Have a 97 Chevy k3500 dually. 454 Vortec. Clean old truck. Runs great, tows good. It has a custom tune in it from that Blackbear performance guy, meant for 89 octane. Anyhow, last week, I did some data logging with it.

Timing map calls for 20* spark timing, at WOT. I am getting 6* of spark retard, in 3rd gear wot, not towing, on a cool day, 180* deg coolant temps and IAT temps in 80's. Stock timing map, was 12* I believe at WOT.

Once I run the 87 fuel out, I plan to fill with 93, and see if I am still getting this knock retard. Thinking about a meth kit, to help cool things down, and eliminate spark retard from knock. Anyone ever try meth/water injection on a N/A engine?

Might sound silly, but It probably be cheaper to run a meth kit, than using 93 gas all year. Main thing is i'd like to be able to cool things down when towing on those hot humid summer days, plus, im bored.

not at all silly,guys have been doing it for a long time at the track.it is just a tool in the toolbox of speed.on those hot humid days the air entering the engine can reach 175 deg or more so cooling the intake charge makes for a denser charge and we all know cooler denser charge makes for a happier engine.

Just took it for a ride today. Was 55-60 deg ambient. Idle iat temps get up to 120 degrees . On highway, they drop down to 75ish. Stock intake setup. Gotta burn out the 87 gas, then put in 93 and see if its still getting knock retard. It was getting it again today when i floor it on the highway . Wanna make sure its octane related knock, and not false knock, or something else.

Thing has no timing in it as it is, dont need to be pulling another 4-5 out of it lol

wouldnt it be easier to figure out why a truck that should run on the cheapest crap speedway has at the pump is detonating?? A fancy tune on an otherwise stock 97 truck motor really isnt going to ad much I wouldnt think

Nt to sound like an ass, but is the gain really worth the expense?

Actually, it made a big difference , once the stock torque management was removed, and at light throttle position, etc.

Gotcha... I thought being a 97 it would have been before all that type stuff... My Denali has so much computerized bullcrap its not even funny.

dumb question but have the intake gaskets been changed? mine is the same truck but a '96. I finally quit putting it off and changed the gaskets (280,000 miles) and was surprised at how bad they were. I am sure that I had a vacuum leak at the gaskets that was causing a lean condition. truck runs much better now.

Yes, I did them about 15k miles ago. They were weeping coolant .

Truck runs great. Would not have known it was pulling timing, without the snap on scanner that records live data

Great cost effective option, especially if the 93 shows improvement, plus it could even help more than higher octane fuel alone!

True Gearheads always trying to improve our toys! Nothing better than that!

Your long term and short term fuel trim's good ? ie: not + or - a big % ?