LSOHOLIC

iTrader: (3)

I searched and found little to nothing......if I missed it, feel free to post a link.

I'm going to go out on a limb and say that atleast 50% of "us" who spray wet, spray with a stand alone system. That being said, has/will anyone tested different fuels ?? With equal testing/conditions ??

It would be interesting to see the track/dyno results of such a test, to dis-spell any myths about these fuels advantages or disadvantages.

Here are some "standards"......

Sunoco 110------------(MON=106)---SG.728--BTU/lb=20,000+---LHV=135+
VP C16-----------------(MON=117)---SG.735--BTU/lb=20,000+---LHV=135+
VP C23-----------------(MON=119)---SG.710--BTU/lb=20,000+---LHV=135+
Renegade Pro-120 n2o--(MON=120)---SG.710--BTU/lb=20,000+---LHV=135+
Methanol---------------(MON=91)----SG.790--BTU/lb=9,800-----LHV=473
Toluene----------------(MON=111)---SG.870--BTU/lb=18,500----LHV=151
Xylene-----------------(MON=114)---SG.860--BTU/lb=18,650----LHV=147

I'm on a 91 (MON) motor tune...and looking at some of these options for my stand alone system (82 jet).


Thanks..............

87silverbullet

iTrader: (11)

The only thing about that is if you adjust you timing right you will damn near run the same time no matter which fuel.

Then the amount you are spraying is so little it won't make much of a difference.

LSOHOLIC

iTrader: (3)

82jet=200+ish on a flycutt sbe....is that "little" to you ??

So.....you think a 106 mon/oct number will make the same "power" as a 120 mon/oct number ?? with the increased timing in the 120 ??

Or another way to look at it would be....the 120 is "safer" on a given tune....aka...less timing sensitive than the 106 oct fuel.

Do you agree with these statements ??

Thanks.......so has anybody tested these theories ?? Or is it just assumed, because of what they read or where told ??

Sales@Tick

iTrader: (3)

Higher octane fuel with the same given tune-up will not change E.T. in fact it may hurt it.

With added timing and leaner mixtures it will make more than the lower octane fuel. The lower octane fuel will not allow the timing the higher octane fuel will.

Mainly a higher octane fuel allows you to change variables in your set-up that allow more power to be made like compression, timing, fuel mixture, amount of nitrous sprayed etc. The added power doesn't come from the fuel, it comes from what the fuel allows you to do with the added octane it gives you if that makes sense.

LSOHOLIC

iTrader: (3)

So Martin....just like you just stated.....more octane will make more power (can handle more total time), if tuned for it. So a 82 jet will make more power on higher octane than less, based to total time.....is that a fair statement ??

Or another angle would be.....be safe/soft with the total time and run the added octane as a saftety blanket (temp or DA swing at the track).

So....let me ask this, is there any dis-advantage to running more octane in this senario ?? Other than the obvious price ??

Thanks......

My6speedZ

iTrader: (18)

Octane only really effect the tuning window to my understand. Higher flash point like Martin said effects the amount of timing, compression, and nitrous that can be ran. If you increase the flash point to much you can hurt combustion.

I am more familiar with the reasons higher octane is preferred on FI application (due to the heating of the compressed air) than nitrous. I would assume that you should only increase the octane if it is need for control of the flame front? Prevention of detonation and such.

I can't understand how higher octane with more timing would make more power than a lower octane with less timing given jet and AFR were constant between the two.

Sales@Tick

iTrader: (3)

It depends on what your compression is right now really to determine if you could make more power with a higher octane fuel than pump gas. If you're on stock compression then a higher octane fuel really wouldn't pick it up because you're not having to pull the timing near as much as you would a more sensitive motor with a higher compression ratio that needs to run race fuel. Stock compression with a 110 fuel would make the same as C16 IMO on a 82 jet.

To expand more on what I was telling LSOHOLIC and what I've explained to you while we've been at the track testing my car before is each set-up will have a timing value that it likes to make peak power at and not go past the point of maximum efficiency with timing. I think I explained the up and down movement of the 4 strokes of the engine and how if you advance it too far it fights the natural up and down movement of the piston or too little and the piston begins to slow down before it reaches the point of ignition advance.

Now, here is a point where that ignition timing value whatever it is will flat line for 1-3* timing normally before it starts to make ash trays and that is in that position where you start to fight the natural up and down movement of the piston and excess heat is created. Higher compression and higher amounts of nitrous can change that window. Even though it's not making ashtrays yet or losing power it's creating excess heat in the cylinder and that is absorbed in the cylinder walls, valves, piston, and it shows in the spark plugs as that.

A lot of times you'll hear ATV or Shiz say, "back it down a degree or two and see if it stays at the same mph it did on the higher amount of timing", this is how you will find that spot.

Now to expand on that a lot of times to make a motor happy that only runs on pump gas or a lower octane fuel it needs less than that optimal amount of timing that I just discussed to keep the motor happy and from detonating because of the amount of nitrous or compression that is trying to be run on that fuel. Basically you have to run a low amount of timing with the lower octane fuel with a lot nitrous or compression to not detonate, but if you could or did use a higher octane fuel in that situation you could add timing to get back into that optimal efficiency zone to make peak power again without going too far.

I would say up to 200 shot it wouldn't affect much if anything unless it was on a higher compression motor.

LSOHOLIC

iTrader: (3)

Thanks guys and Martin......I really think I had a brain fart on this one...LOL. I do understand what goes on in the chamber. And I think I got away from my original question here. I guess what I was trying to ask was.....how to tell what octane to run in a pump gas motor....with a wet stand alone fuel system ??

About my brain fart........
I understand that "most" motors like the peak cyinder pressure to occur somewhere in the 15*-20* ATDC for maximum "push" on the piston (leverage advantage). And that the more efficient the design (chamber, runner, intake, piston top..etc) the less lead time is needed. But when you add an oxidized environment, it speeds up the burn rate. So to achieve your 15*-20* ATDC goal, you must retard the timing. Also the 21% nitrogen in the N/A atmosphere also helps slow/cushion the N/A burn rate. But when the oxidizer is added it speeds up the burn but also displaces the nitrogen....thus increasing the burn rate even faster. And thats where the the retarded timing come to play.

Martin...for the record, I'm a flycutt sbe 346. 11.7 scr & 8.9 dcr, made 517/441 on a 91 oct
tune. And plan on working my way up to an 82 jet, but with the shitty pump gas I kind of wanted to be extra safe and run something "strong" in the stand alone. Partially because of the strong N/A numbers (N/A cylinder pressure) and also thats the whole reason of going stand alone...to run the good stuff and still maintain 100% streetability with a big hit.

Thanks....and sorry if the spelling suck...on my phone..lol

Sales@Tick

iTrader: (3)

It sounds like you have a good grasp of what goes on in the cylinder already.

If you're going to be running 93 in the main tank then I would run C16 in the stand a lone as they will be blended in the combustion chamber obviously.

C16's specific gravity and stoich is close(not exact but close) to that of ethanol enriched pump gas where as some race fuels are vastly different.

Hopefully this helps your dilemma.