Crank question

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srixon4406

srixon4406

TURBO TOAD
Joined
Oct 1, 2010
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What's the best crank for performance choice for the 225 /6 forged crank I have a 62,68, 72 the 68 is a truck motor
I'm getting ready to go through my 72 block for my turbo motor and I have three separate era motors and I was wondering which crank I should install into the block if you guys could help me out id appreciate it
Aaron
 
Not sure what trans you will be using but the 68-newer have the larger crank register for the torque converter if you are going with a later non cable shift auto. Just a thought..
 
Darter6 said:
Not sure what trans you will be using but the 68-newer have the larger crank register for the torque converter if you are going with a later non cable shift auto. Just a thought..
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I didn't think about that I'm running a 72 904 non lock up
Thanks Aaron
 
Yep I made that mistake,or I should say I learned that when I bought my first aftermarket converter and it didn't fit my 67 crank.
 
Ok thanks is there any tricks I can us to lighten the crank I've heard of having it knife edged but I've heard that's pricey any help would be appreciated
Aaron
 
Doug Dutra build one that was a hybrid of some sort over on .org. He used a cast crank where one didn't come stock in a effort to make one with a really light weight rotating assembly. I think it came out pretty good. Might be worth the read.
 
srixon4406 said:
What's the best crank for performance choice for the 225 /6 forged crank I have a 62,68, 72 the 68 is a truck motor
I'm getting ready to go through my 72 block for my turbo motor and I have three separate era motors and I was wondering which crank I should install into the block if you guys could help me out id appreciate it
Aaron
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A lot will depend on your level of performance. Knife-edging a crank is overkill for anything but serious high RPM racing. For the street, I'd grab a forged crank and give it and the rest of the build a good balance job.
 
cudamark said:
A lot will depend on your level of performance. Knife-edging a crank is overkill for anything but serious high RPM racing. For the street, I'd grab a forged crank and give it and the rest of the build a good balance job.
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Mark it's for a turbo motor that I hoping to get 550 to 600 hp at the crank in a 2500 pound toad
Aaron
 
I spent two days grinding and smoothing up my crank,looked polished,then sent out for balanceing.Might not have gained anything,but if It got me 1 more hp it was worth it to me,and just might bee the reason I have six records.I know it definately didnt hurt and possible helped.I built my motor that way.Did LOTS of things that could only possibley add a hp or two and its made me happy I did everything that might have gained me hp.Alot of what i have done probably wasnt needed or helped,but when I am done I know I gained something.Gratifacation.And which one made my car stupid fast.Guzzi Mark
 
Shaker,just think if your crank was smooth and balanced I bet you would bee in the 10s.Just a thought.Mark
 
madmax/6 said:
I spent two days grinding and smoothing up my crank,looked polished,then sent out for balanceing.Might not have gained anything,but if It got me 1 more hp it was worth it to me,and just might bee the reason I have six records.I know it definately didnt hurt and possible helped.I built my motor that way.Did LOTS of things that could only possibley add a hp or two and its made me happy I did everything that might have gained me hp.Alot of what i have done probably wasnt needed or helped,but when I am done I know I gained something.Gratifacation.And which one made my car stupid fast.Guzzi Mark
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Mark,
I think you're probably right about the importance of the sort of detail work (polishing, knife-edging, and crank-balancing) you have done on your normally-aspirated motor, but Tom's engine is turbocharged, probably makes over 500 HP, and the gains that you've experienced with YOUR motor, might not show up on his. For sure it couldn't HURT to do the detail work you have done, but I think he's right; with 25+ pounds of boost, you're not going to see a measurable difference.

Just my 2-cents', and probably over-priced at that!

Have a Merry Christmas!!!
 
madmax/6 said:
Shaker,just think if your crank was smooth and balanced I bet you would bee in the 10s.Just a thought.Mark
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If I didnt have a 15 mph headwind I would be in the 10's. Regardless, the mph supports it and I have not turned up the wick. I still have 8 psi of boost to add if I like. A bigger carb might just work before I add boost.

Plus, I shift at 5500 rpm and launch on the foot brake around 3300 rpm. According to all the dyno testing I've read the gains are made way above where the slant 6 makes its power.
 
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