Originally Posted by Chevy_force
I am wanting to build a Snorkel for my 89 Chevy. It has a 350 TBI. I have an air intake on it that did away with the old system, It bolts right down on the intake, and just has one bolt going throught the top. A tube goes from there all the way to the fender. I was wondering if I could seal it around there and go from there? Or is there another way I should go? I see a lot of people going with the old air intake and just sealing it up. Any help or ideas would be great.
While there is power to be had feeding the engine cold air, Very cold weather such as you see in Alaska brings with it other problems. TBI like a carb is dependent upon the manifold to distribute fuel into the correct mixture ratio to each cylinder. A job that isn't done all that well by these things. The intake port sizes (exhaust as well) are a compromise in size between what's needed for low speed performance and high speed performance. The result is a system that is usually too big for the bottom end of the RPM range. This reduces the speed of the flow in the ports to where it becomes difficult to keep air and fuel properly mixed especially when the incoming air is cold. The factory's solution is to apply heat to the intake manifold to force the fuel to evaporate into the air stream which helps even out the distribution issues quite a bit but reduces the density of the incoming A/F mixture. The hot rodders dilemma is that cold air makes power thru density but also losses power thru inadequately mixed and variable A/F ratios.
Extremely cold A/F mixtures at low to moderate engine speeds cause inadequate air fuel mixing and inequitable distribution by cylinder which not only reduces power but increases vibration and wear. The big impact of this is with the rich running cylinders where the excess fuel washes the lubrication off the cylinder walls increasing wear. This can result in quite severe wear that greatly reduces engine life. From a vibration stand point, when the cylinders are not applying equal force to the crank, the crank becomes subject to a lot of unresolved forces that cause it to jump around in its bearings and work the damper literally to death.
So the answer is the minimum amount of heat that's required to achieve proper mixture ratios delivered equitably to each cylinder. The idea of sealing the incoming air stream in cold weather is a high risk option if you're not in an economic position to replace or rebuild the engine when it gives up. Besides, sealing is assumptive of being able to supply some pressure against the TBI or carb from ram effect, the fact about this is that below a 100 mph there is insufficient ram to have any effect. Whatever power is gained from these set ups comes from feeding the engine cold air, which is good for almost a 1% power increase for every 10 degree drop of inlet temp. But where you live, the back side is poor mixture distribution with decreased power and increased internal wear.
The fact everybody does it, doesn't mean they know what they're doing. This is a very common affliction in the hot rod community.