Fuel Octane Requirements on a 200 shot?

[Joe Lynch]

I've been running a 150 shot for a while in my 99 Cobra with a forged motor on 93 octane pump gas and timing retarded 2 degrees from stock, 5 degrees from best motor timing.

When I go to a 200 shot, will I need to change to a higher octane fuel? I will probably start out backing out another 2 degrees of timing.

What about the fuel?

Joe

[white99gt]

With that kind of power .I would run at least 100 octane or better.With 100+ you should be able to leave the timing like it is.

[Nitro Lew]

...108 and leave the timing were its at then check the plugs .


Lew

[Joe Lynch]

Thanks for the replies.

Have you guys ever datalogged the knock sensors to see what was happening during a pass? My plugs have always looked fine and I have never heard any detonation, so I don't really know what to look for. May sound strange from someone that has run a 10.77, but I haven't had too many problems at 150 shot.

Joe

[Nitro Lew]

I think the safest thing to do is just put the car on a dyno with the 200 shot and see what your air fuel and everything else is doing .


Lew

[Joe Lynch]

Lew--Yep, I was going to do that. I've never datalogged the knock sensors with an Autotap before, so I guess I better learn. With my new SCT flasher, BAP, separate pump controls, and wide band, I should be able to get everything just right.

Joe

[DARKHRSE99]

Joe, I'd at least put in a 105 octane or somewhere near there with the same timing and putit on a dyno then pul the plugs after a pass to see how they are burning. On a 150 shot I run 100 octane and 10 degrees of timing, and I've had no issues.

[Brandon Alsept]

I would say the unleaded torco 104 Joe. That is just me though .

[TheNitrousEdge]

Originally posted by ALLMTR2V
I would say the unleaded torco 104 Joe. That is just me though .

I agree. Anything over a 150 shot and I have run at least a 50/50 of 93/104

[Brandon Alsept]

I would try and run a full tank of the 104 myself. With mixing 104 and 93 if you even get it at a perfect 50/50 mix you will yeild a average of 98.5 octane.

[Joe Lynch]

I take it everyone suggests increasing the octane rating roughly about 0.2 points per HP shot increase over the 150 but leave the timing where it is for starters. 50 hp x 0.2 = 10 and 93 +10 = 103.

Thanks guys. That is what I needed to know.

I will see what unleaded race gas I can get here locally. That may be a problem, LOL.

Joe