Another Exhaust question, seriously though :)

[Ponyperformance6]

I am planning on buying either an off-road h or x-pipe or getting electric exhaust cut-outs here soon. Which do you think would be better ? If i get the cut-outs they will probably be mounted right before my mufflers and after the stock h-pipe, I know that the power improvements will be minimal either way, but i like the utility of the electric cut-outs a lot better. Ideally i would get both, but i think it will be one or the other for now, so which do you think ?

[Brazen6.0]

I'd do the off road pipe (X or H), you'll gain more hp with that, hands down.

[OnequickZ28]

I dunno, vutouts really free up the exhaust. i would go with them. Do the off-road pipe later, seeing you already have an h-pipe.

[Ed]

I'd go with the offroad H or X. I'm not sure which would give a better performance gain, but either one would be better for the Mustang setup than cutouts.

[Luke01GT]

X or H pipe then the cutouts if you still feel you need them.

[Brazen6.0]

cut outs after cats don't do ANYTHING far as freeing up exaust...now if you put them BEFOR them, then it would be a better way....your cats are more restrictive than your stock mufflers and even more than your aftermarket ones!

[OnequickZ28]

I thought, he didn't have cats, my bad, i misread the post.

[Brazen6.0]

you'r forgiven :D

[Ponyperformance6]

well, the pipes after the mufflers are stock and that is very restrictive because of all the non-mandrel bends in it. Now let me through this one out to those of you who may not have considered it.... You take the cats off your car and on an OBDII vehicle and Mustangs require MIL eliminators which fool the computer into thinking the cats are still there and the computer runs the same way did always has, Therefor is any horsepower really gained ???

[Ed]

Of course horsepower is gained. O2 sensors don't control a/f mixture or anything like that. They're for emissions. If the computer thinks everything is kosher, it won't throw any codes and keep on going. The motor will still be able to pump out more exhaust air, which means more power.

Remember... An engine is an air pump. The more efficiently it can suck and blow, the more power you get. With the right amount of intake and back pressure, it is able to produce more torque.

[Lawman9C1]

[quote="Ed2002SS"]Of course horsepower is gained. O2 sensors don't control a/f mixture or anything like that. They're for emissions. If the computer thinks everything is kosher, it won't throw any codes and keep on going. quote]

Umm Ed, OBD II cars actually read the emissions and use them to help calculate the proper air fuel ratio, thats why performance nose dives when you crack a manifold. The Sensors read alot more oxygen in the line then should be and thinks your not burning enough fuel and runs super rich. You can have the PCM reprogramed to ignore the O2 sensors, or buy a set of simulators instead either will fix the problem.

Id go with Cut outs for now if you can fit them infront of the cats and not have a problem with heating up something important, IE tranny ect. The offroad pipes may also be a problem if you leave Florida, and end up in some state with Emissions testing.

[OnequickZ28]

you'r forgiven :D

Thank you, sir :D

[Grannynational]

O2 Voltage has a relationship to mixture, thats one of the things I use.

780 millivolts at WOT works just dandy, they do sell scanmasters for Fbodys, I highly recomend them.

Joe

[Ponyperformance6]

do they sell them for Mustangs tho ?

[HORSEpower]

They don't sell scanmasters for mustangs, nor does Will need one. He can get a chip dyno tuned anytime.

Cut-outs are a waste of time. They will hurt your performance more than help it. An exhaust with a good muffler, longtubes and a powerchamber flows better than open exhaust. The extra weight from the cut-outs will just slow you down.

Kurt

[Ed]

Okay, so I don't know shit about engine electronics. Sorry. :$

[Anonymous]

Hey Will, what year is ur Mustang?

I say X-pype and no cutouts

Mike

[OnequickZ28]

They don't sell scanmasters for mustangs, nor does Will need one. He can get a chip dyno tuned anytime.

Cut-outs are a waste of time. They will hurt your performance more than help it. An exhaust with a good muffler, longtubes and a powerchamber flows better than open exhaust. The extra weight from the cut-outs will just slow you down.

Kurt

I have never seen a dyno run that "proves" that an engine with backpressure makes more power than an open exhaust. I would say that on a stock car a cutout will hurt you due to lose of low-end torque but on a modded car it can only help, providing, of course, you have the right air/fuel ratio, timing, and exhuast setup)

BTW: the 1993 Camaros have chip, 1994s and have the chip soddered in and need scanmasters.

[Ponyperformance6]

Actually, 5.0 Mustang did a test of an engine on a static dyno and like, 20 different mufflers, all mufflers that they tested made more horsepower than open headers, pretty crazy i know, but dyno's don't lie. I have also heard that open exhaust underneath the car also creates a certain form of drag that slows the car down some as well..

Anyways I think i have decided on a prochamber or x-pipe, the cut-outs are more of a trick thing only i guess. HEHE the plans will hit and Jon's garage will become Mustang central for a while.

[HORSEpower]

Ultra-flows produced 118% flow of an open pipe on a flowbench.

Kurt

[OnequickZ28]

Like I said, I have never seen one that showed otherwise. In my experince my car runs faster with the cutout open. Every car I have seen before and after a cutout has lowered their ets. Every engine builing book I have ever read has showen that the engines run better with an open exhaust, but MUST BE PROPERLY TUNED for the open exhaust. I will quote one such book: "I have no doubt that someone, someplace, at some time produced a power curve that "absolutly proved" that an increase in backpressure resulted in an increase in power. My years of dyno experence tell me that this test must of been done under questionable conditions." he goes on to say that reduceing backpressure with gain power 999 out of 1000 times. Like anything with cars, it must be done right to gain anything. Therefore, I must respectfully disagree with you guys.

[Ponyperformance6]

that is understandable, no problems in disagreeing at all, i think it is universally understood that reducing backpressure will increase horsepower ... to a point, but as with all good things in life, there comes a point where too little backpressure will hurt performance... otherwise why would we need exhaust systems at all ? Just run no headers :D

[HORSEpower]

Who said mufflers increase back pressure. 118% flow is not back pressure. A tuned exhaust will help the engine run better.

Kurt

[OnequickZ28]

Who said mufflers increase back pressure.


"How to build Horsepower, Volume 1" By David Vizard, Sa Design

was the one I quoted, but everything I have ever read said that a muffler will increase backpressure.

Anyaway, I have never heard of an ultra-flow, can you post a link?

[HORSEpower]

Just go to the Dynomax website. Modern muffler technology has made cut outs a thing of the past. I would rather be quiet, so they never see it coming. Steeda sells Ultra-flows under the super-quiet name.

Kurt

[Brazen6.0]

also your muffler locations has an impact on the backpressure. With today's tech, you can create scavanging with mufflers, which in turn will create more power than open headers...remember an exaust isn't just some high pressure gas flowing out, it has certain caracteristics such as pulse and pressure waves....you also have to compute exaust pipe diameter...the proper size will make close to the same power than open headers....

[Stang8YourImport]

Hummmmmmmmmmmmmmmmm.... The same article that Will is talking about showed my old mufflers, Warlocks, (that are now on Lukes' car) out performed ALL TESTED MUFFLERS in the "uncapped" state. Of course this is not really "open headers" as "open headers" means you have no pipe after the headers. But this was open exhaust.. and Will is right, they said that all mufflers outperformed open headers, but with these mufflers in the upcapped state it's basically cut outs. So all you sayin' they don't work..... You just got :boink: :hyper:

Nick

[Mr. Bueno]

Kurt put me on to the dynomax ultraflos mufflers.

I have not looked back ever.

Great muffler, great flow. :cheers:
great stainless build quality.
Tim

[HORSEpower]

Yeah Nick, that is because better flow doesn't always mean more power. If you have too big of an exhaust system, that can be a detrement to the power too.

Kurt