question about flowmasters
Thread Starter
TECH Apprentice
Joined: Dec 2005
Posts: 314
Likes: 0
question about flowmasters ok ok ok, before all the flaming begins, i just have one simple question. i have used the search feature and only came up with 13 results (something fishy there...) none giving me the answer that im looking for. i want to know exactly the problem with the flowmaster 80 series muffler. i know that when anybody posts this they get a resounding no 
from all that reply. one guy said he lost low end torque, but thats all ive seen in the ay of reason to avoid it. heres my deal. i got a flowmaster 80 muffler with tips that i like for free. he witched to tsp true duals. (after i told him that i wanted a td setup on my bird, that bastard!!) my exhaust is stock for now, but i plan to go to a td setup in the future. why should i scrap this thing and not put it on my car? and please, i only need explanations not fights 
from all that reply. one guy said he lost low end torque, but thats all ive seen in the ay of reason to avoid it. heres my deal. i got a flowmaster 80 muffler with tips that i like for free. he witched to tsp true duals. (after i told him that i wanted a td setup on my bird, that bastard!!) my exhaust is stock for now, but i plan to go to a td setup in the future. why should i scrap this thing and not put it on my car? and please, i only need explanations not fights 
The flowmaster 80 series crossflow muffler does not flow well at all. If you were to put it on, I'd put a cutout in the i-pipe for sure. IMO, duals are the way to go (biased obviously 
) but if you're getting it for free, I'd say go for it until you do a dual setup. You're not going to lose power from stock, but probably won't gain any either.
) but if you're getting it for free, I'd say go for it until you do a dual setup. You're not going to lose power from stock, but probably won't gain any either. 
TECH Addict
Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
I've never checked, but is the 80 series the muffler used on their off the shelf catback for the Fbody?
If so there is a simple reason people don't like it. And it's due to flow rate, if you check the sticky (MOD GUIDE) David Vizard explains that for a zero or low loss exhaust you need 2.2cfm per 1 hp flow rate.
I don't know what the Flowmaster actually flows at, but it is sufficent to say that it doesn't support the STOCK bhp rating of these engines. It is probably better than the stock exhaust and evidently sounds better. But as a performance mod it is very limited.
Stock bhp is ~345bhp, so times by 2.2 = 759cfm minimal flow rate. I would guess the Flowmaster is below this thresh hold hence it restricts power.
The same muffler on a Mustang however would not be so bad, as a Mustang has duals, so each exhaust bank is only producing half the exhaust flow and thus requires half the flow rate. That combined with the lower bhp output of the Mustang.
So on a Mustang you'd have 2 mufflers (one per bank) and they's only need to flow (260bhp x 2.2 = 572) / 2 = 286cfm compared to 759cfm for a stock LS1 Fbody.
Duals on an Fbody can work well, but so most of the off the shelf catbacks.
-SLP Loud Mouth
-Hooker
-Magnaflow
-GMMG
-Borla
-Stainless Works
To name a few. None of these are really going to be a problem on a cammed bolt on LS1 with ~400rwhp.
Hope this helps.
If so there is a simple reason people don't like it. And it's due to flow rate, if you check the sticky (MOD GUIDE) David Vizard explains that for a zero or low loss exhaust you need 2.2cfm per 1 hp flow rate.
I don't know what the Flowmaster actually flows at, but it is sufficent to say that it doesn't support the STOCK bhp rating of these engines. It is probably better than the stock exhaust and evidently sounds better. But as a performance mod it is very limited.
Stock bhp is ~345bhp, so times by 2.2 = 759cfm minimal flow rate. I would guess the Flowmaster is below this thresh hold hence it restricts power.
The same muffler on a Mustang however would not be so bad, as a Mustang has duals, so each exhaust bank is only producing half the exhaust flow and thus requires half the flow rate. That combined with the lower bhp output of the Mustang.
So on a Mustang you'd have 2 mufflers (one per bank) and they's only need to flow (260bhp x 2.2 = 572) / 2 = 286cfm compared to 759cfm for a stock LS1 Fbody.
Duals on an Fbody can work well, but so most of the off the shelf catbacks.
-SLP Loud Mouth
-Hooker
-Magnaflow
-GMMG
-Borla
-Stainless Works
To name a few. None of these are really going to be a problem on a cammed bolt on LS1 with ~400rwhp.
Hope this helps.
Dude if you want it than get it. It's your car so do what you want. I have a flowmaster on my car but it came with the car and I'm going to swap over to true duals. Sounded good when I got it and that was all I cared about at 1st
Thread Starter
TECH Apprentice
Joined: Dec 2005
Posts: 314
Likes: 0
Thanks for the response guys. thats what im looking for. i can see the correlation between the bad flow and hp loss now. i dont think im going to get a noticeable seat of the pants loss, and im not going to the track anytime soon. also no dyno runs, (unless i get my cam in there anytime soon) looks like for now ill put it on there. stock, i dont think that im going to have anyproblems. thanks for all the help guys.
Originally Posted by 01 Red WS6
Dude if you want it than get it. It's your car so do what you want. I have a flowmaster on my car but it came with the car and I'm going to swap over to true duals. Sounded good when I got it and that was all I cared about at 1st
Moral here: If it's way cheap, go for it. Use the money for other mods! It'll still sound good.
