# Direct drive SBC

Discussion in 'Chevy' started by Natty Bumpo, Oct 24, 2011.

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1. Oct 24, 2011

### Natty Bumpo

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Began work this wweekend assembling an engine to test the concept of running a direct drive power plant. This engine is for bench running only. Will keep all you posted.

Nathan

2. Oct 24, 2011

### Jay Kempf

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Please report back on props, RPMs, static thrust. Inquiring minds wanna know how you make out with that. Are you stroking it to move the torque available to lower RPMs?

3. Oct 24, 2011

### Natty Bumpo

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I do plan a stroker as well as boring to maximum allowable dimension. In reality this will be a while in doing. Talks cheap, it takes money to buy rum! Props are my greatest hurdle, the rest is not a big problem.

4. Oct 24, 2011

### Jay Kempf

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I don't think prop design is a big hurdle, at least a prop good enough to prove your design point target. There is probably a way to load the engine and get a basic static thrust number to start getting a ballpark. You can get a used ground adjustable prop or a prop that is run out that would be adequate for testing and then sell it again to the next guy after you have your data. I am guessing you are going to need multiple blades on a small diameter spinning at a bit more than standard LycoCont RPMs to make this work. It really boils down to what speed are you targeting. Just noticed you are in Bristol. I am in the People's Republic of East Warren in the hear of the hippie ski bum belt. Too funny.

5. Oct 25, 2011

### skeeter_ca

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What does SBC stand for? What engine are you running?

6. Oct 25, 2011

### Jay Kempf

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Small Block Chevy

7. Oct 25, 2011

### Vigilant1

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Are you planning any provisions for prop thrust loads and to reduce bending moment on the crank, or are you just going to beef up the crank (radius, hardening, etc) and use the stock end bearing?

8. Oct 25, 2011

### Autodidact

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Just food for thought, if you're already on top of this then disregard:
The cooling of a SBC can be improved; it was found necessary to do this for NASCAR racing and was also necessary by the factory for the 400ci SBC. It appears to involve drilling holes in the gasket surface of the heads to route more coolant to the area between the two middle exhaust ports which are right next to each other and tend to cause a hot spot under continuous high power settings. I'm not suggesting that you try this out unless you do considerably more research than just reading the articles below.

From Crankshaftcoalition.com, and note that while most of this is for the 400 SB, it does improve the cooling and could also work on "non-siamesed" block engines if done correctly, and that's where more research would come in,

I also found these articles:

Drilling SBC Between Center Cylinders for Cooling?? - The Dart Board

http://www.chevyhiperformance.com/techarticles/90678_small_block_400_cooling_tricks/index.html

9. Oct 26, 2011

### Natty Bumpo

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I intend to use bell housing and a short shaft to a bearing on the housing. Similar to an Olds conversion described in another thread. For test purposes I will not be inverting this engine. I will be using an iron block to test, and the hope is to see simply how much thrust I can generate at around 2800 rpm. Others will surely suggest that I should spin it faster, but I disagree. My thoughts are to see if I can swing a respectable diameter prop with a direct drive. Folks all over this forum are very good at stating all kinds of reasons why this won't work. To my knowledge none of them have tried.

This experiment is not intended to show that an auto conversion is better, because it's not. The HP to weight is ghastly. As far as an aircraft application, the performance numbers should put me square in the early 1920's. The win is when overhaul time comes.

Thinking in my minds eye of an 88% Ford 4AT......

10. Oct 26, 2011

### RJW

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I’m interested. Let us know what you get out of your motor. Here’s a pic of my inverted junkyard 305 test anchor. It should have been running weeks ago but a move and more work happened. Should have it smoking and shaking in a month or two once I’m settled at the new place. And yes, at a mere four pounds per horsepower this 200K-mile mule will easily outperform any Lycoming or Continental.

Rob

11. Oct 26, 2011

### Natty Bumpo

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Nice to see I am not alone. I truly believe that if we are willing to fly aircraft suited to these engines, then we have the long sought awfter reliable autopo conversion , within limits of course.

12. Oct 26, 2011

### Richard Schubert

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Gary spencer has been flying a ford powered longeze for some time now.

13. Oct 27, 2011

### Autodidact

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I have a book titled How to Build Big-Inch Chevy Small Blocks :grin:, it's a 20 dollar one that you buy at B&N and probably designed mainly to excite the gear heads that look through that section of the store, but if it is accurate at all then there is a dyno chart from a 406ci small block with stock iron heads and a "short duration" camshaft that makes 260 hp @ 2800 rpm. If true and applicable to a 350, then that would be a potential 225hp. I think the power to weight ratio would be similar to an early Wright J-6, just right for a Travel Air 3000 or something. I don't see why it couldn't be done and I hope you guys show that it can be. If you can develope a way to build up a reliable DD v8 conversion using easy to obtain/make parts, then the next obvious step would be to start designing airframes specifically for these engines.

Did Wittman make his prop shaft from a cut-down automotive rear axle shaft?

14. Oct 27, 2011

### wally

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Hi,
a guy named Roger Flower or maybe Flowers used a direct drive Chevy LS1 on the front of a plane he built a few years ago. He was our EAA chapter pres. (Memphis) for a while. There is a story about it in the EAA magazine but I will have to look for which one. It is probably available on-line at the EAA website. He called the the plane "junkyard dog". The engine was "as removed" from a Camaro. He didn't do anything to it other than put new spark plugs in it. He got the transmission with it and later sold it to reduce his cost.

He used a plastic adjustable pitch prop if I remember correctly and drove it from the flywheel end. He used the car computer. He asid the hardest part was straightening out and figuring out what of the engine wiring to use. He got the complete wiring with it. He tried various radiator locations but finally got it to stay cool. It was not the most aerodynamic looking plane, kinda blunt and only one place. Part of the one-place reasoning was to limit a passenger exposure to something going wrong.

It flew pretty well and he took it to Oshkosh.

Wally

15. Oct 27, 2011

### Toobuilder

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There is also a replica P-6E running around with a stock 350 HO crate engine, prop bolted directly to the flywheel. I spoke to the builder and he reported that it flew pretty well, but he wished he had a 500 inch Cadillac in the nose.

Personally, I think there is great promise in auto engines as long as one does not expect them to be superior in performance to existing aircraft engines.

16. Oct 27, 2011

### RJW

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Yup. Choose the engine. Accept its strengths and weaknesses. Build an airframe to suit.

Here’s a concept that might be fun: Gross weight about 1500 pounds. 100 square feet of wing. 200HP motor.

Rob

17. Oct 27, 2011

### Toobuilder

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This is all fine and well, but the day of the SBC is past. It is a 60 year old design after all. The latest generation (LSx) is a vast improvement in architecture, and commonly available in aluminum. Even the common as dirt 5.3l truck engines have a better BMEP than the equivalent SBC at a lot less weight.

You are going to spend the same amount of time working on the supporting subsystems (drive, cooling, induction, etc) so you might as well start with the superior foundation. JMHO.

18. Oct 27, 2011

### Autodidact

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I hear it's a great engine with a high nickel content block, already set up for low rpm torque, and only slightly heavier than a SBC. The newer LS engines are nice but already they cost a bit more and you have more complex systems, the older technology is good for low cost and simplicity and I'd be willing to put up with the slightly lower efficiency. But I like the LS, too. One small problem with the LS is that one of the bell housing mounting holes is missing on some of the blocks, maybe that's not a big problem, though.

19. Oct 27, 2011

### Jay Kempf

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The Northstar is a great engine but the beauty of the first post is the idea that you can build a motor out of the cheapest and most available parts. The SBC is the most prevalent series of motor parts out there. Not light but very available. There are more tuner parts out there for less dollars than any other platform. I think the Northstar is significantly heavier than a light 350 build. All that cam and fuel injection gear adds up.

The Northstar is very similar to the Porsche 32v V8 of the mid 80s. It is really similar in overall layout. Many of those 5.0 liter engines are available and they do have the cooling capacity and they do have a long life aluminum block and heads and lots of tuner parts but they are not as cheap and available as a SBC from the junkyard for $100 and then$500 to put it to zero time if you have the desire.

There are also a ton of 4.5L 16V Porsche engines out there. These things can be had for less than \$1000 and mostly will run hard for 300K miles with normal maintenance. I have been beating on one for 15 years and haven't killed it yet. I have another one on the stand. I get offered them all the time for shipping.

20. Oct 27, 2011

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