Hi Guys (and Gals),

It's been quite a little while since I've been on the board but it looks like everything is going strong over here!

So far, other than my Big Block 79 T/A, no other F-Bodies in the corral at the current time. Not for long though.

I do however have a question about a project that I'm working on. Now no flames (ok, mabye a few)..... I'm a 3rd Gen and 4th Gen guy at heart..

This project is my 2nd V8 Fiero. (1985 Pontiac Fiero (Ferrari 308 Replica) with a Mild SBC, Getrag 5-speed w/ 4.10 final drive ratio).

I'm limited by space on what I can do for exhaust and I wanted to get some opinions. My easiest option is to use a Flowmaster 80 series Crossflow w/ 2 inlets and 2 outlets. Or to use a Flowmaster 40 series with the same configuration. (I'm leaning toward the 80)

Lately though, I've been checking out what some people over on LS1sounds.com (and I'm sure here as well) were doing with the "DynoMouth" conversions of the SLP Loudmouth Systems.

My other cars were all full exhaust sytems with performance Cat's, headers etc. This car will be using Factory Corvette 2-5/8" ported Rams Horns Cast Iron Exhaust Manifolds, no Cat's and not much exhaust pipe since the engine is mid mounted.

The enigne dyno'd at 323HP which is exactly right in the range I was looking for in the 2600lb Fiero. (My last conversion was 411HP and was totally undriveable (unless you love going 40 mph , punching it and spinning around in circles).

I'm in Bucks County PA (New Hope). Any "East Coasters" close by with the following combo's I may be able to listen to?

Flowmaster 80 series CrossFlow
Flowmaster 40 Series (SUPER 40 Series Only)
DynoMax Ultra Flo Bullet Mufflers

Stock Exhaust Manifolds/headers, No convertors and any of the above would be really what I need to hear.

I can't quite tell by the sound clips on some of the sites. I really need to hear a few in person (besides flagging people down in the street... and when I do, they all just say Flowmaster and never know which series...).

I'm keeping the gear drive in this engine (until my passengers go deaf with it screaming behind their heads) and I'm looking for a Nice DEEP, DEEP DEEP sound that sounds nice and solid but does'nt get obnoxious when you have your foot into it. I want the car heard but not "Un-Godly Loud".

Any other combos that you are using? Let me know. I have Dynomax Super Turbos on the T/A but I really need a small block to listen to.

I've even heard some Dodge Rams with the Truck Flowmasters that have sounded really nice. I bleive I could adapt the 50 or 70 series if I had to. Dodge Ram drivers, feel free to reply!

Take Care,
Brian

I think you're barking up the wrong tree here. Any of those would be obnoxious to the max. You should be looking for something quiet because you won't have any piping to assist the sound.

You need to look at Borlas. Big bux, big flow, nice sound, happy passenger.

We've got 2 40 series on the Engine Test Jig which connect directly to the headers and even those are'nt obnoxious in that "short configuration".

By the time I Bend the exhaust from the Manifolds around the engine, through muffler and to the tailpipes, I'll still have about 4-5 feet of 2.5" per side which is equivilent to just dumping after the mufflers on a G-body car so I don't think it will contribute to a much louder configuration. I'm also open to adding 2 High Flow Cat's if I need to lower the sound a bit.

i could e mail you a clip i think of my 86 iroc with dynomax shorty headers, no cat and flowmaster cat back"80 series"its not the best sound clips but it might help you

My brother saw a dyno proven 60whp increase on his car by going from a 80 series to a spintech muffler. the spintech was a little louder than the 80 series but a lot deeper and all around better sounding.

was the muffler completely clogged?
i dont see you making 60hp in a muffler change.

Lol, 60 Whp increase by switching mufflers huh? It's posts like these...


I sure hope he had a 700 hp vehicle.

321whp on a mustang dyno:
With 1-5/8" mid-tubes and a 3" flowmaster cat-back

381whp on the same dyno:
1-3/4" longtubes and a 4" cat-back w/spintech muffler.

the 3" and midtubes should have been enough for this motor. the 4" is overkill and probably the same for the Long tube headers, so we blamed the muffler.
see signature for engine mods

With an estimated 18% loss through the T56: ~465 flywheel hp

edit/add:
My car lost 50 hp with the addition of two 3" magnaflow catalytic converters.

only mod wasnt the muffler. i had figured as much.
i still dont see 60hp difference even with upgraded headers.
not at that power level.
what other changes were made?

you caught me! but thats it. seriously!

edit: the flowmaster 80 series is really THAT bad on any thing over bone stock.

id have had to be there to see it.
im from missouri. you gotta show me.

you can probably search for muffler test results on google. One of the magazines did a comparison on like 10 different aftermarket crossflow mufflers and a stock muffler on a flow bench... Flowmaster BARELY beat the stocker, and Dynomax was the best; closely followed by Spintech.

oh i know mufflers.
ive had 7 different ones on my car.
i know sound, power levels and track times.
ive tested manifolds, headers, different size and style y pipes.

just hard to believe that much power.
its possible, but id like to see it.
not arguing, but there has to be more of the story, like the headers you brought up.

maybe he was on 7 cly before and changed out the entire ignition system in between. plugs and wires gotta come off in between anyway.
so many variables.

I have to lean toward Dynomax over Flowmaster.I've used them on several different vehicles over the years with excellent results.Nice mellow but throaty idle without the resonance of Flowmaster's(any series except maybe the "80")at highway speeds.Like ttype states you can look up test results that support Dynomax Super Turbos outflow Flowmaster "40" series below 3500rpm and at least equal above while being less obtrusive.

I couldn't believe it either, but I was there and have the Dyno printouts. No other modifications were made. Same spark plugs and wires: Accel 8.8 LT1 wires, New GM optispark, Bosh platinum +4 plugs. The plugs were temporary for the break-in/tuning period because I had them sitting around, but he just left them in there.

He had it dyno tuned after I got the tune close by ear/guess. They tuned it to 12.6-12.8 AFR 321hp. The tuner guy at the dyno shop told us that flowmasters were junk and we should get longtube headers, AND he predicted 380whp with just exhaust. Thats why my brother sunk $1400 to upgrade the exhaust that we thought should have been fine for that motor. The dyno guy said he's seen 40 and 60 hp increases in the past by just switching from a flowmaster to open headers. And that 4" catback is the next best thing to open headers.

So he changed the exhaust system over...thats IT! He took it back to the dyno and the WOT AFR was 14.4-14.7 & 352whp (with the new exhaust and the old tune). So they re-tuned the fuel to 12.6-12.8 AFR, and saw a ton more power, 381whp.

My scanner is in storage untill September with all my college stuff, but if you want to see the dyno sheets hit me up in a month. Or I could take a picture of them with the digital camera. Or mail you some copies. If you want to see the car, we live in Baltimore, MD.

For objective information... contact Bret at F-Body Central and see if he remembers Justin's OBD1 95 convertable transam. If he doesn't remember... tell him Justin is the guy who's brother Aaron knows a lot about chip burning and helped a little on the White 87 STS Iroc.

I picked up one tenth, and one MPH, installing a DynoMax UltraFlow, in place of a FM muffler, on a 3" single system. This was on a 500 hp engine. Less, or more power levels will obviously have different results. IMO, the sound was much better too.

edit:
I'm obviously wasting my time defending my arguement for the better muffler.

Random thoughts to fill this post:
GM claims 425+ with the LT4 kit... so we figured LT4 plus bigger valves, plus 383, plus a hottER cam, plus portmatch/blueprint/balance, intake, exhaust, and 6" rods should have been around 500hp, conservatively. I guess GM was just kidding with the 425+hp. even if they meant at the flywheel. All that should have been worth more than 40hp. If not, next time he'll save 4grand and stay with the LT4 kit on a stock used short block.

dynomax

I removed the "dyno recalibrate" part. It really was meant to be funny though.

You mean you didn't drop 1 second and gain 20 mph?

Thats Funny!

I'd rather have a Flowmaster and have better sound than gain MAYBE a tenth on a high HP setup with a Dynomax. Everytime LOL.