Alright I plan on buying another PCM to use specifically for drag racing with high octane fuel. I only want to dynotune once due to pricing. So since I will be using 110 octane and be able to advance timing will I get any noticable gains over normal timing with le1 heads and a 306 cam all motor? Compression is around 11:1 Thanks for any help.

 

I hope so, I plan on trying the same with my second pcm. I'll be using some 104 unleaded and adding 2 degrees to see what happens.

 

I'd guess "no". We did extensive engine dyno testing on my setup. Original design was a 10.8:1 SCR, and a fairly mild solid roller cam (230/242 114LSA) but after we got the heads back, we had to take another couple thousandths off to insure they were flat. We found we got peak HP at 94 octane, and nothing above that made much difference. Not even a simple move to 100 unleaded, which we eventually used with the 125-shot.

We did baseline the engine running NA with C16 (117 MON) before going to the 275-shot, and found that we picked up 6HP over the 94-octane results, with no changes at all, but that was attributed to the higher specific energy content of the C16.

More timing does not always make more power. Once you get past the "sweet spot", it can cost you HP.

 

Thanks for the info. I will still try a little more timing with the 93 though just because it's a little on the safe side (NA) to begin with.

 

You should pickup some torque by adding timing in the lower rpm ranges 4k on up and I dynoed with 11.1 compression 355", made the most power on pumpgas. I will be ddoing testing in the next couple weeks with my new 383, with 12.1 compression on the dyno to see how much timing it will like on pumpgas. I also have another PCM that will swap to for a racegas tune if it's needed b/c I will add 5gallons of C12 to 1/4tank of 93octane, my normal concotion for a good 100octane cocktail. LOL Then add some more timing to see if we pickup hp/tq if not I plan on using that PCM for a custom n2o tuneup. That way at the track if you want to try something it maybe quicker to swap PCMs then reprogramming the pcm. I'll post the info when done. Later

 

Please do post any info you might find. Your 100 blend is pretty much what I do at the track. Run the 93 for a few NA runs to see where the car is at, and then throw some 104 in as a mix to run the nitrous. I also prefer the two pcm route, as I don't need to lose or have a miss-cue when reprogramming and have something unwanted (bad) happen. I let Ion do my tuning as I'm sure I could screw it up faster than you can say boo.

 

why don't you get a mallory 685 box or similar for nitrous instead of having a handful of pcms to swap?

 

Just b/c I have an extra PCM lying around that cost zero dollars and I don't change just timing most of the time.

 

In my case I do have a 685 box, but timing is not the only difference sometimes when running NA and then the bottle. I prefer to keep the rpms down a little on the bottle, hence the second pcm will need to be used down the road. I run 2-3 tenths slower in the 1/4 just dropping the rpm 2-300 rpm at the shift points. Now on the nitrous it doesn't care. This is what I've been told and tried with no ill gains. A slower moving piston is actually taking in more nitrous.
Down the road I would like to pull some timing with the pcm and run a second stage with more timing pulled (685 box) when the second stage comes on in second gear.
TA LT1 is in a very lonely club and I would love to join him some day.

 

you need to read on what a 685 box can do.. you may want one sooner then you think.

 

Well I am running the LTCC igniton on this setup and you can change the timing with it so that may make things easier for timing changes.