Diablosport Forums

I am using a U7194 predator on an 08 Chevrolet Silverado(4.8L) and I believe it is revision 9r05a(or something along those lines).

I have read a lot that the diablo performance tune is designed for 91/93 octane. On the U7194 description it states that 91 octane is for corvettes only:

93 Octane Performance Tune
91 Octane Performance Tune,Corvette Only
87 Octane Performance Tune,Truck & SUV only

Does this mean that if I install the performance tune on my truck that I must run 93 octane? Another question is what kind of damage would I be looking at if 87 octane was put in accidentally with a performance tune? The reason I ask is I don't want to get my head in the clouds one day at the pump and by habit put in 87 octane and ruin my engine. As you can probably tell I am very weary about hurting my baby .

Also I am considering getting flowmasters some time in the future and am wondering if this is going to affect my tune.

Edit: Also what would be a safe maximum speed to enter into it without over revving the engine? Also whenever I installed the tune(currently 87 octane) I noticed that for a little while my door ding did not sound right...Is this normal? It sounds like it always has now.

no.. the TRUCK tunes are made for 91 octane or higher.. .so, you have to use at least 91 octane gas...

that's why you only have a choice of the performance tune and 87 tune... and not a separate 91 octane tune... because the performance tune for trucks IS the 91 octane tune.

06MonteSS wrote:no.. the TRUCK tunes are made for 91 octane or higher.. .so, you have to use at least 91 octane gas...

that's why you only have a choice of the performance tune and 87 tune... and not a separate 91 octane tune... because the performance tune for trucks IS the 91 octane tune.

Thanks for clearing that up! You make Diablo's tech support guys jobs a lot easier lol.

Another question that I have is I currently have a K&N air filter and am planning on putting a flow-pro muffler in and was wondering if this is going to require a custom tune or if it is still within the acceptable limits. I'm a college student so the reason I am asking is because I can't really afford a custom tune yet.

Thanks again for all of your help!

nope... no need for a custom tune...

just do some logging and get your LTFT's dialed in to the proper range via the injector slope adjustment...

http://diablosport.com/index.php?name=P ... opic&t=917

06MonteSS wrote:nope... no need for a custom tune...

just do some logging and get your LTFT's dialed in to the proper range via the injector slope adjustment...

http://diablosport.com/index.php?name=P ... opic&t=917

I have my interface kit ordered so I will do that whenever it gets in. I don't have my muffler yet, but I may go ahead and dial it in so I can for one get the hang of it and two maybe it will be a little closer whenever I go to dial it in with the new muffler. I have the U7194 with the short log time, but luckily I have a laptop, so I should be good there. Thanks again for your help.

Well I just did a run with it and just read the numbers with the predator in hand. The LTFTs pretty well stayed in the -1.5 range and there was 0 KR even at WOT, so until I get my muffler I think it may be pretty well dialed in.

yep.. .sounds like it...

You ought to check out my exhaust clip on youtube, just look up my user name. As soon as I clean her up again, i will be doing a few more clips.

BigBlueRado wrote:You ought to check out my exhaust clip on youtube, just look up my user name. As soon as I clean her up again, i will be doing a few more clips.

Actually I already got my exhaust on.(Had them installed yesterday) I ended up going with a flo pro and dual exhaust with 4 in tips. I am very pleased with it. I ended up with exactly the sound I was going for.

Now all I've got to do is wait on my interface kit to get here and get to tuning. I think it is supposed to arrive today.

Well I got my cable in and tested the LTFTs and they are still averaging -1.5. Is the PE logging/adjusting still necessary?

Edit: Ok now that I am home I can post my log file. As you can see from it I drove for a while with my RPMs below 1800, but I corrected it about half way through the log. The reason is my truck has a 3.23 rear end so it doesn't run 1800 RPMs at 70!

log in a lower gear to get RPM up

CANUCKPREDATOR wrote:log in a lower gear to get RPM up

Well I just bumped it up a few MPH to get the RPM above 1800...Would that be ok?

yes, that's fine..