Small block w/ 3.79 crank

-
I sold a W7 shortblock that had some crazy good parts but was beat up like a lot of those engines were. r block, Arrow rods, Calias crank, two sets of pistons my buddy had loosely thrown in a brown box in the back of his open truck for a few months. One of those times I needed some cash so I sold it all off.
 
I sold a Molnar 3.79" stroke crankshaft and 6.400" rods to a guy in Minnesota who drag races. I've had several inquires about 6.500" rods, but no one has ever purchased any from me.

3.79" stroke/ 6.500" long rods yields a 1.715 rod stroke ratio and gives you approximately a 1.25" compression height pistons.

3.79" stroke/ 6.400" long rods yields a 1.688 rod stroke ratio and gives you approximately a 1.305" compression height pistons.

Given that better flowing heads need less rod stroke ratio because dwell time needed at TDC using a super long rod is unnecessary.

With all these factors I would advocate using a 6.400" rod for several of these reasons and having an extra .050" of compression height in the piston will allow for more stability

and more room for the ring package. Unless it's a Comp Eliminator/ Heads Up Pro class engine and you need the last 2-3 HP I would build it for more longevity with the 6.400".

Tom
 
Last edited:
lead69 said:
That is going to be awesome, my dyno partner Tim has a couple 3.79 cranks and at some point he is going to build one. We are always discussing builds to dyno test with and really wanted to find a way to do one with a 3.79 crank. We think the hp would peak at a higher rpm than a 4" and make more power as a result. I would love to throw one in my stick car, I may have to make it happen at some point.
Click to expand...
We're do you get your machine work done ?
I just got a K1 3.79 crank its new and K1 rods
And a used Callies 4.00 crank
Cast iron 810s
Thanks Doug
 
SandyDoug said:
We're do you get your machine work done ?
I just got a K1 3.79 crank its new and K1 rods
And a used Callies 4.00 crank
Cast iron 810s
Thanks Doug
Click to expand...
I have used quite a few, feel free to pm me if you want to talk about them.
 
tvt59 said:
They ran those heads in some NASCAR classes and made about 850 hp. I can do what I want to do with 800 hp. I hope it's works out.
Click to expand...
Respectfully, I've never looked at the W7 or what may have been the last iteration of a w7 before the w8 but, I'd think 800 is possible! Only person I know of that had a good running W7 was Laverne with the Duster but, I'm not privy to many SBM combos. One thing I can share here is even the W8 NEVER made 850hp in a NASCAR application. It wasn't until the r5p7 when teams were able to get 850hp which is likely because the valvetrain was better in design. Conversely, most of us know of one or more W8 builds that make 1000+ today but they aren't NASCAR friendly. Based on your more recent posts it sounds like you're doing a w5 now?...or is this another 'side project' ?
 
You must log in or register to reply here.
-

Back
Top