Exhaust questions for 460 V8 Motorhome
 

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.

TallPaul, I don't have any answers for you but I too have a similar need and am looking for advice/recommendations.

I get the feeling that RV/motorhome applications don't really catch the interest of most of the people on this forum for whatever reasons. I suspect it's because RV's are not as cool as rock climbers and asphalt ripping pickups.

I hope you get some good responses as I, and I'm sure others sure could use the advice of some of the great talent on this forum. LL

I did some calling around. I no longer am looking for headers, but will fix the broken stud and see how it goes. 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.

One poster at another site had some good advice: 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.

Some other posts that came up:
Most headers are very poor in the sealing surfaces. Banks has very thick flanges and they are usually stainless which is nice. I’ve installed Banks kit on a V-10 Motorhome and a 454 Dually pickup, both responded very well. I was surprised at the quality of the Banks gas engine products. Doug Thorley also makes great headers; I have not had a set of Thorley’s leak from header a flange warping.

My biggest reason for doing a good set of headers wasn't so much for the power (although you never have too much of that) but to exhale some heat. Those cast manifolds are a big log-o-heat. I was cracking them left and right. Almost every trip with the trailer would crank one, so I installed a set of Thorley's and didn't have another problem.

Good info TallPaul and thanks for sharing.

I always let my rig idle for 3-5 minutes after a good run (at least 1 hour). Don't know if it helps but I don't have any exhaust/manifold leak problems and the engine heat guage definitely drops by the end of a couple minutes.

I've also spent many hours reading through the various posts here and am coming to the conclusion that headers really are a performance item that only help top end speed and really only above 3500 rpm's. I use a light foot and usually talke my time driving this rig (max about 65mph) and cruise between 2000 & 2500 rpm's.

Based on everything I've read, I'm going to start with the cat & exhaust system and then address the air intake process. I'm hopeful mods here will be enough of an improvement to make me stop.

An interesting article is posted at:

http://performanceunlimited.com/projectmpg/overall.html

I read the whole thing ... it's long but very imformative. What a neat study. I really liked the concept of addressing the little things in a DIY way ... although they did spend a pile of dough (almost $5K) along the way. If you take away the Gear Vendors OD system, it makes it easier to swallow.

Good luck to you!

For now I just had the broken manifold stud repaired. Manifold was slightly warped at that end (probably from the stud being broken), so he put a gasket on it and it sealed up fine. Cost was $375. Sounds good now.

Performance Unlimited site has many very interesting articles.

"I've also spent many hours reading through the various posts here and am coming to the conclusion that headers really are a performance item that only help top end speed and really only above 3500 rpm's."

Not so. The right set will give power gains far below 3500 RPMs A set of long tubes with smaller primaries will help you and your driving habits far moe than the usual big tube headers.

Hi TallPaul - or anyone else out there who can help.

I'm from UK but spend around 3 months every year cruising round US and Canada in a Ford E350 7.5 litre V-8 23 ft. motorhome. After this year's trip (2011), it is parked up near Halifax, Nova Scotia ready to set off towards British Columbia next May 2012. Ever since I first had it (2009 at 33000 miles) there was a slight exhaust noise which disappeared about a minute. I now know that this was the rear end stud (RH passenger side) losing its head. At the end of this year the noise got worse - due to the next stud breaking, and so next May I have to get something done. Reading the posts on this site it seems that this is a common problem on these engines when heavily loaded - the motorhome has a gross weight around 3.5 - 4 tons.

There is now a gap of around 0.5 mm at the end of the manifold. Will this mean a new RH manifold ? Can this be done without too much trouble?

Better still, is there a knowledgeable and sympathetic workshop near Halifax who would like to do it?

I have read many posts from folk who think this. Same with "you'll loose low end torque" When I am towing a mountain pass I'm not polkin along at 2000rpms I have my foot mashed to the floor in second gear spinning 4500rpms +. The headers really help. Personally headers would be the first thing I did if I had a motorhome.

Replacing the studs is fine, but they will probably break again. Here is what happens.

The stock manifold is a solid piece, with all the passages joining together in a log type design. This causes the manifold to heat up. Then it heats up, it invariably transfers its heat to the studs. This softens the metal when it is hot, and over repeated cycles can also weaken the metal. But this isn't all that happens. No, when the manifold heats up, its expands, and since all the exhaust gases are entering the same space so close by the motor, it causes the whole manifold to heat up and expand a lot. This expansion puts sideload on the studs, basically shearing them off at the base.

Headers move the exhaust though their own individual tubes. Since the tubes are thinner, and don't merge with the exhaust from the other cylinders till later, they neither get as hot, nor expand as much. This makes the headers not only freer flowing that stock, but more durable, and less stressful on the exhaust studs. Your engine will also run cooler.

Interesting, Khan
Can a set of headers and down pipes fit in the same space as the original manifold and would they connect to the main exhaust pipe at the same point as the manifold?
Roughly how much would a set of headers and down pipes cost? (I'm not looking for high performance!)
Colin UK

There are some that fit in the same space for some vehicles, but a long tube will flow better. I would use a header that uses a slip joint and a leak proof clamp as opposed to the 3 bolt flanges that many headers use. You don't need expensive ones, the Gibson or JBA units would be great choices.

Does anyone know where one can get a " Y pipe" for a 1996 Ford 460 motorhome with the F53 chassie? I've had it to two different repair places and they can not find the replacement part anywhere.

Thanks

You are probably going to have to make it.