180sx blacktop redline? 72 or 75 hund?

[302INMY240]

i need to know what the stock redline for the 180sx s13 black top sr20det engine is, thats what i have in my garage and im getting JUN single valve springs and i have eagle h-beam rods.

i was under the impression that the sr20det redline is 7200 rpm but i just heard otherwise,

this is pretty important since i am raising my redline up to about 7800-8000, and i want to know exactly what the redline is for my motor. any help is appreciated. thanks

i block most mail except for aol users

[HaLo]

7500rpm

[FRpilot]

when raising rpm, be sure to get rocker arm stoppers to prevent valve float. i dont know what i just said.. haha.. but i always hear that when ppl ask questions about raising rpm limits..

can someone explain?..

[302INMY240]

yeah i am going to get stoppers also, they are only like 100 bucks i think, they stop the rocker arm, actually the hydraulic pivot from extending to far and keeping valves open and potentialy hitting the pistons, thats what i gather anyways

[huntz0r]

Well as far as I understand it:

Basically how the valvetrain operates is, the cam lobe pushes the rocker arm, which pushes the valve open to allow air into the cylinder, or to allow exhaust out. Valve springs act the opposite direction so when the cam lobe comes away from the rocker arm the valve snaps shut again. Well when you go a certain amount above stock redline, the "pushing" gets more forceful, and some bad things can happen. Now the valve springs are not strong enough to balance the force of the cam lobe against the rocker, and the valve flies too far into the cylinder and can't close when it's supposed to. Thus the term "valve float" as the valve sort of floats inside the cylinder without closing properly. Obviously this results in bad things if a valve is open during the compression and ignition strokes.

Now you can imagine what rocker arm stoppers do. They stop the rocker arms (no really? :)) so the valve doesn't overstep its bounds. Stiffer valve springs are also vital in high-redline application so that the valve snaps shut as fast as that cam lobe turning 8000rpm releases the rocker.