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Oil Turbulence... Is it an Issue

gatorforge

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I've finally gotten my engine torn down and since I'm going to rebuild at 836CC, I decided to go with new rods. Now I'm considering a new crank as well. Looking at the Cycle X race cranks, they list that the balance holes have been welded to reduce turbulence. How much of an issue is this really, and how much horsepower is turbulence draining if any?

Thanks,
Lance
 
Not an issue unless you are going all out racing. Just go with their standard light weight and balanced cranks and go with their Super Rods. No need to go with the high dollar welded crank and Carrillo rods on an 836 motor. You would never know the distance on a little 836 street motor. Let me know if you have any questions I have done my fair share of big bore 750 motors.
 
X2, oil friction is measured in hundredths of a hp. Balance holes ain't spit to the rod ends thrashing around in oil bath there. Maximum wind making at its' finest.
 
Thanks guys, especially the info on turbulence horsepower and the comment on Carrillo rods. I was considering them and you guys just saved me a lot of money. On a side note, the $100 APR bolt upgrade for the super rods...worth it?

Digger - I probably will message you as the build goes on. Right now I've finished the tear down and just starting the rebuild.

AMC - What would you recommend for reducing the thrashing of the rod ends, or is it necessary or worthwhile to attempt?

Thanks,
Lance
 
Leave it alone unless you are drag racing in pro stock. The engines already have some goodly oil control in them with dry sump being used.

Dirtdigger knows what he is talking about.
 
I am running their older Super Rods before they had the ARP option, its in a street 970cc motor now, had them in a 836 before that. I think there is a picture of them in one of my photo galleries on this site. If you are going to race or go bigger then 836 then I would say yes go with the ARP bolt option but if its just a street 836 motor then you can easily go with the standard bolts that they come with. You never really mentioned what the motor is for so I am just assuming its a street motor. No need to get to involved if its just a street motor, but I have some things I do on absolutely every motor I build....heavy duty cylinder studs, cam and primary chains for sure even if its a stock displacement motor.
 
Sorry should've explained, it is a street bike, I'm building a street tracker. I hadn't planned on replacing the cam and primary chains but I will now. I definitely plan on putting in heavy duty studs. i have two of the old ones stuck right now though, broke off at the base of the top threaded section, so just two inches of shank sticking up. Any tricks on getting those out?

I appreciate all of the knowledge and experience from both of y'all its been a big help.
 
weld a nut to the stud sticking up, the heat will help loosen it up and you have something good to put a wrench on.
 
Unfortunately I don't have a welder, so that bit may get outsourced.

Also, on the transmission drum, I've mic'd both sides, the large side is well within spec, the small side is way below spec. While it doesn't appear to be very worn, spec for the small side is .5154" and the actual measurement was .4738" which seemed awfully low considering every other part has been in spec. is there a different F2 spec for that measurement I'm missing?

Thanks,
Lance
 
What size is the hole it fits into? That much difference if worn should show very obvious severe wear, if not then obviously the spec in error or something like that. If the hole fits the small side within the same number error the bigger calls out for that would tell you itself the spec changed.

You often have to work that stuff out for yourself using the parts you have right in front of you. I've seen mods that are in no spec book ever. Things like slight overbores or tappet diameters that make no sense, sometimes a bunch of parts get made off spec by mistake and the OEM makes a running change only on a few engines to recoup expensive parts they would otherwise have to scrap. You won't find it in any book likely but sometimes the engine code may have a marker of some type showing it.
 
Hi AMC,

Thanks, I'll measure the hole. It seemed to fit well, was shiny, but showed almost no wear which is what made me suspicious. As you pointed out changes were made on the spot if necessary, and I think that may just be the case. For as good as it looks, there is no way it has worn off .04" of material.
 
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