Help with exhaust

[01sapphirebob]

So with me having the horsepower bug as of late I have been woundering about exhaust for my car. Normally I would'nt think about modding one of my cars (big fan of the car the way it is) but I figure I car keep one stock and mod the other.

So what does everybody reccomend. A little education is in order as well. What I mean is I have read that if you are going to get a 3" cat back exhaust for you car you should get 3" headers as well. It has been explained to me with the example "Try pouring water down a funnel backwards." Is there any truth to this?

From what I have heard the system to go with is a corsa exhaust and belanger headers with high flow cats. Everybodys input would be great!!!! BTW...My car is a '01 GTS ACR.

 

[Chrissss]

All I can tell you is that Chuck and Sean recommended the B&B system with the Rowe high flow cats. I went with that and it is awesome. Dramatically lower heat, fantastic low rumble and definite pick up.

 

[PhoenixGTS]

If your goal is feedingthe horsepower bug an exhaust will be one of the worst bang for the bucks out there. Yes headers make power, but not much compared to their huge cost on this car. And I think a search will show you that cats and cat-back exhausts don;t make any noticeable power. For a guy who like factory stock cars, I'd think a nice little nitrous shot would be the way to go.

 

[dave6666]

My side exhaust conversion on my '01 was $5K. Take the new sills out and it is $4K for the exhaust parts/headers. I haven't re-dynoed but I've also heard the same bang-for-buck theory. As in low bang for buck.

I was doing so much other work at the time that though that it was great timing (pull headers to do motor mounts... replace headers!) for changing parts.

I do plan on doing another dyno run after I do gears and before I do an SCT tune. I'm assuming the post exhaust pre SCT dyno numbers will be pretty close to what it was before I did all of the work.

But it sure does sound and look good.

 

[VIPER GTSR 91]

So with me having the horsepower bug as of late I have been woundering about exhaust for my car. Normally I would'nt think about modding one of my cars (big fan of the car the way it is) but I figure I car keep one stock and mod the other.

So what does everybody reccomend. A little education is in order as well. What I mean is I have read that if you are going to get a 3" cat back exhaust for you car you should get 3" headers as well. It has been explained to me with the example "Try pouring water down a funnel backwards." Is there any truth to this?

From what I have heard the system to go with is a corsa exhaust and belanger headers with high flow cats. Everybodys input would be great!!!! BTW...My car is a '01 GTS ACR.

Correct: Belanger, Corsa, and hi flo cats is the way. Sound , HP gain, less weight, cooler temps.

 

[Lawrenzo]

Why not look into a Paxton or Roe Just imagine 600hp and 600+ftlbs

 

[All Blue ACR]

Why not look into a Paxton or Roe Just imagine 600hp and 600+ftlbs

HMMMMMMMMMM

 

[Chuck 98 RT/10]

So what does everybody reccomend. A little education is in order as well. What I mean is I have read that if you are going to get a 3" cat back exhaust for you car you should get 3" headers as well. It has been explained to me with the example "Try pouring water down a funnel backwards." Is there any truth to this?

Not exactly. Fluid doesn't compress or expand by much, gas does. Therefore they have completely different properties when flowing through a pipe. The funnel example is a poor illustration IMO.

A catback can get you 10-15hp. I removed the muffler and picked up 5-10hp, at least if stock numbers are accurate. My 98 dyno'd at 426rwhp with K&N, smoothies and muffler delete, other similar stockers that day were in the 410 range.

Sounds like nitrous and blowers are a bit more than what you're after? Personally, I'm not a fan of either.

 

[2000_Black_RT10]

Exhaust is tricky.. an example when working in the Viper engineering group, to gain more hp they tried reducing the cylinder head exhaust port to increase velocity which provided more hp. Big pipes provide a larger cross section and less restriction but this is not always a benefit.. Smaller pipes provide higher exhaust velocity (too keep the flow going). Sound is one thing but performance is another... Cats are a disadvantage.. nothing more than a big filter that f'ks up the flow and an abrupt change in exhaust temp (cooler).. So.. my advice is stock pipes before high flow cats and big pipes after the cats for some lower freq sound and to expel the cooler exhaust rapidly, just like Chuck 98 RT/10 said.. once it leaves the cats, best to just blow it out of the system.. anything after the cats is just restriction.. I work in automotive engineering and also have a patent regarding air induction and resonators.. Don't get me wrong though... stepped headers are ideal for performance, but for the cost, it may not be worth it.. regarding the bang for buck as Dave mentions.. deep pockets vs. shallow pockets.. and hp # envy..

 

[01sapphirebob]

Great input everyone. Keep it comming!!!

 

[Chuck 98 RT/10]

That said, I would love to put some SVS headers on my tracker but not for the price currently expected.

 

[FE 065]

..once it leaves the cats, best to just blow it out of the system.. anything after the cats is just restriction..

Maybe..

I added a 3" Borla 4 muffler catback to an experimental undersill system that had no cats on my '01 and lost .25 second at the strip. It was louder-but not quicker. One of two others have noted an ET or HP loss with the 3" Borla on a near stock Viper.

Exhaust is tricky stuff sometimes. When first testing my homemade crossover on a Gen 1 back in '96 that bolted up to flanges where the flex screen formerly was, the car wasn't any quicker the same day at the strip letting the exhaust just exit out the flanges. Bolting up the crossover to those flanges that same day though netted an instant drop in ETs from high 12.30s to 12.16 and 12.12 on a car that had a shift lite and DRs for consistency.

Theory's a good starting point, but cars can be different. Nothing like talking to those who've done the actual testing on a given car

 

[eliems]

Bang for the buck, wouldn't the biggest smiles come from moving to a 3:33 or 3:55 rear gear?

 

[Chuck 98 RT/10]

Bang for the buck, wouldn't the biggest smiles come from moving to a 3:33 or 3:55 rear gear?

Some folks swear by them. Of course there's a downside to gears too. That said, I'd love the chance to swap out gears between runs at Sebring. I've got a spare pumpkin if any suppliers are willing to donate gears.

 

[eliems]

What would be the downside to going to 3:33s? The car is doing 1700 RPM at 75 MPH!

 

[Chuck 98 RT/10]

What would be the downside to going to 3:33s? The car is doing 1700 RPM at 75 MPH!

It's still gonna be a few more rpms than 3:08s. Which means more heat and more wear and more fuel. Not enough for most folks to worry about but still more nonetheless.

If you're tracking it may or may not be a hindrance. Gotta test to find out but if it adds a few more shifts to a 3.7 mile track like Sebring it might result in slower times. Then again it might not, that's why teams have multiple setups and test...and test...and test.

And I think the 1700@75 is a little generous. If I recall my stocker is doing at least that.

 

[GTS Bruce]

CDI (archer headers) high flows from jon b, corsa cat back, Jesel RR, computer tune by DC. 465 rwhp,498rwtq on dynojet. GTS Bruce