2.7RS rev limit? Options

[john77]

I competed in my second auto x yesterday and after being on the limit of second gear a few times I want to install a rev limiter.

Does anyone know what I can safely push a 2.7RS spec engine to?

My car has an MSD 6AL ignition that takes plug in modules in 100 rpm increments - so 6900, 7000, 7100 etc.

Thanks
John

[Downunderman]

With an RS twin plug motor with good valve gear; viz titanium retainers, Vmax springs good for 8k, 10.3:1 compression, albeit relatively small ports but smoothed out, gave about 190 rwhp at 6,300 with GE 80 cams, but safe to 7,300 on upshifts all day long. Its giving it a buzz on a downshift that you have to worry about, which is why i have a downshift light set to come on under 5k.

It pulls strongly from 4k and anything over 7k is wasted. I set the orange shift light at 6,900 and the red one at 7,100 and the limiter at 7,300.

Cheers,

[john77]

With an RS twin plug motor with good valve gear; viz titanium retainers, Vmax springs good for 8k, 10.3:1 compression, albeit relatively small ports but smoothed out, gave about 190 rwhp at 6,300 with GE 80 cams, but safe to 7,300 on upshifts all day long. Its giving it a buzz on a downshift that you have to worry about, which is why i have a downshift light set to come on under 5k.

It pulls strongly from 4k and anything over 7k is wasted. I set the orange shift light at 6,900 and the red one at 7,100 and the limiter at 7,300.

Cheers,

Thanks. I'm new to auto x, can you explain the danger with downshifting? And come to think of it a down shift light? I'm assuming that's an aftermarket piece of equipment?

[brant]

Thanks. I'm new to auto x, can you explain the danger with downshifting? And come to think of it a down shift light? I'm assuming that's an aftermarket piece of equipment?

over reving the motor occurs during shifting
in 2 ways:

1) a missed shift. intending to go up but accidently going down. results will usually break non forged rocker arms or the shaft they ride on if its caught before the clutch is fully out. If worse, it bends the valves when they hit the piston face.

2) often people down shift and have the motor doing brake work. Sometime without even realizing it. A shift light or tell tale tach, will point this out and can be used as a training tool.

[john77]

Thanks. I'm new to auto x, can you explain the danger with downshifting? And come to think of it a down shift light? I'm assuming that's an aftermarket piece of equipment?

over reving the motor occurs during shifting
in 2 ways:

1) a missed shift. intending to go up but accidently going down. results will usually break non forged rocker arms or the shaft they ride on if its caught before the clutch is fully out. If worse, it bends the valves when they hit the piston face.

2) often people down shift and have the motor doing brake work. Sometime without even realizing it. A shift light or tell tale tach, will point this out and can be used as a training tool.

Thanks Brant. A shift light sounds like something that would definitely be of use to me.