Exhaust for max performance.

[XfireZ51]

Brad,

I agree that extending the tips past the rear valence helps
control resonance.

Ricky,

The FBI makes sure u get the best bang
4 the buck.

[HAWAIIZR-1]

Okay, Marc H helped me to identify my B&B mufflers and I found out I have Version 3.....that sucks the big one. So I guess they are coming off and being replaced by the Dynomax 17228 Ultra-flo or the 17519 that appears to be the same but polished. I am thinking of going with Dynomax 36473 tips that are doublewall with 4" round.

Any particular things I have to know about the length of the dynomax or being able to put hangers on them, etc? I'm like Ricky said and don't drive it often enough to care about how loud or resonance and just want balls to the wall all the time, especially having the cams should be music to my ears.

Thanks!

[Hib Halverson]

Originally Posted by rhipsher

Ok I've made a few decisions. My long term goal is to aquire a prestine low mile 385 or 415 stroker. And Im sure one way or another I'll have it. I've decided not to sell mine to get one. I've got way to much time and labor invested in all the work I've done to it. And Id be lieing if I didn't say im a little emotionally attached to it. A good ZR-1 friend. Suggested that after the top end porting I did almost two years ago that I owe it to myself and finish it by getting the headers X pipe high flow bullet cats and a good exhaust system. Im gonna get rid of the Borla. Im gonna have Corey fab me up the Jeal headers and make my high flow bullet cats removable so I can remove them after emissions testing and a pipe to fit in place of the cats if its possible. My question is 2.5" or 3"exhaust. Corey once told me that a 3" B&B is to much for a stock displacement LT5. And that it will cost me torque. Then a year later he tells me I need a 3"B&B. That's confusing. I know everybody has their opinion but what are the facts?

Facts?
Well...the stock exhaust is 2.75-in but has some restrictors both ahead of the resonator and ahead of the mufflers.

B&B is about the loudest "street" system available but loud doesn't always translate in to low-restriction.

If you're going to run headers with no cats, the ECM cal is probably going to need to be changed and if you don't do that, any performance change due to the exhaust will be mitigated by a less that optimal cal

If you want to read about a custom-built system for a C4 which performs well but is not as loud as a B&B or open exhaust see: http://www.corvetteactioncenter.com/kb/questions/311/1992+-+1996%3A+Tech+Article%3A+Quietly+Powerful%3A+How+t o+Build+a+C4+LT1{47}4{47}5+Exhaust+that+Gains+28+h p+and...is+Quiet

[Corbusa]

Ok set me straight on what you think. I do like the OBX system ( a lot) and I was ready to order , But its only 2 1/2 in.. So I'd be better off with 3in.? whats the power loss dropping down a size in the pipe? I can not find 2 3/4 stainless pipe .. My thoughts are now to order the dynomax 17228 or 17519 . I found 3 in stainless pipe pretty cheap and I have a friend who is a pro who can install it.. just so I got it straight , 3in is better and the X pipe ( magnaflo) will replace the resonator? and it is 3 in..?
Will it be an issue to go from the factory exhaust 2 3/4 to the 3 in X pipe and make a connection? ( i'll do the OBX headers later ) , & I noticed the polished mufflers are cheaper , that seems backwards .. also what length exhaust tips are usually used? I see the muffler says 2 1/2 exits and the tip says 2 1/2 will that slip fit correctly? Well I guess that enough dumb questions for this evening.. Your wisdom are greatly appreciated..Thanks

[HAWAIIZR-1]

Originally Posted by Corbusa

Ok set me straight on what you think. I do like the OBX system ( a lot) and I was ready to order , But its only 2 1/2 in.. So I'd be better off with 3in.? whats the power loss dropping down a size in the pipe? I can not find 2 3/4 stainless pipe .. My thoughts are now to order the dynomax 17228 or 17519 . I found 3 in stainless pipe pretty cheap and I have a friend who is a pro who can install it.. just so I got it straight , 3in is better and the X pipe ( magnaflo) will replace the resonator? and it is 3 in..?
Will it be an issue to go from the factory exhaust 2 3/4 to the 3 in X pipe and make a connection? ( i'll do the OBX headers later ) , & I noticed the polished mufflers are cheaper , that seems backwards .. also what length exhaust tips are usually used? I see the muffler says 2 1/2 exits and the tip says 2 1/2 will that slip fit correctly? Well I guess that enough dumb questions for this evening.. Your wisdom are greatly appreciated..Thanks

Okay, flame suit on here is my opinions for what it is worth. I personally cannot get the concept of smaller pipes than stock 2.75...period. Although proven my Marc H and others to provide more power, please see why on Marc's presentation here: http://www.zr1specialist.com/HAT%20W...%20Systems.pdf

Having said that, I know the weakest link in my B&B system is the mufflers itself and I don't know that a 350 motor actually can benefit from 3" pipe, but I like it and have it already so I'm going to work with what I have. Beside it looks cool as heck from the rear and everyone says, "Wow, them are some big pipes!" Everyone has an opinion of what is loud and too much resonance, or their own reasons for why they like what they do and what sounds good to them. I have no idea what an LT5 sounds like with the dynomax ultra-flos but I like what I read and how some other cars sound on you tube. If you are a conservative person, you probably won't be happy and too loud and too much resonance.

As for the X pipe, I would not put a 3" unless that is the size of the exhaust you are using. I only chose the SW x-pipe because it is 3" and B&B would not work with me. As a matter of fact, I received my x-pipe from SW today and very pleased and not chambered, just plain x-pipe (will post a photo later). From what I found there was a little bit of clearance issues with MF and other X pipes with our narrow tunnel area and I also don't like the design and transition with too many degrees in the X.

About the tips that I wanted (double wall from dynomax) they are a bit long at 12" and 9" before the taper (3" to slip over pipe). A 2 1/2" tip is designed to slip over a 2 1/2" pipe. I'm trying to confirm the measurements since the dynomax is 1" shorter in length than my B&B mufflers and I think too much will stick out the back. Right now the B&B tips are flush with the bumper and I might need to find different tips that are a few inches shorter than dynomax 36473. I think dual 4" tips would looks awesome and double wall, rolled edge is nice with slant cut. Some have said that the doublewall might even help on drone, but not sure where it actually comes from. It might also help to have tips extent a little beyond the bumper too, but not sure.

If I was anywhere else in the US I would have ordered my dynomax ultra-flo mufflers and tips to get some custom work done. Here in Japan the labor is crazy expensive so I might live with my B&B, Version 3 (restricted mufflers) for a little bit and see how I like the X pipe first. Anyway, that is my 2 cents for what it is worth......not much, but it is my story and I'm sticking with it. The proof of principle will be when I get to tune and dyno my build so see if all the theories are confirmed.

If not in a rush, I would go to the Gathering and listen to all the Zs there to see what you like. Then max power is a whole different story and advice from folks like Marc H and Hib H and invaluable since they have dyno proof and years of knowledge and experience. Best of luck.

[Pete]

To keep cost down use the stock exhaust cut resonator off install X-pipe,cut mufflers,install Dynomax mufflers, done.

My first mod was i cut resonator off stock exhaust,installed 3" H-pipe with Flowmaster mufflers 3" inlet/dual 2 1/2" outlets, Z was running low 12's at 116 MPH,after that was headers and ported plenum/IH best was 11.59 @ 120 on GSC's had to slip clutch i used to go thru clutches like they were going out of style this was almost 10 years ago and it was unheard of.

I still have that old exhaust.

Pete

[rhipsher]

Originally Posted by Pete

To keep cost down use the stock exhaust cut resonator off install X-pipe,cut mufflers,install Dynomax mufflers, done.

My first mod was i cut resonator off stock exhaust,installed 3" H-pipe with Flowmaster mufflers 3" inlet/dual 2 1/2" outlets, Z was running low 12's at 116 MPH,after that was headers and ported plenum/IH best was 11.59 @ 120 on GSC's had to slip clutch i used to go thru clutches like they were going out of style this was almost 10 years ago and it was unheard of.

I still have that old exhaust.

Pete

I like that idea. Nice and simple. I went over some railroad tracks one night 5 years a little to fast and it ripped a big hole in my Borla resonator so until I could find another one I had the muffler shop just weld me some straight pipes from the cats all the way back to the mufflers. It was a quick fix but I hated the way it sounded. Sounded like a giant lawn mower. Once I got the res from Brad I had it installed and it sounded so much better. I don't really know if the straight pipes actually added hp but it did dyno at 339rwhp with them so I never dynoed it with the resonator. The next time I dynoed the car was after the top end porting so I'll never know if the straight pipes helped. All I know is it sounded funky.

[HAWAIIZR-1]

Originally Posted by Pete

To keep cost down use the stock exhaust cut resonator off install X-pipe,cut mufflers,install Dynomax mufflers, done.

My first mod was i cut resonator off stock exhaust,installed 3" H-pipe with Flowmaster mufflers 3" inlet/dual 2 1/2" outlets, Z was running low 12's at 116 MPH,after that was headers and ported plenum/IH best was 11.59 @ 120 on GSC's had to slip clutch i used to go thru clutches like they were going out of style this was almost 10 years ago and it was unheard of.

I still have that old exhaust.

Pete

Pete,

If the stock pipes are good and no replacement needed, this is the best budget conscience upgrade I have ever heard of. Do you think the LT5 needs at least 2.75" and up pipes? It would seem GM/Lotus/Mercury Marine would have done some testing during development with the exhaust systems? I'm sure some guru out here already knows the answer. I wonder why even companies like Corsa when developing the 2.50" went smaller instead of at least staying with 2.75"? Did they think it was too big? I know they had sound, db level, resonance, comfort, emissons and many other things to consider during development.

[Gunny]

Pete, Craig, et al,

Pete's mod of removing the restrictive parts from the factory pipes and adding flow mufflers & H pipe got me to thinking. I have spare parts in the garage that I've been wanting to mod & fab up similar to Pete's description. Here's what I have ... a complete LT4 cat back (reportedly one of the most free flowing exhausts for the C4) and a pair of Magnaflow SS mufflers (3" in - twin SS tips). I'm looking at a 3" x-pipe sold by Summit part #643130 that indicates the following dimensions: 3" aluminized pipe, 5" center to center spacing, and 22.75" total length.

But the photo tells a slightly different story unless I'm looking at this thing completely wrong

According to my calcs a 3" x-pipe on 5" centers should have a 2" clearance between the 2 pipes. The LT-4 pipe centers (at each end of the resonator) is very close to 3.5" leaving approx. 3/4" space between the pipes. This is why a narrow x-pipe is needed if trying to align original pipes as well as fitment in the tunnel. Looking at the photo it certainly appears to me that the summit x-pipe doesn't have much more than 1/2" clearance between pipes which should make for an almost ideal fitment to the stock pipes.

Has anyone measured this particular x-pipe? Is the photo correct or is the description correct? I live about 3 hours away from Summit-Atlanta but I don't have time to make that trip in the near future. Last time I was at Summit and wanted to check a "catalog" item, I was told that I had to buy it at the counter, then the item would be pulled from the warehouse & given to me within 10-15 minutes. If I didn't want it then I had to go to customer service and do the return merchandise bit ... when all I wanted them to do was to look at the item and check a measurement. That process seems bassackwards for the customer. Nevertheless, if the Summit narrow x-pipe is a close fit it should be fairly easy to fab up my spare parts into an interesting exhaust for very little out of pocket cash.

Thoughts? Advice? I'm curious about the possibilities and I've really been interested in the good info coming from this discussion. Thanks in advance.

George

[XfireZ51]

George,

If you need some Mflow muffs for your system, I'll have some available in the very near future. Very good condition.
BTW, I think the SW Xpipe is 4-4.25" c-c.