Full catback made my car slower...

[CrazyFukr]

I'm going to start posting here because when I post in the street racing forums I get flamed by the import-haters.

Anyway, I replaced all of the piping from the cat and back with 2.5" piping, removed the stock muffler, and put a bigass 3.5" tipped muffler that I found on ebay. Now the car is hellof loud (not that pussy loud either like those weedeater civics either) and sounds really tough. But now I cant accelerate at all in 5th gear unless I'm going at least 55 in 4th when i switch to 5th.

I have 91 Integra GS 5 speed with intake and the exhaust setup that i described above.

Could this be because there is not enough back pressure? I noticed that the car hella takes off once i hit 3500 rpm, but below that its slower than when I had stock exhaust...

[Marasmus]

You should read the AutomotiveForums article on the myth of backpressure. It's at the top of the Technical forum.

Chances are that the exhaust system isn't sealed and you're having flow problems due to this.

Also, going to 2.5" piping on a B17/18A is absolutely useless unless you're going to FI your engine to oblivion or redline around 9 grand. All it's going to do is lower your airflow efficiency and hurt your exhaust's ability to aid in scavenging air from the cylinders. I'd expect a noticeable loss in high-end performance (perhaps as much as 10hp) if you're working on a generally-stock engine.

[CrazyFukr]

this shit was supposed to GIVE me 10 horsepower, not TAKE AWAY 10...

[spotovi]

Hi,

I have a B18B with 2.5" piping. This mod changed the nature of the car. You have to rev at higher rpms to get the motors power on the road. Change the way you drive the car a bit and you won't be sorry. You can't expect to drive the car the same as you did when you do mods to your car. These mods change the basic nature of the cars function and your driving has to reflect that. Articles are good for education but you have to put these theories into practice. Hope this helps. Now get out there and kick some ass. hahaha.

Regards,
Spotovi

[CrazyFukr]

that seems hella gay if you have to rev higher to get the same power that you had before. you shouldnt have to rev to 5000 rpm to get the same power as you could get before at 3000.. so you are basically PAYING for an exhaust system to SLOW YOUR CAR DOWN and use up MORE GAS at high rpms

[THE4TH]

yup.. that's what ya get when ya buy junk off ebay.. and do custom work .. bigger isn't always better..
they have some good stuff there just make sure you've seen it on another car and see how it works..
the reason that mugen, comptech, spoon, and all the big $$ companies charge so much is cause their stuff works.. really well..
save up and try one of those.. you won't be let down ..

[CrazyFukr]

On the greddy ad it says that it doesnt lower low-end torque (im assuming low rpm is what it means).. how does it do that and be able to support 800 horsepower (every 800+ hp supra ive seen has a greddy)and still not lose low end torque on small engines like b18s. like.. i have big piping, and the greddy must also if it can support 800 hp, so how does greddy not lose torque at low rpm with the same size piping but mine does?

[spotovi]

Hi All,

Increase the diameter of a pipe you decrease low end torque. No matter the price of the pipe. 2-21/4 is the highest you can go with a 1.8 NA. That's what I think. The orginal posting must have something wrong with the install. Did you use flanges or welds. Check the stuff out when you get a chance.

My low end torque is down a bit but who cares. The car goes good after 3500 in 1st gear.

The factory setup is made for the masses. You modify your car to be more of a racer then you lose somethings and gain others. Think about it. Different products won't change things that much. The change is bigger in your head when you tell your friends you got DCSport or Greddy.

Regards,
Spotovi

[redmanjd]

when you enlarge your exhaust you get less back pressure back pressure makes low end torque . so free flowing exhaust give you more horsepower rather than torque

[Vtec]

Your piping is to big the only way you'll get your power back is down sizing to 2 1/4 ,should have done your home work before you decided to put something on your car which you have no clue about. Oh ya never beleive what you read on ebay,if you beleive what you read on there well then I got a header that'll give you 40hp guranteeded I'll sell you lol.

[spotovi]

Opps.

Your right 2.5 is too big. I can't read and I made a mistake. I have 2.25" and it works good. Ya 2.5 is huge. You'll have to get a Turbo or SC or something now. lol

Regads,
Spotovi