Calling all v6ers who have gone from 2.5" to 3" exhaust...

[HBHRacing]

it highly depends on a lot of things. Realisticly if you think abou it from a total restriction standpoint you will find it easier. Restrictions come from ANYTHING in the way of teh exhaust flow. Cats, bends, mufflers ect ect. Remove all of that. you want ZERO restrictions. Think of the velocity argument as restrictions as well. Sure, really small pipe will be a restrictions, but large pipe will be as well. this is why you want optimum flow in relation to diameter. There is A LOT more to it then this. But might be easier to understand. You want to get as much exhaust out as fast as you can. If your pipe is too large for the amount of flow then you are going to be fighting the atmospheric pressure in the exhausts journey out of the pipe.


but yes. I agree.

The only thing you are going to get by asking people what their gains were, are seat of the pant guesses. Guesses that are influenced by someone who has just forked over a few hundred dollars for an exhuast and are desperate to see a gain.

The Best and really onlt test would have to be of 2 things. 1 car, same day with both exhaust systems (one a 3 inch and one a 2.5 inch of teh same company) on a dyno. Don't look at peak. look at average power gained in the RPM range that is used. Then take the same car to the track and do the same thing. 2 runs, both systems, same day.

Since no one has the want or ability to do this it will be hard. Like I said in the other thread maybe one day when I get my shop going I can do just that and show you all.

The problem is fighting an uphill battle that the hill is gaurded by many people who oppose you. Everything is on the band wagon. One person will cliam this gain or that gain and it will all be accepted. Once enough people do this it will snow ball.

Again an important fact to remember is this. you WILL gain when you put a 3 inch system on replacing the stock exhaut. The point is that you could be doing better with the correctly tuned exhaust. If you gained from a 3 inch thats great. But if you took the time to attack the system in the right way you would find that you can net yourself even more of a gain

[shenanigans]

but the problem you are missing...

is people with 3" catbacks are running better times then people with 2.5" catbacks.

once again talking nothing of dyno numbers etcs....


the cars are going down the track faster. To me that means 3" is making more power then 2.5"

[Chris Camaro]

best for the 6 is a 3 inch, for the 8 i would say 3 inch dual, or single 4 inch, the 99 vette i drive has dual 3 inch, and yes its a vette, but same **** in the z28.

if you like anoying high pitched sound, go 2.5 or w/e or smaller, i went 3 inch, its louder, but much better then that ***** sound i had before, now with the pacesetters, much better of a sound

i know the difference of the 2.5 to the 3inch, and the 3 inch pwns.....

[ August 09, 2005, 09:54 AM: Message edited by: Chris Camaro ]

[1DangerousV6]

i have a 3 inch open borla with no cat..its pretty loud and mean sounding..yeah for a 6 id definitely go 3 inch [img]smile.gif[/img]

[ellik]

Ive had stock exhaust, 2.5" Flowmaster and now 3" Magnaflow. True, different companies, but Im sticking with 3".

[articacid]

full 3 in exhuast here! ok so what if the 2.5 are even tuned for optimum flow blah blah blah. almost every single 3 in intake/exhuast car here is fast than the 2.5 exhuast, and they definately sound a hell of a lot better.

so which one would you want, a car with the "optimumly tuned exhaust", or the faster car with the too big 3 inch exhuast. i think im going to stick with the 3 in exhaust...

you can talk all day about the maximum velocity of root times square equals whatever. but when it comes down to it, you keep ignoring that the 3 in exhuast cars do run faster. ok maybe there not up to you "tests", but in the real world the 3 in run faster. but then again like you said in your other post to mustangeater, his real world experience doesnt mean anything. so i guess as long as 2.5 looks better than 3 on paper you should buy it. and as far as the brand difference's, there are differces, but there not THAT significant. yes some will flow better than others. the piping on these systems is all very similar. the mufflers (who need a muffler anyway ;) ) are the only real difference in these systems and they arent all that different.

[shenanigans]

Originally posted by articacid:
full 3 in exhuast here! ok so what if the 2.5 are even tuned for optimum flow blah blah blah. almost every single 3 in intake/exhuast car here is fast than the 2.5 exhuast, and they definately sound a hell of a lot better.

so which one would you want, a car with the "optimumly tuned exhaust", or the faster car with the too big 3 inch exhuast. i think im going to stick with the 3 in exhaust...

you can talk all day about the maximum velocity of root times square equals whatever. but when it comes down to it, you keep ignoring that the 3 in exhuast cars do run faster. ok maybe there not up to you "tests", but in the real world the 3 in run faster. but then again like you said in your other post to mustangeater, his real world experience doesnt mean anything. so i guess as long as 2.5 looks better than 3 on paper you should buy it. and as far as the brand difference's, there are differces, but there not THAT significant. yes some will flow better than others. the piping on these systems is all very similar. the mufflers (who need a muffler anyway ;) ) are the only real difference in these systems and they arent all that different.

Thank you for awhile I thought I was taking crazy pills...

[articacid]

its like he ignores you when you say 3 in is proven to be faster and he goes right back to his scientific crap.

also whats with all the secret mods that hes working on? why dont you tell us what those mod that knocked off .33 are?

also why does he keep avoiding the comment about having the 3.08's in a 5 speed?

[HBHRacing]

you all missed most of teh valid points. Your showing me no gains. I have people that went from a crappy flowmaster to a borla that showed gains. Peolle that also switched to a high flow cat that showed gains. This is because you are REDUCING THE RESTRICTIONS. Not because you went with a bigger pipe.


Again. Apples to apples. Same car, same track, same day, same company cat back. Only difference being 2.5" and 3". So me that. Untill you can, you are only guessing based on your own SOTP feel and guess work.

and to the guy saying that 3 inch duels on a V8 and 4 inch single is best you are sadly mistaken. again. get the bigger is better thoughts directly out of your head. Why do hondas and other VERY small Ci motors have such small diameter pipe? Simple, if you threw a 3 inch on it you would be shifting the power so far up the RPM band that it will never be used. you are also creating a brand new restriction because of the incressed pressure needing to be pushed away by the exhaust.


One catback company to another proves nothing
one catback to another along with a high flow cat proves nothing
one sounding better then the other proves nothing
your friends uncles, brothers, sisters roomate running faster with a 3 inch proves nothing
your own bias that because you think it will be faster actualy makes it faster proves nothing


argue something with me that you can back up. Flow theory, actual apples to apples proof ect. Spouting about sound, V8's needing 4 inch and all of this other crap will not help you to learn anything.


I could car less if you agree with me and switch yours out or not. What I want is for everyone to learn and understand WHY the 2.5 inch will work best. If you actualy use your new knowlage or not I don't care. i just want you all to understand it.

EDIT: it wouldn't be a secret if I told you. Product development is oftem kept under wraps.

I'm not ignoring that people claim that 3 inch runs better. You all need to provide actual valid proof based on the structure that i have given you.

Edit again. I found where I said 3.08's It was a typo. All fixed now. our project car had a 5 speed with an open diff and 3.23's

[ August 09, 2005, 07:44 PM: Message edited by: HBHRacing ]

[toast]

So let me get this straight; you mean to tell me my car would have had more power if i had put a 2.5inch system on there instead of the 3inch??
So it would work like this: 2.25inch coming off each manifold, then merging into a 3inch (stock now-not aftermarket-from the factory) Y-pipe into a 3inch highflow cat and then coming out of the cat (you would think 3inch right?) into a 2.5inch pipe. To me that looks like a big restruction there, infact .50inch restruction causing the exhaust gases to bottleneck and constraining it to flow through a small 2.5inch pipe. Now i would think on paper you want as little restruction as possable so flowing out of a 3inch cat into a 3inch pipe would be the best and smoothest flow for the exhaust gases to travel out of. Maybe i am missing something or just losing my mind or i have been inhaling to much exhaust gases that i can not think straight. I am not at all saying bigger is better, but what i am saying is the lesser restrictions the exahust has to travel is better. Now obvously you cannot take care of all the restrictions and you do need some for backpressure. Yet this is true for every engine wheather 4, 6, or an 8 the better the engine can breath both through the intake and exhaust the better it will perform.

[ August 10, 2005, 12:36 AM: Message edited by: toast ]

[BLLDOGG]

other than HBHRacing, you guys are not taking into consideration the point of each car is different. not two cars will perform the same. brand new or not. the only way to do it is with pressure and flow testing. i would even go as far as to say to take flow reading off the manifolds of each car and use that to even out the readings. with all that, its still not even cause no two converters/mufflers will flow the same, same brand or not. there is no way to get a track/dyno readings that are correct because traction is different, lanes are different, dynos are different. if you say same lane, same dyno, then its a matter of different weather conditions. its an answerless battle and i have a millions answers to why you cant prove anything so keep argueing.

[ August 10, 2005, 12:51 AM: Message edited by: BLLDOGG ]

[shenanigans]

Originally posted by BLLDOGG:
other than HBHRacing, you guys are not taking into consideration the point of each car is different. not two cars will perform the same. brand new or not. the only way to do it is with pressure and flow testing. i would even go as far as to say to take flow reading off the manifolds of each car and use that to even out the readings. with all that, its still not even cause no two converters/mufflers will flow the same, same brand or not. there is no way to get a track/dyno readings that are correct because traction is different, lanes are different, dynos are different. if you say same lane, same dyno, then its a matter of different weather conditions. its an answerless battle and i have a millions answers to why you cant prove anything so keep argueing.

I agree on that waaay to many variables...


but we can see "on average" gains.

[shenanigans]

PS HBHracing, not sure if its a best for business to be designing products for a customer you call clueless on other boards....

[HBHRacing]

Toast. Because you think your right I will help you out.... your not. NO BACKPRESSURE will make the MOST power. you want NONE, ZERO, NADA, ZILCH. restrictions are what cause power loss. 2.5 inch will NOT create a restriction untill your either pushing A LOT more HP then mildly modded or if your shifting at 8000 RPM.


Listen close. this is important. the bigger pipe that you use the MORE atmopheric pressure will be inside this pipe. This means that it takes MORE exhaust pressure to move this out of the way. for this reason 3 inch will take MORE effort to move through and will MAKE it's own restriction.

Again. people. the answers are out there. Simply read and understand them
http://www.camarov6.com/ubb/ultimate...=006136#000006
http://www.magnaflow.com/07techtips/faq/question10.asp
http://web.camaross.com/forums/showt...exhaust+theory


and yes. All cars are different. but you know what? Fluid dynamics isn't. These princapals will adapt themselves to ANY car. V6, V8, V12, I6, I4, H4 what ever

your last statment is key.. even under ideal conditions it's hard to prove. This is your excuse NOT to belive any of this and actualy use the theory and princapals that the best minds in racing have been using for years and years. They know, understand it and use it. There is no reason that you guys should be afraid to as well.


The problem comes from missconception. Just like toast. he was 10000% wrong. "you need some backpressure" WRONG, do you know how many people still belive this? I bet half the people here do even tho it's widely know that it's false. They just take what other people say as correct and burn it into their minds as right. Same for the 3 inch. you said it yourself. it can't be proven. So then were have all of these theorys come from that 3 inch is better? Again. you said this yourself. You can't test JUST the theory that 2.5 on teh same car, same track, same day will work better. So instead you make bleive that it's better to suport what you like better.

[Nicklz]

The 3.8 are at a disadvantage, compared to some other popular cars/engines. While they have been around for quite sometime now. Nobody has actually taken the time/money to compare on a dyno the different size exhausts, and to what extent it's best to "size up" on the exhaust. (to my knowldge anyways)

And from my understanding on the backpressure issue. To have zero backpressure would be ideal, but impossible. So to optimize any exhaust you'd run short headers like that of top fuel drag cars, just enough exhaust to get the heat away from the engine. While maintaing the straightest route possible. There is bound to be a mathematical equation to figure out air volume displaced by engine in relation to optimal size exhaust pipe-flow rate. But then again you'd have to some how factor in restrictions like cat/hi-flo cat and every bend in exhaust.

So in short back to my original point nobody has ever actually done the testing. (to my knowledge)


IMO-I'd personally go with 2.5in if I was only doing intake/exhaust. If you go SC/TC, NOS or engine build. Your drastically increasing the volume of air displaced by engine.