2 EZ QUESTIONS

[jimdrechsler]

1)Would running 87 octane hurt at all when you run the 1/4 mile a tthe track? Especially if the guy who burnt my chip for my car said he programmed it to run with super. Is there really a difference? ive always used regular, especially with gas prices

2) what is the easiest way to hollow out your cats? AND what is there to be gained by doing this? I have the H pipe with cats on there now.

thanks,

jim

 

[$uperstang]

As for question 1. If the chip was bunred to use super then using anything less may cause detonation due to the way the timing curve is programmed in the chip.

For number 2 just buy an off road H-pipe they are cheap hell you can probably find a used one for under $100

 

[JChalfan]

$uperstang, your post wasnt there when i started mine, so this is kinda a repeat...

What kind of mods do you have done that you had a chip custom burned for?

1) If the guy said to run premium, you should run premium, otherwise you will almost certainly have a problem with detonation which could damage the engine. I would say either run premium, or pull out the custom chip and set base timing to 10 degrees and run regular.

2) I've used a long prybar (probably about 3 feet) and a big hammer to hollow out cats before. One of the cats you can't get a straight shot at, so I used an exhaust pipe cutter (though sawzall or hack saw would probably work) to cut the end of the pipe off, hollowed out the cat, and re-welded it. You will pick up a little horsepower since you are removing a restriction in the exhaust, and your exhaust will be louder especially at wide open throttle.

An offroad H-pipe is only about $100 I think, and they are 2.5 inches instead of 2.25, so if you already have headers and 2.5" catback, you would probably be better off buying the H-pipe.

Jeff

 

[89Notch]

To answer your question if you run a lower octane (as long as there is no detonation) your car should run faster at the track.

 

[Bolt on 5.0]

I read somthing about hollowing cats out can reduce power. Somthing about the air pocket slowing down the exhaust flow. I would not waste my time hollowing out the cat. Are the cats in good shape, maybe Ill trade you for my offroad pipe.

 

[jimdrechsler]

i want my car to pass emissions though, so i have to keep them on here. thats why i want to hollow them out. do most think i should gain power? thats what i heard! i may have to switch to super then and suck it up at the pump! thanks for replies.. anyone on here hollow out their cats with success? thanks,

jim

 

[HISSIN50]

Jim, as was said already, remove the H and keep it in the shed in case you need it. A used H is so cheap (or a new one - if corrosion isnt an issue, my 100 dollar Summit H works great) that it's a shame to hack up a stock H. It can really make the exhaust sound like crap with the resonance chamber you create (hallowing the cats).

If your tune is for premium, I'd run premium personally. If it runs well on lesser octane, I'd wonder why premium was specified.

Just MHO.

Good luck.

 

[rickd93_lx]

i know a couple of guys at the track who save there catted exhaust, and when it comes time for inspections they put the stock h pipe back on. or you could find a guy who will pass you, guys here in tx do it for around 60 a pop.

 

[jimdrechsler]

thanks for replies. i understand it makes sense to get the offroad h pipe (my other car had it). But, would i see gains in hollowing it out? im in ny, so i dont think i want to change it every year for inspection only. i may just leave it as it is, if it isnt worth any gain.

thanks again,

jim

 

[HISSIN50]

Jim, if you havent already, post up your sig. The chip indicates a nice combo.

Were it me, I'd get an aftermarket catted H (that meets local requirements - I can tell you that passing Fed standards doesnt always mean the local laws will allow it). The high flow cats will not be a restriction on all but about the sickest street cars, and will be the best of both worlds.

If you note your manifold vac readings decreasing while at constant throttle, that can indicate an exhaust restriction (A quick way to keep tabs on the state of restriction).

Good luck.

 

[jimdrechsler]

i added a signature now, i want to see if it shows now. i may be missing things on the sig. i was going to have my friend (mechanic) hollow out the cats when he does the adjustable clutch cable and reinforce the torque boxes. i may just forget about it now.

thanks,

jim

 

[donsbad68]

Use the right gas dummy.

As for question 2 there are many cheap aftermarket off-road h-pipes

 

[HISSIN50]

And for your mods, I dont see why high flow cats wouldn't work, should you desire to go that route.

 

[jimdrechsler]

LOL-- OK, super it is!!

BUT-- WILL I SEE ANY GAIN IF I DO HOLLOW OUT THE CATS?

I know off road is the way to go, but will i gain anything by doing this? i can only think that i will gain some power??
i know i asked this tons of times, but only 2 replies directly answered this question. one thought no, and the other described how to do it.

thanks,

jim

 

[JChalfan]

jim,

I have hollowed the cats before, and the only thing I can swear it did was make it louder. But that was on an almost stock 5.0. I never dynoed it so I don't know for sure if it added any power.

I personally think it will add a little power. I can't imagine that the empty air pockets from the cats would disrupt the exhaust flow more than the same pockets with the restrictive cat material still inside, but I could be wrong.

I think no one has answered your question for sure because no one here has dynoed a car to check, and most people just switch to an off-road instead of hollowing the stock h-pipe.

Don't forget the stock h-pipe is 2.25", and I asume the rest of your exhaust is 2.5". Even if you hollow the cats, the stock h-pipe will still be a bit of a restriction, considering your combo.

Your best bet would be a high-flow catted h-pipe. Don't waste your time with the stock h-pipe with your combo.

Jeff

 

[jimdrechsler]

Thanks again,

UHOH, I forgot to mention it is a BBK h-pipe with cats. Are these still 2.25"? i thought they would be 2.5". I think I am going to have them done anyway. The guy working on my car is super cheap for labor.

Sorry i didnt say they were BBK's. Now is it even better to do or what?????

This site is the best mustang site ive been on before. thanks again for all replies to my dumb questions!!

 

[JChalfan]

I'm sure it's 2.5" if it's a BBK.

I think the aftermarket cat h-pipes all have high-flow cats, and people say they offer almost no restriction.

Since it's a BBK, I wouldn't touch it, leave it just like it is.

Unless of course you WANT a stock h-pipe, then I'll gladly trade you straight across for your BBK...

Jeff

 

[jimdrechsler]

i looked up the pipe i have and it is like 350 bones too. what a rip off. oh well, it looks like i will keep it the way it is. sorry for the confusion and thanks for all replies.

i learned to use super, and keep the cats today!

always something new each day.

 

[HISSIN50]

I agree with Jeff and your final conclusion all the way - keep that sucker as it is.

You can install a vac gauge and monitor it if you think you have a restriction, but I'd be real surprised if you did (it'd be a cat failure and not the flow characteristics of the cat itself that present any sort of issue).