8 replies to this topic

[Dusky]

Hi peeps
Can someone explain me the difference and the (dis) advantage of a soft /hard rev limiter?
Cheers

[lawrence]

From my experience
(Bike carbs megajolt ignition management)

The Soft limiter retards the ignition gently towards the limit to stop over revving the engine
Hard Rev limit retards the ignition immediately

However if you have a injection system and fit a soft limiter it cuts the fuel I think as well as the ignition
Hard limit leaves the fueling running so when your ignitions stops being cuts it makes big pops and bangs

Edited by lawrence, 14 August 2015 - 11:27 PM.

[nicklouse]

First you need to see what is compatible with your ignition system.

But a hard set up cuts out at a set limit. A soft starts cutting out before the limit. How depends on the system.

To sum up it does not really matter.

[Midas Mk1]

I've got a mk6.5 zs fiesta, and it makes me laugh on the fb owners group when people fit an omex rev limiter, then two or so weeks later they're asking why they're cat is blown, and there's a big hole in the side of the engine.. aha

 

That said, i'm hoping the limiter will be useful addition when I fit my sc injection kit soon to my MPi, :)

[blackbelt1990]

My old Saab had a hard limiter, it was a surprise the first time I hit it because the revs just stopped dead and the car wouldn't carry on until I'd literally taken my foot off the accelerator!

[Coxie]

Is it just me that thinks rev limiters are just a bodge to fix a broken conection between brain and foot.

[Ethel]

...or hand if you miss a gear change.

 

A soft limiter is always going to work by retarding the ignition. Hard limiters can just switch off the ignition, that can do more damage as your ignition generates the sparks by turning itself off at exactly the right piston position.

[Dusky]

I ll be using an omex clubman if it helps, so wont have my fuelling cut, so probably not much difference between hard and soft for me?
I want one to protect the rebuild engine from being pushed too hard in the first miles, especially now I ditched my main rev counter. Thanks again :)

[carbon]

Soft limiters for traditional carb engine work by starting to cut some (not all) of sparks above a set rpm (say 6,500rpm) and do this in a way that it won't cause odd harmonics or other undesirable side effects.

 

They are often used together with a 'hard limit' (say 7,000rpm) above which all sparks are cut.

 

Fuel cut-out limiters don't respond quickly enough to be effective when using a carb set-up.