VandykeT/A

I just made the change from 3" true duals ( a hack job) to a 4" single so I could pick up some ground clearance. Well after doing it everyone around here is saying I'm stupid for going to 4" single that I've lost power. I'm curious now as to whether this is true. Honestly looking at how my systems were curved the 4" looks to be a better flowing setup but I can't help but look at 2 3's equal 6 and a 4 is a 4. Have I given anything up going from the duals to the 4" at my power level. Its the H/C car in my sig. The car doesn't feel any different. And at what point will I out grow the 4" single.

sheikss

iTrader: (11)

I had a pretty nice set of 3" duals. I swapped them out for a mufflex 4" with magnaflow race muffler. I also switched from a ls6 intake, ported stock tb and lid to a ported 90mm fast, 90 tb and fast toys lid. I also upgraded to a ls6 maf while I was at it. The car felt alot stronger down low and seemed as strong if not stronger up top. My 3" duals tucked pretty good so ground clearance wasn't a primary concern. The duals were tearing the floor out of my car due to the way they were hung. I am glad I went to the single 4" and am keeping it with the 383 F1 combo. Did you use a cross flow muffler? Mine is a single in, single out.

VandykeT/A

I'm running a single dynomax bullet lol. Its screams and my car feels alot smoother to me. Like the power band comes on alot smoother than before. I've only got maybe 2 feet of actual 4" pipe. Its dual 3" to the tailshaft of the transmission and then a 3 to 4 flowmaster merge and then the bullet with 4 inches of piping after it with a slashed end.

sheikss

iTrader: (11)

I like how my car quieted down until I give it gas and then it seems as loud as the duals did.

VandykeT/A

My car seems to be just slightly quieter at idle but its still loud. How do you feel going by cops with your magnaflow? I've only had the set up a week or so and I was all ready considering going to a magnaflow muffler to quieten it down some.

Joe69z28

Well I dont think your stupid. But its not 3+3= 6 or 4=4 . Its total area, 4" is 12.58 and Dual 3" will be 14.14 It going to hard to beat a well designed 3" TD But a 4" will beat a dual 2 1/2 in area.

Exidous

iTrader: (11)

Dual 3" certainly provides more flow however, if the motor isn't flowing enough going too big causes you to lose power in some areas. I remember reading an article about a BMW race car team that actually went to a smaller exhaust and got a more broad power band that they wanted. It scavenged better.

In a H/C car I'd say the 4" would be better(maybe even too big). I'll be "upgrading" to a 3.5" which I think will be enough. It will still be better than the 3" single I have now.

01ssreda4

iTrader: (96)

3+3=6 and a 4 is a 4. You're fine, stop listening to dumbasses.

BOBS99SS

iTrader: (2)

Lol,im sure its fine lol,im a fan of magnaflow outside of the catback system for our cars,bu,t there mufflers/race mufflers sound great,still the best setup for a street car imo is a magnaflow catback n cutout,best of both worlds,post a vid if ya can

adamantium

iTrader: (3)

Is the car raspy? Hows it sound? Im literally in the process of doing the EXACT same thing going from 3" TSP ORY with magnaflow 3" bullet to flowmaster 4" ORY and dynomax 4" bullet.


Honestly ive seen true duals make power on everything, if technically a 4" flows less air then true duals i don't think OP has anything to worry about. Especially if he's H/C, im doing this setup on my bolt on car. What it comes down to is not piping size but how well it scavenges.

gouldy

Google: exhaust size calculator.
There is a couple of good ones out there that will give you all the info you need.

dr_whigham

iTrader: (49)

Just remember it's not only the cross sectional area of the pipe... There's a lot going on "behind the scenes" as far as scavenging goes as well. An X pipe is always going to prevail and give you better midrange and upper RPM power.

Jwright41

iTrader: (2)

Post #19 in the Mod Guide Sticky:

A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…

RTBenny

Not sure wher you got the numbers from Jwright but I like them. Definitely makes me want to switch out my 3 inch single. I figure I'm making 620-630 at the motor through it now.

Jwright41

iTrader: (2)

Hey RTBenny, I got them from the sticky in this section - https://ls1tech.com/forums/generatio...e-posting.html

It is the 19th Post in the sticky.

RTBenny

That's awesome. I've been searching exhaust diameters for days and haven't came across that. Thanks.

thunderstruck507

iTrader: (18)

I don't put a lot of faith into those numbers, seems to be a little on the generous side based on my results switching from dual 2.25" to dual 3" at my cam only power level.

Jwright41

iTrader: (2)

That is why I posted up the sticky and the post number so that every one could see what all was involved in it. What results did you have from changing on your setup thunderstruck? Just curious.

thunderstruck507

iTrader: (18)

When I was cam/bolt ons (350-370rwhp depending on the dyno and day) with 2.25" duals the car would routinely pick up .15-.2 and 1-2mph with open cutouts. This makes me think saying they should be good to 470 fwhp with 0 loss is on the very optimistic side.

Even now with 3" duals, the car picks up a small amount if I uncap the cutouts. It's usually around .5 mph which isn't much but still kinda contradicts the zero loss statement.

Maybe I'm thinking about it the wrong way? If so I apologize.

RTBenny

Sounds legit. Either way, I'm curious about it all now!