INTAKE: The 4.3 engine in
these vans is pretty much the same as the 5.7 liter V8, just minus 2 cylinders.
The thing I can't understand is why Chevy put such a small intake on these
engines. The Holley Pro-Jection
model 502-4 fits just about any fuel-injected 5.7 or 4.3 engine.
This is a pretty worthwhile upgrade, especially if you tow trailers, like
I do. When you're runnin around in the hot, humid summertime, air
is less dense, and this engine was running out of breath trying to breathe
through the "soda straw" OEM fuel injector throttle body. The Holley
solves this problem.
The installation is rather straightforward, and can be done in about an hour or two. There are some vacuum outlets on this unit that may or may not be used depending on the age of your engine, they will need to be capped. Since this throttle body is made to fit a variety of vehicles, you may need to tweak the the Throttle position sensor, and the fuel pressure regulator. The best way to do this is to use a code scanner. You need to try and get the BLOCK LEARN code as close to 128 as possible. Low number is too rich (too much pressure), and a high number is too lean. A fuel pressure gauge is also useful. If neither one of these tools is handy, you can get it into the ballpark by watching the CHECK ENGINE light for code 45's (too rich) or code 44 (too lean) and tweak till you don't get any lights.
I also recommend installing K&N air filter, or some other type of high CFM air cleaner with the Holley, because the OEM one is just simply too small.
Holley's Pro-jection system for the Astro Van
EXHAUST: Now that we got the van inhaling OK, we need exhale too, after all, an automobile engine is nothing but a self-powered air pump. For this job, I chose to use a MAGNAFLOW muffler. The one I chose splits into two outputs, which come out underneath the rear bumper, giving the illusion of a full dual exhaust system. The Magnaflow muffler is sort of like the old-style glasspacks, but is oblong in shape, and is not quite straight through. The muffler gives pleasing mellow sound below 3000 RPM, and really makes some noise when the engine's crankin over that. That's all I've done to the exhaust system so far, future upgrades include headers, so stay tuned!
Magnaflow Performance Mufflers
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