Real tech discussion on design, fabrication, testing, development of custom or adapted parts for Pontiac Fieros. Not questions about the power a CAI will give.
fieromadman wrote:I think you should go with the single in dual out crossflow Magnaflow muffler and vette tips. Magnaflows are generally quieter than others. I am going to be switching to one this summer even if it means making the skinnier part of the trunk skinnier. My flowmaster is shit anyhow.
I just installed this exact setup on a customer's L67 swapped Fiero. Hands down the quietest exhaust system I have ever assembled and not used a cat or turbo.
The biggest problem with the 3800's is the drone. And this is something I have been fighting for years in these swaps. But I found the answer in this latest setup I came up with.
Single 3" off the manifold to a 90 deg mandrel bend thru a 3" flex to a mandrel 180 deg bend into the magnaflow crossflow (f-body) muffler (Summit P/N: MPE-12267). This muffler has dual 2.5" outlets. However, the customer supplied C6 vette resonated tips that only had 2" inlets. So right after the muffler I installed 2.5->2.25" reducers and pipe that had 90 deg mandrel bends. Then right before the tips were 2.25->2.0" reducers.
Since this swap was using a stock L67, I don't think this is going to be restrictive; and it sure seemed to take care of 95% of the drone these engines usually suffer from @ highway speeds.
Even though it has a 2.5" inlet; the inlet is necked down from 3" where it goes into the muffler body so you can easily open it up for a 3" pipe if that's what you need. These sound decent enough but the noise level is pretty high. The F-body Flowmaster muffler that has a similar design to this sounds better (actually makes V6's sound like V8's at idle) but as you know the flowmaster unit has to be notched to fit. The terminator muffler needs no such modification.
The Dark Side of Will wrote:How does this compare to the Holley you referenced in the Hard-To-Find Parts thread?
The Holley FlowTech Terminator is basically a cheaper, smaller version of a Flowmaster. Because it has a smaller case and a bit different design, it doesn't quite have the drone of a flowmaster but it does have more of a raspy sound than what the flowmaster produces. Despite this, the Terminator has more drone (and transmits more noise inside of the car) than the Magnaflow.
I should note that I have used a single in, single out magnaflow muffler on another 3800 SC swap before where I split the outlet so it would go to dual tips, and that car was not as quiet as this one (had overall louder exhaust). But we were using larger pipe in that instance as well. However, that single in/out version of the magnaflow you could see straight thru. This crossflow magnaflow muffler has the Y-split on the inside, so the exhaust has no direct line-of-sight path from the inlet to the outlet which I think helps kill some of the noise it produces.
This is good news. I just got the engine out and after looking at it again I'm not sure I could go with a true dual setup. The oil cooler takes up a lot of space. I'll still remake my headers in as equal length as possible without crapping up the entire engine bay. Is the crossflow muffler as good as a regular straight through magnaflow? I'm curious what it looks like inside the crossflow.
not much to see right now. Engine is out and I'll drop it off at the machine shop this week. He said 2 weeks to get it done. I have a few things to take care of in the mean time, so no big deal.
Well, you guys talked me into it. I'm buying Don Kraus' old 3.69 gears and input shaft. It's a good price, he's 10 minutes from work and with the engine and trans out the timing won't get any better. Big cam, long tube headers and lower gears should make a decent improvement in the car. Not trying to scare you Jeff!
Probably not going to happen. I still need to order the rest of my exhaust, pay for the gears to be installed and the cam installation. I am way over budget. if you guys knew what I've got tied up into it I'ld be in the other thread getting laughed at.
Josh just likes to talk shit about how someday his car will be faster than mine
The gears should be a nice improvement though Josh! And as far as money tied up into a car... well yeah, I probably got you beat. Besides you got he chop top custom paint and a whole slew of other things that cost a bunch of money.
I didn't go with the given advise, sorry guys. I did build some long tube headers. 5 came out between 31'' and 32''. cylinder 4 was short at 26''. 1 5/8'' tube merged into 2.5'' pipe with a merge pipe. couldn't swing a real x-pipe so I worked with what I had. Cutting the lower trunk I fit two corsa red mufflers. I chose these after listening to youtube. I don't think I got the sound I was after but it is quiet. It's almost creepy quiet after owning a 3.4tdc and 3400 both with spintec mufflers. i also have the corvette tips and they did help a lot. The car is running great with the reground 3400 cam. I'm talking with Sinister before I take it to the dyno.
yeah, I had some lifter noise. In case anyone goes down this road, don't use the LS6 lifter springs in the lifters. Some pumped up and some didn't, stock replacements fixed this problem. My oil pressure is around 45psi and doesn't fluctuate much with rpm's. I'm guessing this isn't compatible with the stiffer springs.
I got the 3900 dyno'd. Sorry sinister, the shop talked me into just making the changes. It's got 166tq at 3000 rpm and peaks at 3,381rpm with 239tq. It tapers off and has about 200 at 6,000rpm. horsepower really starts at 3,200rpm with about 150hp and tops at 6,000rpm with 237 hp. I'll be going to the track saturday to see how it does. With the 3.73 gears and a 4t65 it looks like I really need to wind out 1st gear to grab second at 3,300rpm and shifting anywhere after 5,600rpm in 2nd gear will leave me above 3,700rpm in 3rd. I was honestly hoping for more to be able to hit 12's but it doesn't look like it's going to happen. I'm changing out the upper intake with a 2008 version to get rid of the variable setup but that probably won't help that much.
