Hey Turbo Guys

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mbaird

mbaird
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So I have a 78 Dodge C-Class motor home with a 440 that I would like to modify for better performance at some point. At first I thought stroker but now I am entertaining turbo with low boost .
And since there is so much room under the chassis behind the engine I figure going with 2 small turbos mounted directly to header collectors would be the ticket .

Question is ....which turbos to use ? How big ? Are there low buck ones ? How cheap could I do this and still be reliable ? What are the challenges to this.?

I have zero experience with turbos.

Thanks
 
two at the collectors is a great idea when there is not alot of throttle response needed. I imagine an RV spooling up would be like my Isuzu NPR 5 ton truck, a turbo diesel itself. Are you going to blow through or draw through? Draw through is alot easier, not as hard to manage and doesnt require a special carb, but the location of the turbos makes that a poor choice unless you can mount the turbos closer, ie on upswept manifolds next to the motor like a turbo firebird or other Banks turbo setups. So I guess your going to blow through. Look at "Hanger18 carb mods" to make a Holley a blow through or buy one already set up. My friends kid has a corvette that is going to get turbos behind the rear axle! Its EFI so its almost a bolt on kit with nothing but air going all the way back up to the intake.
 
I planned on a blow thru. Never considered a draw thru.... Seems like a long ways to keep fuel atomized . I am not concerned about lag in this application. Min fact a bit of lag will help things survive a bit longer.

How big of turbos will I need ? Can I use the fuel pressure port to feed them ?
My Kevko pan on my 408 has side plugs.... I could run one those and use those ports for return lines.
 
I planned on a blow thru. Never considered a draw thru.... Seems like a long ways to keep fuel atomized . I am not concerned about lag in this application. Min fact a bit of lag will help things survive a bit longer.

How big of turbos will I need ? Can I use the fuel pressure port to feed them ?
My Kevko pan on my 408 has side plugs.... I could run one those and use those ports for return lines.

I don't know how large a turbo you will need, but I have a new one that I am not going to use. It came from Germany. It is an Ebay turbo, but I did my research before I got it. It's a nice one. Built in waste gate it's oil lubed and cooled and water cooled as well. When you find out what size you need, if it happens to be close to this one, you can have it for what I paid for it. It was 250.
 
You can get the carburetor enclosures for Paxton setups fairly cheap, it's usually an easier way to go if you have room.

2:1 exhaust and a single turbo would be more effective for the application. Two smaller turbos is usually done to minimize lag and that's not a concern on a heavy vehicle with an (assumed) automatic. This simplifies the install and minimizes the issues.
 
Most of the people on the turbo forums suggest a 70-76 mm single in HD applications. The Paxton carburetor housing is an excellent idea. Then all you’ll need to control fuel pressure from a high output pump is a boost/vacuum referenced fuel pressure regulator (FuelLab has very good ratings). Any thoughts of an after cooler ahead of the radiator? Also, what’s the LSA on the cam and what intake do you have?
 
I have seen that. No echnical info though.

I was thinking 2 small turbos would be less than 1 big one. And easier to package by mounting them directly to the connectors vs a Y-pipe into 1 large turbo which will move it further towards the back of the vehicle. Which also means I have to extend oil and cooling lines.

So far this is just an excercise.... I need to complete my 408 Swinger and Kitchen remodel first .lol
 
I don't think turbos are a good idea on a gas engine RV, especially without EFI. Too many variables (temp, load, throttle position) and how do you think it could handle a long steep grade? Would you just go ahead and keep it on boost for 5 or 10 minutes straight? That thing would be a pinging short fused grenade!
 
I don't think turbos are a good idea on a gas engine RV, especially without EFI. Too many variables (temp, load, throttle position) and how do you think it could handle a long steep grade? Would you just go ahead and keep it on boost for 5 or 10 minutes straight? That thing would be a pinging short fused grenade!

That was my initial concern about running a turbo in a constant load gas application. But I thought maybe if I kept the boost low....
 
@mbaird Gale Banks did a LOT of these back in the day. Your best bet would be to get ahold of one of his complete kits. They show up on eBay from time to time. Now for my opinion, convert the Gale Banks setup to blow through. Draw through sucks (pun intended) and you cannot intercool. If you’re going put together a kit yourself either two 55-60mm turbos or one 76-80mm will get the job done. Smaller twins will be more efficient ultimately. Mount them high, don’t mess with trying to pump hot oil back to the pan, I do it and it’s a hassle. Aeromotive makes nice boost referenced fuel pressure regulators for carbed applications and they’re reasonably priced. Spend the money on a good blow through carb with replaceable brass and keep it small, like 650cfm, you’ll thank me later for that. Don’t worry about constant loading in a heavy rv/towing application, keep the boost low, 6-10 psi, and the tune conservative and it will live. I pull 10-15k pounds behind my 8.1 Chevy 3500 at 10psi on 91 octane California junk gas and it’s been fine for 400,000 miles, (Not a typo) and it makes gobs and gobs of torque. Yank the pistons out, gap the rings wide and run it. Man this post got AJ long.
 

Richard Holdener just did a motorhome 440 with a single.
 

Richard Holdener just did a motorhome 440 with a single.


I have watched that one but 1 pull on a dyno isn't the same as a 5 mile pull over a mtn pass .

Your input on the build was pretty much what I envisioned.
Somewhere in th high 500s for torque is all I am looking for.
Elaborate on your comment about not messing around with an oil return.
 
oil return has to be a 45 degree or greater >3/4 inch tube gravity dump into the block (or collector) wherever the turbos is gonna sit. If it has to dump UP to the pan, it will have to be pumped as the oil gets pretty frothy leaving a turbo even if it is pressurized going in (at little volume as it gets a restrictor jet). come to think of it, I have never seen a turbo that low and how it gets the oil back to the pan. TT5.9 probably has more info on that than I do, but the Holset HX40 service manual specs a 3/4 inch oil return at a minimum of 45 degrees down.
 
I have watched that one but 1 pull on a dyno isn't the same as a 5 mile pull over a mtn pass .

Your input on the build was pretty much what I envisioned.
Somewhere in th high 500s for torque is all I am looking for.
Elaborate on your comment about not messing around with an oil return.
On my truck I have a garret large frame t6 remote mount. It’s mounted right where the stock muffler used to be under the bed just in front of the rear axle. The turbo itself gravity feeds an oil pump and I pump the oil back up to the pan. It was by far the hardest part of the whole system to get right. And when it wasn’t right it was really bad. Like oil filling the intake track, and a smoke screen out the back that would make James Bond jealous. It was very frustrating to get a pump that works. This is the pump I am using now and it flat out works.
http://www.turbowerx.com/Scavenge_Pumps/Exa-Pump/Exa-Pump.html
But it ain’t cheap. With a remote mount there are not really any options you have to pump it back and if I was to do it again id just mount it up high in the engine compartment and drain the oil the traditional way. Mine does work but For a while I was constantly chasing oil leaks and updating fittings to get it right. And I’ll say it again, if the tune is right you can pull any grade you want for as long as you want at moderate boost and it’ll be fine. My engine has stock hyperutectic pistons at 9.5:1, big ring gaps, and head studs on factory gaskets and has made as much as 705 hp at the tire on the big tune up, 16psi. I drive it daily on 10 psi and this combo has LOTS and LOTS of miles on it.
 
I just want to add one very important thing, I run a massive heat exchanger and a very large (1200hp capable) air to water intercooler with a 3 gallon tank on my truck and my intake charge temps are always in check. This is very important and I consider it imparitive to a proper tune. During normal driving my intake temps are always 8-10 degrees above ambient and pulling a grade, loaded in boost I see at the highest 150-160 degrees.
 
What about exhaust temps. How does one keep those in check ?
These old MHs have issues with ex temps already. I wonder if Turbo are designed to lower exhaust temps ?
 
What about exhaust temps. How does one keep those in check ?
These old MHs have issues with ex temps already. I wonder if Turbo are designed to lower exhaust temps ?

On diesels, EGTs are very important. Not so on gas engines. Important yes but not as critical. The size of the turbine housing and hot side plumbing as well as what material they are made of should be considered the critical factors. Very high hp stuff and or very high duty cycle stuff should consider stainless headers, plumbing, etc. I used factory manifolds and stainless exhaust tubing, and my turbine housing is iconel. Also the exhaust valves should be of high quality and materials, again stainless or iconel if a large duty cycle is being considered. I watched a test on the Chevrolet 8.1 a long time ago, where they ran the engine on a dyno at full throttle, full load, at peak torque, for 250 HOURS STRAIGHT! That test can be found online if you’re interested, it was eye opening to say the least. There are similar tests available that Ford has done with the ecoboost engines. In the grand scheme of things 6-8 psi really is very little and increases the load on the engine not substantially. Most factory parts are designed with a margin of safety and reliability and will not be exceeded by simply adding low boost from turbocharging. I’ve recommended books before on here and I’ll do it again. Pick up ANY book written by Corky Bell, any book on turbocharging with relation to sizing and building a system there is lots of information to learn that most do not consider.
https://www.amazon.com/dp/0837601606/?tag=fabo03-20
Start here.
 
To add, turbos are NOT designed to lower heat. It is the heat that makes em work. Heat is your friend and you want to keep it in the plumbing. If you have a problem with heat in the doghouse of a MH a turbo will not make that any better.
 
Which is why rear mounted turbos would be better in this application ....besides the space issue
 
Better is relative. Some aspects of the build will be easier and some aspects of a remote mount will present challenges. But it will be fun.
:steering:
 
If you’re not familiar with Nelson racing engines, you’ve got some catching up to do. Tom is pretty much turbocharger royalty in my opinion. Watch this video.
 
Honestly a stroker is a way better option. But, if you want to get a little drunk on the boost two T04 turbos with big A/R exhaust housings will work killer. No lag and instant torque on demand. 5 psi of boost would make a huge difference in performance. Blow through carbs are readily available at a summit racing. Oil drain back will be a big problem. You will need a pump to move oil back to the oil pan and even at that it will smoke a little. Use the extreme energy carb hat and stagger jet the carb which ever jet the hat points to. If you want to low budget a carb can be built for little to no money. Google the “hanger 18” carb mods. That’s my carb that article was written from. We did that carb in the mid 1990’s.
 
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