I need help on this topic of fuel and force induction.

[Qualitywires.com]

Okay, most of you know I have installed my own paxton supercharger and love it to death besides the tuning part. That part I am learning as I go. My car has made power from 500-600 RWHP and it has veried.

When I was at the V10 Nationals, I was dissappointed in my dyno results and also track results. I actually did better on the track when my car was stock, but that is because my car needs major tuning.

I saw a run that a hemi viper did and over heard the guy say that he thinks that his car puttered out towards the end of the track like it had no fuel. Come to find out later he found something blocking his fuel from going to the engine. That got me thinking why I am not having luck on my car.

I have a **** alcohol injection system on my car and stock injectors. My car is running lean and I also have a smaller pulley on it. Now the **** system is suppose to lower temps and lower the air/fuel ratio, but even though I am running lean and not detonating, I could still be starving for fuel which would mean power loss right?

So would more fuel help me out in gaining more power? I hope this post makes sense. I think I need to richen up my fuel (gas not ****) to gain the power I need right? I can lower my air to fuel ratio with the **** but since the **** doesn't act like a fuel then I am still stuck with fuel starvation?

Thanks for all the advice!

Adam

 

[Gerald]

Was your blow off stuck open like you thought or no?

G

 

[Jack B]

Fattening up (richer) does not necessarily mean you will make more hp. If you run lean too long you won't have an engine to race with. There is a fine line between detonation and lean. Can you post your dyno pull and include the a/f curve. You might also want to log the fuel pressure during a dyno pull.

 

[pullshard]

Air/fuel ratio refers to the ratio of air to fuel exiting from the engine, and it is a good measure (in combination with an exhaust gas temperature gauge) of measuring engine tune. The air/fuel ratio is commonly represented as a single numeral as in 14.7. This actually represents the number of air particles exiting per single fuel molecule (ie., 14.7:1-stoichiometric - or the ideal air/fuel ratio, at which temperatures are controlled and fuel economy is optimized. Typically cars make best power at about 12.5:1 air/fuel ratio, but this is harder on the emissions parts and sensors, which reduces lifetime.
Running an extremely rich air/fuel ratio creates more power.
This is a good one for novices, who think that you need to burn every last bit of air going into an engine. Actually, an engine spits out most of the air it ingests, as the ignition cycle for a particular cylinder is far too small and short to effectively utilize the entire air mixture. When high-power turbo, S.C. cars or N/A cars run extremely rich mixtures, it is to keep cylinder temperatures down. Frequently, cars gain power as they run more optimized air/fuel ratios, typically slightly richer than stoichiometric. In addition, rich mixtures can wear out sensors, waste gas, and clog your catalytic converter. If it were true that more gas equalled more power in all cases, race cars would simply dump fuel directly into the ports instead of worrying about metering. Tuning is key. Dumping more fuel in just results in the need for more spark.

Going lean creates an 'instant detonation' condition.
Again, in the case of street engines, this just isn't true. Manufacturers try to keep engines running as lean as possible as often as they can in order to improve emissions, mileage and power. Thus they build in significant safety margins. Detonation isn't actually caused by a lean condition; it is a result of a lean condition. Gasoline actually acts as a suppressor to the ignition event (ever hear people say "With that much fuel you need more spark"?). Leaning out under hard throttle causes temperatures to rise, which causes lean mixtures to to pre-ignite, but they don't cause preignition. The temperatures do.
With that said, the Paxton S.C. viper in my garage w\8lb pully pulled 682hp. The air fuel ratio around 11. Now before the car was bought, the previous owner had a unichip installed. On the dyno they leaned it out so much (over 14) that it melted a piston. The car with new engine and unichip adjusted properly runs around 720hp (best run), But I keep it unplugged. Learning to drive this beast w\680hp is enough. Do you have the modified fuel pumps that the paxton comes with? I suggest to get it on a dyno with someone who knows how to tune these beasts. I think you will be amazed at much hp can be gained or lost with fuel ratios being "right on". I do not know much about these engines, but I do like to work on cars and have a few. I would say that the perfect a\r ratio for a S.C. is 11-11.5. Anthing lower and your losing power, Anything higher and you risk losing power and melting pistons.
Sounds by your setup that you know your "poop", so I apologize if what I just wrote, you already know about.
I'm sure there are many more on this board that know a hell of a lot more then I on this subect. I'm just a novice.

 

[Qualitywires.com]

Good information Pullshard. Thanks. I do have the modded fuel pumps that paxton has and also a **** system to keep things cool. I am not getting any knocking right now, but I know my car is running lean from the reading at the dyno and also when I was at Larry's M place having my car dynoed, I melted his banner he had hanging on the wall with my exhaust. Pretty hot exhaust gases if you ask me.

 

[Daniel Cragin/DC Performance Inc]

best thing to do is to get that car on the dyno and data log the air fuel. If you are running the 8 pd pulley you will need to upgrade one of those Paxton pumps and resize the injectors.

 

[pullshard]

Daniel, The beast has the stock injectors in it. This to me does not seem adequate w\8lbs of boost. With the piggy back chip, the car's a\f is kind of crazy, but seems perfect at 5500 rpm's. But with out it, it runs leaner. Right now, to me, 680 hp is fine for a street car. Actually it's too much in a certain sense. I'm thinking injectors are in order so this car lasts. What do you recommend?
Also, what water injection system are you using? I have the aquamist system installed in my heavily moded turbo saab. I have had it for 2 years, running 20 lbs of boost. I was thinking that this would, could be a great addition???? What do you think?
Thanks for your help!!