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Buellistic
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Joined: February 04, 2011
Posts: 334
Location: Albuquerque, New Mexico
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 Posted: Tue Feb 14, 2012 9:06 am Post subject: |
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| Eaallred wrote: |
Politics. All you need is one "big name" person on the forums to say "I don't get how they work, so they must not. Waste of money, domed pistons have been avaliable for a long time, there's nothing special about them", or something along those lines, and pretty soon you get all the internet parrots squaking the same thing in masses. It kills the idea.
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Same kind of crap is why my motorcycle was a collectible only 8-9 years after it was produced. No one seems to like the air-cooled sportbike. Everyone claimed they weren't reliable despite plenty of evidence for the contrary. |
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Alstrup
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Joined: July 12, 2007
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Location: Videbaek Denmark
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| Posted: Tue Feb 14, 2012 12:17 pm Post subject: |
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There is no doubt that they work as intended. But to get full potential out of them you must understand how they work, or at least listen to the people that do.
F.i. a guy over here bought a set (not through me) and put them in his 2332 engine with an FK87 cam and the works. I told him how to tune it and set the timing. But once he made it to the dyno, the operator didnt beleive in what he said and jetted it like a normal engine. Results, WAY to little power, like 20 hp and a tendency to run hot. He was also told that the engine had too high CR because the timing should be 4-6 degrees further back. THEN the power would come in.
- The guy took the engine out and reduced CR by 1 full digit and back in and on the dyno. Well, now it would take 28-29 degree advance, but the power was even worse. At that time I was approached. And when I heard what they had done, I just said stop wasting your time at the dyno and bring it to me. He guy and I took it apart - again - adjusted the cam timing, bumped the CR again, and at that time I also performed a better valve & seat job on it. back together and on the dyno again. This time I was the operator and jetting master  After 2½ hours of trial and error I managed to pull a full 30 hp and 20 Nm torque more out of it than it had the first time around, AND with 2 degrees less timing and 0,15 smaller main jet.
Yes it runs nice and cool, even with a power pulley. Yes it makes very good mileage for what it is.
The elderly gentleman that owns the dyno shook his head and said that we were moving on the edge of disaster. Well, going into the 4rth season now and no problems.
T |
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[email protected]
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Joined: August 03, 2002
Posts: 7048
Location: Salt Lake City, Utah
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| Posted: Tue Feb 14, 2012 12:39 pm Post subject: |
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sometimes people refuse to RTFM....... LOLOL
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Steve Arndt
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Joined: August 01, 2005
Posts: 733
Location: Boise, Idaho
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| Posted: Tue Feb 14, 2012 3:18 pm Post subject: |
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Alstrup, what was your final timing at peak torque?
I was running 22* on my 12.8:1 86B 2275. I'm rebuilding it now with a modified 86A 115LC. I'm a few days away from having it running. I'm keeping the compression the same just to push the limits a bit further.
I have the first set of squishies that John sold, from way back in 2002.  |
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Alstrup
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Joined: July 12, 2007
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Location: Videbaek Denmark
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| Posted: Tue Feb 14, 2012 4:20 pm Post subject: |
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| Steve Arndt wrote: | Alstrup, what was your final timing at peak torque?
I was running 22* on my 12.8:1 86B 2275. I'm rebuilding it now with a modified 86A 115LC. I'm a few days away from having it running. I'm keeping the compression the same just to push the limits a bit further.
I have the first set of squishies that John sold, from way back in 2002. |
Cam retarded 3 degrees to 110 degree base circle, 26 degrees total advance. Elliminator 2000 heads massaged by - somebody - in the US. (I suspect Jeff Denham) Quite well done job with very little to improove. 12,8 CR. 48 IDA´s etc.
224 hp @ 6800 and 248 Nm @ 4700. But as usual when the SS combo is used, a relatively wide torque band. Here we had more than 200 Nm available from 3200 to 6300 rpm.
T |
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VIN
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Joined: June 01, 2006
Posts: 886
Location: phoenix
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| Posted: Tue Feb 14, 2012 5:25 pm Post subject: |
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do you run standard combustion chambers in the heads? or a hemi type chamber since the piston is domed??
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veedubcrazy
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Joined: February 14, 2005
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| Posted: Tue Feb 14, 2012 8:12 pm Post subject: |
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Really starting to get me interested in a set for my 2387.
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[email protected]
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Joined: August 03, 2002
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Location: Salt Lake City, Utah
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| Posted: Wed Feb 15, 2012 2:37 pm Post subject: |
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They are designed for conventional VW Chambers. You'll get no squish with Semi-Hemi, there is no deck.
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Eaallred
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Location: West Valley City, Utah
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| Posted: Wed Feb 15, 2012 3:08 pm Post subject: |
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I once heard it:
"The Semi-Hemi bucket shaped design is great for holding lots of carbon buildup..."
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Eric Allred
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Steve Arndt
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Location: Boise, Idaho
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| Posted: Wed Feb 15, 2012 5:49 pm Post subject: |
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Alstrup,
Were your numbers using premium pump fuel? 26* I've been running 91 octane pump at 12.8:1
Steve |
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catbox
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Location: Portland, Oregon
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| Posted: Thu Feb 16, 2012 3:20 pm Post subject: |
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| [email protected] wrote: | | They are designed for conventional VW Chambers. You'll get no squish with Semi-Hemi, there is no deck. |
So when I want to up the power in my 2332.
I can use my Tims stage 2's the way the chambers are?
I will obviously have to up the compression and change to the cam that works best with my combo.
But the chambers....
Hmmm...
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Alstrup
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Joined: July 12, 2007
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Location: Videbaek Denmark
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| Posted: Thu Feb 16, 2012 3:52 pm Post subject: |
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| Steve Arndt wrote: | Alstrup,
Were your numbers using premium pump fuel? 26* I've been running 91 octane pump at 12.8:1
Steve |
Yes that was on EU 98 octane. Thats where this one liked it. going from 24 to 26 gave 9 hp. going to 28 TOOK the 9 hp  So that was definitely the sweet spot.
T |
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VIN
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Posts: 886
Location: phoenix
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| Posted: Thu Feb 16, 2012 5:14 pm Post subject: |
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Sooooo,,, who wants to buy some fresh, brand new AA FORGED 94 mm B pistons, so I can get some super squishies 
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neil68
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| Posted: Thu Feb 16, 2012 7:41 pm Post subject: notches |
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I'm assuming that these pistons would need to be heavily notched for valve clearance, correct? How does that work with a dome, but then notched? Just curious, thinking about whether they would work with my flycut heads...
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DarthWeber
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Joined: November 24, 2007
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Location: Whittier,CA
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| Posted: Thu Feb 16, 2012 9:35 pm Post subject: |
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Neil, go back to page 1 near the bottom and read Eaallred's post about using valve notches with SS pistons.
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| Mitey62 wrote: | | Swapped the Compufire for a Bosch blue and some points I had sitting around, started 1st crank. Took her out for a drive, pulls harder, more RPM, and runs smoother. I think I'll be sticking with points from now on. |
| RockCrusher wrote: | | JB weld the case halves....that'll keep the fretting to a minimum. |
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Eaallred
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| Posted: Thu Feb 16, 2012 9:54 pm Post subject: Re: notches |
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| neil68 wrote: | | I'm assuming that these pistons would need to be heavily notched for valve clearance, correct? How does that work with a dome, but then notched? Just curious, thinking about whether they would work with my flycut heads... |
My recommendation is to follow Johns camshaft advice to a "T" to avoid having to notch. My notched squishies don't have near the advantage as non-notched do. Better than flat tops, but I digress.
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neil68
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| Posted: Thu Feb 16, 2012 10:03 pm Post subject: Re: notches |
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| Eaallred wrote: | | neil68 wrote: | | I'm assuming that these pistons would need to be heavily notched for valve clearance, correct? How does that work with a dome, but then notched? Just curious, thinking about whether they would work with my flycut heads... |
My recommendation is to follow Johns camshaft advice to a "T" to avoid having to notch. My notched squishies don't have near the advantage as non-notched do. Better than flat tops, but I digress. |
With my current flycut heads, I'm down to only 2 mm valve clearance, with Mahle flat tops and 10.6:1 CR. So, as with your engine, it sounds like I wouldn't be able to get the maximum benefit from SS pistons...
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Neil.
"Real men run drums."
Der Kleiner Rennwagens
68 Beetle 2332 cc
12.8 seconds @ 104 mph
http://www.youtube.com/watch?v=FF2gCti3dro |
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Eaallred
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| Posted: Fri Feb 17, 2012 6:17 am Post subject: Re: notches |
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| neil68 wrote: | | Eaallred wrote: | | neil68 wrote: | | I'm assuming that these pistons would need to be heavily notched for valve clearance, correct? How does that work with a dome, but then notched? Just curious, thinking about whether they would work with my flycut heads... |
My recommendation is to follow Johns camshaft advice to a "T" to avoid having to notch. My notched squishies don't have near the advantage as non-notched do. Better than flat tops, but I digress. |
With my current flycut heads, I'm down to only 2 mm valve clearance, with Mahle flat tops and 10.6:1 CR. So, as with your engine, it sounds like I wouldn't be able to get the maximum benefit from SS pistons... |
I'd recommend talking to John. Cam timing that he recommends makes a big difference on if you would end up needing to notch or not. I wouldn't count it out until I talked to him.
But you also have to go by EVERYTHING John recommends (ignition timing, etc). Only listen to part of his recommendation, and you only get part of what you should get out of them.
Squishy's work best for people with open minds.
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Stripped66
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Location: Charleston, SC
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| Posted: Fri Feb 17, 2012 7:52 am Post subject: Re: notches |
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| Eaallred wrote: | | neil68 wrote: | | Eaallred wrote: | | neil68 wrote: | | I'm assuming that these pistons would need to be heavily notched for valve clearance, correct? How does that work with a dome, but then notched? Just curious, thinking about whether they would work with my flycut heads... |
My recommendation is to follow Johns camshaft advice to a "T" to avoid having to notch. My notched squishies don't have near the advantage as non-notched do. Better than flat tops, but I digress. |
With my current flycut heads, I'm down to only 2 mm valve clearance, with Mahle flat tops and 10.6:1 CR. So, as with your engine, it sounds like I wouldn't be able to get the maximum benefit from SS pistons... |
I'd recommend talking to John. Cam timing that he recommends makes a big difference on if you would end up needing to notch or not. I wouldn't count it out until I talked to him.
But you also have to go by EVERYTHING John recommends (ignition timing, etc). Only listen to part of his recommendation, and you only get part of what you should get out of them.
Squishy's work best for people with open minds. |
As Eric mentioned, cam timing is a big part of it. I had to retard my cam 8 degrees to achieve the proper valve-to-piston clearance. Keep in mind, the cam was ground with 4 degrees of advance to start with, so it only had a total of 4 degrees retard as I installed it. Your cam card should verify how much advance your cam already has ground into it.
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R-Baja
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| Posted: Wed Jun 06, 2012 12:58 pm Post subject: |
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First off, the semi-hemi combustion chamber is stupid, you need at least 36 degrees of ignition advance to make them work. As for the theory behind the super squishy pistons, here are some great links. You can design the "squish" properties into the piston crown or the combustion chambers.
http://www.theoldone.com/articles/The_Soft_Head_1999/
Read the last two sentences here regarding exhaust temps:
http://www.jagweb.com/jagworld/v12-engine/page4.html
And do a Google search in images for michael may fireball combustion chamber. You will see the intake valve is flat and at near the piston crown which also is flat. The exhaust valve is also flat but considerably recessed in the head creating the actual combustion chamber and has the spark plug in that location. 1981 design!
And for the 21st century, check out Mazda's upcoming "squishy" combustion chamber:
http://www.mazda.com/mazdaspirit/skyactiv/engine/skyactiv-g.html
14:1 compression ratio! |
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