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Thread: Red-lining

  1. #1
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    Red-lining

    This may sound like a stupid question but i have to ask it. I have a S1 405 mi16 and on occasions (as we all do) drive it pretty hard. I have two questions to ask both relating to redlining an engine.
    The first is why is there a power cut at around the 7000-7500 rpm mark?
    and is it a terrible thing to redline it occasionally?
    I could probably think of a million reasons not to do it but are there any positives or am I being far to optimistic!

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  2. #2
    Budding Architect ???? pugrambo's Avatar
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    405T16:
    This may sound like a stupid question but i have to ask it. I have a S1 405 mi16 and on occasions (as we all do) drive it pretty hard. I have two questions to ask both relating to redlining an engine.
    The first is why is there a power cut at around the 7000-7500 rpm mark?
    and is it a terrible thing to redline it occasionally?
    I could probably think of a million reasons not to do it but are there any positives or am I being far to optimistic!
    as far as i know the cut out should be at 7000RPM which is the redline on the S1 Mi-16
    if the engine is healthy there is no harm in gitting redline occasionally but i myself wouldn't drive the car for any period of time like that but that's just me
    the quick spurt every now and then is fine
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  3. #3
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    The rev limiter is there to protect the motor however factory limiters are pretty conservative.
    My mechanic keeps telling me i need to get up the car more often...apparently its good to blow the gunk out now and again.
    Witness cars that are getting upped and you'll always see a grey junkie type matter coming from the exhaust in big gulps...thats the stuff thats good to get rid of.
    Hope this helps, jr

    Sorry officer i was just clearing my exhaust!!
    jr20516v

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    1000+ Posts tekkie's Avatar
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    *cowebs*

    lol,

    the higher the RPM the more likely any imperfections will be brought forward, especially on older engines, things crack, snap, pop, oil stops to lubricate due to higher loading, cracks in belts become breaks, oscillating componets begin to act like hammers etc etc.

    having said that.... redline is the limit of the engine as guaranteed by the manufacturer. As with all things its conservative aiming for the 'worst of the bunch' engine component (lowest common denominator factor). Hence the reason for blueprinting of race engines.
    Yelo20's engine should most probably safely rev to 8000+ RPM because it has been properly balanced.

    Does that give you an idea whats up with the redline?

    now back to clearing the cowebs out of the exhaust.

    <small>[ 30 June 2003, 09:32 PM: Message edited by: tekkie ]</small>
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  5. #5
    Gus
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    My understanding is, ironically, that the part that's bad for the engine can be the factory engine management's redline cut-off, rather than the redline itself! (no doubt for prolonged redlining, or catastrophic failure, this is not the case.)

    The cutoff usually works by switching off sparks until the rpms drop back within the limit. This is fairly bad for the motor, AFAIK, because it comes as a bit of a shock at that speed. Some might work by switching off the fuel, too, which is not quite as bad AFAIK.

    (However, I heard tell one time of a Mustang drag car that was turboed. The rev limiter cut off the sparks as above, but before takeoff the driver would open it up and leave it revving at redline, bouncing it off the rev limiter. With the sparks missing, huge amounts of fuel would pour out into the hot exhaust where a lot of it would burn/explode, leading to an afterburner/jet turbine type effect in the turbo... Something which came in handy when he finally got going.

    I doubt the above would be a good method for any extended use, though!

  6. #6
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    Yeah that makes sense. I don't drive like that often its either when I get pissed off because of someones bad driving or when racing off from the lights that I give her a bit. I do however take note of the engine temperature and never do it when the engine is cold.
    Just out of interests sake where do you get your car serviced in Brisvegas jr20516?
    I have another question regarding mi16 headlights too. I have noticed that the front head lamps on the 405 mi16 are directionally adjustable. Mine don't seem to work from the cabin and there are no "hoses" etc. going from the headlight either. I know you can adjust them manually but i want the lazy option. Do they work on some sort of vacum tube priciple or something? Will it be an expensive exercise to rectify? spanner

  7. #7
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    The hard stuff i get the troopers at Advanced
    performance centre @underwood. The easy stuff i do
    but if i lived on the nth. side i'd deffo get Stuey or the boys at Eurocare to do it. theyre good.

    hope that helps m8. jr
    jr20516v

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  8. #8
    Moderator Alan S's Avatar
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    As has been said, the rev limiter chops in at about 72/7300 rpm. I often hit mine in the lower gears around town or sometimes in merging traffic. If you hit it in 5th I'd suggest you check the speedo though eek! you could be a tad over the legal limit.
    With the kind of driving I do,I don't find it all that hard to hit the limiter & according to overseas experts, up to about 9000 is possible without getting serious with bottom end mods. I think the way that these engines don't really start to get moving until 4500, there's plenty to suggest that where these kind of revs could be fatal to a car that redlines around 55/6000, with these it's reasonably safe to do so, however, constantly running around that figure would have to be risky in the long term as regards stress on production line standards of parts which whilst of good quality, aren't made to competition specs.

    Alan S
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  9. #9
    XTC
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    What are peoples rev limiters like ? I've found the 206GTi's to be very very soft, hit it mainly in 2nd at 100kph .. and once in 3rd (don't ask how fast) - it gets there so damn quick - but it's not a hard cut (like some rental cars I've driven - more soft loss of power.

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  10. #10
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    When I've hit the GTi6 limiter on the road and on the track, it's always been fairly savage. It's very noticeable on the track, as you're moving pretty quickly and every second counts. I've ruined laps by hitting it on the straight at Wakefield.

    The ST170 I drove recently was quite a noticeable hit as well.

    I guess it depends on your definition of "soft". To me it's savage as you hit it as you have to wait a decent amount of time before you get the power back. It's that time between power off and power on that is painful.
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  11. #11
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    XTC206:
    but it's not a hard cut (like some rental cars I've driven - more soft loss of power.

    - XTC206 -
    Funny bout that. A Hyundai Accent rental car I rented once had a really smooth rev limiter. In most cars, the engine tends to bounce off the rev limiter, whereas this one just stayed there.

    You couldn't do the "gas pedal trick" in it either

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  12. #12
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    Where is the rev limiter on the 306 2.0L 16v engine? I've never hit it. I'm sure Brenno will know this one wink

    Derek

  13. #13
    2000+ Brad's Avatar
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    Mine is at 7,000 and hits it HARD, then takes time so come back on power, unlike XQ's S16 which bounced off it. I think though that it was changed on his during an ECU tune.
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  14. #14
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    The 205 will have a "soft" limit at about 7800 and a "hard" limit at 8000rpm. God I love revs. head_ban

    A final decision will be made when its on the dyno and we see where the peak power is. The rev limit is generally set a few hundred rpm after that.

    Darren

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