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MG MGF Technical - redline cutout damaging?

Just a quickie.

Ok, yes, I know I shouldn't drive so enthusiastically, but the road WAS bendy AND deserted, and the White Stripes DID sound better played very loud, and the hood WAS down, but..

Anyway, I redlined my VVC F and the rev limiter kicked in. Felt like the engine had self-destructed for a split second, but then the car fell to lower revs and everything seemed fine.

I know this cut-out is a protective thing, but can I just check, it doesn't do the engine any harm to have it cut out occasionally does it?

It's so bloody easy to do in a VVC. It doesn't *feel* or *sound* like it's getting to its limits!!

D
David Bainbridge

The limiter is there to prevent damage so should not be a problem, it'll just slow you down a little. For what it's worth my car gets to the red line even quicker and Kingsley quicker still.
tim woolcott

nope, engine should be fine, but you will cause more/faster wear on the engine if you keep doing it.
Will Munns

indeed it does Tim. i've 2 limiters, soft and hard cut, one slows the engine reving down, the other cuts it out all together.
As long as you're not hanging it on the rev limiter (above the red line) no damage to the engine should be caused, but as power curve is on the way down by then, you should realy change up.
Kingsley

A fellow White Stripes fan, I shall watch out for for the temptaton to drive too fast when I put one of their CD'c on, the trouble is its not just the White Stipes that make me behave in this way, you are correct in saying the VVC engine races up the rev range extremely rapidly with the resultant rapid gear changes, great isn't it !!
Art Jacks

Just out of interest.. I've had my VVC for a year now and never really gone about 6k revs (and rarely at that) for fear of the engine going bang. How justified are my fears?

Ta,
J.
J

Interestingly enough (but unfortunately for him) the case of a MGZR160 owner who severely damaged his engine was reported on the French site. MGR seems to argue that only by changing gears dramatically down he would have caused this issue (e.g. moving from 4 to 1st at say 6000 rpm)... yep, they're actually basically suggesting this is the owner's responsibility so that they can get away without paying anything. Whatever the cause, the engine was blown out straight away. I've had a chat with some friends in car engineering and they've confirmed that hitting the rev limiter whilst applying full throttle (but no gear change) is kind of Ok (hinting that basically one shouldn't do it too often) but that hitting this zone by changing gear down could be dangerous (since it creates some extra pressure on the engine).
I must admit I have rev'd hard my TF160 in the past and I was a bit worried to hear bout this. I am basically avoiding doing it these days. But then I am not an expert in engines. Any other views out there?
Stephane

>for fear of the engine going bang.
>How justified are my fears?

As said, do it, but don't do it too often should be fine when overtaking, but not so good when speeding.

>yep, they're actually basically suggesting this is the >owner's responsibility so that they can get away
>without paying anything.
The rev limiter is a tool, using it as a brake is the wrong use for this tool, forceing the engine to over-rev will lead quickly to it's destruction. If you don't understand this then an automatic may be a better bet.

>Whatever the cause, the engine was blown out straight
>away. I've had a chat with some friends in car
>engineering and they've confirmed that hitting the rev
>limiter whilst applying full throttle (but no gear
>change) is kind of Ok (hinting that basically one
>shouldn't do it too often) but that hitting this zone
>by changing gear down could be dangerous (since it
>creates some extra pressure on the engine).

Yes, there are two ways to make the car hit the limiter, either you put in the power using petrol, or you put in the power using a road, the road has no limiter, use the road and drive the engine over it's max RPM and things will start to break.
Will Munns

J

If you have a VVC you really arn't using its full potential. The VVC only comes into effect over 6000. The engine has been designed to do it so go for it, you'll love it....
tim woolcott

Thanks for the advice. It's pretty much what I thought. I rarely go above 6500, but when I hit the limiter I wasn't really in a situation to notice the torque dropping off. Also, I just accelerated up to it, rather than changing gear to hit it, which I can imagine might be rather disastrous... The engine sounded quite happy!
David Bainbridge

Hit the limiter for the first time in 11 months the other day, overtaking and the car took off i didnt realise it hit the redline!!!

FUN!
R Goodman

Still getting used to my 1.8i F (bought it two weeks ago). Frankly, if the VVC is *even* pokier at high revs than my car then I'm scared...
Jamie

Jamie & R (Russell!?)

You ain't seen nothing yet ..... :0)

If that was fun then what about indulging yourself with some track days....
tim woolcott

Guys,as suggested by others be careful when changing down through the box, but going the other way you are missing a trick if you keep hitting the limiter.I think the limiter kicks in at 7200rpm on the VVC, power is falling off so you are better off finding the point just below its cut in to change up. Obviously we all only hit the limiter in first and second gear!Unless we are taking part in a track day!
My 1997 VVC has encountered its limiter many times without any damage.Usually when I make a farce of a gear change!

Cheers MGTerry
Terry

Going up the box use the revs and let the limiter save you from an expensive blowup - that's what it is for. As everybody else has said - going down the box is different. The F does not have the benefit of a slipper clutch or a LSD so banging it down at too high revs is a recipe for a short life.

I'm thinking of fitting a changeup light on the bike as I tend to use the limiter most days in most gears on the way up as ear protectors and a helmet do hide engine noise. It can come as a shock to hit limiter in third (115 mph).
JohnP

I used to hit the limiter on my '96 MPI at 6,750 rpm quite regularly. It would to take me to 105 km/h in second without having to change up. After 70,000 kms the standard 1.8 would rev quite willingly to 6,100, slowed down a bit upto 6700 but was sill very revvy.

Of course my VVC is much revvier, but not until it had loosened up around 10,000 kms. Before that it was no more willing than my old MPI.

Someone on the French board also suggested that the VVC mechanism being very complex suffers from the "jolt" when you hit the limiter (especially in lower gears) which might wear it prematurely. I wonder...
Anthony Braham

>>>suffers from the "jolt" when you hit the limiter (especially in lower gears)

Interesting idea.

I doubt I'll ever hit the limiter in higher gears!!
David Bainbridge

David, IMO you need to do it at least once so that you will know what it feels like and recognise it next time when it happens by accident. It feels quite different in higher gears at higher speed.

BUT find a quiet stretch of road with no "Es and Es" to distract you or ferry over to France for a midweek break and return with cheap but very good wine as a bonus.
JohnP

Does the resulting "misfire" have any effect on the Cat, I wonder???

(Why does misfiring effect the cat anyway??)
SimonKE

I think not, because it's a "programmed" misfire so the petrol supply will be cut at the same time as the plugs stop firing. Damage to the cat from misfiring results I think from unburned fuel going through the exhaust and burning in the cat (which is very hot).
Anthony Braham

Sounds feasible, Anthony, thanx!!!
S R Kenyon-Edwards

This thread was discussed between 25/04/2003 and 14/05/2003

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