Approximate octane of SMC kit + 94, 93, 92 octane gas

[Awesome T]

I just installed my dual-nozzle SMC kit, and everything went great. Car runs at 22 PSI with no knock, yeah baby. Presently I'm running Sunoco 94, but may try a lower (cheaper) octane gas. What will be the results? Anyone know an approximation of effective octane with different grades of gas and alcohol spray? Car has PTE FM, LT-62, 009's, dual Walbro's, Joe L street chip. TIA. John.

[YGETV8]

Hi John,

I can't give you the answer you are looking for, but I know there are those that run 22-25 psi boost on 91 octane gas with the alky! I personally have run 26 psi on 93 octane.

The "relative" octane level has been discussed before, with some chiming in about what the octane is with alky. But it's my belief that it isn't that "cut and dried!" If I inject twice as much alky as another person, how can our "effective octane" be the same, you know what I mean?

[BLACK6PACK]

Run 93 octane and don't worry about it. If your willing to risk your motor to save a couple a bux on 91 octane then go for it.

BTW, it isn't the octane of the alky that lets you run high boost, its the drop in intake tempatures. On 18 lbs of boost and no alky I was getting almost 1800* exhaust temp. With the alky on, I was running 25 lbs of boost with 5* more timing and only running 1600*.

[Awesome T]

Jay and Blackpack 6, thanks for the info. I will try running 93 octane, and save a few pennies for the denatured. It is really weird to go from getting so much knock and worrying about headgakets, to having O2's in the 780's with NO knock. What will they think of next?
PS Want to say thanks to SteveC for such a great kit. And to Jay C and the others who pioneered this field for the TurboBuick crowd. John.

[NC87GN]

Some of it has to do with the amount of timing your running in the chip. I'm in the middle of playing with the timing vs. boost game. I'm able to burn my own chips so here is some info that may help... 22 degree chip 24-25# 1-2 degrees of knock. 24 degrees 22-23# 1-2 degrees of knock. 26 degrees ~20-21# 1-2 degrees of knock.. I run a 51, 009's, V4 and SMC alky (air temps ~ 75F).. This is for my personal car and another local and it has worked out great for both... However it took some tweaking with fuel tables, inj constant, blah blah blah to get it right.. HTH


Mike Banas
87 GN

[Awesome T]

Mike,
That's great info, thanks for sharing. Have you ever talked to Jim Testa? He also really knows his stuff, and is out of NJ. I'm sure you've seen him post. I am considering getting an alky chip, and have talked to him about doing it, and was wondering if you two are going at it from the same approach? I have a JoeL chip now, and it has always felt a little soft. When I first started in the game, I had a PitBull chip, and despite its unpopularity, it really got the turbo spooling, and I liked it. I am going to assume that you always have to run alky on an alky chip, or race gas, right? Is there a difference in how you would set-up an alky chip and race gas chip? I haven't been to the track to tune my combo, but it flats out a little when the alky come in - still hauling azz, but know there is more there. Thanks. John.

[NC87GN]

I have talked with Jim Testa several times. I gather and share information with Jim Testa and Jay Carter. My chips are a little different from Jim Testa's and Jay Carters. I've messed with the alky chips on 009's and 50's and stock only. I've had good luck with with burning chips for these injectors but have not messed with any others. My experience with Jow Lubrant chips has not been good after running a couple. The questions was asked if you can run the same chip on pump gas and race gas. I like having the same chip for both the street and the strip. I run a 22 degree chip with 17-18# with no knock (pump gas 93). However with the Alky on, I run 22 degrees at 24-25# with 1-2 degrees of knock. HTH...

Mike Banas
87GN

[tim87tr]

BLACK6PACK, would you care to elaborate on the EGT temps. I would like to know a "starting" point to look for on the EGT temps vs boost level. I see a lot of people talking about 1600 *. With the boost levels I am running with my setup now, I can definitely see 22 to 24 lb boost with the SMC.

The SMC is my next upgrade. I am going to get his EGT and use it awhile to get past the learning curve before installing the SMC kit. I know the EGT will be important to watch with the higher boost level with alky.

I have just begun running the extender and trans +, but have not messed with the timing yet. Going to use some xylene and try a little more timing. I have been able to run 18 and even 19 lb boost with the extender and 94 octane, no kr. This was up 1 or 2 pounds when I began using the CNC TB bore and Powerplate. Your comment on the 1800* with 18 lb without alky kind of makes me wonder if this could be bad for my engine at the boost I am running now without the alky.

[BlackBeauty]

Originally posted by BLACK6PACK
BTW, it isn't the octane of the alky that lets you run high boost, its the drop in intake tempatures. On 18 lbs of boost and no alky I was getting almost 1800* exhaust temp. With the alky on, I was running 25 lbs of boost with 5* more timing and only running 1600*.

I thought the alky mixing with fuel did raise the octane level. And I believe the drop in EGT's has to do with the advanced timing. Try 18psi vs. 25psi with same amount of timing.

[BLACK6PACK]

The alky does raise the octane, but that is not where the big benefit comes from. Upping the timing causes even higher exhaust temps.