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Alstrup
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Joined: July 12, 2007
Posts: 7208
Location: Videbaek Denmark
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 Posted: Tue Apr 20, 2021 1:30 pm Post subject: Re: Type4 Camshafts for low RPM |
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OK. I did the math. A Web 73 on 108 LC and then advanced 2-3 degrees will give the best oveall torque below 3300 rpm. I would have thought one with 104 LC was better, but the numbers say different.
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Anatolviper
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Joined: April 18, 2021
Posts: 19
Location: Rus
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| Posted: Tue Apr 20, 2021 1:39 pm Post subject: Re: Type4 Camshafts for low RPM |
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Unfortunately, I don't really understand these numbers. What does 104LC mean?
Which camshaft should I choose from that list at the beginning of the topic? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Tue Apr 20, 2021 1:57 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Anatolviper wrote: |
Unfortunately, I don't really understand these numbers. What does 104LC mean?
Which camshaft should I choose from that list at the beginning of the topic? |
"LC" means lobe center. For example.....a lobe center of 108° means that the peak opening point of the intake valve lobe is 108° or rotation away from the peak opening point of the exhaust valve cam lobe.
It not only controls when the peak torque comes in....it controls the rhythen or smoothness of the intake air flow and vacuum signature. That last point is not critical to you (as far as I know).....but is critical to the metering devices of some of the older style factory fuel injection systems. Many do not understand that point and therefore have big issues with uprating the cam in factory injected engines.
Here is a decent explaination of lobe center of the cam.
https://www.claysmithcams.com/lobe-center/#:~:text...m%20range.
Ray |
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Alstrup
Samba Member
Joined: July 12, 2007
Posts: 7208
Location: Videbaek Denmark
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| Posted: Tue Apr 20, 2021 1:58 pm Post subject: Re: Type4 Camshafts for low RPM |
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None of them. Go get a Web cam instead. Web makes very good and precise camshafts.
The lobe center, or lobe separation is among other things an indication on how and when the valves open in relation to each other and in relation to the cam duration.
You can get both cam and cylinders etc here:
https://aapistons.com/
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raygreenwood
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Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Tue Apr 20, 2021 2:36 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Alstrup wrote: |
None of them. Go get a Web cam instead. Web makes very good and precise camshafts.
The lobe center, or lobe separation is among other things an indication on how and when the valves open in relation to each other and in relation to the cam duration.
You can get both cam and cylinders etc here:
https://aapistons.com/ |
I would tend to agree. Unless one of the suggested camshafts has been PROVEN to be successful for aircraft engine use.....with the engine combo and aircraft you have in mind......dont use any of them.
As I noted in a previous post.....do some reading and ask questions on some of the MANY kit build aircraft sites....specifically about VW based aircraft engines.....AND.....also call webcam and talk through your application with them. There ia no way that tbey DO NOT have considerable experience with making cams for VW based aircraft engines. Ray |
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Anatolviper
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Joined: April 18, 2021
Posts: 19
Location: Rus
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Anatolviper
Samba Member
Joined: April 18, 2021
Posts: 19
Location: Rus
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| Posted: Tue Apr 20, 2021 2:43 pm Post subject: Re: Type4 Camshafts for low RPM |
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| raygreenwood wrote: |
| Alstrup wrote: |
None of them. Go get a Web cam instead. Web makes very good and precise camshafts.
The lobe center, or lobe separation is among other things an indication on how and when the valves open in relation to each other and in relation to the cam duration.
You can get both cam and cylinders etc here:
https://aapistons.com/ |
I would tend to agree. Unless one of the suggested camshafts has been PROVEN to be successful for aircraft engine use.....with the engine combo and aircraft you have in mind......dont use any of them.
As I noted in a previous post.....do some reading and ask questions on some of the MANY kit build aircraft sites....specifically about VW based aircraft engines.....AND.....also call webcam and talk through your application with them. There ia no way that tbey DO NOT have considerable experience with making cams for VW based aircraft engines. Ray |
unfortunately, the main VW aircraft engines are made from TYPE 1 engines, everything is clear for them and spare parts are widely sold.
I have a Motor Type 4. |
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Alstrup
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Location: Videbaek Denmark
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Anatolviper
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Joined: April 18, 2021
Posts: 19
Location: Rus
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Anatolviper
Samba Member
Joined: April 18, 2021
Posts: 19
Location: Rus
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| Posted: Tue Apr 20, 2021 3:36 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Alstrup wrote: |
| OK. I did the math. A Web 73 on 108 LC and then advanced 2-3 degrees will give the best oveall torque below 3300 rpm. I would have thought one with 104 LC was better, but the numbers say different. |
Can you check the parameters for setup Web 73+stock pistons/cilinders(94mm)?
which power (hp) will be at this setup? |
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oprn
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Joined: November 13, 2016
Posts: 12690
Location: Western Canada
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| Posted: Tue Apr 20, 2021 5:00 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Alstrup wrote: |
| oprn wrote: |
| 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. |
That is partly because of significantly stricter maintenance requirements. If car engines were built and serviced the same way there would be much fewer failures. |
In Canada and the USA where the reliability results are that I am talking about, the owner is totally responsible for any and all engine maintenance in the homebuilt/experimental class. This also includes commercial aircraft engines along with the automotive conversions used in this class. The only government requirement is an annual oil change and spark plug/oil and fuel filter checks when the rest of the airframe gets it's annual inspection. That is it! Nothing more.
It's a "You built it, your a$$ is in it, you do as it suits you." situation.
These rules may be different in other countries.
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Alstrup
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Wreck
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Joined: July 19, 2014
Posts: 1216
Location: Brisbane
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| Posted: Tue Apr 20, 2021 5:21 pm Post subject: Re: Type4 Camshafts for low RPM |
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How about a CB 2280 cheater cam , ground on a type 4 billet , it’s the same duration as the #71 but a little more lift . 0.466” versus 0.426”
I’d guess Type 1 lifters may be needed but that is easy with TP bushes etc .
An adjustable straight cut gear to advance it the same as the Web 71 .
It is also cheaper than the Web 71 . |
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bugguy1967
Samba Member
Joined: January 16, 2008
Posts: 4340
Location: Los Angeles, CA 90016
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| Posted: Tue Apr 20, 2021 6:06 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Wreck wrote: |
How about a CB 2280 cheater cam , ground on a type 4 billet , it’s the same duration as the #71 but a little more lift . 0.466” versus 0.426”
I’d guess Type 1 lifters may be needed but that is easy with TP bushes etc .
An adjustable straight cut gear to advance it the same as the Web 71 .
It is also cheaper than the Web 71 . |
.358" lobe lift doesn't warrant a T1 lifter. Above .400", you'll want to transition.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Tue Apr 20, 2021 7:03 pm Post subject: Re: Type4 Camshafts for low RPM |
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| Anatolviper wrote: |
| raygreenwood wrote: |
| Alstrup wrote: |
None of them. Go get a Web cam instead. Web makes very good and precise camshafts.
The lobe center, or lobe separation is among other things an indication on how and when the valves open in relation to each other and in relation to the cam duration.
You can get both cam and cylinders etc here:
https://aapistons.com/ |
I would tend to agree. Unless one of the suggested camshafts has been PROVEN to be successful for aircraft engine use.....with the engine combo and aircraft you have in mind......dont use any of them.
As I noted in a previous post.....do some reading and ask questions on some of the MANY kit build aircraft sites....specifically about VW based aircraft engines.....AND.....also call webcam and talk through your application with them. There ia no way that tbey DO NOT have considerable experience with making cams for VW based aircraft engines. Ray |
unfortunately, the main VW aircraft engines are made from TYPE 1 engines, everything is clear for them and spare parts are widely sold.
I have a Motor Type 4. |
Again....webcam makes type 4 camshafts as well...and not all aero engines are type 1. Most.....yes...all .....no.
Also....from the point of view of a cam for a specific rpm/torque peak range......it makes no difference if its type 1 or type 4.
The prime difference is stroke length (if you are using stock rotating parts)....it will be 66mm, 69mm or 71mm. If you are using a custom/welded crank and stroke length....you can get any crank for either engine.....right?
You will be using non-stock valve sizes right?
You will be using a non-stock piston diameter and compression right?
While the type 4 heads have more fins and a different exhaust manifold set up....it makes no difference. You wont have a muffler. You will have open headers...right?
You will not be using a cooling shroud....right?
So all of the "stock" details that make one engine a type 1 and the other a type 4.........will not be used anyway....right?
So in the eyes of the "cam shaft"....its just another flat, four cylinder aircooled engine. It could be a VW type 1 or 4...or a lycoming or a continental....right?
So again....look around and find on the airplane forums....for AIRCRAFT....people who are working with a flat four aircooled engine in the displacement, HP, torque, rpm range and peak, stroke length, propeller type and diameter....range.......and ask them what their camshaft specs are.
From there....buy a cam like that...that fits in your type 4.
Ray |
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Wreck
Samba Member
Joined: July 19, 2014
Posts: 1216
Location: Brisbane
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| Posted: Tue Apr 20, 2021 7:52 pm Post subject: Re: Type4 Camshafts for low RPM |
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| bugguy1967 wrote: |
| Wreck wrote: |
How about a CB 2280 cheater cam , ground on a type 4 billet , it’s the same duration as the #71 but a little more lift . 0.466” versus 0.426”
I’d guess Type 1 lifters may be needed but that is easy with TP bushes etc .
An adjustable straight cut gear to advance it the same as the Web 71 .
It is also cheaper than the Web 71 . |
.358" lobe lift doesn't warrant a T1 lifter. Above .400", you'll want to transition. |
I was thinking from the short duration the ramps may be a little fast for the small diameter type 4 lifter . CB could grind it advanced ,saving on the cost of a straight cut gear , but then that is also a little more HP . I’m guess noise will not be a factor . |
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Vanapplebomb
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Joined: November 03, 2010
Posts: 5400
Location: Holland, MI
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| Posted: Wed Apr 21, 2021 7:00 am Post subject: Re: Type4 Camshafts for low RPM |
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| Anatolviper wrote: |
Can you check the parameters for setup Web 73+stock pistons/cilinders(94mm)?
which power (hp) will be at this setup? |
This is a loaded question. What stock pistons?
You have a bus engine which originally came with low compression dished pistons. Unless known to be relatively new, they are likely worn, so you will want to replace them. The question is with what? You say stock pistons... which leaves you with dished or flat top pistons. Compression has a pretty crazy impact on the power/torque output of these engines. Switching from the ‘76 - ‘83 dishes pistons to the earlier ‘73 - ‘76 flat tops will get you a lot farther along to your power goals.
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