302 for airplane

[dgonzalez]

im using a 302 for my airplane engine, but heres the problem. airplane engines make max hp at 2500-2700 rpm, because if you exceed this speed the propeller tips will be moving at the speed of sound (340 meters/sec). usually when auto engines are used for aircraft they are fitted with PSRU's (propeller speed reduction units) which have a 1.5-2.2 ratio on it, so the engine can spin 5000 rpm max while turning the propeller at the necessary ~2500 rpm. These psru's are uhh...sketchy eyeballed contraptions...usually. and they weigh close to 70 lbs. Also I'm not too fond of the idea of running my engine at 4000 rpm cruise for over 2 hours.

So I'd like around 300-350 hp. Not sure if aluminum blocks are available, but I definately will be using aluminum heads and other lightweight components where available. Hoping to spend less than 8k.

My question is: how can I move the power range down from 5500 rpm max hp to as close to 3000 rpm as possible?

Bore and stroke?
Different cam profile?
Forced induction? (this is more weight and complexity so probably not, although this keeps your power levels high when air thins out above 8,000+ ft)

and if you're wondering why i dont just use an airplane engine, the 200 hp model is 22k and IO-540 (300hp) is 30k! and these engines haven't been changed since the late 50's...

 

[dgonzalez]

ah well i guess i'll show you what kinda plane it is..

www.mustangaero.com

yeah it's called a mustang also

 

[Mustang_Punk]

you are rad!

 

[powertrax91]

why don't you use a turbo diesel? it makes lots of power at low rpm

 

[Mustang_Punk]

don't they weigh a ton?

 

[HISSIN50]

I'd be pretty confident that Jrichker is going to have some ideas for you. He might see this in the morning.

Good luck.

 

[TomCat]

Small turbo! Can you run aviation gas in it? Maybe N/A with an insane compression ratio!

lol... project sounds badass, good luck with it.

 

[dgonzalez]

although I want to get rid of the 2:1 ratio unit, I still need an external unit to attach the propeller to. crankshaft bearings dont exactly like being the link between the propeller and airplane. i just want the engine to be most efficient in the 2500-3000 rpm range.

 

[cbarr300]

well, as far as cams go I'd say that u want a close to stock one....as well as the intake...If I'm not mistaken U can't really beat the low end that the stock equipment puts out..I could be wrong on that statement.

So if you want to get an engine to perform better in the lower rpms wouldn't you want heads with a smaller port? Just a question I'm wondering. My figuring is that if you want an engine to do better higher up then you get higher flow heads....so if you want it to do better down low you would want ur head to be more restricted, right? Or am I wrong in this thinking? just curious.

I think that the best way for you to go would either be more cubes or forced induction pullied to start making boost earlier on in the rpms. The more cubes it is...the less you gotta rev it to get the same power numbers granted VE is about the same

interesting project though, good luck with it and keep us updated

 

[poneypower89]

mate it to a t-5 and leave it in 5th


lol, but in seriousness.. if ANYONE is gonna know it will be J.

I have a feeling you will end up HAVING to use that 1/2 converter...

so, here is my suggestion.

Do exactly the opposite of what you are attempting to do. Build the engine for extreme HIGH RPMS. De-stroke it, strong valve train, etc.. make it able to spin at 9k... that way, when your spinning at 4k for two hours it wont seem so bad.

 

[Daggar]

Honestly...

I don't think a small block v8 is going to give you what you're looking for in an aircraft that size.

You want to make 300 hp at 3000 rpm and that fine. But you will find it EXTREMELY difficult to do without building an motor capable of a LOT more than just 300 HP and you'd likely end up having to use forced induction.

It's cake to generate 300 ft/lbs of torque with these motors. What you're asking though... I just dont this it's suitable; particularly for the cost of what the whole thing will weigh.

 

[srothfuss]

Why not just use a regular engine designed to run (and fit) on the fuselage. You can buy them used and overhaul or rebuild them for much less than new. Especially if you start hanging out at Fly-In's and Airshows in your local area. The reason I say this is the instant you throw the switch to crank the propeller with a giant V8 engine the plane will:

1) either flip over
2) the chassis will twist and you'll break a motor mount

I'd also like to know what kind of plane you are building. Something from VAN's? GlassAir (my favorite) or completely uniqe? Now that I am done stating my opinion...


Yes there is an Aluminum 302 block. It's called R302 (?) and you can find them on the internet from a company in Texas for around $1,000 IIRC.

 

[Mr. Rustypwnz]

what about like a gsr b18 vtec engine? really light, and it will go to 9k with out even thinking about it. it would get off the ground alot easier also.

 

[MYSTICSVT]

Sorry I don't have any input for you. But, as a student pilot I'm subcribing out of interest.

 

[MikeC]

Looks like you will need some major modifications to get a V8 into the nose of any of those planes. The front cowling is made for an air cooled flat 4 or 6 cylinder. Not to mention the extra weight will throw the balance of teh whole plane off. The reasons the other plane engines have not changed sice the late 50's is they are dead reliable. I don't think I would want a supercharged 302 powereing my plane at 20,000 feet!

 

[JChalfan]

First off, I'm no airplane expert, but here's my thoughts.

Airplane engines are really expensive for a reason. They have things like dual (seperate) magnetos for the ignition system. That way if your ignition fails in the air, you can just switch over to the other magneto and keep on flying. Also, air cooling makes a lot of sense when you're... well... flying through the air. A liquid cooling system seems like another system to fail, not a good thing on an airplane.

I also noticed that the plane you are talking about is an aerobatic plane. I don't know how a 5.0 would respond to running upside down. You might need a dry sump oiling system or something...

The little quirks that most of our 5.0's have from time to time are annoying in a car, and deadly in an airplane. I would suggest sticking with an airplane engine, and living to tell about it.

Just my 2 cents.

Jeff

 

[8950HO]

Sounds like a bad idea.

 

[BlackVert]

sounds like an application for a kenne-bell. those put out lots of torque in the lower rpm ranges.

 

[MYSTICSVT]

Automotive engines have been used in aircraft for many years. I used to work in the parts department at a Subaru dealership and we sold plenty of those engines to people building custom planes. I see no reason why a 5.0 wouldn't make a good plane engine. Dimensionally it's the smallest and lightest V8 out there. And they are very reliable if maintained. I think I'd build a 347 stroker with Edelbrock Performer heads and intake with a stock camshaft and a Kenne Bell on top. That oughta make 300 HP @ 3000-3500 RPM.

 

[jrichker]

I spent 11 years as an aircraft mechanic & 8 of that as a FAA licensed A&P. Believe me when I say, the 5.0 engine is not what you want in that particular experimental aircraft. You will never get the CG in limits, even with an all aluminum block & heads. You would need a reduction gear assembly to ger the prop speed down to reasonable limits. These are commonly found when automotive engines are used in airboats.That will add more weight to the engine, making it even harder to get the CG anywhere near the center of lift.