Small block Chevy Ideal Setup

What do you all think the weight of a Small block chevy (350) with a Iron block, but aluminum heads and an IVO prop, also, What kind of instalation issues might we forsee using this setup?

 

Heavy. Low power output if it's direct drive. Do a search on this site for small block Chevy conversions, or "SBC." Lots of stuff here. It's not a simple thing to do.

Dan

 

Weight is very close to 425 pounds runnable but not including flywheel, prop drive, motor mount, or cooling. Add weight of Ivo prop. Expect around 200 to 225HP for direct drive. Add 80 pounds for a gearbox for an additional 75HP. Politely ignore those who say 6 liter V8s of any (affordable) kind will make a reliable 400 or more horsepower. And as Dan said, do a search here. There is a lot of stuff on the subject.

What are you working on? I am designing/building for SBC power. I live in KCMO.

Rob

 

RJW, how much does your bell housing weigh? I would like to get an idea of how much a direct drive would weigh if it uses the bell you have, a lightweight flywheel, an auto bearing housing, and a custom made shaft.

The reason I think the auto bearing housing would work is because in a car, it would have a constant radial load of about 1000 lb centered on the lug bolts. This is outboard of the outer bearing race and the inner race is about the same distance away; so that it has to push up with a 1000 lb also. This 1000 lb load will be on half of the race, and about 70% of it will be on the middle 1/3 of the race. If the constant propeller thrust load is as much as 700 lb, it will be distributed evenly all around the race instead of half and the load will be about 1/6 of the load when used in a car. But the speed will be doubled, at least. Still, in a car, these bearings will last about 3000 hours. I think you could get about a 1000 hours use in an airplane; even if it were only 300 to 500 hours they only cost about $150.

 

AD,

I’m a little embarrassed to admit that I didn’t weigh the thing before I bolted it to the test motor. Guessing from my admittedly poor memory, it must be at least 20 pounds. I don’t think a stock aluminum manual transmission housing weighs more than about 10 pounds. Next time I’m at the other place I’ll pull the housing off and weigh it.

I’m sure the wheel bearings would work fine. Who cares if they only last 300 hours? That would be plenty durable. The motors probably won’t last that long anyway.

I haven’t done any building in about three weeks. I’ve been wasting too much time obsessing on race plane ideas that will never be made actual.

Rob

 

I bet it would weigh no more than 45 lb. The custom made parts would be the hard part and potentially expensive as well; it might be easier to just do this (as PTAirco has pointed out a couple of times before):

: Rotator Reduction 1.53:1 Aircraft Airboat Reduction



They want $1695.00 for this 1.53 to 1 ratio and they advertise it as an aircraft ratio. Weighs about 60 lb. At 4200 rpm, that's 2745 at the prop. These things are splash lubed, so I have to wonder how they will do droning on for 2 or more hours. They use a special oil that some of the airboat guys call "green snot" - they say that you have to boil it or it takes for ever to refill the box - must be thick or something.

I'm guessing 560 lb including radiator for a 285 hp engine, not too bad - 1.97 lb/hp.

 

I have yet to start on my build. I live near the Legends. I plan to use a 383 stroker that's in a friends garage. I don't plan to go for all out proformance but something that I understand. I am interested in seeing what you have done so far.

 

Streff, I am restarting building so don’t have much to show. I started one “finalized” version of my two-seat tandem design but have since thought of ways to make it simpler and more attractive. I got somewhat further on this version than what you see in the pictures but have since abandoned the work. All was not lost however in that I learned quite a bit about making metal airplanes (i.e. I made a load of very helpful mistakes that will not be repeated in the next version). I will start on the new “finalized” version in a few weeks.

The motor stuff for airplanes I have been working on is an inverted, direct-drive SBC. The test motor is a worn out 305. A 383 is a great choice for a simple and cheap motor. It is what I will use.

I would be happy to show you what I have and talk airplanes and motors. Are you interested in building a metal plane? If so we could help each other out.

Rob

 

AD, You are probably right that a cheap, 65-pound airboat gearbox would be best. If a direct drive comes in at 40 pounds then the additional power and thrust made possible using gears would easily make up for the extra weight. The argument for direct drive comes from expense and simplicity. But at $1700 for gears the direct drive loses some of its luster. And again, the durability of one of these boxes would probably be fine for the kind of use I would put it to.

The gear grease: 120W gear oil? That stuff stinks (I mean really smells bad) and is thick as peanut butter.

Rob

 

You really can't beat that Rotator gearbox price, whether you are working on a custom direct drive system or a PSRU. It hardly seems worth the effort. Unless of course,going your own way is what you really want to do.

 

...IF (big "if") it will survive for hours on end at maximum output with simple splash lubrication, it still does not have provisions for a constant speed prop. And, it's another 65 pounds on an already porky powerplant.

Get a few thousand hours of aircraft use and I'll be more enthusiastic.

 

And herein lies a problem, when there has been what seems like a reliable prop reduction, it has always been very expensive; Geschwender, EPI, Bud Warren's Geared Drives, etc. Also, they seem to be mainly just the reduction and no accessories, really. What is needed is a relatively simple and inexpensive and PROVEN kit to convert a small block Chevy to a reliable, if somewhat heavy, aircraft engine. In my mind, and many other folk's as well, the whole point of using an auto engine is to save money.

I think there is an opportunity for someone to sell a complete package to convert an SBC. If the whole thing could be bought, including the prop drive (direct, most likely, since it represents the simplest, most reliable, and least expensive engineering solution), accessory drives including dual distributors (solid state, if you like, but still nice and simple and cheap), dual alternators with at least one driven direct off the crank, and a direct drive coolant pump, and a radiator - in other words a complete system - for no more than $3000, I think it would be very sucessful. And if the Rotator gearbox can be sold for $1700, then $3000 for a direct drive with accessory drives should be possible.

The mythical "cheap auto conversion" doesn't really exist, but I think it could - with a relatively small amount of engineering and manufacturing know how.

P.S.
As far as the Rotator box goes, if someone could replicate the old Army Air Force "50 hour test", where the engine was run on a ground based test stand at 100% power for 50 hours straight and get it to pass, it would be very helpful to anyone considering using one for an aircraft. But it would have to be independent of the manufacturer, and it would be somewhat expensive and involved, I mean, how many crews would it take to run the thing for 50 hours non-stop? How much would it cost to build a test cell? Even if enough qualified people volunteered, I bet it would still cost $15,000 or more just to do the test.

 

Hey there RJW,
This is interesting to me..I've toyed with the idea of building a chevy for airplane use for close to 15 years using one of the aluminum racing blocks as the foundation..I still have a couple dozen books on chevy small blocks (and big blocks) so I know a little bit about them. I've rebuilt a couple when I was younger. Anyway, I still like the idea and I still think a guy like you (or me) could end up with a practical and reliable setup that delivered plenty of torgue and HP. One thing I figured out a long time ago was that I needed as big a cyl bore and as much stroke (4" or slightly more) as I could get...and some of those GM aluminum blocks intended for racing were perfect for that. In effect I would be using GM performance parts to build me a very torguey, very strong truck engine. And I was also leaning towards direct drive and inverted dry sump setup. But I'm completely open to upright and gears too. I think that gearbox for airboats would probably be pretty rugged. I've seen these guys in these airboats and it looks like they routinely get run pretty hard and continuously to me! I started on an all wood airplane intended for the 6 cyl lycomings or continentals for power, but stopped working on it a while back. Now I'm thinking seriously again about it, but I'm thinking if I'm going to spend the next few years working and spending money on this I might as well build what I've always dreamed about....You only live once right?....Anyway here is my idea. It seems ambitious, but I realized it really wouldnt be any more difficult than what I have already started...just a little more expensive, so I'm actually getting serious about it at this point...It would use a pair of chevy's for power..either a custom build up as I mentioned or maybe on of the newer Chevy LS series of engines.
This is a rendering of the 3d autocad model I've drawn. I've posted it elsewhere on here recently but don't have a clue whether you might have already seen it. Take care and would enjoy hearing more from you...You think a lot like me.
Eric
View attachment 14874

 

One thing though...I also noticed it looked like no easy way to get a constant speed or controllable prop on that particular gear box and I would definitley need controllable props

 

There are some gear boxes available with the prop governor/controller etc, but holy cow are they ever pricey!

 

oh I forgot..This airplane would be all wood and some composites

 

AD, I’ve had the same thoughts. A simple direct drive conversion package should be a winner. It really doesn’t seem difficult to put together a cheap, reliable, 500-hour-durable, 225HP package weighing less than 500 pounds. But would anybody want it?

I think most designers and their potential customers kid themselves. They are in love with the idea of 400HP. They fool themselves into thinking it is easy and cheap to get 400HP because that is what the magazines and Detroit tell them. Then they kid themselves further believing it should be easy to get that power to a propeller. It doesn’t matter that the goal of cheap, reliable 400HP has never been realized. It is what they want.

In order for a 225HP package to be successful you’d have to convince people that it is cool. I was talking to a friend who is interested in selling stuff for airplanes. I showed him the inverted direct drive motor. He told me that nobody would buy it because people who love V8 engines love upright V8s, not inverted ones. He is probably right. I guess the best chance of selling the idea of 225HP is to get a few examples in the air. But I’m not even sure if this would work. Folks seem to prefer marketing hype to actual things. It would be tough to sell 225HP when there is attractive, 400HP fantasy being tossed about.

Ok. I’m done with my ignorant marketing rant. Sorry. I’ll go back to airplanes and motors. Besides really knowing nothing about sales, I’m not really interested in selling anything.

Sorry. One more thing: I like the idea of a 50-hour test to help convince skeptics. But you are right. It would cost a ton of money. It would cost more than $3000 just for the gas! Since this is about homebuilt airplanes we will be forced to do our testing in the air (not that it bothers me really—part of the fun actually).

Rob

 

Hi Eric, I’ve seen your model. It’s very cool. Keep working on it. It would be great to see your concept fly.

If you understand truck motors then you are on the right track. Remember the old dump trucks? Gas motors with steel cranks and 4-bolt mains making 250HP and gobs of torque? They ran at 4000RPM all day long for 50,000 miles. Build one of these using aluminum parts and you’ll have it.

Bigger is better. But watch out for price. Stroker motors with race blocks will cost a lot of money. Try to stick to as many stock parts as possible otherwise you will end up in an engine land where a pair of O-540s will be a better buy. We wouldn’t want that to happen. It would really mess up your beautiful design!

I know very little about CS props. It seems they will be expensive no matter what. But really I am ignorant on the subject. I have not looked into them much at all yet--eventually though.

Nothing wrong with wood and composites. I just happen to be a metal guy. I simply like metal. It is what I enjoy working with. There are people here on HBA who know about composites. Be sure to consult them. And be sure to understand your structure.

Keep at it!

Rob

 

If I have read the Dino charts right, with about $1500 worth of upgrades (cam, crank, carb), a standard 350 can be stroked to 383 ci. and put out about 250 to 275 hp at about 3500-3700 rpm. Would it sell??? probably not. Why? Because most props are built to run at about 2700 max. but with a little shorter prop, we could run in this power range all day long. The small block would hardly notice at all. This is my understanding of the matter, but could be wrong. Are we going to put 400 hp to the prop direct drive?? HELL no, but would it be a reliable, cheap way to put 200-275 hp in your EXPERIMENTAL (i think we forgot what that means) airplane?? HELL YES!!

 

xxxx