1971 340

[jerry6]

Easy ways to make power:

-Lighter rotating assy
-Roller Camshaft (Hydraulic Roller is fine)
-lighter/lower friction vale train (beehive springs also help)
-stroker
-airflow
-complete combustion w/o detonation
-control oil

my engine has everything but the stroker. I didn't go stroker because I wanted the car to hook on the street (didn't need the extra torque). Turns out it made 400 lb-ft at 2800 rpm anyway. 455 lb-ft at 4000, and 470hp at 6000.

It rips. Pulls 3.23's like a champ and hooks well enough on the street. Pulled 13.5 in Hg with the 750 double pumper at 950 rpm. I was looking at my EFI log today and it now is running 58.5 kPa at idle which is over 17 in Hg at the same rpm, so yeah this thing is streetable.

We took a TON of rotating weight out of this thing with the pistons and K1 rods. Beehive springs and the hydraulic roller helped a lot. The heads are stock edelbrock other than the valve job (no porting). Box stock intake. You just plain can't throw it together with X or J heads, the old heavy TRW/FM pistons, flat tappet cam and expect it to make this much power.

Those LSX engines don't make all that power for no reason. The same tricks they applied work on these too.

What pistons you use ? I'm looking to build another 340 and want options , last time I used Mahle , are there lighter pistons available ?

 

[nm9stheham]

Dunno the Mahle weights, but the KB's are 575 grams with a 132 gr pin (vs 719 & 154? gr stock). Put in some SCAT rods and you have dropped the rod+pin+piston weight to around 1309 gr, versus the 1630 range for the same stock parts. The KB's come in the widest range of oversizes that I have seen so far.

Ross has some flat tops at 514 grams, and domes at 560 grams with similar pin weight as KB. Not sure if the Ross's are forged or hypers.

SRP has some hypers at 530 grams.