Mixing Fuel Octanes

[dpenta13]

I am going to be running 33cc domes on my ported 735

i was told I could run 93 octane but have to limit the time im at WOT

Does anyone mix with somthing like a 110 octane? or i believe a C12?

Not looking for more power, but if i am running a higher compression will it be worth running higher octane if i have access to it?

 

[dpenta13]

its a stock stroke motor as well so not nearly as agressive as some of the other motors out there

 

[Supajet]

I mix c12 with 91 pump gas at a 50/50 ratio and run it in my stock stroke 771. I pinned it a few times and didnt have any issues, its at 210 psi in each cylinder.

 

[Harbor]

1 was mixing 110 with 91 @ 50/50 and makes 100.5
You running a dry pipe and run wide open, compression pressure around 190, MSD enhancer with zero advance @ the stator, total timing about 22 deg thru rev limit I was and after switching to this mix it no longer took the tops of pistons Off
I should add I was not holding open like I'am racing anymore if I was I would just run the 110

 

[Quinc]

Will Octane booster work?

 

[N-D-Red]

A 50/50 mix is very common and necessary as the compression goes up to avoid detonation. I can't comment on your particular engine configuration.

 

[McDog]

No. Octane boost is crap. 100 low lead avgas mixed 1/1 or 4/1 with 93 is my fuel of choice with compression around 200.

 

[Freakrider]

Yeah what McDog said....my 735 had 205 psi with 35 cc domes so you should be near 220 I believe depending on your altitude. What load will you have (hull type) ? Don't waste money on octane boosters.

 

[BruceSki]

I have always ran 33cc domes on ported motors(and non-ported but its risky)

WOT is no issue with 93 octane if you tune it right.

 

[550/440]

What is the formula to calculate octane on mixed fuels? Example: 4/1 with 91/100ll, would you do (4x91 + 100) / 5 = 92.8, or is it more complex than that?

 

[Freakrider]

I have always ran 33cc domes on ported motors(and non-ported but its risky)

WOT is no issue with 93 octane if you tune it right.

How about 83mm bore like OP has ? I know JM and company have run 220 to 230 cranking psi on pump gas with no problems.

 

[BruceSki]

I think the motor I was running like that was at .50 over. I have one running like this at stock bore right now with 0 issues.

 

[oside-tanner]

I realized most people think octane booster is crap, but before you right them all off you should consider torco accelerator. My current setup is the 780cc 4 mm stroker from phpski, I had them set it up to run 91 octane. If I feel the quality of the fuel is questionable, a little bit of the torco accelerator is a little bit of extra insurance in my eyes.

 

[txsuperjetfreak96]

Isn't there more to the consider other than compression. Depending on what ignition your running. What curve your set at etc.

Sent from my SCH-I535 using Tapatalk

 

[oside-tanner]

Need to factor in your porting also

 

[dpenta13]

I am not running a dry pipe

and at the moment im not sure of timing plan on running an ATP epic hx3

is a higher octane required for my set up or do u think i will do ok with 93 octane

 

[dpenta13]

it has JM top end porting abd cases done by php

 

[OCD Solutions]

I realized most people think octane booster is crap, but before you right them all off you should consider torco accelerator. My current setup is the 780cc 4 mm stroker from phpski, I had them set it up to run 91 octane. If I feel the quality of the fuel is questionable, a little bit of the torco accelerator is a little bit of extra insurance in my eyes.

That's about the only time I ever run the boosters as well. There are times where you just can't get your hands on premium or like you said, the available fuel is in question so it's a little added protection in a small bottle.

 

[Harbor]

What is the formula to calculate octane on mixed fuels? Example: 4/1 with 91/100ll, would you do (4x91 + 100) / 5 = 92.8, or is it more complex than that?

That's how I do it

 

[Harbor]

it has JM top end porting abd cases done by php

You may want to talk with a reputable engine builder about your end game engine set up and riding style, finalize your engine set and timing parameters and get his recommendation on fuel requirements based on all that info once youve decide it.
Hope this makes sense
jetmaniac or php may the ones to ask since you mentioned them as doing some of the work