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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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 Posted: Wed Jan 09, 2013 2:11 pm Post subject: Build a new 2387 - please advise -- now 88 stroke TF-1 case? |
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Let's first get a few things out of the way. 1. already searched. 2. Not a newb.
OK I'm thinking of building a 2387. I finally cracked my mag case on my 2276. So what better time to go bigger?  I'd like to reuse some existing components and buy only whats needed.
I've got:
044 wedge ports 44x37.5
FK45 cam w/1.4:1 rockers
5.5 rods vw
Plan to buy:
CB raised roof alum. case
94mm long barrel AA cylinders
5.6 chevy rods
So what crank should I get? After some research I think at a minimum it would be T4 center main. I'd like to use my existing flywheel so no wedge or flange (remember I'm not drag racing).
Should I go DPR 86mm with T1/T4 center main, chevy rod? Full circle needed?
I'd also like to keep the engine narrow. Thinking of Wiseco or JE pistons in "C" comp height. Does pin comp height neglect any gains of using 5.6 rods when figuring rod ratio & minimizing wear to the piston skirts? I'm calculating that 86 stroke + 5.6 rod + C pin = 8.348" and my 82 stroke + 5.5 rod + B pin = 8.494". So it might be narrower. That correct? Stock 69mm is 8.319"?
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1970 Beetle - Rally car
http://www.Rally-America.com
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Last edited by markhuebbe on Wed Jan 16, 2013 9:10 am; edited 1 time in total |
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Dan Ruddock
Samba Member
Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Jan 09, 2013 2:26 pm Post subject: |
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| What 82mm crank do you have now? I have a preferance for the six circle demello cranks. Dan |
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DarthWeber
Samba Member
Joined: November 24, 2007
Posts: 7543
Location: Whittier,CA
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| Posted: Wed Jan 09, 2013 2:34 pm Post subject: |
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Are you a newb? Or are you serious?? 
http://m-specmotorsports.com/M-SpecProducts/M-SpecProducts.htm#BilletCranks
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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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58Dub
Samba Member
Joined: June 02, 2004
Posts: 1713
Location: Davison, MI
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| Posted: Wed Jan 09, 2013 2:35 pm Post subject: |
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the shorter pistons will not change your rod ratio.
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58 Beetle (now just a pile of parts in the corner)
60 Beetle (2221 turbo under construction)
70 Beetle Baja project |
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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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Ian Godfrey
Samba Member
Joined: September 25, 2006
Posts: 1137
Location: Melbourne Australia
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| Posted: Wed Jan 09, 2013 2:37 pm Post subject: |
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I went 86 crank, type 4 centre main, porsche 5.5 rod, custom JE pistons. It is stock width, all tin just bolted on, studs work etc.
I don't see any advantage in the longer rod, with 5.5 rod the oil rings are still just above the piston pin, 5.6 I think you would be over the piston pin, which makes assembly a bit harder.
I am sure you could use chev journal rods, the porsche journal gives more overlap with the mains (stronger).
You will ned a clearanced cam. Or clearance the one you have.
I have had very good quality and service from DPR. I'm in OZ |
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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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| Posted: Wed Jan 09, 2013 2:38 pm Post subject: |
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I'm not made of money.  Just trying to figure out a way to get a bit more torque. The thought crossed my mind just to replace the case, but if I'm rebuilding the whole thing why not go a bit bigger while I've got it apart?
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1970 Beetle - Rally car
http://www.Rally-America.com
http://www.HuebbeRally.com |
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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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| Posted: Wed Jan 09, 2013 2:51 pm Post subject: |
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| Ian Godfrey wrote: |
| ...with 5.5 rod the oil rings are still just above the piston pin, 5.6 I think you would be over the piston pin, which makes assembly a bit harder.... |
How does rod length have anything to do with where the oil rings are positioned on the piston in relation to the pin?
Am I not following you correctly?
Does anyone have specs for "C" pistons? Would I just give them specs for a shelf stock "B" piston but with a different compression pin height?
If I'm using custom pistons does it make sense to spec a different ring package? 2x2x4, 1.5x2x4, etc....
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1970 Beetle - Rally car
http://www.Rally-America.com
http://www.HuebbeRally.com |
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58Dub
Samba Member
Joined: June 02, 2004
Posts: 1713
Location: Davison, MI
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| Posted: Wed Jan 09, 2013 2:53 pm Post subject: |
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Aircooled.net lists the compression height of the C piston at 1.055. by moving the pin up, you can also make the piston shorter, so lighter. I havent purchased a C set yet, but do plan to in the near future
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58 Beetle (now just a pile of parts in the corner)
60 Beetle (2221 turbo under construction)
70 Beetle Baja project |
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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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| Posted: Wed Jan 09, 2013 2:59 pm Post subject: |
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| 58Dub wrote: |
| Aircooled.net lists the compression height of the C piston at 1.055. by moving the pin up, you can also make the piston shorter, so lighter. I havent purchased a C set yet, but do plan to in the near future |
Yes I think they list a "C", but it's their squishy one. I thought you needed a wider base circle cam and possible head work? I'd like to use my existing cam and heads.
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1970 Beetle - Rally car
http://www.Rally-America.com
http://www.HuebbeRally.com |
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58Dub
Samba Member
Joined: June 02, 2004
Posts: 1713
Location: Davison, MI
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| Posted: Wed Jan 09, 2013 3:05 pm Post subject: |
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| markhuebbe wrote: |
| 58Dub wrote: |
| Aircooled.net lists the compression height of the C piston at 1.055. by moving the pin up, you can also make the piston shorter, so lighter. I havent purchased a C set yet, but do plan to in the near future |
Yes I think they list a "C", but it's their squishy one. I thought you needed a wider base circle cam and possible head work? I'd like to use my existing cam and heads. |
I'm not sure on the cam, but I was told through their tech email that they did not require a specific head. With the compression height spec, you could have most any piston company make up a lightweight piston.
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58 Beetle (now just a pile of parts in the corner)
60 Beetle (2221 turbo under construction)
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Ian Godfrey
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Joined: September 25, 2006
Posts: 1137
Location: Melbourne Australia
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| Posted: Wed Jan 09, 2013 3:30 pm Post subject: |
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| Markhuebbe, if you decide on the engine width (barrel length), deck and stroke, the 2 variables left are rod length and pin height in the piston. I found a good compromise with 5.5 rods and custom pistons. |
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markhuebbe
Samba Member
Joined: March 08, 2006
Posts: 379
Location: St. Louis, USA
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| Posted: Wed Jan 09, 2013 3:42 pm Post subject: |
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unanswered questions:
Specs for "C" pistons? Would I just give them specs for a shelf stock "B" piston but with a different compression pin height?
Does it make sense to spec a different ring package? 2x2x4, 1.5x2x4, etc....
Full circle crank needed? Help with crank flex?
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1970 Beetle - Rally car
http://www.Rally-America.com
http://www.HuebbeRally.com |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Jan 09, 2013 3:57 pm Post subject: |
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There is a wrong way to do full circle and a right way. The thick cheek can be full circle but the thin cheek should still have the counter weight shape. If done in a complete circle you lose the counter weight effect. The crank in the center of this pic is done the right way. It is by Demello. Even better is a porsche rod forged berg or okrasa because the narrow rod makes the cheeks thicker. The longer the stroke the more crank flex you will have so it is important to get something strong. Dan
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Wed Jan 09, 2013 4:40 pm Post subject: |
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dan those are just counterweighted not full circle, but like you stated you loose some of the counterweighting affect.but that can be addressed in other ways, but it's just a vw so why bother  .....depending on the oiling of the crank the throws can be drilled,some more than others.and or heavy mettell added to the crank counterweights.the full circle does give some added strength & cross section too.also windage is reduced somewhat. |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Jan 09, 2013 4:53 pm Post subject: |
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| The thick cheek that connects the two rod journals are full circle but the rod to mains are not. Dan |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Wed Jan 09, 2013 7:34 pm Post subject: |
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| Dan Ruddock wrote: |
| If done in a complete circle you lose the counter weight effect. |
Considering that boxer engines are inherently balanced because of their design, it matters not if the crank has counterweights or not. So long as the parts connected to it are all the same weight, you would not be able to tell the difference between a non c/w and one that has them. Now if material is being added as a strengthening means, that's a perfectly logical thing to do. I wish someone would come out with a VW crank that was just plain stronger, the gimmicks are real old at this point. Especially the heavy 6 circle thing, totally pointless.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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Dan Ruddock
Samba Member
Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Wed Jan 09, 2013 8:13 pm Post subject: |
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| miniman82 wrote: |
| Dan Ruddock wrote: |
| If done in a complete circle you lose the counter weight effect. |
Considering that boxer engines are inherently balanced because of their design, it matters not if the crank has counterweights or not. So long as the parts connected to it are all the same weight, you would not be able to tell the difference between a non c/w and one that has them. Now if material is being added as a strengthening means, that's a perfectly logical thing to do. I wish someone would come out with a VW crank that was just plain stronger, the gimmicks are real old at this point. Especially the heavy 6 circle thing, totally pointless. |
I guess porsche was wasting there time when they counter weighted the 912 crank. Your position amazes me. Dan
Words from Berg
Why a Counterweight Crankshaft? The VW air-cooled engine is designed for low RPM, low power output and high mileage use. When used that way it gives many years of trouble free service with little or no wear. However, the higher the RPM, power, or the quicker the acceleration, the more the centrifugal force bends the crank at the center main. This bending force occurs because the two center rod journals are on the same side, putting all the weighted forces on one side of the crankshaft. This pounds out the case at the center main saddle, plus makes the pulley and flywheel run out often damaging the case at the pulley end. |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Wed Jan 09, 2013 8:32 pm Post subject: |
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The counterweight/gusset welded all the way around is what Bob calls his "raceweight", you can have him just do those or do the middle webs too. $$$
they gussets/weights are seamless, unlike some other crank guys  |
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vwracerdave
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Joined: November 11, 2004
Posts: 15303
Location: Deep in the 405
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| Posted: Wed Jan 09, 2013 8:40 pm Post subject: |
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| miniman82 wrote: |
| I wish someone would come out with a VW crank that was just plain stronger. |
There are stronger cranks out there, most people just won't pay $1500-$1800 for them. You're not going to find a stronger Chinese crank for $300, and your not going to get srtonger by welding up a stock crank..
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