race gas questions

[j_biggz]

So my question is about adding a couple gallons of race gas when I go to the track this coming weekend. I want to know if there is any dangers / benefits to doing so. We get crap 91 octane out here at the pump and I can pick up some sunco (I believe) that is 110 octane unleaded. My car is mostly stock besides a few mods: exhaust mani, intake, side mount hard pipes, mbc, and a MHI S16g @14psi. Any advice would be great. Thank you in advance

 

[j_biggz]

The cat is on it way out when I do the cat back exhaust. We don't have emissions where I live at so I don't have to worry about the law. I usually use Royal purple 10-30W. I heard (on here) that I will most likely run into boost creep with no cat? Anyone know from experience? So I would also need to go open dump to eliminate the creep. as far as tires go I'm pretty much stuck with the street radials but they aren't horrible. I dropped 10psi on tire pressure and it seemed to help. I might do 15psi next time and see how she hooks up.

 

[starktech1]

I use a high flow cat...or "catless" not sure what the difference is ...big ass pipe. mines 3'' all the way

 

[j_biggz]

I thought boost creep was caused by opening up the exhaust? A high flow cat is still a cat and not a test pipe. At least that is my understanding of it

 

[j_biggz]

Yes, dont go any higher than 14 psi. I wouldn't run it any higher because you would be running extremely close to 100% IDC. MOST people don't like to go over 80% on the fear of boost creep and boost spike therefore going over 100% and hitting fuel cut (maxing out injectors). I personally would keep it around 13 psi just to be on the safe side.

Lets say if you did have some knock, running higher octane (110 oct.) would help eliminate SOME of that knock and give you better timing advance (more power). I believe for every either 2-3 counts of knock, you loose 1 degree of timing.

I suggest getting a datalogger to see if you are running close to 100% injector duty cycle and see if you have any counts of knock. You would be surprised at what you find.

This is a little info I found on injectors/ fuel pumps and thought it was prudent to the topic. Hope it helps some one I know it helped me but Im still pushing my luck at 14psi for the mean time. http://www.dsmtuners.com/forums/tuning-engine-management/244522-injectors-fuel-pumps.html

 

[hurricanecris24]

Opening up your exhaust will mostly give you boost creep happened to me. I still have that downpipe and catback if your interested