procainestart
New member
- Joined
- Sep 9, 2003
- Location
- PNW
Red Box APCs were fitted to the last two years of SPGs (90-91), as well as the Commemorative Editions that followed. Additionally, prior to that, you could buy a red box APC out of the Accessories Catalog; depending on the year, it came with a slightly higher pressure fuel regulator (by 0.3 bar), as well as a distributor with a better boost retard curve.What are the advantages of a red box?
Stock, run-of-the-mill 900 Turbos made 160 hp/188 ft-lb, while the hottest, latest (90+) red boxes made 185 hp/low 200s ft-lb. The standard, 160 hp version allows about 11 psi (assuming high enough octane) max boost. If you fit one of these APCs to your Volvo, and you are not running more than 11 psi, then it makes no sense to modify the APC to "red box specs" (e.g., the "recipe" at 900aero.com). A nice thing for 900T owners is the ability to add 25 hp for the cost of a few resistors, a used fuel regulator from a non-turbo car, and a minor mod to the distributor vac capsule, all for $10 or so.
Your "base boost" (wastegate opening pressure without APC hooked up) should be half of max boost. If you always run good gas, then you can bump that up a couple psi.
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