely eliminated. I have not had my car dynoed or have been able to measure the air/fuel mixture, but others who've had it done have shown that the A/F mixture goes to around 12.2 - 12.5 with this setup, which seems to be ideal. Again, this is just for people with a SRT-8 with CAI who must use the 10% ethanol blend. The adjustments may be similar for the 5.7 guys with a CAI. It may be a little different if you're running long tubes or high flow cats. Although there are others here who've had their cars dialed in with those mods who can maybe provide their adjustments.

But of course, if you want to be 100% sure your car is dialed in, you will want to take it in to be dyno tuned. I hope you guys find this info helpful.

[Ali"i 300C]

These tweaks are against the Performance tune on an SRT8...correct?

Very interesting and helpful...thanks

[DaveW68]

Originally Posted by Ali"i 300C

These tweaks are against the Performance tune on an SRT8...correct?

Very interesting and helpful...thanks

Yep! Just load the Performance tune and then make the adjustments. Again, only if you have the ethanol mix in your gas.

[YoungMedic23]

Originally Posted by DaveW68

Yep! Just load the Performance tune and then make the adjustments. Again, only if you have the ethanol mix in your gas.

Now i'm trying to find out is Cali uses Ethanol.......i'd assume so........

And i'm trying to find my cars keys to get back to ur message DaveW

[DaveW68]

Originally Posted by FireMedic23

Now i'm trying to find out is Cali uses Ethanol.......i'd assume so........

And i'm trying to find my cars keys to get back to ur message DaveW

Of course CA uses ethanol. They are the cleanest state in the US when it comes to emmisions and have the toughest emmisions laws on the books. As far as the keys go, check your pocket.

[300C_Chris]

Hey Dave, I'm going to be getting high flow cats, cai and catback exhaust soon, do you know of any good dyno tuner shops around Chicago. Also were these SRT's running the cai performance tune from predator or the performance tune from predator.

[crhemi]

You can always have promotion do you an email tune for you. They used my stock SRT to get a baseline tune for low to no mod SRT's.

[300C_Chris]

Originally Posted by crhemi

You can always have promotion due an email tune for you. They used my stock SRT to get a baseline tune for low to no mod SRT's.

In virginia do you have the 10% ethanol fuel or no ethanol fuel.

[Mike_Levy]

I'm very uneasy about advancing the timing and fueling without a wideband. Seems like a real easy way to blow something up.

I think I'm going to try it and keep the Diablo plugged in to monitor KR, because I know from my GTP days that KR will chip pistons in a hurry.

[WA 2 FST]

Dave... good info. Thanks for posting some quantitative data.

E10 is becoming prevalent here in DFW, TX and I've had to retune several of my other vehicles b/c of it. In both cases, just adding a little fuel (especially in the peak TQ range) took care of any knock issues and restored power.