Thread: 350 Winnie 20' 1981 motor home

Tweet

10.200 427to525 truck block a 4.500 crank flat top pistons . small O port heads small hyd roller cam ... done .this will out pull any 350 out to a 383 . if you do not like that a 9.800 deck 454 to 496 flat tops hyper pistons cast steel crank . small O port heads small hyd roller cam would not be that much cost over a 383 for parts .

Originally Posted by pat mccarthy

10.200 427to525 truck block a 4.500 crank flat top pistons . small O port heads small hyd roller cam ... done .this will out pull any 350 out to a 383 . if you do not like that a 9.800 deck 454 to 496 flat tops hyper pistons cast steel crank . small O port heads small hyd roller cam would not be that much cost over a 383 for parts .

You know Pat.That M/H came with a BBC option.Want to venture a guess what kind of gas mileage I could get??.Let's say I beefed up a 4L series tranny with a stand alone programmer,changed from the 16.5 tire/rims to 19 or 20 tires/rims and change out the 4.10 rear end gears to 3.73's.I would have to check,but I think the brakes didn't change with a 454.It did have a dual rear wheel option for the 454.

Maybe you could tell me the truck/bus,etc years to look for a tall block.Been awhile since I looked at that.

How about who's kit to use for the bottom end??.

Hummm-you ever consider a road trip to beautiful snowy Roch,NY.I could show you all the sites when you bring by the engine.Like well,there is the snow and then there is more snow....and look now!!.There is a old guy called Gary in well..............who knew..........the snow!!.

If I where to change to 8R19.5 tires/rims and change up to 3.73 gears,at 65mph by the engine rpm calculator I use,it would be turning 2448rpm's.That is using a beefed up 400 tranny and not a 4L series O/D which by using the 400 it might be a better answer anyways.Question then would be could I build a torquer BBC tall engine that would start pulling there and would it suck a lot of gas because of that??.But there again with the current 4.10 and the larger tire/rims update, it would be turning 2691rpm.

This is the ref calculator I am using.

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

355 cu. in.
Carburetor: 600 vac secondary
Heads: GM L31 Vortecs,
Intake: Edelbrock Performer RPM Vortec
Camshaft: Comp Cams Xtreme Energy 268 , 224/230 of duration 0.050 (Corrected valve lift with 1.6:1 rockers is 0.508/0.512 in.)
Rockers: 1.6:1
Headers: 1 5/8 in.
Comp. Ratio: 8.75:1
MAX HP: 390 @ 6000
MAX Torque: 426 @ 4000

{{Taken from Ryans combo page}}


Here is a example of what you could close to do with your current engine, I would go a little smaller on the cam, a little less compression and use a roller cam to keep the torque number close to this and at a lower rpm.

Someone with a dyno sim could play with the numbers on compression and cams to get it narrowed down to a usable combo for your application.

I am betting with the right mix of parts you could still make 400 ftlbs at close to your crusing rpm at 65 to 70 mph.

I have no experiance with the load you wish to put on this engine...it looks like about 14,000 pounds in all, so I imagine the compression will have to be lowered to 8 to 1 or lower...I do not know.....

But with the right mix you can get 400 ftlbs or more I think and still not break the bank......step up to a 383 and I would guess at 450 ftlbs at about your current 65 mph rpm.......

I still say for about 2000 bucks you can do 400 ftlbs out of 350-355 no problem.

I would think once you went 383 and bought all the associated parts the budgett would be more than that..... possibly 3000 or less

I am sure pat could set you up with a mean big block towing engine that would smoke the tires on that thing for a good deal also.....

Not really sure what that would cost or what the other options you mentioned would cost........they all sound like plausable ideas to me.

Just boils down to how much money and time you want to spend on it and what makes you happy...........

5.9 6BT turbo Cummins can Pull down a House . Just Last Week I used our Service Truck to Pull Trucks hooked up to Loaded 45' Trailers off Docks stuck in 4 Feet of Drifted Snow that were Parked there for Days and Froze . Used a Heavy certified Chain and Pulled Like Crazy . The IHC 7.3 and T444's Diesels don't have that kind of Torque .

Originally Posted by 1gary

You know Pat.That M/H came with a BBC option.Want to venture a guess what kind of gas mileage I could get??.Let's say I beefed up a 4L series tranny with a stand alone programmer,changed from the 16.5 tire/rims to 19 or 20 tires/rims and change out the 4.10 rear end gears to 3.73's.I would have to check,but I think the brakes didn't change with a 454.It did have a dual rear wheel option for the 454.

Maybe you could tell me the truck/bus,etc years to look for a tall block.Been awhile since I looked at that.

How about who's kit to use for the bottom end??.

Hummm-you ever consider a road trip to beautiful snowy Roch,NY.I could show you all the sites when you bring by the engine.Like well,there is the snow and then there is more snow....and look now!!.There is a old guy called Gary in well..............who knew..........the snow!!.

i have a engine shipper door to door with drop gate very fair on price for shipping . back to a496 or 427 tall deck .i pick the rods .crank .pistons from a list of suppliers so if there s a deal going on one part or i like one over another make i buy the parts i like to use .then it gets balanced on a hines machine so it right when done . for gas i have i hard time thinking it going to great .but a 383 would work harder .. getting way past 400 QT with any bbc build is not hard.the last 525 i did was for a air boat were max TQ needed to be very low. has prop speed was a big deal . it would really push that engine was about @ 2000rpms TQ653 and max TQ 650@2500 HP500 @5000rpm looking at the cam as i have the card in front of me i would go abit smaller and use the small O port head so TQ should come in very good .that engine i used a 750 HP holley. guy s stop in tell me were tall deck are for sale . but i never wast much time with them .there good for a build like this . the 496 out of a short deck can get about the same numbers a 9.800 block may be hard to fine fast. i have heads and i know were a 427 block is

Pat,with all due respect and I am serious when I say that,the main goal is better fuel mileage.I take you suggestions to heart,but if I am not much farther ahead or the same with more power,why do it??.Correct me if I am wrong,but that leads me right back to a turbo diesel swap.

Originally Posted by 1gary

Pat,with all due respect and I am serious when I say that,the main goal is better fuel mileage.I take you suggestions to heart,but if I am not much farther ahead or the same with more power,why do it??.Correct me if I am wrong,but that leads me right back to a turbo diesel swap.

well you would have to work out price best bang for the buck but with 650 QT at 2500 rpm you use a over drive tranny . your not getting that with a sbc the big block is a bolt in .what about the diesel that not a bolt in what the mpg on it.are you going to get better MPG when your lugging a sbc ?

Well Pat while I am thinking about this,maybe Richard has got a program/formula to figure out what the gas mileage would be with you spec's on a tall block and my wt/final gear ratio/maybe wind resistance.I'm going to pm him and ask him to post on this thread.I haven't found anything on the net yet.

The stock 454 M/H's which are usually much bigger are in the range of 8 to 6mpg.Ouch.It would really suck if I went the route of a tall block and ended up there.

I do know that the M/H's are gas hog's.I do believe that given the size of mine,I can improve on that.

The thing is I am trying to temper the Hot Rod heart in me with the common sense of a M/H that I need to use over the road for my business and need to watch the fuel costs and I don't mind investing in that part of it.

So let me see if Richard has something to add to this.

Thanks Pat.

I don't know how readily available they are or what they are bringing, but how about a 6.0 or 6.2 SBC out of a salvaged wreck? Plenty of power & tq. and they get fairly good mileage running on 4 cyl. at cruising speed. My truck with a 6.2 - 403hp - 417 tq. is a brick @ 7500 lbs. & flat front end although not as much so as a M/H. I can get almost 20mpg if I keep my foot out of it. Pulling a loaded car hauler I get around 11-12mpg on short trips around the area. Haven't tested the trailer out on a long trip yet. SB with a 6 speed auto should be an easy fit.

How about going to the M/H dealers lots and looking at some of the give away 4-5 yearold late model stuff??

The issues(besides weight and brakes) that you will be dealing with---cooling, exhaust, linkage, trans and coolers, driveshafts, hubs and wheels---

Originally Posted by jerry clayton

How about going to the M/H dealers lots and looking at some of the give away 4-5 yearold late model stuff??

The issues(besides weight and brakes) that you will be dealing with---cooling, exhaust, linkage, trans and coolers, driveshafts, hubs and wheels---

I hear you Jerry.Thing is I own this and have a investment in it already.Trans and cooler is already covered with the current set-up.I am not pulling anything bigger than a 12' dual axle trailer.Really nothing.The build spec sheet I have I do think the brakes part of it is covered along with the trailer brakes.The size I have fits very well for it's intended use.125"w/b.The frame beyond just a M/H GM used for a number of different trucks,so I am not that worried about a class three hitch with load lever bars.Even at that,it would be over kill for what I am towing.I think to have to mod it for the utility use of it is where I have been with it all along.We have a tow vehicle for the drag race enclosed trailer and this would never be used for that.

Best part is the custom interior.You know mirrored everything.A single old timer's rolling play house.

Yeah-I'm just kidding.White Oak is planned.

OK---your not pulling you car ---

My 1984 1 Ton Chev crewcab with single rear wheels, 454, t400, 4:11 gears, 16.5 wheels--8 to 9 mpg towing 38ft chapperal 5th wheel trailer and pro stocker---buddies with duallies and non 5 wheel traillers got 2 to 3 less---

3300-3500 rpm at 70-75---had plenty of power/torque for the job

your wind resistance is what will cost you the most ---

Not to be disrespectful, but is throwing $10,000 at a 30 year old motor home in the quest of gas mileage really the solution? No matter what has been described, an engine/transmission/rear gear/wheel or tire swap is going to be $10K. Looking on EBAy, a 30 year old motor home is worth perhaps $4K.

Like Jerry says, looking at a later model unit might give you a better basis. In the late 70's and early 80's, Winnebago built some slugs....GM didnt spec the engine, they offered a chassis/drivetrain combo that winnebago choose to slap a body onto.....(you did say Winnie in your first posting).

Towing a dual axle enclosed trailer with anything will result in poor gas mileage. Think about an unloaded diesel pickup.....perhaps 18 unloaded on the highway is a reasonable all around figure.....some will claim more but they probably are not averaging over a long time. Load the truck up with a trailer, etc and it drops. Add a motor home body that pushes air really bad and it drops more. The second question is "will spending $10K to get 4mpg more really pay off in my time frame? The body is good for perhaps x years if it is really nice now. Will you drive enough in x years to pay for the mileage increase?

Another suggestion is to ask people who own similar rigs with a diesel what mileage they get....with a similar trailer. Big weight and big wind are'nt ever going to win any awards for mileage.

mike in tucson

lets chop it no need for welding just wood screws .some time ago i help some guy put a 455 in a MH did it at my shop pulled the403 engine out the front window i think a GMC look like a beer can on its side . he did use a holley pro jection mpg was about the same but more power to pass could of been better but i know it was not less