does anyone out there know what effect premix has on detonation?

 

I heard if you premix, that it lowers the octane of the gas. That's all i know though..

 

Correct. You want to be careful in the winter on how much premix you put in. I does lower the octane rating of the gas and if you live in CA where you can only get 91 octane, thats not a good combo, if the outside temps dip low enough. In most cases the West coast is warmer so you won't need to be as concerned as us guys on the east coast.

 

Just go to a 76 station and add a couple gallons of 100 octane to the fill up!

 

Fill'er up with ethyl!

 

how much does it drop it?

 

It can't really be that much of an octane drop. You should only add 4oz of premix when you fill up your car. www.pettitracing.com sells premix.

 

Good thing I get 94 octane here..

 

the premix isn't going to lower the octane any lower then the stock OMP system did....

(asuming you are premixing because you removed it?)

 

Not true, the stock OMP is inadequate and is the reason for many to use the premix in addition to the omp. I have a Haltech so I have to use premix.

 

ditto

 

Yes it does lower octane, no you shouldn't have to worry abou the change. Worst case is that the 2 stroke has 0 for a performance number, ie this stuff explodes if you look at it wrong at the temps we're talking about. Then lets say you mix at 100:1 pretty rich for a street car. OK, 100 parts of 91, vs 1 part 0... thats 91 * (100/101) = 90.1. Thats worse case... not to much to worry about more likely to be less than a .5 point hit

 

i figured youwould have more detonation problems in the summer, yet i have no experience with turbos... please explain??

Justin

 

Air is denser in the winter (colder something is the denser it gets simple science) The more air you have the more fuel you need. It is easier to lean out in the winter because of it.

Summer you could have detionation problems because the air is hotter going into the engine.

There you have it! There are other variables but thats about how simple I can make it.

 

gotcha, i guess NA doesnt have to worry about detonation in the winter since our injectors arent that taxed

 

If i'm going to get on it, then i try to add some 100 octane avgas. couple gallons to my 2-4 to my half tank when at the track. long highway trips i don't really think about it becauase, i don't get on the boost, just like under 8 psi.

 

I remember reading somewhere that 100:1 premix would lower the octane rating about .2 octane. Could make a difference if the air/fuel ratio is borderline to begine with.

Fred Jin

 

If you're borderline, then you're playing with fire to begin with. I've heard that you should account for .75 for worst case scenario.

 

128 oz's in a gallon, 20 gallons in an FD tank, ~2500 oz's of gas-o-line. I was premixing with ~1oz per 3 gallons, so wasn't concerned. My OMP is still working, however.