I have sourced some leaded 110 octane (turbo blue) race fuel for $4.50 per gallon. I usually run 103 octane street blaze fuel.

I understand leaded gas kills O2 sensors and coats valves.

I have a few questions:

1. If I run 5 gallons of pure leaded fuel once per week, what is the average life expectancy of the O2 sensor?

2. When running race gas I set my boost table to 100%. This normally causes a much larger boost spike at peak torque but the boost still tapers to nearly the same PSI at redline as a non-race gas map. Basically I am not getting more power from more boost but rather more power from a leaner 12.5:1 AFR and additional timing 3-4*. Can I make use of the additional octane offerec by 110 or is it simply overkill? (I could cut 110 and 93 with 50/50 for 100 octane)

 

No, there's no need need for you to use 110 over 103 - the performance difference would be minimal while risking damage to your o2. You should really try to raise the boost for real instead of just the spike. YOu should be able to hit 25psi peak and hold 21-22psi by redline with proper boost control.

 

In taller gears my pump gas map does hold fairly high PSI at redline. The XEDE acts as an electronic boost controller so 5k-8k is already set at 100% boost. When switching to the race gas map 3k-5k gets bumped from 80% to 100% which is really the only gain I see from boost and that is only in first gear.

It should be noted that I have run with C16 and the line off the wastegate which resulted in higher PSI but not much of a return. If the return from added boost is simply a wash from increased intake temps I would rather run less boost and more timing.

If you feel I cannot benefit from higher than 100 octane at 22PSI then I shall begin cutting pump with the leaded fuel.

 

You can run 24-25psi on 103oct. I didn't see a reference to 22psi and 100oct.

Back when I used race gas before alky, I didn't get any gains using 110 in place of 104 (based on many trips to the track), but I was running 24-25psi on both with fuel removed on my SAFC, so I opted for 104 whenever possible, since it was unleaded.

 

I can spike to 24-25 but only down low. At most I can hold 22PSI @ higher RPM.

On race gas (103 octane) I spike to 25 then it drops to 22PSI around the shift point. Whether on race or pump, my higher gear power band consists of mostly 22PSI.

My gains mainly come from addition timing. Normally on pump my higher RPM is retarded 3-4* but with race gas I zero those variables. It would be nice to see gains from adding even more timing but from what I have read the EVO doesn't really need **** loads of timing. The timing benefit from the recovered 3-4* as well as the additional timing picked up from the leaner mixture seems to be maxed out at 100 octane.

 

Yes but you had no timing control.

 

Yes it would be nice to be able to put the 110 to use by adding some timing. I just dont know how much more I could go with. I know playing with timing can be a dangerous thing.

 

I use C16 on a monthly basis! I went from 390hp to 433hp just with the C16 over 91 **** and advanced timing. The C16 does shorten the life of your O2 sensors, but if you use it not on a regular basis my tuner says it has little effect on the sensors.

 

How much additional timing have you added? I am basically not retarding any timing, my timing is zero'd but I'm sure I could add a degree or two with the higher octane fuel.

 

If you want to run the leaded can't you just empty your pumpgas at the track and add a couple gallons of leaded race fuel before your runs. The O2 sensor signal shouldn't degrade with such miniscule amounts used, over such a short period of time. Alternately, there is a 109 octane unleaded race gas available, I think.

Isn't there a recommended fix on the Vishnu forum for increasing boost beyond 22#, via some sort of bleeder valve/restrictor orifice in the WGA hose? You should see more power by increasing boost from 22 up to 25#, than you would from adding 3-4* timing. Although, both 25# and increased timing together would be best(as Warrtalon says:...with a custom tune and monitoring AFR's and knock counts).

As a last resort, you can always go to an MBC to control boost and just zero out your boost table. BTW, are you running a custom race gas map or the off the shelf 100 octane map?


Edit: orthographic changes

 

Double clicked the post button.....sorry.

 

Right, but keep in mind that he has a DF flash and AFAIK Al does not retard timing by much on his flash. IIRC, Al runs 8* timing at peak boost/torque which is as much as stock or even more depending when peak boost hits. On my car I have seen 1-3* stock timing at peak boost/torque.

So he might not need timing control to run high octane since his timing is already advanced in SOME areas.

 

When removing a lot of fuel on the SAFC, you get a lot of timing in return. I had no direct control, but my timing went from 20* peak to 24* peak, and I ramped up to 24 sooner than I ramped to 20* on pump gas. It was always a full 3mph gain and sometimes 4mph, which indicates 30-40whp, and I always had a mix of 104/93 or 110/93. With custom tuning and full control of AFRs/timing, you could probably squeeze even more power, but I still haven't seen any benefit personally from running 110 over 104.

 

I don't really know how much timing was added on racegas. I am using the AEM EMS which was tuned on both 91 and C16 on the dyno.

 

I am running a custom race gas map tuned only for AFR and no additional timing via the XEDE.

As for adding more boost, I tried the bleeder trick and didn't see much more boost in the actual power band. It would spike higher but it won't hold that boost up top where I need it most.

I'll just stick with a 93/110 mix and run my 100 map.