Ok so i am setting up to build my motor, long rod, short stroke big bore. plan is as follows

4.185 bore
3.185 stroke
6.560 rod
12:1 compression
carbs
solid roller ect ect

350ci, heads im still looking into.

Now i am thinking of the piston design and i have been following something many builds in cup motors, drag cars ect have been doing and its shrinking the wrist pin sizing down some. i have 2 sets here that are .787 diameter 1.800" long. one set is a .180 wall the other is .210 wall. pretty thick. They are cassidium coated, hardened and fit for round wire locks.

My question is, how do you think these will fair in a streetable motor? assuming the block has piston squirters in it and proper oiling system i think they would live. But im asking for others opinions on the situation.

I am not doubting there stregnth, more or less worried about heat.

 

The pins will not be a problem if used with a properly designed boxxed strutted piston as used in Nascar. Requires custom rods with a narrow small end to maximize piston pin bore bearing area. The main thing I've got to ask you is what is the build for...a specific displacement class?

 

i ended up getting a callies magnum xl crank in the classifieds on here and ive been wanting to do a short stroke long rod motor for years. was going to do a sb2 or ro7 motor but found this crank. so now its lsx block with everything i wanted to do with the nascar motor, but in a lsx block.

main thing is i want to keep it N/A , unless i find out from callies this crank will work with a turbo setup. it is lightened to 38lbs, which is what worries me.

 

rpm's will usually kill rotating components long before power will.

And it sounds like what you're proposing you intend to be spinning some serious rpm's ?

 

would like to see 9k plus. few things i would be doing is aluminum rods which im getting the pricing and design on now, and the pins was another idea ive been tossing around.

aluminum rods will help the bearing life. the balancing and all should as well. the rods themselves are very stout pieces i have no worries with them.

compression height i need is 1.087, which can be had and i was looking into exactly the box pin design that was mentioned above.

 

If you aren't class racing, I'm not a proponent of small cubic inches just for the sake of small cubic inches....but if like the rpm and you've got the heads/intake/rockers/ and spring budget to match...that's cool. Any particular horsepower target you have in mind? Are you planning on going LS7 based head or can you get into the high dollar stuff with a singleplane/Holley/Sheetmetal?

As for the parts, that long of a rod is going to be pretty lazy at pulling air in at tdc intake stroke...offsetting the gains of longer dwell period on the power stroke. You're stuck with the tall deck height, so you may want to consider a rod that's .150-.200 Longer to crutch it a little bit. The increase in piston weight is offset by the lighter/shorter rod and you'll reduce piston piston rock with a taller piston for a bit more power and increase the 2nd land thickness for a large pressure seal groove. As for boost, I don't know your rod journal diameter, but the increase in journal overlap helps crank strength. If you stay NA, you're going to need a taller dome for any given compression ratio. There are some thin ring packs that really pick up the power if you're running vacuum/drysump. Other than that, piston speed is low at 9000rpm and the bottom end isn't going to give you any troubles with an aluminum rod and boxxed piston.

 

my thoughts were ls7 style heads, LSW -2 heads is what im looking at now. and i would like a holley hi ram intake. i think that would be a good setup on the motor with around 12:1 compression.

pistons will be flat top with smaller chambers, 50-52cc is what i need chamber size wise. i am leaning towards a dry sump right now. not 100% sure i want to get into a vaccum pump.


as for power goals? honestly what it does it does. i cant afford to get into mozez type heads and sheetmetal intakes ect. plus i would like to run pump gas. really would not like to pay for race gas lol

also rod journal is 1.888 honda journal size.

 

That combination will be a lot of fun and those castings can support Jesel and large springs. When you get ready to build, if you want, I can work with Bob at AllPro on the valve drop numbers and your cam guy to dial in your valve pockets perfectly, get s.e. rod eye width dimensions to your rod guy,and run a Cup forging with 3d internal mill to really reduce the reciprocating

 

for right now im getting the rotating assembly and block parts needed. so it will be a while before i get to the top end. plan is a LSX block, cam bored to 60mm, 4.185 bore stock deck height of 9.240.

These are the rods im getting the pricing and information on. Ive dealt with FFWD a long time ago and the guy Darren is an awesome guy. These rods have done very impressive things in other applications and i know his machine work is outstanding. These rods will support everything i can throw at them and then some.


but yes when the time comes i can go that route. i have a lot of little details ive been going over in my head. just need to figure out which ones i want to put in the motor. callies did say this crank would be perfectly fine with up to 25lbs of boost or so.


http://www.ffwdconnection.com/rods-1.html