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-   -   technical quiz (http://forums.pelicanparts.com/911-engine-rebuilding-forum/998914-technical-quiz.html)

faapgar 06-07-2018 07:19 PM

technical quiz
 
Which crank will spin the motor quicker from point A to B.The 22.5 lb.Chrome-Moly on the left or the 32 lb.boat anchor GT-3 crank on the right.http://forums.pelicanparts.com/uploa...1528424124.jpg
http://forums.pelicanparts.com/uploa...1528424124.jpg
Crank on left is 66mm stroke with late main bearings with 2 inch chevy rod journals and 9 bolt flywheel flange for a SS 3.0. 66 X 98mm bore

rennzeit 06-07-2018 11:13 PM

Sweet stuff Fred! I'm building a motor around a similar setup now...
66mm 6-bolt S crank with rod journals turned down for Ti GT3 rods that will go in a 3.0 turbo case.
How fast have you spun yours?

cheers,
dug

faapgar 06-08-2018 04:37 AM

spin it up
 
You will like that setup.Your Ti rod is 1mm longer at 130mm.I have one built on 76 turbo 3.0 case that spins to 9300 rpm.I like 132mm Ti rods that make the rod / stroke ratio 2 to 1.What heads are you using?Enjoy your build

Dpmulvan 06-08-2018 05:58 AM

Sounds pricey, I'm getting ready to build a 3.0 any suggestions other than the usual stock crank, 964 cams et ?

lvporschepilot 06-08-2018 09:45 AM

That sure is purdy.

Trackrash 06-08-2018 11:09 AM

Interesting. Who made the non-counterweighted crank? Why no counterweights?

Seems that the extra 10 pounds could be subtracted from the flywheel with equal results?

TimT 06-08-2018 04:13 PM

The T crank will spin up faster..MOI is less without those pesky counterweights..

Good short stroke T cranks, that measure within spec and ring true, are desirable to certain small displacement class racers..

MST0118 06-08-2018 04:22 PM

Fred, who makes the crank on the left and what cam are you running with it?

Trackrash 06-08-2018 04:42 PM

Quote:

Originally Posted by TimT (Post 10066876)
The T crank will spin up faster..MOI is less without those pesky counterweights..

Good short stroke T cranks, that measure within spec and ring true, are desirable to certain small displacement class racers..

Porsche put the counter-weights on for a reason. Surprising that someone would make a modern crank like the old T cranks.

FWIW, I ran a SS2,5 based on a T motor for years. My new 3,0 L revs up just as fast.

Mark Henry 06-08-2018 06:28 PM

The non counterweighted will spin up faster, but the counterweighted will beat it for longevity.
There's no such thing as a perfect engine, everything is a compromise.

BURN-BROS 06-08-2018 06:31 PM

Factory 66mm 9 bolt on the right and modern equivalent on the left. I want as much counterweight as you can give me. :)

http://forums.pelicanparts.com/uploa...1528507705.jpg

faapgar 06-08-2018 06:37 PM

22.5 lb.crank
 
Crank was made in South America.I have a friend Peter Dawe who has used their 4.0L Crank for many years with no issue.I will choose cam after the heads are flowed with intake and exhaust pipe.I use early 3.6 head and narrow the stud spacing.The early heads that have not been machined fit right on the 95 or 98mm cylinder.I will post some more pics tomorrow.Ciao


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