Exhaust question

[Schtauffer]

I'm taking the Malibu to the exhaust shop this coming Friday 9/27 for a little work. I'm changing mufflers and having the tails redone so they exit just behind the tire instead of all the way at the rear of the car.

That aside, my question is with putting in an exhaust crossover. When I was on PT '05, I spoke with Kevin McClelland regarding the tone. It develops a "crack" in the tone around 2500 rpm, and I hate they way it sounds. He recommended a crossover to smooth the sound out. Does it matter where in the system that is welded in? Obviously its gotta be behind the trans but in front of the mufflers-- is there any advantage to keeping it front or back as much as possible?

The car is a 67 Chevelle, 327 making 325-350 hp, 1.75" headers, 3" collectors, 2.5" exhaust, currently Flowmaster 40 series mufflers.

[CTX-SLPR]

Re: Exhaust question

as close to the manifolds as possible is generally the best. The farther away the longer it takes for the scavenging pulses to reach back and the less energy they pack.

Personal note.... Flowmasters are for trucks, get a set of Dynomax or Magnaflows.

[ls7gto]

Re: Exhaust question

dynomax ultra flows welded case oval.... picked up the GTO, and no drone

[CTX-SLPR]

Re: Exhaust question

I like my Magnaflows but the Dynomaxes were nicer but I couldn't find one in the case size I needed.

[goat racer]

Re: Exhaust question

I'm personally a fan if the X-pipe. I have one with a set of ultraflows and full exhaust and the car is really pretty quiet. No "drone" anywhere in the RPM range.

Textbook placement of a crossover is almost never attainable. Make it fit as far forward as it will comfortably fit. Stepping up the cost factor a bit, but next time I make a change to my exhaust it's going to have a set of v-band clamps in front of the mufflers so the center section can be dropped out without disturbing mufflers and tailpipes.
Just something to consider.

[biginch]

Re: Exhaust question

v-bands = awesomeness collector gaskets = crap

[ls7gto]

Re: Exhaust question

good to see you Brian!

[TC]

Re: Exhaust question

Spray a line of spray paint on to your exhaust pipe from the collector towards the mufflers. Make it about 36 inches long. Let it dry, and then go take the car out for a drive, hammer on it a few times and then come back and see where the paint burnt off. Basically you want to install the cross-over where the paint stopped burning. So if the paints not burnt 26 inches from the collector, then that is where you'll want to install the crossover.

[JOES66FURY]

Re: Exhaust question

i had asked the same ? here..... I was told it didnt matter....My H pipe is just behind the trans cross member

[Schtauffer]

Re: Exhaust question

I'd prefer an x-pipe, but at 350 hp or less it probably wouldn't make much difference. Plus, I promised the wife to keep the costs down.

I have a set of Flowmasters that I won on PT '05 by making engine sounds into the mic in front of 3,000 people. They gave me a certificate to choose which ones I wanted, then shipped them to me. I've had them 3 years, so its about time I got them on.

Thanks for the tips, everybody.

Spray a line of spray paint on to your exhaust pipe from the collector towards the mufflers. Make it about 36 inches long. Let it dry, and then go take the car out for a drive, hammer on it a few times and then come back and see where the paint burnt off. Basically you want to install the cross-over where the paint stopped burning. So if the paints not burnt 26 inches from the collector, then that is where you'll want to install the crossover.

What's the logic? Wouldn't all the paint burn off after an hour or so of run time? Not trying to be a smarta$$, just trying to figure out how the exhaust pulses are affected by temp?

Now that you mention it, the nasty crack it makes is worse when the exhaust is cold. After driving a couple hours on the freeway and the exhaust is fully hot front to rear, the tone is more mellow...

[CDMBill]

Re: Exhaust question

From what little I know the paint stripe concept came up as a method of determining collector extension length in an open header/collector racing application. I don't know that it would work in a full exhaust system and it has been somewhat discredited in several magazine stories in any event. As noted by others, you are likely better off looking at where the H-pipe will fit for ground clearance, ease of maintenance and assembly and keeping clear of things you don't want melted. As Brian mentioned above, being able to easily remove the middle section of the exhaust will make life easier down the road.

If v-band clamps aren't in the budget, but header flanges are, have them welded with an offset so that the tube extends through one flange and into the other such that the second just catches the end of the tube. That will help your header flange gaskets last much longer and it makes rough assembly easier. I do this with the V-band clamps as well.

[Schtauffer]

Re: Exhaust question

Got the new exhaust on today. It sounds much better, lots more mellow. Its not much quieter, but it sounds a lot less "trashy". Thanks, Kevin McClelland! It feels a little more responsive, no doubt thanks to the crossover.

He welded the crossover in just a few inches behind the front u-joint.

[milner351]

Re: Exhaust question

which flowmasters did you win in the contest?

I've heard some of them that are just ridiculous, and others that are not bad at all.

A friend has the american thunder series on a mustang convertible with the X pipe from bassani - and it sounds pretty good -but still a little too loud for a convertible - but, I'm conservative like that.

[Schtauffer]

Re: Exhaust question

I got a certificate to mail in; I had my pick of any pair of mufflers in Flowmaster's line-up. I picked 50-series. The mufflers I just removed were 40-series; they were in fact ridiculous sounding. Again, it wasn't the volume that bothered me so much as the tone-- they sounded like poop. I love the new mufflers-- they sound perfect. No rapping, cracking, or droning, just a nice deep rumble.

[milner351]

Re: Exhaust question

Sounds like the 50 series are the ones to get.

Nicely done- there's something very satisfying about turning the key and listening to a nice mill fire up through a good leak free set of pipes.... progres - always good!