2" or 2.25" single exhaust with a stock manifold?

[Frankenstang]

For some background, I'm installing a 68+ manifold with a 2" outlet for a single exhaust setup. I want to increase the pipe size as others have suggested, but stay with a manifold. I was originally thinking 2" all the way back with flowmaster 50, but this got me thinking.

Any reason to step up to 2.25" pipe after the manifold if the manifold outlet is only 2" (don't want to start a family brawl on back pressure ) just wanting to find out if it's justified considering my mostly stock plans (if anything I'll have some porting done to the head in the future but keeping the cam and valve train stock and likely go to electronic ignition at some point)?

2.5" with stock manifold seems like overkill, but not sure 2.25" isn't as well. Appreciate any thoughts. Hoping to get some gain from the additional cfm this new pony carb is supposed to flow, understanding the other limitations on my mostly stock setup and no desire for headers.
Thanks

 

[Asa]

considering how poorly the manifold flows, why do you not want headers?

 

[Frankenstang]

Asa that’s a good question, not sure I have a good answer/reason. Doug hit on part of it, cost. I found the manifold for less than $140 all in, and from what I’ve read this later manifold is supposed to flow a ‘little’ better.

http://cgi.ebay.com/ebaymotors/200-FORD ... 03012241QQ

So it's a combination of cost, looks, preference. As well I figured headers would not give me a whole lot more gain without a cam, two barrel, etc, etc. (I could be wrong on the gain part…it wouldn’t be the first time). Basically just not in my plans right now.
Thanks guys!

 

[falcon fanatic]

I'd just go with the 2.25". Most of the power gains will be in the upper rev range, which you won't reach with your stock cam, but it won't hurt anything, should cost about the same, and you *may* gain a wee bit of power and run a little cooler. Then, if you decide to upgrade your cam, or your header or whatever later, you'll already have a decent exhaust in place.

 

[CZLN6]

Howdy back Robert and All:

The real question is- what will be your long term plans for this engine/car? FF hit on it.

If you're really satisfied with your current performance level, then consider that a 2" system will maintain higher velocity and heat better. THe lack of velocity and heat would have the two larger diameter pipes rusting out sooner. The performance difference at this level will be negligible. The 2" system may be a little cheaper too.

What distributor are you using with the new Pony Carb?

When you do the head/porting- be sure to specify a three angle valve job, a back-cut on the intake valves and a port divider. Don't be tempted to get to aggressive with Compression with a stock cam. It already builds good cylinder pressures.

Adios, David

 

[Frankenstang]

Thanks guys this is very helpful.

David, long term plans I'm close to where I'd like to be. Economical DD with a bit more pep than stock setup. For me committing to the $400 carb was pretty much committing to a relatively stock setup.

When you do the head/porting- be sure to specify a three angle valve job, a back-cut on the intake valves and a port divider.

You read my mind or I read your book Other than upgrading to electronic ignition the head work would about do it.

I'm still running the Mallory dual point mechanical advance only. It's been a good performing little distributor. I plugged the scv vacum port on the carb with a brass plug.

 

[Frankenstang]

Well decided to go 2â€￾, and bit the bullet on a Borla Performance Turbo. I found this site to listen to some sound clips.

www.mustangexhaust.com

You only get to listen to 10 clips before you have to register, which is free. No i6’s, but there are some bent6’s and clips do include info about configuration of headers, exhaust, mufflers so some apples to apples comparisons can be done.

Found the Borla on amazon for $106 all in (about 3x what I’d want to pay for a turbo, but expecting/hoping the SS means it will last 3x as long).

http://www.amazon.com/gp/product/B000CIMDR8

Found the 2in. 68-70 manifold on ebay

http://cgi.ebay.com/ebaymotors/200-FORD ... 0303012241

They charge too much for shipping but still the best price I could find.

Am hoping to use half of a stock dual exhaust for intermediate and tailpipe, if I can figure out how a 68’s i6 head pipe is routed (its 2â€￾). Looks like it could cross sides from passenger’s to driver’s, but can’t tell…anybody who can shed some light on this?

Edit: or I'll just let the local shop fab the head pipe.
Thanks

 

[CAMDEN289]

Hi Robert,
I'm going to do a similar type exhaust on my 66 vert at some point(after my current sytem rots off).I was planning on basically ordering a stock exhaust system for a 68 and then adding the muffler of my choice,I assume I'll have to do some possible cutting or bending but I think it can be done as the 64-70's have the same basic body dimensions.I noticed the link you listed for the manifold ,for the record that is the earlier(wrong ) for what you are looking to do.Please keep us posted on your progress,that way when I eventually get around to doing mine I'll have a better idea as to what I have to do.

 

[Frankenstang]

Hello CAMDEM289,
The one I purchased from the ebay link above actually appears to be correct, although it is an aftermarket so it is not exactly like the originals. For example, one small area on the left and above the outlet does not have as much iron as the original, and there is an area where a '68-70 or later original would have a bung for attaching some type of emission accessory, but on this aftermarket it is casted over smooth(I'll try to post a pic with a tape measure over the weekend).

It does have a 2" outlet (I measured to make sure), and the big X on the casting that seems to denote the larger style. It also has more meat on the left side of the outlet than the skinny 1-3/4" manifold I have on there now, and this requires a couple additional longer mounting bolts. In the meantime here are a couple threads where this same issue was being discussed, and the second thread actually has pics of an original X casting manifold courtesy of Wallaka.

http://fordsix.com/forum/viewtopic.php?t=54205

http://fordsix.com/forum/viewtopic.php?t=50014

 

[CAMDEN289]

I must have been thrown by the part number,Plus the application said for up to 67 which concerned me because 67 and earlier would be the smaller version.I'll double check my originals and see what they have as far as numbers?

 

[Frankenstang]

Wow, going on two years later and this project is finally completed (for now). Little things like floor pan repairs and a rear end swap got in the way. Actually had always intended to do this project somewhat in conjuction with the 8in rear end swap since the old system was rusting out and was a hodge podge of a C3, 1.75" manifold and 1.75" pipe going only as far back as the muffler. Then just ahead of the old muffler it changed to a 2in nipple leading into a 2" tranverse hung muffler that exited out the driver's side.

Anywho, I ended up going with the 68 (C8 or 'X') manifold as mentioned, and the 68 head pipe (2 inch). I used the intermediate pipe and tail pipe from a 289 dual setup...2 inch all the way back now. I also added an inexpensive resonator for the time being to cut down the raspy/ricey sounds. The results are 'under-whelming' compared to those with headers and a non-stock cam, but I'm satisfied.




I got the $14 Jones resonator from Summit figuring the shortest length version would make least impact on flow, and then played with installing it two different directions (first with louvers/scoops going with the flow, then with them facing into the flow...as intended to be used AFAIK).



Folks at Jones Exhaust were very helpful and said that the first method would give the best flow and the second would give the best sound attenuation. I had originally planned on putting the resonator upstream of the muffler at a low spot where the 68 head pipe met the 66 dual/intermediate pipe (an apparent unwanted side effect of mis-matching stock pieces). I ended up deciding to put in after the muffler figuring it would impact flow less; since in theory exhuast gas would be more fully expanded and velocity would be lower at this point (prolly lessened the sound effect as well though).



And the results...[note: prepare to be un-impressed if you've got anything other than stock...ie headers, cam, 2bbl, etc....but I'm happy with it]
First is straight pipe after turbo muffler, then resonator with flow, then resonator against/into flow, then the final result

Straight pipe after muffler
Resonator with flow
Resonator into/against flow
Final with 2 to 2.25 ss tip

As cautioned it's not dramatic, and things like the straight pipe coming up short of the rear valance in the first clip, or moving the camera in the final clip may make it difficult to tell the difference...but the difference in person and driving down the road is about what I was hoping for, which is good by me. Obviously, it wasn't like it's a big deal project, but having finally gotten it done last weekend inspite of the Tx heat...

...is at least one more item off the list.

It was actually cool to post to this old thread because it helped me kinda reassess my long term plans. A slightly modified stocker, or following the FFPH now what's left to consider is a 3 angle valve job & backcut along with possibly high ratio rockers=$$$