5.2 vs 5.7 Bottom End

[TC65]

WE have been running a 5.2 rod bottom end for years and decided to go to a 5.7 rod bottom end. We used everthing from the old 5.2 bottom end, clutch, flywheel, etc. After running the 5.7 bottom end our rpms had dropped about 100 rpm and my son said that the car did not come off the turns like it did with the 5.2 bottom end. We run on a 3/8 asphalt track with good banking. Has anyone seen this same thing? We ran 3 races with the 5.7 bottom end and went back to the 5.2 bottom end. The rpms went back to what they had been and power off the turns was better. Has anyone experienced this? Our engine builder says we are crazy and that the 5.7 is faster.

Thanks for any info
TC65

[themotorshop]

what rods and pistons,

[TC65]

Light Wiseco Pistons and LIght rods. I am not sure but think the pistons are chevy

[themotorshop]

and what about the 5.2 setup

[FLYIN-9]

From what I've been told from some engine builders, the longer rods like a longer track unless you can keep the RPMs up. I'm going back to the short ones for a 4/10 & 3/8 track

[let-r-eat]

Did you verify compression between the two assemblies? The lighter weigh piston and better rod angle promotes less drag and better ring seal and is more durable and less prone to cylinder breakage.

Very little difference in performance overall, things equal.

[oilman]

I ran both over the course of 10 years. The 5.2 rods always came off the corner better.

[dave41]

rod to piston crossover is faster on a 5.2