Autosport Labs

Hey,
Just wondering if it safe to use the hard limiter on a fairly standard 998 mini engine, and if its really worth it.
Luke.

Bump

Well, it depends.

Some engines and/or certain levels of tune and modification make it easy to push past the soft rev limiter. Example: high revving engine where the powerband is near the top. For others, the soft limiter cuts power enough so that the engine can't produce enough power to push past the hard limit. This, of course depends on varying factors like what gear you're in, uphill/downhill, etc.

Other factors- is the vehicle being used for racing? is the engine brought to reline often? Is it an interference engine where you absolutely cannot float the valves, or is the engine more tolerant of such things? (Of course, floating valves is always bad...)

Hope this helps provide some guidance.

yer thanks well its only a 998 mini used for everyday use, but im building a fast road engine that may be gettin more revs, so i think i may aswell get it aslong as its not going to blow it up lol

You also need to take into account (probably by setting the rpm appropriately) hitting a hard rev limit during, say, an overtaking manoeuvre.

A hard rev limit is an instantaneous and highly effective method of bring your bhp being applied to the road surface to exactly zero!

...plus, on some engines, a rather entertaining set of noises (aka explosions) and flames when the sparks come back, as the unburnt fuel in the exhaust manifold/pipe ignites

MartinM wrote:...plus, on some engines, a rather entertaining set of noises (aka explosions) and flames when the sparks come back, as the unburnt fuel in the exhaust manifold/pipe ignites

Sounds like fun!

fire!! thats it im getting one lol.
as for the overtaking i plan on setting it very high just for insurance as when im on the motorway down hill its reving scarly high lol.

LOL- since fuel is still being delivered to the cylinders, the flames should be quite fun. "MJLJ, Now with 50% more flames!"

It goes without saying the hard rev limiter will offer little protection against mechanical over-rev, such as accidentially going into 2nd instead of 4th. Funny, I have direct experience with that and floating valves.

Brent

brentp wrote:LOL- since fuel is still being delivered to the cylinders, the flames should be quite fun. "MJLJ, Now with 50% more flames!"

Brent

ha i think we should get stickers with that on when wee but rev limiters! lol
Well as soon as the shift lights are on ill get one orderd,
Thanks for all the replys.

Sorry to bring back a somewhat old thread.
In your post Brent you said 'depending on tune, la la la" the soft rev limiter wont completely cut... ie. some engines will push through it.

I took mine to the drags and the engine is tuned and extremely poweful and was tuned highly... when it hit the rev limiter - it was like someone pulled power from a TV - just died instantly... so I had to shift then bang off she went.

Im curious how others are finding hitting the soft rev limiter on their cars... how it behaves.

Pete

I find it like driving into a great big, squishy pillow on the road, the power just backs right off. Again, this is a 998cc Mini with a stage one kit - so barely enough power and rev-band to hurt itself without the limiter in the first place. A mate's 1293 stage 3 is much the same though, simply like the fuel's run out, until you give it another gear.

hard rev limiter also protects against a stuck throttle when not in gear. i dont have the hard limiter, but have had a throttle stick on recently. obviously had to turn the motor off asap, but damage could be done quite quickly.

alexande.r

I don't feel the soft limiter on mine. It screams straight up to the hard limit when it immediately starts popping and banging and feels like a sack of spanners has replaced my engine.