Predict gas mileage-A formula??.

[1Gary]

Darn it.LOL-well if the third time isn't a charm.

http://www.csgnetwork.com/automotiveconverters.html

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[kamenz]

Gary,just putting on studded snow tires reduces my mpg's by 5 mpg not to mention the crappy winter blend gasoline.

[LiftedAWDAstro]

Are you planning on towing an enclosed trailer behind your van as well? Now try to add in that weight, wind resistance as well as rolling resistance, cross winds, wet or dry roads, uphill, downhill, ambient temperature, humidity, elevation, fuel quality.....well, you can see that there would be no way in your lifetime, could you compute what a combo will give for mileage! You're not a young pup after all!

As you do the build, look at things that reduce rotational mass like light weight wheels, tires, aluminum driveshaft (from an S-10 maybe), electric fans etc. I know in my truck, I can improve mileage by 20% across the board with a wheel/tire combo in the 65# range. The 33's and steel wheels weigh 100# each. Problem is the tires are just a standard load rating and are not heavy enough for towing the camper with firewood in the bed. The truck was just too squirrelly.

[LiftedAWDAstro]

For the MH, you really need to look at diesels and get a 6 speed tranny with double overdrives. With 4.10 gears a diesel will be screaming with the TH400 tranny. A mild Cummins 6BT with around 450 - 500 torque would move the MH along nicely. You want the cruising rpm's around 1400 - 1600. You'll see 15+ mpg this way.

[1Gary]

Dean,I found a ring and pinion source for the Salisbury rear end that is in the M/H.They offer about the same ratios as the Astro vans have.So with a diesel I could get as low as a 3.23 gear ratio.The thought occurred to me to treat this swap the same way Peter did with the ZZ.Bread trucks have the same type of lay-out and maybe I could use a front clip/frame to mock up the swap and maybe not exclude a pipe lift to help fit it.The cool part about this is the bread trucks with 4 cylinder diesels use the same engine mounts as the 6's do.So it is either a stock O.E.M. part or a junk yard find for a bolt on.The diesels are heavy.1,100lbs.But the optional BBC front end has a wt rating of 5,500lbs.So I think that part of it is covered.A diesel site suggested a Dodge 47 tranny.The down side is they don't suggest a long run over the road.That you should stop after about 5hrs and let the tranny cool down.I have found out the torque curve on 5.9 diesels is really short as is the hp.So like you said,you have to watch the RPM's.I would have to find a crashed donor for the engine/tranny.


On the flip side of that with a tall deck 427-I know a builder that said with a stroker/long rod combo I could easily match the torque and beyond which would be a true bolt in because of it being a bbc option.I knew that most people don't even want those for performance applications.But if built right with small intake runners and small chambers,they are a torque monster.That in used with a gear change and a 4L80E stand alone might be really nice.I think I could bring that home as a long block solely because it isn't a highly wanted engine for $5,000 or a little less.

I have convinced myself there isn't anything to be gained by stroking the 350 to a 383 that is in there.The costs benefits isn't there.

Peter-thank you for your input on the newer style engines.I don't think that is a viable answer for me on this project.I knew about those and had excluded them.

Soooooo it kind of leads me back to the title of the thread.Which one and what would be the outcome??.I am leaning towards the diesel just because of what they are known for.

But first and foremost is my beloved Ole Yellar project.So I have still time to try to learn more about the M/H possibilities while I work on that. Just got to get the M/H in somewhat shape for the 2011 camping season.Not done,but usable.

[Kidhauler]

Gary for what your looking at spending on rebuilding a old motorhome and doing a major engine and drivetrain swap have you thought about just buying something newer. Try going to the local rental place now that your in the dead of winter and see what they have in the way of used conversion van motorhomes. I have a place at the end of the street from where I work and they seem to blow out a bunch of 2-3 year old units every year.

They seem to be around $25-30k for 2 year old unit with a v10 ford in it. By the time you rebuild a motor to what you seem to want you will have 7k in give or take a few bucks. then you will need a trans that will be $1500 plus a rebuilt rear end for close to another 1000 by the time a shop sets up a decent posi. So now on a shoe string budget you are in for around $10000. At that you still have not touched the inside of the body of the vehicle. If you need to redo the propane system thats going to be expensive. I am sure with the economy in the states if you spent some time on Craigslist you could find a decent unit less than 10 years old for $15-20k. It would probably be alot easier and more reliable than rebuilding a old unit. Plus at the end of the line you have a newer unit that should hold its value decently as it has depreciated about all its going to for a while. I know that building your own custom unit is fun but at the end you it will not be worth much if you ever need to sell it.

I am not trying to rain on your parade just giving a different suggestion. Have you thought about getting a travel trailer since you will have a nice v8 van to pull it?

[1Gary]

Hey KH,nice to talk to you.Been awhile.Yeah I looked at that and decided to hang with what I got.This unit has a bunch of things I want and need that newer units don't.I have money in this one and I don't owe anyone for it.At my age being semi retired what I need to do is own what I have paying as I make it into what I want.It is going to be used in part for my business to travel and live in.Yearly it mostly won't see anymore than 3,000 miles.That is travel south in the winter and north in the summer.The gear set I found is just short of $300 and I don't really care about posi.

Thanks for your help.

Gary for what your looking at spending on rebuilding a old motorhome and doing a major engine and drivetrain swap have you thought about just buying something newer. Try going to the local rental place now that your in the dead of winter and see what they have in the way of used conversion van motorhomes. I have a place at the end of the street from where I work and they seem to blow out a bunch of 2-3 year old units every year.

They seem to be around $25-30k for 2 year old unit with a v10 ford in it. By the time you rebuild a motor to what you seem to want you will have 7k in give or take a few bucks. then you will need a trans that will be $1500 plus a rebuilt rear end for close to another 1000 by the time a shop sets up a decent posi. So now on a shoe string budget you are in for around $10000. At that you still have not touched the inside of the body of the vehicle. If you need to redo the propane system thats going to be expensive. I am sure with the economy in the states if you spent some time on Craigslist you could find a decent unit less than 10 years old for $15-20k. It would probably be alot easier and more reliable than rebuilding a old unit. Plus at the end of the line you have a newer unit that should hold its value decently as it has depreciated about all its going to for a while. I know that building your own custom unit is fun but at the end you it will not be worth much if you ever need to sell it.

I am not trying to rain on your parade just giving a different suggestion. Have you thought about getting a travel trailer since you will have a nice v8 van to pull it?

[LiftedAWDAstro]

Gary, why would you build a 427 BBC to put into your MH? The topic of this thread is all about mileage. At best you won't see more than maybe 10 mpg with a gas engine. Newer MH's with the Ford V10 chassis are getting less than 10. A diesel is the ONLY way to get decent mileage in a heavy vehicle. Just by design a diesel is 30% more efficient give or take a little. If you are in a hurry to get to 65 mph then the BBC is the way to go but if you simply want mileage and are spending upwards of $10k, a diesel swap would be the cat's ass!

If you want more hp and tq to move the MH along easier, why not build a nice 350 and put a nice 4L80E tranny with stand alone controller. Then put the extra cash into the interior.

[Kabey's Van]

Here are some numbers to consider Gary.
My last build was a mark IV 454 taken .60 over to 468 c.i. in a 1977 Chevy shortbox stepside, 4800lbs truck.
It had a 750 Edelbrock AVS carburator which was a bit small, an Edelbrock 2.0 aluminum intake, iron heads with about an .850" stroke at the valve stem. Four bolt main block, Scat forged crank, Scat lightweight h-beam forged con-rods with Lunati forged 9.5 to 1 cr pistons and long tube 1 7/8" primary, Hooker headers. Lunati roller cam with roller rockers, March Performance serpintine system, Flex-a-lite dual electric fans with some aluminum dress up parts, water pump, P/S pump, valve covers etc. to make it look decent.
MSD alternator and ignition with a few other go fast goodies. It produced over 500 horse with 550 ft./lbs of torque all in before 5000 rpm. It had a TH400 with a stage 2 shift kit, TCI Street Fighter 2200 stall speed T/C and a 4.11 posi. My goal was to have a better than 1hp/10lbs. ratio, which was achieved. The cost, $12,000 just the rebuilt short block was $2500.
My milage, , was 2km. per lt. In Floridian terms that works out to 4.7 miles per gallon. If I started to have some fun and totally disregarded the milage, I could easily cut those figures in half to 2.35 mpg.
So that makes that LS3 and LQ9 look pretty good. What was your reason to bypass these two power plants, they are proven engines?
If milage is a deciding build factor keep the cubes down and play with your gear ratios, a nice stout 350 with a 4 speed automatic will be easy to build, and repair further down the road.





Peter

[1Gary]

Peter-you can drop the new style engine out of this project.Ant going to happen.Peter's ZZ got 13mpg over the road.Hummm.

I told you the tall deck 427 stoked with long rods could be had for just short of $5,000.Maybe you missed that. #-o

[Kabey's Van]

I did miss that, sorry Gary.
I too looked into a 427 TD when I did this 454 build. I found that there are not too many after market parts available. You need to use spacers on a SD intake manifold or you have a very limited selection of TD manifolds. Also, try to find a distributor at a decent cost. Stock ones won't fit, there to short.
I do agee you can make gobs of torque from these engines but if you are so concerned about milage I would steer well clear of this particular engine or any big block for that matter. Granted it will last a long time as this motor will not have to work very hard and if my memory serves me right some of these blocks were high nickle content.
I'm sure you'll keep us posted on the build, how's the new digs working out?

Peter

[1Gary]

If your talking about the new shop.I am still unpacking and setting up.I am not a pack rat and yet I still don't know what all this stuff came from. #-o

[Kabey's Van]

I moved two years ago. When I moved out of my place in East Sooke I had all this "good stuff" I needed to put into storage for a while until I could find another house. When we bought our house and started moving in, all of this "good stuff" seemed to be junk all of a sudden.
You'll have to post some pics of the place some day.

[Kidhauler]

If your only planning on 3000 miles a year gas mileage is not as important as what is the cheapest engine to put in. If you spend a extra $10000 to put in a diesel to get 5-10mpg better you will never make that money back in gas savings. With the low miles per year driven it will never pay back the money. You would need to drive it for 30 years at that rate to pay the difference in install price. Unless you plan on. Camping at 100 you might be better off with a cheap and cheerful 350 build making a little over 300-325 hp. You will only get 12mpg but you will save a fortune on the build and will live long enough to enjoy it.

[1Gary]

Well my mother in Florida this past Dec just turned 90 ..........so you just never know.

Don't think a diesel conversion would be $10,000.

If your only planning on 3000 miles a year gas mileage is not as important as what is the cheapest engine to put in. If you spend a extra $10000 to put in a diesel to get 5-10mpg better you will never make that money back in gas savings. With the low miles per year driven it will never pay back the money. You would need to drive it for 30 years at that rate to pay the difference in install price. Unless you plan on. Camping at 100 you might be better off with a cheap and cheerful 350 build making a little over 300-325 hp. You will only get 12mpg but you will save a fortune on the build and will live long enough to enjoy it.