I went to replace my crossover pipe on my FE 360. Ordered from Napa. Pipe arrives but is 2.25". My current exhaust is 2.5". Did Ford make more than one size of exhaust pipe for the 360? The truck is my daily driver. I would like to replace the whole system front to back, but need to know the correct pipe diameter (OD). This is a dead stock motor and truck (it's the truck in my avatar). Any thoughts?

Thanks,

zenmater

 

If your gonna replace it all, then just go with 2.25" duals. Or pick the diameter you want. Do a single 2.5 or 3.

 

351Cleveland C4,

Thank you for responding. Now you've got me thinking... I gather the actual diameter of the pipe isn't critical in an engine of this type. Can I assume that the stock manifold will accept various diameters of exhaust pipe? If the above holds true, then wouldn't the smaller, lighter pipe be the most efficient choice?

In the past, I've always replaced whats there with whatever is the same, unless there's a problem.

I'm just looking for the most efficient, cost effective solution.

I would prefer to do the work myself, as I have to work (like everyone else) within a budget.

Thanks,

zenmaster

 

The manifolds will accept any size with the right adapters. While pipe size is not critical, it is still somewhat important. The factory system works, but it is undersized. Most guys go with 2.25-2.5" dual exhaust. However, for simplicity's sake, a 3" single would work well too.

I understand wanting to do yourself. I am in fact building a 2.5" header back dual system for my truck right now. But, if your not as picky and **** as I am, an exhaust shop can whip it up in a couple hours for around $200. That saves a ton of work and hassle on your part.

 

351Cleveland C4,

Thanks for your reply!

I think I'm gonna go with the 3" pipe. I'll talk with the muffler shop down the road and see what they have to say. If they can bend it for $200, then we're good to go!

I appreciate all your help!

Thanks again,

zenmaster

 

If going with a 2.5-inch system, the head pipes should be 2.25 inches and merged to a single 2.5 tube.

The same principle applies to a 3-inch... 2.5-inch head pipes merged to a single, 3-inch tube.
Still, yer leaving some HP and TQ on the table by sticking with stock and very restrictive FE manifolds.

 

HIO Silver,

Thanks for your reply. I know what you mean about the stock manifolds, but at this time I can't afford the headers and dual exhaust. I figure it may have to get done in my next lifetime... :-)

"The same principle applies to a 3-inch... 2.5-inch head pipes merged to a single, 3-inch tube."

Thanks for that, I didn't know about that - I will see if the muffler shop can do that.

Who ever thought exhaust would be so complicated?

I wont be doing this for a couple of weeks... cash flow issues... but will post pics when it's completed.

Thanks again to everyone who helped me figure this out!

zenmaster

 

Backpressure in the exhaust system is the nemesis of any engine.

An exhaust system should have good scavenging of the engine's spent exhaust (it should exit the combusted fuel mixture quickly).

The exhaust pipes should be sized for the horse power output the engine is rated (or, dynoed) for.

Too small a pipe diameter and exhaust flow will be choked down. Too large a diameter and the flow velocity will be too slow exiting the exhaust system. For a street engine operating ~ 3,000 RPMs or less, it's generally better to error on the smaller side of pipe sizing than on the side of being too large.

Large diameter exhaust systems might (visually) look impressive but, unless your truck is a race truck and normally operating in a high RPM band, large pipes will kill any true performance and any potential added mileage for the sake of looks alone. If you're not making 600 + horse power, 3" pipes are going to do more (performance) harm than good.

Exhaust pipe size should remain constant throughout the system, once it leaves the manifolds/headers. Necking exhaust pipe diameters up and down creates turbulence in the exhaust tract, where these expanded and contracted stepped places exist, in going from one pipe diameter to another. This creates backpressure and remember, backpressure is what you do not want in an exhaust system. You want flow velocity.


Pipe(s) diameter vs. engine horse power output.

How To Calculate Muffler Size and Exhaust Pipe Diameter - Exhaust Videos | Exhaust Videos

What Size Exhaust Pipes Work Best?

In order to get maximum performance from the engine and flow from the exhaust, the carburetor, intake, heads, rear end gears and cam would have to be optimized for the system and how you plan to use the truck, along with the addition of free-flowing headers.

Uncorking the bottle neck with new exhaust is a good start but, maximum potential will not be realized without addressing all the other areas.

 

A single, 3-inch system would be okay.

Dual 3-inch would be overkill.

 

Agreed on a single 3", IF the OP's engine is producing approximately 340 hp.

....sounds like it's pretty much stock though.

A single 3" on your trucks 360, with what you've done on it, would probably make a happier home for it.

 

ultraranger,

Thank you for those links. Very informative! I have a new question now: What is the approximate HP of a 43 year old stock 360? If I had to guess, I'd say 175 hp. Does that sound right? If so, based on my reading, I could probably get away with single 2.25" pipe... I don't race this engine. In fact, I rarely exceed 50 mph on the highway. This is my daily driver, and I just want it to function as designed.

I'm actually beginning to enjoy this process... I really appreciate everyone's input!

zenmaster

 

2.25 is the original, single exhaust size. There would be no gain per se. However, given how restrictive single, factory exhaust systems tend to be I would be looking to release the HP and TQ that is already there. The addition of headers and duals would reveal seat-of-the-pants gain for just a bit over what it would cost to have a factory system replaced.


Your call.


The warranty plate would state the factory HP rating. Keep in mind there was a change from gross to net HPs rating in the early 70s.

 

HIO Silver,

I agree with you 100%. Perhaps I have over estimated the cost of headers. The long term plan has always been to replace those restrictive stock manifolds with proper headers.

Any suggestions as to brand of headers? I seem to remember there is also a choice of inside or outside the frame rail...

Any real world experience with respect to header choice would be very much appreciated!

zenmaster

 

I went with Sanderson FF427 3/4-length heads simply because I did not want to deal that comes along with long tube versions. They dropped right in, don't trap the starter in a cage, nor require having to disconnect and jack up the engine for installation.


Visit the tech info hyperlink compilation linked in my sig and go the FE engine section for pics.

 

HIO Silver,

Wow, those Sandersons are real pretty! I like the look, although I'd probably opt for the black. I think the benefit of shorties makes these a real possibility. It says on their site that wrapping the headers in anything will void the warranty. Not sure why this would be...

In any case I will see if I can track down a pair of these for a reasonable price. Shipping is always a big deal here in Canada, plus there is duty as well... And some places won't ship to Canada at all.

I'm also glad I don't have to shell out for one of those wee baby starters.

You've saved me hours of work on this, and I thank you. After the long weekend, I'm going to show the muffler shop what you have, and see how much it will cost to run 3" dual pipes.

It's a work in progress,

zenmaster