Headers on a Ford 460 Class A Motorhome?

[TallPaul]

My dealer wants $2320 installed for Banks Headers and exhaust (no intake mods). And they want $1770 installed for the Gibson headers and exhaust in stainless steel. For Gibson in aluminized they want $1266 installed. Gibson header flanges are 3/8" thick and use a gasket. Banks are 5/8" thick and don't use a gasket. There is no question in my mind that the Banks is the best, but I don't want to spend that much.

Does the Gibson give decent power improvement on the Ford 460 V8?

Will the 3/8" flange on the Gibson hold up or am I going to get leaks?

Are there other header/exhaust systems I should consider?

I heard that just replacing the muffler in the stock piping can produce a big gain, nearly as much as if the piping behind the manifolds are replaced. Is that true?

I have a 1990 E350 Class C with 85000 miles (that I am selling) which has never had a problem with the exhaust, but my newer 1997 Class A has a broken exhaust manifold stud at only 41,000 miles. How reliable are the stock exhaust manifolds?

Why would an exhaust manifold stud must snap off like that? I bought used so don't know the history, but that likely the previous owner towed with it.

 

[Oil stain]

Any brand of headers will help. Keep in mind you might want to have a ceramic coating on the headers. This will cut down the heat. Non coated headers will cook everything under the hood, wires, hoses etc. Make sure the header flanges are straight and true. This will ensure a tight seal. Use a straight edge long enough to cover the whole flange. I've seen and heard a lot of leaks because of this. People would try all different types of gaskets and nothing worked.

The thicker the flange the better, but 3/8" should be fine.

 

[mechtech]

I'd consider the potential gains vs. costs.
Headers will help power production and fuel mileage, no doubt. But they present future maintainance problems, and can warp and rust through. Ceramic coated stainless is the best.
You are looking at a great deal of initial outlay of cash, for your particular vehicle.
Getting a freer flowing muffler should help, and I would do that first, and see how you like it. You'll need a freer flowing muffler if you get headers, anyway, to maximise their efficiency.

 

[TallPaul]

Seems the places telling me horror stories about stock manifolds are those that sell the headers. All the shops that only repair broken studs tell me not to bother with headers. I think a Flowmaster 70 series RV muffler would be a great benefit along with repairing the broken manifold stud. The Flowmaster will reduce back pressure a bit and that has to help it run a tad cooler. One mechanic I trust and who has had motorhomes suggests running it at slow speed or idle for 10 minutes or so before shutting it off after a hard run. Seems reasonable. In fact even the Onan generator says to run it unloaded a few minutes before shutdown. That's probably good advice for any engine.

 

[55Test]

I've heard that idling a turbo'd engine after a hard run is a good idea, but a NA engine?

 

[Steve S]

Headers usually make more power if sized for the operating range of the engine. I would bet cracking manifolds are the ones heated up to fast.

 

[TallPaul]

quote:

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Originally posted by Steve S:
Headers usually make more power if sized for the operating range of the engine. I would bet cracking manifolds are the ones heated up to fast.

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So I assume the stock manifolds are undersized.

 

[Gary Allan]

quote:

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Originally posted by 55:
I've heard that idling a turbo'd engine after a hard run is a good idea, but a NA engine?

---

At high power output the heat production is way high. The higher flow of the coolant keeps it "just in time" to prevent localized boiling/cavitation. That's why they warn you in the owners manual on stuff like VW (NA) not to come off the highway and pull into a rest stop and just shut down. They want you to allow the production/rejection rate to get reduced to the normalized levels at idle. Otherwise you may have a mountain of heat that's now got nowhere to go and do nasties to your aluminum heads and whatnot. I imagine the risk is lower for domestic iron ..but the concept is the same

 

[TheTanSedan]

A motorhome isn't a pickup truck. WOT can go on not for seconds but for fifteen-twenty minutes at a time on long grades. Ordinary headers not only cook themselves out, they also cook anything around them.

BANKS would likely work, but that is no cheap price to pay.

What kind of RPM's are you running?

I've been looking into motorhomes again (we had one in the 1970's), and the model we're interested in runs the Chrysler Marine & Industrial 440-3. Owners are reporting that the majority of time is spent between 2500-3800 rpm with stock gearing and tire size. Thus far, no reports of success with headers (and, no ideally made ones, either) in this application.

The above may not apply to your situation TallPaul, but I'd be searching like crazy on RV boards and the rest for rigs identical to mine.

At $2,320, break-even is 775 gallons saved at $3/gl. Or, from 7 mpg to 8 mpg, more than 40,000 miles of driving. After that, another 10,000 miles (90,000 total on engine) would yield a savings of 175 gallons; or, at $3/gl, $500.

A family would have to be running a lot more than the (I believe) average RV miles of 5-7,000 to make this worthwhile.

For a fulltimer (with some depth to his pockets) I'd say it was worth the trouble to find out.

I'd rather run the motor hard and keep the money for tires/brakes/steering replacements before the wear-out point (no slop, no slack, etc).

For economy I'd rather install a FloScan meter
http://www.floscan.com/html/blue/index.php
and a vacuum gauge plus a highly accurate tachometer to read in conjunction to train myself.

 

[TheTanSedan]

Even on replacement cast-iron manifolds (preferably, ductile iron) the problem of vibration is common as a fatiguing factor.

I don't find any listings for Ring or A.R.A. that used to be suppliers. I do find the site at www.stevensparts.com to be well-laid out with a nice selection.

On older engines, the change to headers would also need to include changes to fuel delivery and spark delivery curves to preclude burning exhaust valves. I'm not up to date on the TBI/EFI motors, but, again, I'd sure be searching like crazy to see if this problem exists.

While headers -- properly designed and built -- may give increases in economy and part-throttle power, the cost for a part-timer may not warrant it.

If we go ahead and buy one of the motorhomes we've been looking at, the stock manifolds will remain. I may get out the die grinder and clean up the interior of some roughness, possibly send them out for stress relief and a true thermal barrier coating (versus the hot rodders one for appearance sake), and look into truing the flange and head at a machine shop. I believe I'll stop there. Just go with a decent 2 into 1 exhaust pipe of proper internal diameter and flow to keep velocity high in the working range.

I believe that Flowmaster will guide you to the big-case 50-series over the 70.

Look forward to hearing what you decide.

[ August 16, 2006, 10:36 PM: Message edited by: TheTanSedan ]

 

[TallPaul]

According to John Geraghty's Performance column in the February 1994 Trailer Life magazine, in response to a question about a 1988 F250 with a 460 V8, "With the introduction of the EFI engine in 1988, Ford corrected the retarded camshaft position [retarded in early 70s for pollution control] and upgraded to a steel, double-row timing chain assembly. Unfortunately, the cam profile was changed and exhaust-port size reduced, which limited the engine's flexibility."

So now I wonder how much the better muffler would even help. Right now I'll just get the broken stud fixed. I've only driven it about 500 miles. Need to drive it more before I decide to do much of anything else.

But you make a good point, TanSedan, that the headers are not cost effective. I will have to call Flowmaster and see what they have. My motorhome has a resonator and a muffler. I wonder if the resonator is restrictive too and maybe should be replaced (with what?).

I have to check out the big case 50. Never heard of it. Last I visited the Flowmaster site was a couple or so years ago and the 70 was the RV choice then.

Thanks

 

[Volvohead]

I don't know motorhomes, but I know that engine.

With that engine, I'd definitely redo the exhaust system FIRST. I trust you're running a dual exhaust, or an enormous ID single past the Y.

You won't even begin to enjoy the benefits of headers until the back end has very low restriction. Any significant improvements will require corresponding upgrades to the intake tract as well.

If you want durability, you don't want headers. The stock manifolds are more sturdy. Why can't they set in a new stud?

All in all, headers are a high dollar proposition if you want to do it right. Saw too many kids flush money down the toilet on this "just headers" nonsense during the '70s. And they do rust and cook everything in their vicinity.

 

[TheTanSedan]

http://www.flowmastermufflers.com/50_bb.html

The 70 series was, (when I inquired a few years ago) only recommended by Flowmaster in a twin-muffler, dual-exhaust configuration when sitting behind a big-block V8 set up for heavy/high loads.

The biggest 50 (3.50" i.d.) was their recommendation for a truck (or other) with plenty of room and ground clearance in a single exhaust configuration.

I suppose it will depend how many feet the system on your 'home will be. Velocity drops as temperature drops, so a decent-sized single ought to do the job. It is what I would want in the application I'm looking at.

 

[jsharp]

quote:

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Originally posted by TheTanSedan:
A motorhome isn't a pickup truck. WOT can go on not for seconds but for fifteen-twenty minutes at a time on long grades. Ordinary headers not only cook themselves out, they also cook anything around them.

---

I agree from seeing people I know try headers on gas engines in old dump trucks. Not too different an application than a motorhome really.

The headers cook everything in the engine compartment. If you add header tape to them to save everything else the headers get so hot they don't last but a few months.

Stock cast manifolds last much longer but tend to eventually warp or crack depending on the engine brand.

 

[TheTanSedan]

Here's a recommendation by a well-known MOPAR guy [edited] on a system that is comparable (slow & heavy):

"Best bet for single exhaust: get a Flowmaster 2-into-1 collector and have a local shop fab something. Minimum recommendation: 2-1/4 off the manifolds to the muffler. Hemi muffler will fit (today, a WALKER "Dynomax" Super Turbo Part #17769). This is a MEGA torque adding goodie! Maybe 20ft./lbs., it's amazing."

I had a pair of the Walker's behind my BB Chrysler and it was a sound of the good old days (DODGE Police Pursuit 440); though I am not going to claim it is ideal for your application.

http://www.dynomax.com/


This article by David Vizard is much the best one on exhaust I've read. Between his points (very well made) and what you see in the BANKS system for your motorhome, you may well see yourself clear to an improvement that fits the bill.

http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/

After having read that article, then some understanding exists to properly use the following:

#17769 OAL 27" Inlet & Outlet 3.00" Flow 551 cfm (LossFree Horsepower: 250 single exhaust/500 dual exhaust)

Case size does matter in a motorhome/tow truck application.

I'd review what others are doing (can they verify mpg power increases other than anecdotally; mpg figures/speed on a grade/op-temps, etc), ask for under chassis photo's, etc.

Vizard is nicely clear about the muffler role, the pipe issues, and how to exit them.

[ August 17, 2006, 11:47 PM: Message edited by: TheTanSedan ]

 

[TheTanSedan]

Looked into this cost/benefit ratio some more in regards the GEARVENDORS OD/UD unit. MSRP is $3,095 and installation is $750, so figure a little over $4,000 when done.

At $3/gl = 45,000 miles break even.
At $3.50/gl = 40,000 miles (same)

This is if fuel usage goes from 7 to 8.75 mpg

I find this to be a better performance enhancer than headers as gear-splitting keeps HP/TQ between shifts, and one can select a better gear for conditions.

In terms of safety, engine braking can be "enhanced" by matching speed/traffic/roadway better.

Still, gonna need to drive a whole bunch to pay this off properly.

In the meantime, maybe upgraded brake linings and brighter (aftermarket, such as GROTE) stop & signal lamps . . . 55-62 mph is looking better.

In truth, a 600 mile day (a reasonable maximum) is covered in 9.75 hours at 62 mph, and 8.50 hours at 70 mph. There is no question which is the safer of the two, and is less wearing on the driver and the rig.

In a non-OD rig (with BB and 4.62 gears), 62 mph is about 25-2700 rpm in the rigs we're looking at.
Any gas motor will live a long time at that rpm, and a Chrysler Marine & Industrial 440-3 will live about forever.

 

[mechtech]

A good resonator won't hurt flow.
A cheap one has louvres sawn and hanging up in the exhaust stream. They restrict a LOT.
A good one, like a stainless Magnaflow, have punched louvres going the other way. They flow well, and take away a lot of harsh noise, and loudness.
Some stock resonators are hollow, and are actually Helmholtz resonators - they work well.

 

[TallPaul]

Seems my best bet is to replace both the resonator and the muffler on the chance that the resonator is restrictive. Or, maybe just a stright pipe in where the resonator goes. Why do we need a resonator?

TanSedan: Excellent article. I am halfway through it and can see that the muffler is very important. Off topic, I note the very interesting discussion of why the V8 engine has the distinct rumble.

 

[TheTanSedan]

I'd email FLOWMASTER about the big case 50-series and their dedicated resonator.

http://www.flowmastermufflers.com/50_bb.html

http://www.flowmastermufflers.com/accessories.html

Or, MAGNAFLOW, or BANKS (and other aftermarket suppliers) about a system for your vehicle.

Mandrel-bent systems (where the interior diameter of the pipes is kept constant in curves) is recommended. The engine "sees" the narrowest point as the system i.d. Most shops use a hydraulic press-bend that squeezes the curves down to a smaller i.d. (FLOWMASTER, and others.)

Pics of current system, and any others that can be garnered are a good idea to include in that inquiry.

 

[another Todd]

TallPaul, When I put the Flowmaster and Banks headers on my MH 460 I threw the resonater in the trash. It's not needed. Large pipe to large Flowmaster works wonders.