Opinion on exhaust

[MN69Grande 203]

So I'd like to ask everyone's opinion on a self induced problem. A couple years ago I bought an exhaust kit from mustangs unlimited (a dual flowmater kit). The plan at the time was to just use the stock exhaust. The Kit is 2 inch pipe. So as life tends to do I was delayed installing the kit and decided to do some motor work first. When I went in to put the exhaust manifolds back on I noticed one was cracked.

 

So I bought some Headman Short Headers not really thinking about how it all matches up. None of this has been installed. So here is the dilemma - the headers end with a 2.5 inch collector. The H-Pipe and all the exhaust is 2 inch. So do I try to sell the exhaust and upgrade to 2.5 inch all they way back , do I use a reducer, do I go get stock manifolds?

 

Motor is a 302, mild cam, mild bore, stock heads.

 

Reading a few threads at VMF it seems the consensus is that 2.25 inch is really all the small blocks need and going bigger may actually reduce the low end torque. I really don't want to spend money on new exhaust at the moment as I need a new interior (all of it) but I don't want to install a whole exhaust kit just to replace it in 2 year - then not be able to sell the parts.

 

Thoughts?

Option 1: Use the reducer and what I have

Option 2: Replace the kit with a 2.5 kit

Option 3: Use a reducer and replace the kit with a 2.25 kit

Option 4: Go back to stock manifolds

[Boogerschnot 12]

I say use the reducer and stick with what you have. Nothing wrong with that.

[cavboy78 28]

x2. Spend your money elsewhere.

[MN69Grande 203]

Well looks like it wasn't much of a choice. Now that I've had time to look at everything closer I would have to completely rebuild the h-pipe or not use it. So now I guess I'm down to getting stock manifolds or different exhaust pipes/mufflers.

[cavboy78 28]

people all have their opinions, but the flowmaster kit installed very nicely in my stang. just had to modify the hangers a bit.

[prayers1 153]

I have a well built 289, 512 lift, 194 chevy valves, 570 cfm street avenger, headers and a 2" H-pipe which dumps the 2" exhaust just before the rear axle.

 

I have no problems and the motor screams.

Just get a reducer, your mild motor won't know the difference.

Since you already have everything, just spend your money somewhere else.

[LindenBruce 27]

Well, if you are changing to headers you are going to have to do H-pipe mods anyway. So you might as well keep the headers, your current exhaust system, and have a good exhaust shop make you some new transition pipes and save some money. B.

[Max Power 74]

With stock heads the headers are of little value. I voted to get another manifold and sell the headers.

[MN69Grande 203]

With stock heads the headers are of little value. I voted to get another manifold and sell the headers.

 

I think that means I need option 2b. Replace everything with 2.5 and replace the heads. Probably not in the budget right now though.

[Max Power 74]

I think that means I need option 2b. Replace everything with 2.5 and replace the heads. Probably not in the budget right now though.

 

 

That would wake things up a little....LOL.

[MustangChuck 16]

My vote is replacing the headers with something that would fit, but better than stock manifolds. How much work do you need to do to the H pipe? How easy is it to get new replacement stock manifolds (or something that fits like stock)?

 

Chuck

[grendi 16]

2x 2,5" with a 302....

unless your installing a stroker kit, you will probably be loosing power.

according to the sizing chart that i used to choose my exhaust, 2x 2.5" works best with 300-350RWHP

 

by the way, going too big won't wake things up, it' will make your engine loud and lame cause your loosing the low end torque. it cost me a lot of money to learn this lesson.

 

2x 2" is good up to 250RWHP, (~300+HP at the crankshaft)

 

i would try the reducer first.

[MN69Grande 203]

2x 2,5" with a 302....

unless your installing a stroker kit, you will probably be loosing power.

according to the sizing chart that i used to choose my exhaust, 2x 2.5" works best with 300-350RWHP

 

by the way, going too big won't wake things up, it' will make your engine loud and lame cause your loosing the low end torque. it cost me a lot of money to learn this lesson.

 

2x 2" is good up to 250RWHP, (~300+HP at the crankshaft)

 

i would try the reducer first.

 

Yeah the loss of low end Torque is my worry. I do have a magnum cam kit from Comp, a 4bbl Holly on the engine, plus upgraded ignition with MSD. Heads is on the list, probably some Trickflow Twist Wedge. So in the end I think 300-350 would not be out of the question. But until the heads go on I don't expect that. The FAQ below says 2.5 would be OK but the limit. I've found 1 other site with the same information.. However I have seen 2 other places saying 2.25. So maybe to future proof that is a better option.

 

The problem with 2 is that headers end at 3 inches, though the delivered collector reduces us to 2.5, So we would need a converter after the converter to get to 2. There is a Collector that ends at 2.25 though.

 

I honestly never realized exhaust was going to be this big of a pain.

 

http://www.magnaflow.com/07techtips/faq/question10.asp

[grendi 16]

forget the magnaflow chart. it's only good for modern or tricked out engines.

[RogerC 136]

With stock heads the headers are of little value. I voted to get another manifold and sell the headers.

 

False

 

I'd go with your headers and pick up a reducer that bolts onto the collector and reduces to 2". I'm sure someone has one. 2.5 is too big for a mild 302.

[MN69Grande 203]

Not that anyone was holding their breath wondering what happen. But I used the 2 inch and we modified the h-pipe. With a 302 2.5 just seemed to big.

[maxum96 32]

Glad you got it taken care. The 2.5" pipe would not be too big for the 302. It would just be a bit louder than the 2" you used.

[blueblood 26]

Seems there are a few opinions on this one.

I have a mild 302w (570 Street Avenger, cam unknown, a Hedman shorties) with a dual 3 inch system was on the car when it left the States. Future plans are for a 347.

I wasn't planning on touching the exhaust yet, but after 4 hours in the car yesterday I have to admit it's just too loud! Gets around 95 -100db in the car according to my IPhone app.

What size pipes and what brand mufflers are the 347 guys running in their cars that would also work with the current 302?

[barnett468 418]

Seems there are a few opinions on this one.

I have a mild 302w (570 Street Avenger, cam unknown, a Hedman shorties) with a dual 3 inch system was on the car when it left the States. Future plans are for a 347.

I wasn't planning on touching the exhaust yet, but after 4 hours in the car yesterday I have to admit it's just too loud! Gets around 95 -100db in the car according to my IPhone app.

What size pipes and what brand mufflers are the 347 guys running in their cars that would also work with the current 302?

 

you may have single chamber flowmasters . . see what you have . . the stainless mufflers and thrusu turbos in this video are no too obnoxious.

 

[1969_Mach1 333]

Well, I've read you installed the 2 inch system. This is merely my opinion. My choice would have been to keep the headers installed and sell the 2 inch system to recover some thing from it. Then replace it with a 2-1/4 inch system and possible X-pipe instead of an H-pipe. Mufflers and sound is your own preference. If low end torque is a concern, when the budget permits, consider looking into a larger cubic inch motor. Maybe a 351W or some stroked derivative of it based on the 351W. There is a large low end torque difference between the 351W and the 302. But then 2-1/4 inch exhaust could be marginal for a larger motor.

Edited November 9, 2014 by 1969_Mach1

[Max Power 74]

Well, I've read you installed the 2 inch system. This is merely my opinion. My choice would have been to keep the headers installed and sell the 2 inch system to recover some thing from it. Then replace it with a 2-1/4 inch system and possible X-pipe instead of an H-pipe. Mufflers and sound is your own preference. If low end torque is a concern, when the budget permits, consider looking into a larger cubic inch motor. Maybe a 351W or some stroked derivative of it based on the 351W. There is a large low end torque difference between the 351W and the 302. But then 2-1/4 inch exhaust could be marginal for a larger motor.

 

This thread was topped by a new poster with a different system over a year later.

[MN69Grande 203]

I ended up using a different 302(a Ford racing 306 crate motor) than planned so I don't think a 3rd motor is going to be on the agenda any time soon.

 

So far I have about 800 miles on the car with this set up and like it a lot. I do like the way the kit sounds. I also put some tips on it that have a little resonance:

http://www.summitracing.com/parts/hed-17120/overview/

 

But I'll go out for 3 hour drives and it has a good aggressive sound without blowing my ear drums out.

 

Would I do it again? Mostly. If I was to do it again I'd by the headers at the same time as the rest of the kit so it was all made to fit together. Plus I'd call up and talk to a person rather than going it alone on the internet. But that is what gets me in trouble most the time so hopefully I fully learn that lesson soon...

[Hoover 12]

Like your car. Nice job.

[det0326 179]

I ended up using a different 302(a Ford racing 306 crate motor) than planned so I don't think a 3rd motor is going to be on the agenda any time soon.

 

So far I have about 800 miles on the car with this set up and like it a lot. I do like the way the kit sounds. I also put some tips on it that have a little resonance:

http://www.summitracing.com/parts/hed-17120/overview/

 

But I'll go out for 3 hour drives and it has a good aggressive sound without blowing my ear drums out.

 

Would I do it again? Mostly. If I was to do it again I'd by the headers at the same time as the rest of the kit so it was all made to fit together. Plus I'd call up and talk to a person rather than going it alone on the internet. But that is what gets me in trouble most the time so hopefully I fully learn that lesson soon...

 

Gota ask what is your tire size, wheel size and backspacing?

 

Thanks Dave

[blueblood 26]

This thread was topped by a new poster with a different system over a year later.

Yes, that was me. :)

 

I have started a new thread to keep things on track.

Sorry about the confusion.