i have a few friends with these cranks and one is having some problems with drinking oil and they are saying it is the crank.how the hell does the crank make a motor drink oil ?



please give me some info on this it is driving me nuts

 

Possibly more side load in the cylinder on a shorter skirt piston. Didn't 1slow01z71 have the same oil consumption issue?

 

I think 1slow01z71 had a piston problem, I dont think it was the crank causing it... and to answer your question reddevil, I do not see how a crank can cause oil consumption. It has to be a piston or ring problem.

 

I thought that the issue was with the Diamond pistons.

 

Pretty much everyone I've seen with over a 4" stroke has oil consumption issue's with Gen III and IV blocks. The piston skirt is just too short and the pin is too high (ring land issue).

 

It also pulls the piston down in the cylinder farther at BDC. Combine that with the short skirt pistons required and at BDC you get a lot of rocking causing the oil ring to do funny things.

 

Part of it is side load, part of it is piston travel, but the biggest contributor is the piston pin location penetrates into the oil control ring land location. Without a proper ring land, the oil control rings are left to fend for themselves for nearly .75 inch on each side, which lets oil slip by. Stick with a 4" stroke as max allowed without getting into the oil control ring land area.

 

Richard@WCCH told me the reason why i had oiling issues in my 418 was due to a bad piston skirt design egg-shaping my cylinder walls. I did alot of searching over on tech and I found a couple of cars running the same combo as me without problems. I have also been talking to a few of the big name engine builders and it seems my combo isnt all that uncommon. When using the long stroke like mine it moves the wrist further up into the ring pack allowing more oil to move around in the wrist pin area. It also pulls it further out the bottom of the sleeve causing bad piston rock at BDC. From the research I have done both internet and talking to a couple people on the phone, it seems the main component to making a 4.1 stroke work in an iron block is piston skirt design. It has to have a wide skirt and a special ring pack. Ross pistons apparently makes a good piston for the 4.1 and 4.125 stroke, I waiting on someone to get me some more info on a couple other piston manufacturers that specialize in the long stroke. I want to get a list of good working combos so if anyone else wants to run the long stroke they can skip the headache I have gone through. You can skip alot of the heartache by going to an LS2 block which has longer sleeves and reduces piston rock at BDC.

 

A piston for a 4" stroke still encroaches on the oil ring just not as bad as a 4.1 or larger stroke piston. That is why the stroker motors are known for burning oil.