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Vivid Racing Dynos the X - first dynopull on the X
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so he thinks it will go over 300 with just some bolt ons and a tune well thats good then.
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That thing is running rich. I wish they would throw an mbc on there and get a few more psi.
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A car can run rich, lean, or anywhere in between.
What this refers to is the air:fuel ratio of the motor.
Ideally, while not on boost, a standard gasoline engine runs a 14.7:1 air:fuel ratio.
That means that for every 14.7 parts of air in the cylinder, there is 1 part fuel. 14.7 is an ideal ratio that cars run as a good balance between power, fuel economy, and emissions.
if you run 13.7:1, you're running a little richer, and if you're running 15.7:1, you're running a little lean. Remember, the LOWER the number on the left, the MORE fuel you are running.
To understand it, take it to an extreme. If you ran a 1:1 air fuel ratio (which the engine couldn't actually run at), then your engine would burn as much fuel as it did air. On the other hand, if you ran a 100:1 air fuel ratio, you'd barely be burning any fuel at all.
Under load, most engines run a bit rich (in the neighborhood of 12:1) for two reasons.
1-a slightly richer air:fuel ratio will usually give you more power.
2-It's safer to run richer than leaner. Extra fuel in the cylinder will keep the temperatures lower (the fuel cools the combustion temps) whereas too little fuel will cause the combustion temps to rise, which is dangerous to a motor.
Most boosted engines I've tuned make the most power at 13:1 or so (which is slightly rich). However, it's dangerous to tune a car for that ratio, as it has little room for error...if it leans out a little, you could lose your motor. With that in mind, we normally go a full point richer for a safety margin (so 12:1 or so). Mind you, this is only under load (full throttle, etc). Under normal driving, you won't be boosting, so you should be running 14.7:1 or so.
Anyway, the air:fuel charts on the dyno posted earlier indicated an air:fuel ratio deep into the 9s. Mitsu obviously did this for safety...they detuned it on purpose. When a car is THAT rich, the fuel is actually hindering performance since it doesn't get to fully burn, and it tends to bog down the motor. I can almost guarantee you that if you pulled some fuel and ran it at 12:1 or so,
you could probably pick up at least an extra 12-20 horsepower (guestimate) without too much work.
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+1 I learned something. Havent touched that stuff since the good ole days of twisting the mixer nob on Holley 650's. :rock:thanks for the info, Kooldino
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Old school!
To whoever asked, the main difference between the mustang and dyno jet dynos are as follows. Dyno Jets are what is called inertia based. This means that the way that they measure hp and torque is calculated based on how quickly then spin the rollers. This is not a very accurate method of measurment, and tends to read much higher than what the car is actually making. Mustang dynos, much like Dyno Dynamics, are what is called load based. This means that the measurment is based on load values like what a car actually sees when driving on the road. Since certain manufacturers, i.e. subaru, uses different power splits other that 50/50 (sti is 65 rear, 35 front), the load based dynos can be tuned to provide diffferent levels of load for the front vs the rear for safe, accurate simulation of the road weight that the engine would see in real world driving conditions. FTR, inertia based dyno's are notoriously bad when it comes to ensuring that the speed of the front and rear wheels is the same. When they are not, bad news for center diff. Plus, since the car will most likely see greater load on the road than on an inertia based dyno like a Dyno Jet, the tuner can tune the car too aggresively on the dyno, and then when you get the car on the road, detonation and other issues can crop up. Dyno Dynamics and Mustang dynos deliver a better quality, safer, more reliable tune, and ensure that your transmission is not in jeopardy when on the dyno. I've had my STi tuned on both, and although the numbers were higher on the Dyno Jet, of course, the tune on the Dyno Dynamics was far smoother, and the power band was better. The tuners were of equal knowledge and skill so I would equate the difference purely to be the dyno making it easier to get a proper tune out of. Anyway, I hope that in my long, probably boring, explanation that I answered your questions. KoolDino, please take no offense if you use a Dyno Jet at your shop, I'm sure that you are probably a good tuner, this is just my .02.
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