sleeper84

iTrader: (1)

Ok, so it's time to put a new exhaust on my 84. For the last several (5?!?) I've been suffering from a 2.5" single exhaust. I didn't do my research when I put it on, just guess-timated and missed miserably.

The motor is a 350cid engine, ported 882 heads with 1.60" exhaust valves. I can get cam specs if you need them, but it's been 6 years since I built the engine, so I don't have it in memory. It turns 7000RPM at the shifts, and struggled with that breathing through the 2.5" system. We recently cut the exhaust off at the y-pipe (hooker headders off-road) and I was amazed at how it ran after that. It'd turn 7300RPM and would have kept going some if I hadn't slapped the shifter. This got me wanting a better breathing system since my old 2.5" is going on my g/f's 90 RS V6.

What I'm thinking if following the factory dual cat setup lines with 3" off the collectors (Hooker Shorties) to the passenger-side and back under the heat shields. Putting on two Magnaflow Race Bullets (look kinda like Catalytic Converters to the untrained eye ) then a dual 3" to single 4" y-pipe into a Hawk's Sinister 4". This will keep the rattle out of it that open pipes have and hopefully it'll be bareable at cruising speeds (70mph interstate). I was going to try to get the Race Bullets put on about equidistant from the collectors, if at all possible to balance the exhaust pulses.

Does this sound like a good system for the maximum power and minimum loss scenario?

built91Z28

Unless the motor is really built up, I dont think you would need 4" exhaust. Thats usually for over 500 horsepower.

BTW, you sure your really spinning that thing to 7300 rpm? Thats a lot of rpm. Stock tachs are known for being off.

sleeper84

iTrader: (1)

Old post, but back to working on it I hope soon. I've never had another tach on the motor while turning it, but I have at idle and it's extremely close on the lower end.

I've reconsidered and want to use 2.5" for the sections from the headers to the y-pipe. Still going back and forth between 3.5" and 4". 4" should support ANY engine I put in this thing from now on. Trying to make sure that I only have to spend this money one time. If it wasn't lowered, I'd run a 70's Trans-Am series before-the-axle exit style exhaust. As low as it sits though, I'd be dragging it on everything.

Does anyone make a 3.5" as cheap as Hawk's 4" sinister kit?

sleeper84

iTrader: (1)

Guess you can say I settled again... Had a shop put on a 3" system, but with the head pipes I had wanted on it. Also went with a Dynomax UltraFlow muffler. Not crazy about how it sounds, but it runs a whole lot better now than with the 2.5" and a Flowmaster. The new headpipes work alot better than the Hooker y-pipe I had on it too I'm sure.