what kind of gain could i see if i got a "test pipe" to replace my cat.
I saw one on ebay and it said you could gain 9-15 hp.
someone tell me this is true!

 

if a high flow RT cat conv. claims +6hp(on a 4th gen) IMO a stright pipe could either be equal or BETTER...... I'm gonna try it this summer after I get my WSP exhaust, just don't expect to pass emissions w/ it on! you can also just make your own for about $10-15!

 

Whoa, I think we should have a poll for the fattest sig.
Your's is Phat! (i don't know how to put your sig in my post)

 

You are not going to see any performance increase, and spending $200 on a RT cat is a waste of money, buy one from summit for $80 or gut your own

 

I got bored last night and threw it together... might do another tonight.

 

I have already replaced the cat with a straight through pipe. Fuel economy is up and "seat of the pants" power feels like it is up also. Car does rev out a lot easier (as you would expect).

Brent

 

say what?? How can increasing your exhaust gas velocity NOT increase the volumetric efficiency inside your combustion chamber?

Waste of money on a straight pipe? I beg to differ.

You're recommending gutting the cat? That's even worse. By doing so you create a hollow chamber in the exhaust gas flow. This causes the flow to become turbulent, which DECREASES your exhaust gas velocity. The main goal in exhaust gas upgrades is increasing the exhaust gas velocity without reducing the scavenging effects at the exhaust valves.

 

i dont doubt for one min. that all that is correct....for most cars that is....i thought it woudl do somehting for mine but it might have lost more low end then it gained top end, i will say it revs faster but thats it, i dont think anyone can vouch for the VG engine getting any gains by putting a straight pipe or some $200 RT cat, so to clarify my statement i was not refering to a cat in general, just this particular car

 

I'm willing to pay for the dyno runs if anyone is willing to drop by EIP in MD or ERT in DE and do before/after runs with a straight pipe on a 3rd (or 4th or 5th) gen Max.

 

thanks for the offer phuong i was gonna be dropping by either of those places sometime in june...testing out a couple things....wanna come?

 

I removed my cat and ran straight pipe all the way back. I lost so much power by having reduced the restriction too much. I had more power when I had the cat but ran a low restrictive muffler. This is why I'm going to get the 2k SE muffler. Um, after I get my engine in of course. By the way Phuong, I got that calling card! As far as they are concerned, everything's a go, they just need the injector impedance. I'm still wondering about that collect thing? Think they would accept? Between you and me Phuong, I know what you mean about the "B" guy, he's the one that okayed the modification for what I need! So, that's who I spoke to, I'll probably call back tommorrow!

 

if you guys go up to EIP, let me know, its right around the block from me(well kinda..) then I can finally meet some of you NE guys before Maxus...

 

I prefer ERT over EIP, plus it's closer to you (DE).

You'll lose some low end but mid and top end should yield 4-7 hp (what catback are you running?)

 

Warpeed Y to stock right now...shopping for a used Greddy as we speak

 

dont run stright pipe cause you'll lose power in the long run. Unless you like racing people from 0-20 you will only make your car slower. I ran a straight pipe on mine and I can definitely feel the loss of power. Our engines dont produce enough HP to take away all that backpressure and use it as an advantage. Now if you had serious bolt ons like SC and NOS it would be a different story. It might make more HP on a dyno, but I guarantee you will have slower times at the track.

 

I have a straight pipe in place of the cat and do not believe I have lost power. Whilst I don't think I've gained mega amounts, fuel economy has improved as has the responsiveness of the engine.

Do you have any dyno charts to backup the power loss?

B.

 

I think I'm the minority on this subject!! Hey, I'm Asian, too LOL

Fuel economy has increased since you're increasing your volumetric efficiency in the combustion chamber. The same effect occurs when you install a catback exhaust or an intake.

I'll be putting a test pipe on my 1.8 L small-*** autocross car (97 Miata). This engine is putting out MUCH less HP/Torque than a 3.0L V6. Yeah, I'll loose low end but I could careless about low end since the engine is above 4500 rpm when I'm racing. All that matters is mid and high end gains.

The reason low end power suffers is because the exhaust gas velocity decreases when you move up to a larger diameter pipe. Take for example a garden hose. A smaller diameter garden hose will spray out more water than one that is larger, but, only if the flow levels are low. When there's more demand for water, the water will flow out at a higer rate in the larger diameter hose.

 

Are you running an aftermarket cat-back exhaust or just stock?

 

OK. I'm with you now.

Brent.