MauriSSio

i know my car isnt an LS series but thought id post this as information some of you can use .the purpose of this thread is to see how magnaflows stack up to an open exhaust.

I dynoed my car and made 496rwhp@5900 but engine was LEAN 14.8afr.
jetted up 2 (i know i should have went way higher on jets) = 512rwhp@6200 with LEAN 14.4 afr.
i was running out of time so i tried dynoing it with the cutouts open and came out with a 5rwhp and 3rwtq loss!
exhaust is 2in. longtubes, 3.5 collector, 3"xpipe, 3 inch magnaflow mufflers. Not bad for a power robbing non-locking c6 tranny (worse than th400) + 9in rearend and detroit locker. some people say 25% drivetrain loss while some crazies even say 30% but even at 22% thats 660hp at the crank

heres a vid.
http://www.youtube.com/watch?v=fzDx1J813gc

brians91formula

iTrader: (12)

I have a magnaflow cat back and my open cut-out gives me an 8 rwhp gain. No changes at all in torque and no hp lost throughout the curve.

MauriSSio

Are you running one muffler or two? Don't fbody cat backs (unless custom) run single exhaust to the muffler?

zigroid

iTrader: (22)

your car is awesome, I love big boats. my first car that I still have is a '68 pontiac bonneville. wish it was a convertible, 2 door, and in as good a shape as your galaxie! whats done to your engine? I keep trying to get my dad to do some work to his '69 lincoln mkIII, his car could use an extra 300 hp lol.

t/a98

iTrader: (6)

Dyno it again. Side by side runs will fluctuate numbers. Less restriction is always better, no exceptions. Make sure your tune is optimized for the extra flow. 5 horse is tiny and could be anything, heat soak, tolerance of the machine, etc.

brians91formula

iTrader: (12)

I'm running long tube headers into a Y-pipe with no cats. The cutout is on the intermediate pipe before the exhaust goes over the rear axle. The magnaflow is one single muffler.

MauriSSio

thanks for the compliments. the old Bonnevilles are awesome! doesnt Ahhnold drive a convertible one in "The Last Action Hero"?!?! i loved that car and is one of the reasons i bought this one, you pay for it in weight but at least its different!

i also liked the convertible muscle cars in "joe dirt" and "Tommy Boy" hehe

my engine is a standard 429-460 block bored .080 over
scat 533 stroker kit-theyre pretty cheap about $1300balanced but plenty strong (forged rods and pistons) 10.7comp
TFS 290cc STREET Heads unported
Edelbrock Victor intake
1150cfm Holley Dominator carb
260/269 @ .05 .655/.656 street solid roller.



that wasnt really the point. and no there shouldnt have been heat soak on that run. Anyways the point wasnt really that it LOST power, theyre close enough that you can call them even. The point was that it didnt gain anything at all and 3" exhaust with magnaflows do not pose much if any restriction at this power level at least on my setup. Power is roughly 660ish at the flywheel maybe more.


i see, maybe one muffler just isnt enough i guess!

t/a98

iTrader: (6)

Ohh ok. Yea magnaflows flow amazing an aren't overbearingly loud. I was gonna mention how well they flowed but didn't in my original post haha sorry.

180ls1

iTrader: (4)

hmm well maybe the extra flow with the cutouts open leaned it back up again which is why it lost power.

MauriSSio

AFR stayed the same. 14.1-14.4

ScreaminRedZ

iTrader: (3)

Congrats on the numbers! That much power's gotta move that car around quite nicely

What was the torque number?

LS6427

iTrader: (2)

When my new 441ci goes in I'm doing 2" LT's 3.5 collectors....into a Flowmaster merge with a 4" out to a MagnaFlow dual 3.5 out. I think thats the right numbers for everything.....

Anyway, there is much a cut out will do that makes one worth it. I was gonna do a 4" cutout right after the 4" outlet from the merge.

NOW....I'm spraying a 250 shot....so question is: will that 4" cut out gain allot more when spraying compared to N/A?

.

5w20

iTrader: (21)

True 3" dual exhaust flow very well, thats why you didn't gain much.