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The making of cylinderheads for an Okrasa engine on steroids
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Alstrup
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PostPosted: Sun Jul 25, 2021 2:12 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

I do not want to reduce the stem strength that much. It is after all an older construction and the flow improvement is almost non existant.
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earthquake
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PostPosted: Sun Jul 25, 2021 2:51 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Here's a old post I made 11 years ago [damm where does time go] about using Honda Goldwing [1975-79] valves and springs but I never went anywhere with it.
https://www.thesamba.com/vw/forum/viewtopic.php?t=437391&highlight=goldwing

Might give you another option?

eQ
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TomSimon
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PostPosted: Mon Jul 26, 2021 9:41 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

For pistons, take a look at 1000cc iron head Sportster, they have an 81mm diameter (also available in .06" oversize, +1.5mm) a pop up dome close to the right shape to fit in the Okrasa head combustion chamber, and 20.1mm wrist pin.

If JE has a forge mold, you can work with their custom side of the house, and perhaps order the domes unfinished, maybe undersize pin bores as well.

Ball mill a 'kernel pocket' for the spark plug tip to reside?

Just tossing out ideas
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Alstrup
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PostPosted: Mon Jul 26, 2021 10:29 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

TomSimon wrote:
For pistons, take a look at 1000cc iron head Sportster, they have an 81mm diameter (also available in .06" oversize, +1.5mm) a pop up dome close to the right shape to fit in the Okrasa head combustion chamber, and 20.1mm wrist pin.

If JE has a forge mold, you can work with their custom side of the house, and perhaps order the domes unfinished, maybe undersize pin bores as well.

Ball mill a 'kernel pocket' for the spark plug tip to reside?

Just tossing out ideas

I will take a look at those pistons. I need 83 mm bore though. But the pin height is great, maybe even a tad low.
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W1K1
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PostPosted: Mon Jul 26, 2021 1:30 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

what about some type 3 1500s domed pistons?



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Alstrup
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PostPosted: Mon Jul 26, 2021 2:19 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Good idea, but not enough dome for what I´m after when the time comes. The dome on those are about half of what I need.
Also, the domed 83 mm (1500S) pistons are hard to come by.
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Alstrup
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PostPosted: Thu Aug 19, 2021 9:09 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Soo, Rome wasnt built in a day. Rolling Eyes
One step further.
New alu bronze seats installed for 37 x 32 mm valves. Chambers machined for 83 mm bore. This is max as you can see we juuust broke though here and there. Nothing serius, but this is it.

Next is getting the ports massaged so we can see if our simulations hold water.
Image may have been reduced in size. Click image to view fullscreen.

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gimmesomeshelter
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PostPosted: Thu Aug 19, 2021 9:30 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

May I ask where you purchased the alu/bronze seats?

I presume the benefit of using this material is head dissipation, yes?

Other than cost, what's what are the downsides of using this alloy?

Cheers,

Paul
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Alstrup
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PostPosted: Thu Aug 19, 2021 10:21 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Not really any downsides that I know of.
We buy a 3 meter rod and cut what we need.
We make the seats ourselves. (Westspeed that is) I´m not that good with a cnc. In fact I am worth very little Rolling Eyes
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PostPosted: Thu Aug 19, 2021 12:05 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Can you use a surface gap plug for your spark plug problem?

eQ
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Alstrup
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PostPosted: Thu Aug 19, 2021 2:18 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

To recess the spark plug? I most likely could. But at this stage we are working from the point of view that we will make pistons which protrudes into the chamber, leaving as much as possible of the outer squish and make the center part "356 look alike" This way I can get a little of the benefits of wedge chambers and not suffer so much from the Hemi shape. Sort of like this _/ \_
if you catch my drift.

It will be a while until I get the next step done. I have gotten a new work contract with assisting in setting up a new Mazak cnc for cylinder honing 20 to 250 mm Shocked which will restrain me from working so much on engines for a while.
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PostPosted: Fri Aug 20, 2021 12:38 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Would an AC.net Super Squishy Piston top design work well with the okrasa (or stock 36hp) head chamber design?
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PostPosted: Mon Aug 23, 2021 12:04 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

I love this topic~! Great work and awesome you do share the results!
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PostPosted: Sat Aug 28, 2021 3:50 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

So impressed with you sharing the infiormation and your knowledge, thumbs up.
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PostPosted: Sat Dec 04, 2021 8:53 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Hello Alstrup. Wondering if you've done any more with these heads?
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Alstrup
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PostPosted: Sat Dec 04, 2021 8:57 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

No. I´m swomped with work, so I have very little time to do VW stuff. I expect to make progress during the Christmas hollidays.
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PostPosted: Sun Dec 05, 2021 7:16 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Here is some info on the copper (bronze) alloy seats, guides and other components.
I use their material extensively in plastic tooling, this company started out with the alloys for industry and branched out into engine components.
One of the benefits of high copper alloys is that it work hardens, good for seats.
As Alstrup says you can purchase the material and cut your own.

http://www.performancealloys.net/MotorsportApplications.htm
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PostPosted: Tue Apr 12, 2022 2:48 pm    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Hi Torben, any updates on this monster??
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Alstrup
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PostPosted: Wed Apr 13, 2022 9:44 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

No. I got some issues I needed to adress, so the winter have been very non productive. But I am gearing up to start working on them again.
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PostPosted: Fri Apr 22, 2022 6:11 am    Post subject: Re: The making of cylinderheads for an Okrasa engine on steroids Reply with quote

Alstrup wrote:
Soo, Rome wasnt built in a day. Rolling Eyes
One step further.
New alu bronze seats installed for 37 x 32 mm valves. Chambers machined for 83 mm bore. This is max as you can see we juuust broke though here and there. Nothing serius, but this is it.

Next is getting the ports massaged so we can see if our simulations hold water.
Image may have been reduced in size. Click image to view fullscreen.


Are you planning to use modified 40hp 83mm cylinders?
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