Type4 Camshafts for low RPM

[Wreck]

just link to a nice picture .

http://www.philskr2.50megs.com/images/belt_drive_fitting_1.jpg

[Anatolviper]

Just curious:

whar RPM?
what fuel?
what altitude?
boost?
adjustable fuel-air ratio?
cooling setup (cowlings?)?
carb or injection?
what temps?
twin spark?
service intervals?
oiling and fueling?


RPM cruise 2700-3000
fuel 92-95
up to 4000ft MSL
boost?-???
adjustable fuel-air ratio?-NO
cooling setup-formed intake.
carb or injection?-carb

https://aliexpress.ru/item/4000930517052.html?spm=...1273559380

what temps? -below engine limitations

twin spark?-NO
service intervals?-every 50hr oil change

oiling and fueling?-oil radiator,ctock oil pump,oil separator,electrical fuel pump,stock spark (trambler )

[Anatolviper]

I understand that it is necessary to lower the valve timing to reduce the RPM, I just don’t know which camshaft to choose, I don’t know much about it

[FreeBug]

WOW! Nope, no way I'm leaving the ground with a 30$ chinese carburettor. Uh-uh, no way, no how.

I don't feel I should be giving you advice, too much at risk. What are others doing with their type 4's?

I will say this, because it's important, and I don't see how I could screw up by telling you this: well-performing carb intake and manifold heating are absolutely essential!!! Carb icng is a BIG issue on airplanes.

I would want redundant sparks, and fuel pumps, etc.. not much extra weight, but a lot of extra safety.

As a starting piont, just for discussion's sake, I see the 1.7 is putting out maximum torque (also close to best mileage, then) at 2700rpm, your chosen cruise rpm. what is take-off rpm? from what oprn says, iirc, 3100 should be close to maximum limit. So no way of climbing to 4900...so now to get 85 hp at 3000 rpm is the challenge.

So you want an engine which develops max hp at 3000rpm, if i understand correctly?

[FreeBug]

Cruising the net, I found this:

"some AC cam specs
Post by Waterthunder » Tue Nov 02, 2010 2:55 pm

We are working on some EFI cam's for some aircraft pillion racers and will be dyno testing some A/C engines with various cams soon. So we just put our first A/C Lycoming cam on the cam doctor and here are the specs. This was suppose to be the HOT Lycoming cam. I will post some stock Angle valve and Cont cam's soon too.


dur @ .050 INT 220 EXH 227
Lobe lift INT .348 EXH .356
LSA 112
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done *."

http://waterthunder.com/
321-508-5316"


So that's a "hot" cam, you want something "tamer", I imagine.

Keep us posted, I find this fascinating! Thanks for taking the time to answer. By "boost" , I meant some sort of supercharging, like a turbo.

* this might not be such a bad thing when it comes to flying. Copy something that WORKS

Now you know enough to be REALLY dangerous.
Seriously: be safe and apply KISS.

[Anatolviper]

Yes, the heating of the carburetor will be done by the pressure of hot air from the exhaust manifold area.
Yes, I need a maximum torque at RPM lower than the stock 4100 and slightly raise the power at least to 80-85 h

[FreeBug]

[Anatolviper]

Ok, but my engine is 2.0 litre is was stock from bus

[FreeBug]

[Anatolviper]

Ok. Where i can order the 1.7 Cam?

[Alstrup]

Some years ago I did a couple of aviation engines for light plane racing, but they were type 1 sgl port engines which per design revs slower and has much smaller intake ports. I was able to increase power at 3000 with 12% I only did those two because the mods were banned later. The engines had to stay "stock" Limbach. The 12% extra power along with a propeller with a more agressive pitch gave them approx 7 kmh higher cruise speed at 2,5% lower consumption.
With the 2 liter type 4. I´m thinking about reducing the intake port volume in order to increase port velocity so the engine will produce more torque in the desired rpm range. With the right cam and carbs that could work well. But I will need much more information to determine if that is even an option.

The other way around was, as Anatoly was touching initially, to increase displacement until the port velocity shows max torque and hp in the 3000-3300 rpm range. But I really don´t like big bore type 4´s unless the cylinders get heavily modified.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[FreeBug]

[Anatolviper]

If I understand correctly, I can reduce the intake channel by changing (lowering) the intake phases.? I also want to buy 96m flat top pistons and bore stock cylinders to 96mm.
What can I expect from the motor , what will be the power?

[Alstrup]

That depends on everything else. Like what will you be using for fuel supply?
Will you be using pump gasoline or aviation fuel?
1 or 2 spark plugs per cylinder?
Which again relates to how much CR you can, and will be running.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[oprn]

Many many automotive engines were put into experimental category aircraft with single plug, single ignition systems. To change to dual plug dual ignition on a VW you need not only to machine plugs into the heads from below but you need a second distributor and something to drive it. A magneto is the first choice of most in place of the stock distributor as it is self contained and does not require the weight of a battery and complication of an electrical system. A crank trigger system would be the easiest route to go to fire a second set of plugs and would only require a motorcycle style battery. But then... you need a generator... more weight! Aircraft are highly allergic to weight!

As far as a camshaft goes I don't know if anyone makes a specific one for aircraft use. I think it would be very hard to improve on the stock cam and if you could the gains would be small. Some guys feel that the 1700 914 and 411 heads with the smaller valves have superior low end power. Those combined with the 96mm flat top pistons will get you into some serious compression quickly.

Again, follow up Ray's links and see what the aircraft guys are doing. Us car guys know next to nothing about what works in aircraft.
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[Vanapplebomb]

[Anatolviper]

[H2OSB]

This is a bit out of my league, but 2.0L bus heads have the smallest valves, so you're on the right track there, IMO. Coupled with 96mm pistons, you probably had the most torque possible without going to a larger crank.

The stock 1.7 replacement cam from Web (142 I think) is what I'd look at, but most likely you'll need a custom grind. Perhaps cam specs from an industrial engine meant to run at a steady pace all day long.

This is a fun exercise, but I'm not certain I'm brave enough to go up in any plane powered by a AC VW engine (though I think the T4 IS the wiser choice)

H2OSB
_________________
(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants.

[oprn]

Air cooled VW engines have an excellent track record in homebuilt aircraft. From all reports that I have read they experiance NONE of the problems they do in cars.
_________________
We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[Alstrup]