92RSFivePointSlow

92 305 TBI/auto, 14psi, 95 LT-1 cam, 1.6 rockers, edelbrock TES, Catco cat, jet II chip, open element.

The car runs high 14's with this setup using 2.25" open I-pipe with no muffler. Stock throttle body is 574cfm, and I need a cat-back kit to quiet her up. I cannot see how the dynomax 2.5" super turbo system would slow this car down, as opposed to a more expensive system. Can someone please enlighten, agree, disagree???

Options are as follows
dynomax 2.5" $170
edelbrock 3" $245
hooker 3" $265

each of these flows more than 574cfm, and will rust very quickly due to where I'm parking, so cost IS an issue. Stainless is not an option because I don't have the cash right now. Besides, who knows where the car will be a couple years from now.

curt86iroc

well, i can tell you the I pipe on the edelbrock cat back is 3in, not 2.75. my friend has the same exhaust set up as i did on my 86 as well as the same motor, except he had a dynomax cat back. my car was much louder than his. you could barely tell his car had aftermarket exhaust.

92RSFivePointSlow

Ever race him? Or at least, did you think your exhaust would have made his car faster than it is with the dynomax? Thanks for the correction, summit said the edelbrock was 2.75", but they don't have one on their car, so I'll take your word for it.

vic_V8

edelbrock is 3", and it has a lifetime warranty

I have had this system for almost 3 years now, very little surface rust even after all this time, and the sound is unique

curt86iroc

he went 1/10 faster than me at the track, but i trapped 2 mph faster than he did.

92RSFivePointSlow

hey, what were his times/mph, if you can remember. Thanks

curt86iroc

sorry, i cant remember off hand. hes a member here: anymethod

AJ_92RS

Keep something in mind when buying an exhaust SYSTEM....

The warranty is for the muffler, and the muffler only. Plus, it's for craftsmanship and production tolerances.

Nowhere will you find a muffler that says it won't rust. Rust is inevitable. Even stainless steel rusts. Anyone that tells you otherwise doesn't know metals as well as they think.

Only "aluminized" mufflers have a better chance against winter salt.

I have the Dynomax kit, and for the money spent, it has held up fine through two salty IL winters, going on it's third.

No holes yet.

92RSFivePointSlow

I completely agree with what aj is saying. Alot of people see stainless and get all happy in the pants. It's a sales pitch.

I really like the Dynomax system, the price is right and people seem to like it. My buddy has one on his car and I am aware of how it sounds. But my main question is if this Dynomax system will support a 14sec. 305 with 574cfm on the intake side, without slowing it down at all. At what point will the motor benefit from a bigger exhaust like the hooker?

gmgod

Can't you get a 3-inch dynomax system for about the same price?

92RSFivePointSlow

I'm not sure about getting a 3" dynomax kit for the same price as the 2.5". I also think that the 3" I-pipe that dynomax makes gets reduced at the end to use the same 2.5" muffler, and the catco converter I'm using has a 2.5" exit so I don't really know the configuration of a dynomax 3" "kit". I'd also think that the 2.5" super turbo muffler in question would pose more of a threat to airflow than the 2.5" mandrel bent pipe it comes with. What do you think?

gmgod

I don't know if the pipe necks down to 2.5 inch or not. But if your using a 2.5 inch cat and muffler then yeah, the 3 inch pipe is not gonna help much.

AJ_92RS

You can buy all the seperate parts for the Dynomax 3", but it adds up fast. You'll easily spend just as much, if not more than a Hooker or Flowmaster kit.

intermediate pipe - 44063 ($82.99 thru Summit)
Front I pipe & 43248 ($48.99 thru Summit) a.k.a. the Over Axle pipe
ultraflow muffler- 17227 ($99.95 thru Summit)
RH tailpipe - 43243 ($30.39 thru Summit)
LH tailpipe - 43244 ($30.69 thru Summit)

That muffler will flows 940 cfm; enough to support 427 'loss free' HP.

The 'loss free' part means that no HP will be lost because of restriction from the muffler. I think the Ultra Flows are the only ones with 3" in.

You could replace that muffler with a single 3" in/out and it would cost less, plus you would only need one tailpipe, but I don't know the part number for a 3".

It all depends of if you want the dual tailpipe look or not.

92RSFivePointSlow

I've been using the pipe with no muffler exiting on the driver side ever since I chopped off the stock muffler, and then I just clamped on a pace setter 2.5" split tips glasspack resonator to smooth out the tone. I guess the looks are worth it for some people.

So are you sure about the 940cfm=427hp ? I know it's very crude math but this might mean that even if the super turbo 2.5" flows significantly less, say, 574cfm, which would make it good up to 260hp, it should not affect a 14 second camaro. Am I making sense or do I need to smack myself again?

AJ_92RS

The crossflow Super Turbo muffler is only rated to flow 385 cfm, for 175 "loss free" HP. Anything more and it becomes a restriction.

Go here and read the "PowerTech" index instructions.

Then go here (.pdf file) and look at the specs for the mufflers.

The formula for calculating exhaust flow requirements is HP x 2.2 = CFM needed through the muffler, for the entire exhaust system, be it dual or single.

For example, if someone was able to run two of the Super Turbo crossflows, then they'd flow a total of 770 cfm; enough for 350 HP.

This is one of the main reasons that people who say "I switched to true duals and shaved .5 seconds off my ET." The single muffler they had was the restriction. By switching to two mufflers, they increased the CFM flow of the exhaust.

The same could have been accomplished by using a better flowing single muffler.

BTW, this formula is not something Dynomax pulled out of their asses. David Vizard developed the formula, and if you don't know who he is, you better learn.

92RSFivePointSlow

Alright, so if the super turbo 2.5" crossflow (17739) flows 385cfm/175hp, what do you think the 2.5" intermediate pipe flows? I mean, if I knew my existing 2.25" intermediate pipe flowed no less than 450cfm, then I might as well continue to run a straight pipe from it instead of a muffler, right? Any charts for pipe diameters? Thanks alot for the info so far, I've ruled at least that one muffler out after understanding the cfm/hp conversion. Now I just need to figure pipe diameter out.

TRAXION

FWIW, I did a custom installation (in the stock location) of Dynomax PN 17233. It is a UltraFlo Welded muffler with a 3" inlet and a 3" outlet. It's a straight through design similar to the copy-cat magnaflow systems. I talked to Dynomax before buying this muffler and the following is an excerpt from the conversation ...

"In regards to the 17233 Ultra Flo welded, this has a Sport sound with a 1500 cfm rate. In a single system it can handle 682 hp"

I ran 11.6's @ 117mph through this muffler. For more info click HERE.

Tim

92RSFivePointSlow

hey just as a follow up, I bought and installed the dynomax super turbo 2.5" cat-back(17739). Let me tell you, with headers and a high flow cat, the dynomax sounds like an animal compared to the same system using stock manifolds/y-pipe/cat. This isn't a psychological thing either- my friend has a bone stock LO3 with the 17739 cat-back and side by side you can't even hear his over the one thats also using the headers and high flow cat.
Process of elimination, It's probably the high flow cat that makes the dynomax sound louder. When I put on my TES headers with my old exhaust they didn't make it much louder. The car doesn't "feel" any slower than it did with the unmuffled 2.25" pipe coming off the cat, so I'm left to believe that a 2.25" pipe free flows less than or equal to 385cfm.
So in case you're afraid the dynomax is too quiet for you, if you have a gutted/high perf. cat, you won't have that problem.