[JasonBVHS]

I was looking at a jc whhitney catalog, and saw an exhaust cut out that uses a throttle like design to switch from straight pipe to factory exhaust. My main question is that if i have this cut out put on right after the headers, with it open, will the lack of backpressure affect my engine as much as people say it will?

 

[shoz123]

IMHO yes

 

[RAMdrd]

In addition, you'll have a very loud car that is not going much faster (if at all) than with no cut outs.

Not enough bang for my buck.

 

[dant98]

If you're going to use it effectivly, you only want to open it at high RPM's. better have a remote switch for it.

-Dan

 

[mikehawk]

I think if there was a way to open the cut out after say like 3500 or 4000rpm for a duratec, or I guess 2500rpm for a vulcan, then it would be sweet. If you do decide to get a cut out, you should keep the stock exhaust, then just open it up when you're racing. That way you won't attract any unwanted attention, and your car is more like a sleeper.

 

[dant98]

... and it would still be street legal...

 

[JasonBVHS]

I appreciate the advice guys, but my main question at any point could this cut-oout mess up my engine at all?

 

[silvapain]

No. not having backpressure can only help an engine, not hurt it.

 

[shoz123]

Originally posted by silvapain@Dec 27 2003, 09:31 PM
No. not having backpressure can only help an engine, not hurt it.

That is not true. Without the proper setup with back pressure the intake charge will be sucked out before it has a chance to be compressed and ignited. Resulting in lower power output and efficiencies.

My '97 SHO is a dog with the catback disconnected.

 

[silvapain]

How would the intake air be sucked out if the exhaust valve is closed? the piston cannot compress the air/fuel mixture if the exhaust valve isn't closed. Race cars use straight pipes - they have no backpressure at all hardly. I would think that there is something else going on if you have problems with the cat off.

 

[Sablewagon]

Originally posted by silvapain@Dec 28 2003, 01:34 AM
How would the intake air be sucked out if the exhaust valve is closed?  the piston cannot compress the air/fuel mixture if the exhaust valve isn't closed.  Race cars use straight pipes - they have no backpressure at all hardly.  I would think that there is something else going on if you have problems with the cat off.

The answer to that gets kind of complicated; you need the exhaust pulses from the adjacent firing cylinders to help scavenge the exhaust out. On a fuelie dragster with Zoomie pipes, it's a different story, because you have a supercharger forcing the air into the engine. But, a regular N/A car runs better, especially at lower rpm's, with a set of headers (or even manifolds) than open pipes. Like SHOZ123's car, regular cars will usually run crummy with open exhausts.

 

[silvapain]

okay, but better headers reduce exhaust pressure, not increase it.

 

[shoz123]

There is also the issue of valve overlap. A certain point in time when the intake and exhaust valve are both open WRT headers. And as said the adjacent cylinder WRT OEM manifolds.

 

[JasonBVHS]

ok then that answers that, thanks for the help guys, but where can i get a decent set of headers for a vulcan. I looked at headers for a ranger although the will bolt up with minor mods, the way the header winds down the engine is different.

 

[silvapain]

no one makes them for the taurus. The ranger is RWD, so the engine is mounted differently. I don't think the header would come close to matching up to the exhaust pipe.