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]

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/kb/question.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 (http://store.summitracing.com/partdetail.asp?autofilter=1&part=FLO%2D17115&view=1&N=700+0).

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]

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 :mrgreen:

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

[Hib Halverson]

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.

[quote=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]

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. :)
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

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.



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.

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.
http://temp.corvetteforum.net/c4/demps//dyno_5___12.jpg

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

Ted

[Aurora40]

snip

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.
Right, I mean an unmodified single inlet. I assumed it was bigger than 2.5". Is that the size where the single inlet hits the resonator?

[Hib Halverson]

Darn!
16hp is pretty impressive from just an exhaust.

Were the two pulls made on the same day. If not, is this data SAE-corrected or standard-corrected?

[Aurora40]

Darn!
16hp is pretty impressive from just an exhaust.
I believe that's 26hp. ;) :cheers:

[blackjack]

i originally installed a borla cat-back system,2 1/2"...then i heard about the restrictions inside the pipes,apparently there to cut down on interior resonnance...so i decided to make my owm,with help from some friends..we installed 2 1/2" pipes from the cats,removed the resonator and put an x pipe in its place,and installed back the borla mufflers...we did not dynoed the car before or after,but the gain in power was really noticeable...the sound is deep and mellow,and i didnt notice any resonnance inside,at any rpm
blackjack
91-1735
4:10 , lucas injectors,fidanza flywheel(noisy)

[Hib Halverson]

I believe that's 26hp. ;) :cheers:

My bad on that. Can't add late at night.

I was wondering if those two dyno pulls were done on the same day? If not, can you say if the data is either SAE-corrected or standard-corrected?

[Aurora40]

It's not my dyno run, though the labels for the Y-axis' both say "SAE corrected" on them.

[Hib Halverson]

It's not my dyno run, though the labels for the Y-axis' both say "SAE corrected" on them.

26 hp at the wheels, SAE-corrected, from a stock engine after just an exhaust change is absolutely incredible.

[Demps]

Sorry for the delay. I have my kids for Christmas and we're on the go.

Hib, the car was totally stock. It was dyno'd about a week apart. The values were SAE corrected. Stock dynos were done six times and they never varied more than 2 hp. The modified (exhaust only) dynos were done six times and it gained about 2.5 hp per pull. After six we quit. I drove it straight from the muffler shop to the dyno. The temp varied slightly but I don't remember which way (1st to 2nd). The water temps were fairly controlled but it climbed as the day went.

Ted

[jonszr1]

if i can ask hib if he has given thought to that ultra flow-x . they say its an x pipe in a muffler . I always hear that an x pipe gives alot of resonance. I amnot that knowledgeable but i just got back from having 410s put in as well as ported inj and plenum as well as a tune on the car instead of just ordering a chip that got13 hpextra . Since I have a complete flowmaster system I am very interested if i could gget an extra 10-15 out of her .She is at 409.9 rwhp 373 tq now . But 425 out of a stk motor with the above mods would be would be a dream come true. please advise as to my best path. any advise is much apprieated

[Hib Halverson]

if i can ask hib if he has given thought to that ultra flow-x . they say its an x pipe in a muffler . I always hear that an x pipe gives alot of resonance. I amnot that knowledgeable but i just got back from having 410s put in as well as ported inj and plenum as well as a tune on the car instead of just ordering a chip that got13 hpextra . Since I have a complete flowmaster system I am very interested if i could gget an extra 10-15 out of her .She is at 409.9 rwhp 373 tq now . But 425 out of a stk motor with the above mods would be would be a dream come true. please advise as to my best path. any advise is much apprieated

I want to make sure I understand the above because it's just as amazing as 26hp at the wheels from just an exhaust....are you saying your car, which currently has a stock exhaust, makes 409 at the wheels after porting the injector housings, porting the plenum and having a custom tune done?

If this is correct, may I ask what facility did the dynamometer tests and are the numbers SAE-corrected, standard-corrected or raw data?

[Hib Halverson]

I'm sorry, folks....I forgot to answer this:

Right, I mean an unmodified single inlet. I assumed it was bigger than 2.5". Is that the size where the single inlet hits the resonator?

Unfortunately, I don't know the exact size of the Flowmaster resonator inlet but I'd guess it's 3 in.

[Z Factor]

I want to make sure I understand the above because it's just as amazing as 26hp at the wheels from just an exhaust....are you saying your car, which currently has a stock exhaust, makes 409 at the wheels after porting the injector housings, porting the plenum and having a custom tune done?

If this is correct, may I ask what facility did the dynamometer tests and are the numbers SAE-corrected, standard-corrected or raw data?

I was thinking the same thing as typically you need headers and exhaust along with what he has to get close to 400rwhp. Maybe the heads are done as well?

:cheers:

[Hib Halverson]

jonszr1 is posting to a number of other threads today and I had not read them all when I posted above. In reading a few of them a few minutes ago, as I understand it, the car has headers and not cats. That makes a *huge* difference. Now that I know that, I can see 409 at the wheels.

I'll add that headers and no cats hardly makes the engine "stock"

The AutoMasters Street Skinner in my #140 makes 412 at the wheels from a 475-500hp engine which uses stock manifolds and cats. Where I to switch to headers, with appropriate recal., I'd easily make 425 and 430 at the wheels might be possible.

Also, there's a lot of discussion in recent years of replacing any resonator in the system with an "X-pipe". I've thought about doing that too.

I've thought about revising the article on the CAC about my exhaust system by adding a set of Dawson Racing Headers, cats off a new Z06 and an Z-pipe then going back to WesTech's dyno for more tests.

[jonszr1]

hib ' I didn't mean totally stk . as an old ahra drag racer headers was stk sorry. my car has ported inj housings jeal headers dyno tech hi-flowcats ccomplete flowmasters 21/2 in exhaust. and a custom prom . the best thing is no knock event at 5200. Corey henderson did the porting and the tune as well as installed 410 gears. his ph 210-867-6286. he would have the answers on nthe sae figure. i remember reading your modsto the flow master and really wanted to hit 420 rwhp a personal goal. i really just wanted to share what a fine job that young man did. i have been in hotrodding 35yrs and as we all know it can be hard to find a relly good shop that does what they say and giving a good monitary a plus. I wasn't bragging and sorry if any one felt that way, notmy intention at all. Corey is just getting ready to open up a real business instead of his back yard and thought to share my experience to give the zr1 guys another choice if they so desired. I wanted to pick your brain about that xpipe in a muf to see what your thoughts were. this old guy would like to be a little on the sleeper side .loud is for young folk Imho. if you have suggestion on how to improve my ex tract i would be very thankfull. Maybe i can get corey to post the dyno sheets . alli have is a lapp top. sorry:mrgreen: :thumbsup:

[Hib Halverson]

(snip) i have been in hotrodding 35yrs and as we all know it can be hard to find a relly good shop that does what they say and giving a good monitary a plus. :mrgreen: :thumbsup:

Hard to find a really good shop?

You said a mouthfull there!!!

[jonszr1]

.I have tried for 2 years to find a good zr1 shop in so cal. thats why i took the chance on driving 1500 mi. to coreys" .I amvery glad I did.excellent work done Great priceing and total honesty. I know there are others out there.but for me i have found the guy to do the things i either don't have the time/knowledge to do.. I hopefully will be testing my new exhaust system right after the first of the year . will try to do a same daytest to give a good comparison.:thumbsup: