wat catback?

 

its just a straight pipe i made the pipe bymyself i cuz my cat out

 

i have the RB turbo back..and IMO.....its still loud....i dont like the fact that the exhaust makes the putt putt putt sound at idle...it sounds like a chainsaw or a 2 stroke...but it does give the car character on the road.....

 

Ah, set up some dyno numbers to prove your statement.

Otherwise my dyno tests prove you are barking out your butt

 

I don't have dyno numbers, but I don't see how the stock exhaust manifold is going to provide more power. Do you have dyno numbers proving otherwise?

 

No, but I have consistently seen and posted dyno tests that show at best a header adds only about 5-7 peak HP over the stock manifold and pre-cats, while a down pipe and using the stock manifold typically shows about a 5 peak HP increase. Now this is when using a collected design (since this thread is all about using collected exhausts).

So, this tells me that a header does not provide much HP over the stock exhaust manifold and that the stock manifold is not as bad as some people claim.

Now on uncollected designs where the system is true duals all the way back, there that is where the header excells and blows away the stock manifold and exhaust.

Also dyno testing has pretty much shown consistently that collected headers raise the torque peak to a higher RPM. While this is great for driving at 5500 RPM, it is typically poor for 2000-4000 RPM driving making the motor more peaky. Sure the peak HP numbers go up, but the useable power also is forced higher up the RPM range.

 

The bonez dp / cat eliminator works well. Gained a few hp and it was inexpensive. Don't expect much hp from exhaust upgrades on an NA. You could potentially gain some, but if it is all in the uppermost RPM ranges, it's useless. When you run a header with no catalytic converter your car will be so damn loud that you'll be too embarrassed to take it up that high in the rev range.

 

I see. But you aren't going to really make too much more power from 2000-4000rpms with any modifications. If you want to go fast n/a, you're engine has to be peaky. I don't think too many people would mind the lack of power in that low rev range, if you want more power you just have to downshift.

 

Just the point is a down pipe and stock manifold produce almost the same power (as a header) for half the price on a collected system and half the noise.

And that the stock manifold doesn't suck as you suggest.

 

for all the people who don't believe mark on this-- have you seen the manifold? Theres not much to it... Its not like some manifolds that have bafling or anyhting-- it is straight through...

 

Last summer I changed out my stock exhaust manifold and gutted precats for a RB collected header. I needed to weld on a length of pipe between the collector and mount flange to get it to reach my stock main cat. The car had a street port, weight reduction, ported intake, and a ram / cold air intake.

Before I added this header, my consistent Gtech quarter mile E.T. was 15.7. After I put on the header, *just the header*, the time became a consistent 14.9. This time was reproduced on a local drag strip.

Point being, the stock exhaust manifold is very restrictive, and even a RB header (mine was called a "streetable header" on their web site) made a big difference. It might make a smaller difference on a motor with stock ports, but it is still a very cheap, very good mod. My exhaust sound level did not go up very much at all, because I still had my stock main cat and cat back on the car.

 

The stock manifold is not straight through, it is shaped like a hollow brick with two inlets 90 degrees from the outlet. That is not "straight" through. Point being there is no smooth flowing path for exhaust to take in order to escape like in a header, just a collision with the far end of the manifold housing, and subsequent dump off out the side. Point taken that it has no baffles.

 

88' would your porting have a factor in this testing though? i'm actually trying to build a reasonable low end power daily driver soon, and this thread interests me. i'm not trying to call you out but i want all sides to the story.

 

standing corrected

 

Sure, ported engines respond to exhaust mods a little more than non ported engines, but exhaust mods still work on stock port engines.

 

If you want to make some good power... get Mind-Train or SDJ...

 

Ay Yo... i bought the Mazdatrix Header flange and twin pipe flanges for the rear of the header to bolt to the exhaust. 1x flange B and 2x flange C and associated gaskets


ive ported and matched the Lower and Upper intake manifolds, and the VDI manfold is untouched. the 6PI is completely removed and the actuator rod ports are blocked off w/ Dimes. the 6PI actuator rod guides are punched out. the 6PI actuator rod guide bosses are ported out and flushed with the runner walls. the 6PI sleeves have also been removed.

this is where i could use some input on the exhaust side. i plan to use the flanges to build a 304 stainless mandrel bent header with 2.0" Primaries and place the twin-pipe flange somewhere under the firewall to make the header removable from the rest of the exhaust system. now, after the twinpipe flange, should it remain 2.0" OD or should it flare to 2.25" twin pipe or what? i considered retaining the 2.0" OD all the way to the mufflers to preserve exhaust gas velocity and strength of the resonant pulses. if i flare the tubing to 2.25" OD or 2.5" OD after the twin-pipe flange, the velocity would decrease, as well as the resonsant pulse wave that is sent back to the engine exhaust ports right? would it not be better off maintaining the same exhaust pipe diameter of 2.0" all the way to the rear of the car?

Markus/Ted, true dual or uncollected for a street port should be the best for scavenging and create a power peak before the stock redline of 8000rpm, correct? is 2.0" OD header primaries large enough?

thanks
chris

 

How much of a pain was that to get working? I have already pulled all my emissions and have the full Racing Beat collected header exhaust from front to back.

I've been thinking of putting the S5 intake on for the VDI and better flow from the upper portion but wasn't sure how much of a pain it would be. I only have 5 vacuum lines.

Can you use the S4 fuel rails, injectors and do you have to screw with the electrical at all? Oh yeah, is the exhaust back-pressure enough to pop open the 5th-6th ports and VDI?