Exhuast makes my car slower...?

[Bill]

Alright I have a 99, v6 3.8 camaro auto, and i have 2 10's in the back so i know that weighs it down, but totally stock witht he subs in the back i was running 16.2 and since then i got a whisper lid and got a custom exhaust done, its just a y pipe and then dual out the back but the stock cat and all is still on, and i recently took it to the track and the best time i got was 16.3, i was like of this doesnt make much sense, i did notice that it seemed like it bogged down more off the start but better from the roll, i dunno if im gonna have to take off the cat or get some headers to see a big difference or maybe there is just a little thing i need to change, anyone please give me some input

[The Sandman]

I think the weather and humidity had more to do with it than your mods....

[nofear_102]

Could try re-setting PCM? Don't know, intake and exhaust worked for me [img]graemlins/burnout.gif[/img]

[GrdLock]

Holy sh*t man, if you're running 16.2 or .3 to begin with, you've got bigger problems to worry about! You should at least be in the 15's stock...

If you have an automatic, how do you start? Do you stall it to about 1500 - 2000rpm's? Do you get lots of tire spin?

If you have a manual... do you know how to shift? :D

Only reason exhaust would make your car run slower is if you put a cutout or something on your car that reduced backpressure to little or nothing, which would cause a reduction in low-end torque, which would make your 60' and 1/8th lower, and didn't give you enough horsepower to get a higher top-end gain to balance out the low-end loss.... which a muffler won't do.

[Original 4th Gen V6]

From what i've heard, our cars need backpressure.(I say from what ive heard because I dont know the actual physics of this nor have I tried dif setups so its all hearsay to me) V8's would benefit from say a 4 inch exhaust more than from a 2.5. We would do better with a 2.5 than with a 3.4 or 4 inch exhaust. From your post, you say you got a bigger Y pipe and then the stock cat and I pipe. This would kind of defeat the purpose of getting a larger Y pipe and actually create a bottleneck in your exhaust. Try getting a 3 inch highflow cat and a 2.75 or 3 inch I pipe. You will drop at least a few tenths in the 1/4.

[bluecmaro96]

magnus runs open y pipe, no back pressure at all and he dropped .2 in the 1/4 so that backpressure thing is a bunch of crap

[rob231]

magnus also has more gear and more stall than he does. :D

[V6Bob]

In the motorcycle world it's easy to get an aftermarket exhaust system that doesn't flow as well as stock. They can screw it up in a lot of ways.

[Bill]

<blockquote>quote:</font><hr>Originally posted by GrdLock:
Holy sh*t man, if you're running 16.2 or .3 to begin with, you've got bigger problems to worry about! You should at least be in the 15's stock...

If you have an automatic, how do you start? Do you stall it to about 1500 - 2000rpm's? Do you get lots of tire spin?

If you have a manual... do you know how to shift? :D

Only reason exhaust would make your car run slower is if you put a cutout or something on your car that reduced backpressure to little or nothing, which would cause a reduction in low-end torque, which would make your 60' and 1/8th lower, and didn't give you enough horsepower to get a higher top-end gain to balance out the low-end loss.... which a muffler won't do.<hr></blockquote>

Its and automatic and when it was totally stock the best way I ran it was overdrive all the way i would drop it at like a little under 2000rpms and just floor it the whole way and I ran 16.2's doing it in regular drive and such i was running up to like 16.5, so i dunno, i havent talked to many other people with v6 automatic camaros so i dunno what is that best way to race it

[RacerJ]

<blockquote>quote:</font><hr>Originally posted by rob231:
magnus also has more gear and more stall than he does. :D <hr></blockquote>

I think he also has about every mod known to man and some work on the heads and/or intake manifolds...

[Ttop34]

Sounds like you race at a track much like I do. Stock V6's are in the low 16's and many with a few mods like intake and exhaust are only running 16 flat. If you take a cruise down close to sea level then you'll gain a half a second or so. What rear end gears do you have? What's the lowest RPM's that you drop to when racing?

Since I have a stick, when I race it doesn't drop below 4,000 rpm so low end power and back preasure for me is worthless, I want my exhaust as free flowing as possible.

You can't compare a mod at the track on a different day with totally different weather conditions. I ran .2 faster after the sun went down and the head wind stopped my first time out to the track. Take it to the track a few more times before concluding that changing your exhaust slows you down and notice what other people are running, whether it's a fast day or a slow day.

[MustangEater8251]

<blockquote>quote:</font><hr>Originally posted by bluecmaro96:
magnus runs open y pipe, no back pressure at all and he dropped .2 in the 1/4 so that backpressure thing is a bunch of crap<hr></blockquote>

No you are wrong doin't believe me yank your exhasut then go to the track.

I dropped my cat ran open Y pipe and ran .5-.6 seconds slower, and like 4-5 mph slower, 3 days later put my semi clogged cat and still no I-pipe, and ran my normal times. Difference form a wednesday night to a friday night.

Don't worry abotu the 16s, I have seen plenty of 3.8S running 16s in florida, Humidity will make a huge difference, has made .3 second difference on me before.