I'm thinking about installing a cold air intake system on my 1993 Allegro Bay with a Chevie 7.4. Has anyone tried this? Will I get more power? More mpg would be nice, but I'll settle for the additional power. Is it worth the effort and expense?
Actually, that won't work correctly on a '93 because of the TBI, but you could adapt the idea. TBI is finicky about how the air flows around the injectors, so you need to maintain that open area above the TBI. There are two issues at play when doing a cool are intake. The first is to provide cool air collected from in front of the radiator. The second is to provide high intake velocity to stuff the cylinders better at mid and lower RPM. There is no such thing as utilizing the "ram air" effect of the increased pressure on the front of the coach to ram more air into the engine. You are just not going fast enough to create any substantial air pressure. When you here people talking about ram air effect in the correct sense, it means maintaining air velocity into the engine. Some of what you are trying to overcome at low RPMs is the fact that as the valve closes, it causes a reverse wave back up through the intake. Long small diameter tubes tend to minimize this effect, as the high velocity air maintains its forward motion better when the valve closes. The longer and smaller the tube, the lower RPM that it is tuned to. What you see in my photos is two 2" diameter tubes feeding the intake. For that size tube, you don't want more than ~ 25" length from the head to the air cleaner, otherwise you start to loose some top end. However, if done right, according to a desktop dyno program I was running figured to ad around 35 FT-LBS of torque at 3Krpm. My total length is longer than it should be, but still seemed to ad a bunch of power in the low and midrange. Didn't seem to hurt the top end any that I could tell by the butt meter.
Incidentally, Edelbrock dyno'd this engine with their MPFI and stock exhaust came in at 517 ft-lbs at 3500 rpm. I did a calculation based on acceleration data log and weight. It showed my peak torque was at was 565 ft-lbs at 3600 RPM. That would suggest the headers and the long tube intake were doing something.
I have read where some have redone their cold air intake on the BBC and actually lost power compared to OEM. Likely, they made the intake tube too large and lost some of the intake velocity.
* This post was
edited 07/22/08 11:46pm by Daveinet *
I added a Banks exhaust and intake system to my nearly new 1997 Ford Bounder with a 460" engine. It did improve the power and made the engine a little quietier.
Banks claims that you will get some 45 - 60 HP more than the factory rating. They still sell the same kits for the engines that they installed while the RV's where still nearly new.
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a Porsche or Country Coach!
It doesn't take much to figure out why your vehicle's run much better when it's cool outside and raining. Engine's regardless of size, like cool damp air. Cheap fix, 4" Dryer hose attached to your existing intake tube in front of air cleaner. Just make sure it doesn't suck any water into it when raining. No Rocket Science here, just good old trial an error that's worked on a lot of vehicles. That's what made muscle cars what they were.
David
1997 Fleetwood Southwind 37Y / Ford 460 / Power Platform / Tag Axle
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This is true for the cold air aspect, but not necessarily true for the long tube ram air effect. How the air flows through the engine will have a lot to do with efficiency. If you notice, most modern cars now have very elaborate intake manifolds with long runners. This greatly improves air flow quality, especially at low RPMs, thus improving efficiency.
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