chevy aftermarket rods in an l20?

[hacked521]

well i did a search on here and a search on google to see if anyone has ever used aftermarket chevy v8 rods in a l20b, i couldnt find anything really so im asking you guys. the most info i could find out was that stock chevy v8 rods were weaker than l20b rods. just curious.

[nismo dr]

wait..what?

[Guest kamakazi620]

well i did a search on here and a search on google to see if anyone has ever used aftermarket chevy v8 rods in a l20b, i couldnt find anything really so im asking you guys. the most info i could find out was that stock chevy v8 rods were weaker than l20b rods. just curious.

Post thread or didn't happen!!!!

[banzai510(hainz)]

Believe this is common knowlege now as Most chevy V8 stuff was cast to get cost down. The common V8s. Not to take away fom the later Chevy V8s. LS 1s ect.......

 

 

Theres a place in Austraila hat uses the L motor cranks and machines them down to use in Cosworth motors as the L series are dirt cheap but FORGED

[hacked521]

http://www.team.net/archive/datsun-roadsters/2007-11/msg00382.html i guess it wasnt l20b rods but they said just datsun rods.

 

im trying to find if anyone has ever used aftermarket small block chevy v8 rods in an l20b.

[hacked521]

yeah i kinda figured stock chevy v8 rods were going to be weaker, thats why i said aftermarket rods.

[banzai510(hainz)]

I bet the Datsun ones are still stronger

 

 

Key is using ARP Bolts with those rods

[hacked521]

I bet the Datsun ones are still stronger

 

 

Key is using ARP Bolts with those rods

 

are datsun rods forged? and arp bolts are a known if youre going to build a higher performance engine.

[banzai510(hainz)]

YES Datsun cranks and rods are FORGED. Not that a stock Datsun motor needed this in the 1st place.

Key is lightweight which soemtimes they are not compared to some after market rods.

 

Pretty much most Jap car bottom end parts are Forged

[Master-O-Turbonics]

are datsun rods forged? and arp bolts are a known if youre going to build a higher performance engine.

 

Yes they are.

 

For a friend I built an overbored L20B shortblock with the long 6" Z20E rods and Z22E autozone pistons. He kept snapping cranks and halving blocks with his N/A 180 WHEEL HP L4 motors and was out of money to get another "professionally built" engine. The only thing I did different was put in the ARP Big Block Chevy 3/8" rod bolts instead of Datsun 9mm ARP bolts(the failure point of his "real" race motors)... has gone 4+ races now and no failures(his previous motor made it 2 easy warm-up laps around Road Atlanta when it Hole'd the block, and yes it was WELL broken in). The motor I built him sees 7500RPMs before he shifts. It doesn't have the torque of the bigger crankshaft motors to pull out of the corners but it winds up better in the top end and he just had to put in a little more gear ratio.

[Farmer Joe]

i was going to say i dont think you can use the chevy rod in the nissan engine..

 

it might work... might not..

 

i was able to remember that the smallblock rod journal size was 2.098-2.100in.. the l20b journal is 2.087in.

 

even being optimistic, the diff is about .023-.025in... ive seen journals taken down farther than that...

 

you could, if the small end works, prolly get a set over oversized bearings.

 

BUUUT, like i said, the wrist pin bore might be different. also the width of the rod might pose and issue.

[albyneau]

Evening, folks. I am replying to this thread as a whole to both defend the Chevrolet engine (and all big gluttonous mills), and impart some engineering wisdom to all.

 

First, while I've yet to tweak on the internals of an early datsun, I will proclaim that in all likelyhood the L-rods could well be stronger than the SBC part. Why~ because they HAVE to be! It's a matter of physics~ not manufacturer superiority. A 4 cylinder engine has two power strokes per revolution~ a vibrational nightmare. This mandates increased cross-sectional area in the rod's beam- the third most likely point of failure~ the first being the rod bolts themselves. To a lesser extent an L/V 6 exhibits these vibrations due to powerstroke overlap,and a v8 even less~ as it has a power stroke every 90^o, providing a nearly vibration free experience for the everyday motorist.

 

But I digress. This vibration issue, and the efforts to stem it, go beyond the rods. Compare any motor of varying cylinder count but similar bore and stroke, and the 'smaller' engines will indeed have beefier main caps, main webbings, piston pin bores compared to their v8 counterparts. It's not a sign of 'weakness', but thoughtful and economic engineering to accomplish the task at hand. Now, here comes the segue~

 

Being a GM certified mechanic I have to disagree with Hainz' comment regarding Chevy's use of cast parts~ most of them are NOT cast. In fact, I can't even tell you when a chevy last had a cast rod (PM rods excluded). I did see a mid 60's Pontiac with some once~ a looong time ago. Regarding crankshafts: yes, there are indeed cast cranks out there still in manufacture~ and the predominance of them will be in larger cylinder-numbered engines. That is due to fatigue strength (FS). The more abuse of any kind a rotating part is subject to, the more FS it requires. a lower performance v8 engine requires less FS due to less vibrational loads placed upon it. So, to agree with Hainz on this point in a roundabout sorta way, Datsun didn't need to have forged parts to make them effective- or cost effective. But Japan is a different way of life~ and they take personal offense at things that break before their time; whereas here in the land of OZ we have built-in obsolescence.

 

Metallurgically, the best choice will be the newest piece~ forged from the newest alloys, and machined on more accurate mills. Strength and weight are the two ends of the performance scale the end user must choose from~ one must either sacrifice weight for RPM capability, or RPM's for endurance.

 

Now, for those that thought I had a brainfart~ the second most common failure point on a rod is between the rod bolt head land and the shank of the beam, usually the thinnest part of the rod's big end. Just checkin to see who's payin attention... ;)

 

Peace~

Scott