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SRP1
Samba Member
Joined: January 06, 2007
Posts: 4340
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 Posted: Thu Mar 21, 2013 8:50 pm Post subject: |
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| Glenn wrote: |
| asked Jose @ DPR and he can do a forged cw crank and a stock weight forged 8 dowel flywheel. looks like the way to go. |
Good choice! It will be a balanced assembly, and matched up.
Your own words Glenn "you don't always get what you pay for but you always pay for what you get...
I just received a full race crankshaft built by DPR/Jose, absolutely beautiful workmanship, top shelf. I am a big fan.... |
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GTV
Samba Member
Joined: March 27, 2004
Posts: 2084
Location: Si'ahl
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| Posted: Thu Mar 21, 2013 10:20 pm Post subject: |
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You're adding weight to the crank with counterweights, it's a good idea to at least remove the added weight from the flywheel, even if you don't go the full 12.5lbs (or whatever).
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EMPI Power Rules! |
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johnnypan
Samba Member
Joined: October 24, 2007
Posts: 7431
Location: sackamenna
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| Posted: Fri Mar 22, 2013 6:39 am Post subject: |
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| Glenn wrote: |
| asked Jose @ DPR and he can do a forged cw crank and a stock weight forged 8 dowel flywheel. looks like the way to go. |
Been to his shop...its a real machine shop and Jose is the man...no fancy ass show room, completed cranks cams and buckets of lifters all over the place. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21518
Location: Oklahoma City
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| Posted: Sat Mar 23, 2013 3:01 pm Post subject: |
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| slalombuggy wrote: |
Won't be a problem, done it lots of times. Small motors hardly notice a change in compression even with changes in pistons or combustion chamber cc's, they just don't have the cylinder volume to change static compression that much.
I like playing around on CB's engine calculator. Changing the size of motors and head ccs and how much or little it affects compression based on displacement of the motor.
brad |
Mmmmm...yes and no. With the original injection systems (D and L jet)...the change in compression caused by moving between Dish, flat and dome....was decently signifcant. With carbs...true...you would be lucky to notice it at all other than maybe slightly better throttle response.
This was because of their air metering systems and ignition curves. In the case of D-jet for instance.....the original carbed 1.7L engine had flat tops. It was good for about 68 hp. the very first year or so of imported d-jet injected engines had the same cam and everything else along with the flat tops. It produced about 72 hp. Not really signifcant in power...but about 10 ft lbs of torque better and much better throttle response. It was about 7.8:1 compression
The next one up was the same engine in 1971 with domed pistons and the same EFI....at 8.2:1 compression...and made 82 hp and about 102 ft lbs torque. In between that you have the Calipornia version with dished pistons and about 7.3:1 compression if I recall corectly....and it had about 68 hp....and was a dog...and very hot running and hard to tune fuel mixture with.
L-jet like the 77 that Glenn has is a little less radical in differences between compression.....but likes compression (within reason) nonetheless.
It makes the airflow smoother and makes the vacuum signature (which controls fuel pressure) and the airflow sensor (which controls load enrichment)....work more accuratley.
The primary reason the compression on L-jet engines was detuned...was as mentioned.....for NOX emmissions.
Go for it! It makes a difference. You should do well with slightly reduced advance.....up to about 8.5:1. keep a tight deck and moderate compression and drop your advance back a hair and this thingwill run better than ever. Ray |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76935
Location: Sneaking up behind you
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| Posted: Sat Mar 23, 2013 3:15 pm Post subject: |
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| GTV wrote: |
| You're adding weight to the crank with counterweights, it's a good idea to at least remove the added weight from the flywheel, even if you don't go the full 12.5lbs (or whatever). |
Interesting... very interesting.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sat Mar 23, 2013 3:27 pm Post subject: |
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There may be some truth to the idea that a light flywheel is better for higher revving engines no matter the crank. Is this a high revving engine? heck no
I have one engine with a 6-circle crank, full weight flywheel, and steel pulley. The only difference I note is it runs with less vibration, but when I am moving the engine around it is really friggin heavy. Gotta get a helper. |
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johnnypan
Samba Member
Joined: October 24, 2007
Posts: 7431
Location: sackamenna
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| Posted: Sun Mar 24, 2013 8:12 am Post subject: |
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| Flywheel and crankshaft weight smooth vibration and 'store' energy..it wont rev up as quickly but in a stock application that difference isn't noticeable...what you do notice is a smoother running engine that shifts nicely and pulls good..on highway its real nice doing 75 and 80 without feeling like its rattling the fillings out your teeth..round town it tops out gears sweeter.. |
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Jeff Geisen
Samba Chaplain
Joined: December 21, 2004
Posts: 1882
Location: N.W. Georgia
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| Posted: Thu Dec 18, 2014 2:40 pm Post subject: |
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I am having a difficult time finding dished stock 1600cc pistons, anyone have any leads on a supplier?
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‘63 ragtop - ‘68 single cab |
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VWCOOL
Samba Member
Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Thu Dec 18, 2014 4:01 pm Post subject: |
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| Glenn wrote: |
Nah... it's staying stock with FI.
This guy doesn't care about quick.
Another question... looks like the crank needs to be replaced. I'm thinking of upgrading it to a counter weighted crank. The problem is all CW cranks are 8 dowel and all 8 dowel flywheels are lightened. My thinking is a stock Super vert would be better with a stock weight flywheel.
But all the stock weight flywheels are 4 dowel and cast (not forged) and all 4 dowel cranks are not CW and also cast. I spoke to one vendor and he said a cast crank/flywheels is perfectly fine in a stock application.
Thoughts? |
Use the standard flywheel and eight-dowell it. Easy! Machining 101!
But neither CW crank nor eight-dowelling is necessary 'if 'guy doesn't care about quick'. But while it's apart, a balance/match job will make it smoother |
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Thu Dec 18, 2014 5:27 pm Post subject: |
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| dish them if you need them dished, but I see no reason to do so at all on a engine that size unless somebody has fly cut the holy crap out of the heads and there already reworked chambers and unshrouded around the valves. other wize fix the heads so they work better and have less cc's to get the target cr. and lowering the cr isant always the best way to go.and there are many ways to do so some work much better than others. but remember the entire engine needs to work togeather for the intended app. |
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