Thread: Specs for 350 for a 1990 policepak

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I have a 1989 9C1 Police Caprice, and my main question is always: how to make it go faster and perform better. How fast is it? Well, not fast enough.

Here is what I have done: Rebuilt 700R4 trans, billet servo, shift kit.
Performance Distributor's cap, rotor, module, wires, platinum plugs.
Mobil 1 Syntec extended life oil. K&N oil filter, K&N air filter, and K&N chrome filter lid from Summit Racing. A Flow Cooler hi-perf water pump, also from Summit. Hotchkis springs dropped the stance down about 1.5" and Bilstein shocks. Also a complete Performance Suspension Technology front end kit and performance rear brake (drums) kit. I need to replace the tires, and I am considering a set of Yokohama Avid ST. P225 x 70 in front, and P255 x 70 in the rear. Rear tires, slightly wider and taller. I also have a Hypertech chip which I will install after I get the new tires. All you fellow gear-heads, any more ideas? I live in Illinois, and this car MUST pass their tough emissions test/scam every two years... I am building the car for performance, and better milage. The original style exhaust is still on the car, and I would like to get street legal headers ceramic coated wtih AIR and Oxygen sensors, a Random Technologies high-flow Catalytic Converter, and some type of dual exhaust set-up. Most realistically a Flow-Master one in two-out set up like I have seen on line for Firebirds and Camaros. Does anybody out there have any experience with this type of vehicle, and or set-up. So far I have built this car on a budget. I don't make a lot of dough, and money is always a factor. If you have ever owned or driven one of these vehicles, you know they are one of Chevy's greatest, but I know there is still a lot of untapped potential there still... Thanks. JC

Originally Posted by JohnChicago

... Here is what I have done: Rebuilt 700R4 trans, billet servo, shift kit.
Performance Distributor's cap, rotor, module, wires, platinum plugs.
Mobil 1 Syntec extended life oil. K&N oil filter, K&N air filter, and K&N chrome filter lid from Summit Racing. A Flow Cooler hi-perf water pump, also from Summit. ... I also have a Hypertech chip which I will install after I get the new tires. All you fellow gear-heads, any more ideas? I live in Illinois, and this car MUST pass their tough emissions test/scam every two years... I am building the car for performance, and better milage. The original style exhaust is still on the car, and I would like to get street legal headers ceramic coated wtih AIR and Oxygen sensors, a Random Technologies high-flow Catalytic Converter, and some type of dual exhaust set-up.

OK there is no question that you could get the car running as fast/quick as the still-emissions-legal people with 94/96-era LT1 Caprice 9C1s. But you'll have to do this sensibly.

1. You could either add the 92-93 big Ypipe 9C1 exhaust, with a 3" pipe aft + aftermarket muffler (the easier choice), or opt for the better but more difficult choice: full N10 dual exhaust install from a 94-96 LT1 car. I won't detail that swap here. Instead go here and start reading:

http://impalassforum.com/noncgi/ulti...;f=33;t=009021

It applies to 91-93 TBI Bcars, but the 89-90 are basically the same so it works for you as well.

2. Don't use that chip. Read the aboove link and you will see why. I'll come back to the chip in a moment.

3. Open element air cleaners have very little flow restriction, and they are quite loud and sound powerful, but they are also not as good as an cold-air intake + filter... because ingesting pre-heated underhood air robs the engine of power. With your brick Caprice, you should be able to fit a truck TBI air cleaner lid onto yours that will allow a taller factory filter (more cross sectional area) AND allow you to adapt it for dual snout air feeds, much like the HO air cleaner used on the 3rd gen Camaros. Feed the dual snouts with flex hose to the front of the car, to source good cold air.

4. I think you probably already have a decent roller cam in your engine.... IIRC it's the same as used on the L98 TPI engines. But it could use more lift, so the $75 set of 1.6 stamped self-aligning rockers would be cheap and useful to gain more lift/flow with that cam.

5. The above will all help but it's small gains... perhaps 20-25 hp better than your stock 190 fwhp rating. To get more you need to port the heads for bettter flow, and you need a custom-tuned chip to suit the engine mods.

I'll say more later. Gotta go.