Octane boosters... Do they work?

Apr 08, 2004 31 Replies

It seems that alcohol is more effective than water when the boost pressure gets high (20+ psi) or the engine has a high CR. Most 5.0L Mustangs don't run that high which, IMO, is why straight water works well for the low boost crowd. But then again I might be full of $hit too. :)

Oh. Before someone thinks me naive, if you're not running fuel injection in a boosted motor, you're working with stone knives and bearskins.

Dana

Cool! Pretty popular kit with the TR guys :-)

Mike

1995 Eagle Talon TSi
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of all the old cars

Exactly, which is what i was trying to tell Dana. It simply allows for high boost and pump gas. Sure, 116 is cool, but is expensive and hard on the o2 sensors.

Mike

1995 Eagle Talon TSi
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of all the old cars

V'ger jma(NO SPAM)@snowcrest.net

1965 Mustang Fastback 2+2 Burgundy w/ Black Std Interior 289 ci 4v V8 A Code Dual Exhaust C4 Auto 8" Trak Lok Vintage 40 wheels BF Goodrich g-Force T/A KDWS 225/50ZR-16 tires Petronix Electronic Ignition components oem am radio and am-fm-10cd changer with 7.5" dvd player 120w kick panel speakers Built in San Jose on my birthday, May 10th ; )

You're acting like my assertion was wrong.

If you want to cool your intake air, you use water.

That's my assertion.

How is this wrong? It's not like I don't get it. It's like I think commonly accepted "fact" is simply wrong when it confuses intake cooling with octane boosting via fuel-replacement.

Dana

Most likely your best choice. I had a short deck 351w with small chambered heads and a small SVO cam. The darn thing would almost spark knock at idle. I swapped in a cam with 228@0.50 and a 110 lca and it ran fine on mid grade. Not to mention made more power as well.

MadDAWG

Damn... cool. In-car adjustable timing would be awesome rofl...

-Mike

Have a look at the Jackson Racing Boost Timing Controller, then. It's only for a few specific models, but it actually is a precisely adjustable retardation under boost.

I've been tempted to install one on my supercharged Miata, but (a) they don't have one for a 2002 model year and (b) I'm actually becoming pretty happy with the water injection system I'm using.

Dana

Blown miata? whoah. That'd be interesting to see in person!! Also, can you explain all this water/alcohol injection stuff? I'm assuming it's for F/I applications only or something... but I don't understand what the point of it is. Thanks, Dana.

-Mike

Next time you're in the Napa/Solano area of the SF Bay Area, call ahead, bring some meat for the New Braunfels Silver...

Water injection is intended to cool the compressed intake air charge via evaporation of water (the liquid-to-gas transition of water soaks up a lot of heat). Cooler intake air charge == reduced propensity to ping. The stock '02 Miata compression ratio is actually a little high for forced-induction (10:1) and CA pump gas is, at best, 91-octane. So the water mist is injected directly before the intake manifold.

So people inject pre-blower but that's controversial.

The addition of alcohol is primarily to prevent freezing of the water in the tank/lines/pump but, as you've seen in other threads, is sometimes used to add a higher-octane fuel source under boost.

Dana

Ahh ok that makes a lot more sense. Thanks, Dana. you rock.

-Mike

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