In for the long haul Ultimate NA build thread.

[WHITE]

Gotcha, seems I have some reading to do as I appear to be behind the curve as of late.

[WHITE]

@celek sorry to get back on the topic of rods but I just thought about this. Being that you plan to spin some pretty high rpm are you at all concerned with rod stretch? If so have you factored it into the rod length or piston height?


As a disclaimer, this question is just based on rods in general. Im not trying to debate alum rod vs steel rod stretch.

[Tim Radley]

Originally Posted by celek

Largest problem is Case clearance, The ROD Journal is already smaller to clear the case and the Aluminum rods are bulky to add strength. Then again we are not making 1000+HP

Billet is different than forged though

http://www.bmeltd.com/rods.htm

Not really sure why you'd want to go to ali rods as they add unecessary windage and clearance issues to bottom of bores. Plus the fact the FA20 rods have the big-end offset it's going to require a custom forging. Much cheaper materials out there that really don't weigh much.

[celek]

Originally Posted by Tim Radley

Not really sure why you'd want to go to ali rods as they add unecessary windage and clearance issues to bottom of bores. Plus the fact the FA20 rods have the big-end offset it's going to require a custom forging. Much cheaper materials out there that really don't weigh much.

bore is 89.5mm so it is larger biggest concern is case clearance.
As for custom forging there are a lot of 45 degree angle rods out there besides the FA20 it already may exist.

[celek]

Originally Posted by WHITE

@celek sorry to get back on the topic of rods but I just thought about this. Being that you plan to spin some pretty high rpm are you at all concerned with rod stretch? If so have you factored it into the rod length or piston height?


As a disclaimer, this question is just based on rods in general. Im not trying to debate alum rod vs steel rod stretch.

Rod stretch is a non issue Aluminum rods do expand with heat as are specifically made shorter than the steel equivalent to compensate.
This is only something I am looking into for lighter components.

Aluminum still retains original shape after running its not like they get longer and longer over time

[burdickjp]

Originally Posted by celek

Rod stretch is a non issue Aluminum rods do expand with heat as are specifically made shorter than the steel equivalent to compensate.

Thermal expansion and the relationship between stress and strain are not the same thing.

From what I've seen of the aluminum rod business, it's frighteningly easy to put little to no engineering into a rod and have it achieve success in drag racing.

I would suggest getting some light steel rods, or if you're wanting to be exotic some titanium rods. Aluminum rods are for drag racing.

[WHITE]

Originally Posted by celek

Rod stretch is a non issue Aluminum rods do expand with heat as are specifically made shorter than the steel equivalent to compensate.
This is only something I am looking into for lighter components.

Aluminum still retains original shape after running its not like they get longer and longer over time

Im not talking about thermal expansion. Im talking physical rod stretch from the rpms youll be spinning. From what little ive read it would appear the consensus is that a steel rod can stretch from .030" to .050" depending on how high you spin, and alum rods stretch an additional .010" to .015" more then the equivalent steel.


Wich means if you figured for your piston to be flush with the top of the block deck once you start spinning high your rods can stretch and start smacking your head.


Im just trying to make sure youve looked into every variable of this engine before putting it together.....i wanna see this thing running just as much as you and everybody else becuase its going to be pretty badass.

[Tim Radley]

Originally Posted by celek

bore is 89.5mm so it is larger biggest concern is case clearance.
As for custom forging there are a lot of 45 degree angle rods out there besides the FA20 it already may exist.

It was bore and case clearance I was taking about. I build plenty of engines where you have to take a notch out of the bottom of the bore for clearance due to a larger rod over the stock design. Mostly its on stroker builds.

Life of the rod is going to be your next problem? Changing them every few hours is going to get boring after a while.

[celek]

Today marks the 3 year purchase date for the car... SOA keeps warning me the warranty is expiring. Sorry to burst your bubble Subaru of America, Inc. I am out to crush hopes and dreams.
Still searching for rods, need to make some calls but also need to save some funds for SEMA in November.

[Scavanger]

any updates? I am getting a free motor to build and like what you have done so far just not sure how I want to attack this project yet

[celek]

Still need to order Rods then off to the machine shop. From what I understand talking to HKS & Greddy the stroke causes bottom cylinder interference issues with piston skirts so some modifications might need to be done to the cylinders or the pistons.

Still saving some cash for SEMA as well, main reason for not putting in the order for rods.

Will be visiting some valvetrain manufactures at SEMA and Piper Camshafts told me they will be at PRI in Indy so I want to talk with them as well since they are over in the UK.

[86drift]

Originally Posted by celek

Still need to order Rods then off to the machine shop. From what I understand talking to HKS & Greddy the stroke causes bottom cylinder interference issues with piston skirts so some modifications might need to be done to the cylinders or the pistons.

Still saving some cash for SEMA as well, main reason for not putting in the order for rods.

Will be visiting some valvetrain manufactures at SEMA and Piper Camshafts told me they will be at PRI in Indy so I want to talk with them as well since they are over in the UK.

Interested to see what Piper say about valve to piston interference. I'm guessing there's lower limits on the cam timing. I can't wait to get myself some 280 deg cams.

[celek]

Originally Posted by 86drift

Interested to see what Piper say about valve to piston interference. I'm guessing there's lower limits on the cam timing. I can't wait to get myself some 280 deg cams.

When I had my pistons produced I have the valve pockets made to compensate for 1mm over valves and 13mm lift at a 280 I am pretty sure.
I Thought ahead for the future

[celek]

Shortblock dropped off last Friday at Accelerated Performance... No ETA on being finished though. They seem to have more rapport with the rods manufactures because they can get stuff in under a week.