Flowmasters

[Hammer]

I would like some input from anybody using the Flowmaster catback system #17115. What can you tell me about it? Sound, performance, ease of installation. How did it perform as a bolt on mod, i.e. no aftermarket chip. Thanks for any info you all mght be able to provide me.

[We Gone]

Love mine…good fit easy install, great sound with no resonance

[guinnessdood]

Originally Posted by Hammer

I would like some input from anybody using the Flowmaster catback system #17115. What can you tell me about it? Sound, performance, ease of installation. How did it perform as a bolt on mod, i.e. no aftermarket chip. Thanks for any info you all mght be able to provide me.

Hib did it on his car and wrote it up here...

http://www.corvetteactioncenter.com/....php?qstId=534

I have heard his car...sounds nice.

Uly

[Aurora40]

That Hib article is about a custom system. It looks like he only used the resonator from the Flowmaster cat-back system. One thing I found frustrating about his article was all the custom work done to fit that resonator into the LT4 system, yet there isn't a single picture that shows it!

FWIW, you can get the Flowmaster system from Summitracing for under $600 new.

Also, FWIW, if you were going to have a shop install it, you could probably just have a shop replace your mufflers with Flowmaster mufflers. If you had a '93-95 then it would probably have a similar or better gain, plus you could keep the stock look with the rectangle tip. But if you want to do it yourself or you want to keep the stock system in-tact, or whatever, the Flowmaster is certainly a low-cost cat-back way to go.

I seem to recall reading on the listserv archives about the resonator not being very ideal inside, though I can't recall exactly.

Flowmaster generally has a very nice sound, though.

[Hammer]

Originally Posted by We Gone

Love mine…good fit easy install, great sound with no resonance

Did you by any chance add just the exhaust and did you notice any gain in performance or drivability from just the exhaust? Have you added any other mods since the exhaust(chip, K&N, etc)? The price on these is sure inviting but I am not ready to add a chip yet and am really curious if you can just add the exhaust. I have read that the fuel curve is already about 6% rich, so I am thinking the exhaust would bring it in about right.

Thanks

[We Gone]

Just did the cat back..I also have an open air cleaner & K&N no other mods..I do have one of Marks chips but took it back out as I was getting to much ping. I had old blue dynoed bone stock a few years back at 18K miles and put down 326rwhp. I painted the pipes and muffs flat black.

I've been told you will gain 10 to 12 rwhp from a good cat back system. I can tell a bit of improvment in 1st and 2nd more wheel spin

I hope to get a good dyno tune next summer using Mark's chip I think it just needs the timming reset.

[Hib Halverson]

[quote=Aurora40]That Hib article is about a custom system. It looks like he only used the resonator from the Flowmaster cat-back system. One thing I found frustrating about his article was all the custom work done to fit that resonator into the LT4 system, yet there isn't a single picture that shows it!
(snip)

That's a legitimate complaint and I apologize for that shortcoming. The web-based version of that article was based in-part on an earlier print version of the story and there were some diffculties during the creation of the web version such that some pictures were lost.

I should add that adding the Flowmaster resonator to the stock LT5 head pipes then adding the LT4 rear section to that, while a time consuming job, is a task that any exhaust fabricator should be able to handle....an everyday, low-cost "muffler shop", maybe not...but a facility which has good welding skills and equipment and does high-end exhaust work should be able to handle it.

Originally Posted by Aurora40

Also, FWIW, if you were going to have a shop install it, you could probably just have a shop replace your mufflers with Flowmaster mufflers. If you had a '93-95 then it would probably have a similar or better gain, plus you could keep the stock look with the rectangle tip. But if you want to do it yourself or you want to keep the stock system in-tact, or whatever, the Flowmaster is certainly a low-cost cat-back way to go.

I seem to recall reading on the listserv archives about the resonator not being very ideal inside, though I can't recall exactly.

Flowmaster generally has a very nice sound, though.

I'd think twice about simply cutting off your stock mufflers and putting replacement Flowmasters in their places. No doubt the exhaust will sound better, but you won't see as much performance gain, especially on 90-91s. All ZR-1s have pipe restrictions at the resonator and at the muffler inlets. These restrictions are eliminated when you put on the entire Flowmaster catback rather than just mufflers.

Converting from stock to a Flowmaster cat-back on a stock or near-stock ZR-1 gains between 8 and 12 hp.

[Aurora40]

Originally Posted by Hib Halverson

That's a legitimate complaint and I apologize for that shortcoming.

Heheh, no problem. The article is still great. It's just there are like 10 pictures of the back half of the system, and man I really wanted to see how the resonator fit up.

Originally Posted by Hib Halverson

I'd think twice about simply cutting off your stock mufflers and putting replacement Flowmasters in their places. No doubt the exhaust will sound better, but you won't see as much performance gain, especially on 90-91s. All ZR-1s have pipe restrictions at the resonator and at the muffler inlets. These restrictions are eliminated when you put on the entire Flowmaster catback rather than just mufflers.

Converting from stock to a Flowmaster cat-back on a stock or near-stock ZR-1 gains between 8 and 12 hp.

Yeah, the '90-92 certainly has a worse resonator than the later ones. On the cat-back Flowmaster system, though, is it that much worse than that resonator? If you'd used the cat-back resonator unmodified, isn't the inlet like a single 3" or smaller? Not that different than the dual ~2" pipes through the stock resonator, especially as those are straight-through.

I'm making an assumption, and it may not be the right one. I figured if someone was going for the Flowmaster system, they probably wanted a good sound and a good price, not necessarily the most HP increase. Which is why I suggested doing just the mufflers. It would probably be a fair bit cheaper, especially if you would have paid a shop to install the cat-back system. And I suspect it would have that Flowmaster sound, and be fairly similar in the power change.

The muffler-inlet restriction shouldn't be an issue. The pipe could be cut past the taper, and/or flared out to whatever the diameter of the replacement muffler is. I think the 40 and 50 series can be had in 2.5 or 3" diameters in a case similar in size to stock.

[Hib Halverson]

snip

Originally Posted by Aurora40

Yeah, the '90-92 certainly has a worse resonator than the later ones. On the cat-back Flowmaster system, though, is it that much worse than that resonator? If you'd used the cat-back resonator unmodified, isn't the inlet like a single 3" or smaller? Not that different than the dual ~2" pipes through the stock resonator, especially as those are straight-through.

The Flowmaster catback uses 2.5" pipe and stock is 2.75, however, the decrease in restriction with the Flowmaster cat-back makes using it a net gain.

The Flowmaster resonator, is single in and two out. We modified it to accept a larger inlet.

Originally Posted by Aurora40

I'm making an assumption, and it may not be the right one. I figured if someone was going for the Flowmaster system, they probably wanted a good sound and a good price, not necessarily the most HP increase. Which is why I suggested doing just the mufflers. It would probably be a fair bit cheaper, especially if you would have paid a shop to install the cat-back system. And I suspect it would have that Flowmaster sound, and be fairly similar in the power change.

If you were willing to accept less or, perhaps even no performance gain and just the improvement in sound, I agree--going to Flowmaster mufflers but not the full catback might be the way to go.

Originally Posted by Aurora40

The muffler-inlet restriction shouldn't be an issue. The pipe could be cut past the taper, and/or flared out to whatever the diameter of the replacement muffler is. I think the 40 and 50 series can be had in 2.5 or 3" diameters in a case similar in size to stock.

Interior resonance might be an issue with 40s. The 50-Series Delta-Flow unit would be the best to use in that sitch.

[Demps]

John,

I did a similar experiment back in 2003 as Hib. I used a Magnaflow 2 1/2 inch x-pipe and the Magnaflow Corvette C4 3 inch mufflers. I wanted a 3 inch x-pipe but they did not make it at the time. I talked with Magnaflow and got them (or got on the bandwagon) to produce a 3 inch x-pipe and put it in later. I did not dyno the 3 inch x-pipe but felt the car lost some low end.

Here is the result of six pulls each: 1) stock car 2) stock car until the cats then a 3 inch piped system with a 2 1/2 inch x-pipe and 3 inch mufflers.


The resonance was tough. Slightly worse than a B&B with x-pipe.

Ted