Mis-downshift redline

17642 Views 31 Replies 17 Participants Last post by MexicanFiestaST, Jan 22, 2014

Atlas4gr

Discussion Starter · Dec 18, 2013

Hi guys,

New to this site, I was messing around giving my friend a test ride in my ST and went from 3rd to 2nd instead of 4th, engine went into the redline for a second or two. There was no crazy traction stall or jerking motion, just wondering if there is any potential for damage I might have caused. Should I take it in to the dealer for a diagnostic? Any info would be greaty appreciated

1 - 20 of 32 Posts

Cligedy

· #2 · Dec 18, 2013

I wouldn't sweat it. The big danger with over revving is typically valve float, and then the potential for the piston to hit the valves. If you can't tell any difference, then probably no issues.

Sent from my XT907 using Tapatalk

stuntdoogie

· #3 · Dec 19, 2013

Happened to me once but instead I shifted from 4th to 3rd when trying to shift to 5th. I was paranoid that whole day listening to my engine constantly for any weird noises which it already had...you know that annoying ticking sound from the head lol

rweidman

· #4 · Dec 19, 2013

That is what rev limiters are for. Bounced off of it once and message came up about fuel shut off, Never noticed any further effects.

RodMoe

· #5 · Dec 19, 2013

rweidman said:
That is what rev limiters are for. Bounced off of it once and message came up about fuel shut off, Never noticed any further effects.

msg came up on MFT screen ? i never saw one the only time i bumped it though i was looking at the tach not the MFT screen...

D1JL

· #6 · Dec 19, 2013

If the check engine light didn't come on then I don't think you have much to worry about.
However you may have shortened the life of the clutch by a small amount.

Dave

mamiata1

· #7 · Dec 19, 2013

I had a friend once that while going down the back straight at Waterford Hills in a Porsche 914 6 hit second instead of fourth gear and that was crunch time. But that was a pancake (boxer) 6 cylinder and he went way over the rev limit. Some valves and springs had to be replaced. Still, I pretty much agree with others above that in a modern car with more fail safes like fuel cutoff chances are you're OK. And also consider that if you tune your engine with the Cobb unit one of the first things it does is raise the rev limit. So there's some "fudge" factor in there.

eRic

· #8 · Dec 20, 2013

I almost did a 2-1 "upshift" in my 2011 Fiesta at Waterford Hills on the way up to hilltop. Thankfully I realized that I selected 1st instead of 3rd before completely releasing the clutch. The fuel shutoff won't save you when the speed of the tires/wheels/transaxle mechanically force the engine speed to 7000 rpm. of course this happened when I had a passenger and my onboard video camera recording the session. D'oh!

Reactions: 1

wash

· #9 · Dec 20, 2013

Relax, the 1.6 is an under square engine with small valves and DOHC, the mass of the valve and tappet is very low and turbo motors usually have mild ramp rates and heavy springs (so the boost pressure doesn't blow the intake valve off the seat).

I would be very surprised if the engine couldn't stand short duration over-rev to 8,000 or 9,000 rpm several times.

Also realize that the rev limit is so low because the turbo runs out of air flow, not because bad things start to happen at 6,600 rpm.

D1JL

· #10 · Dec 20, 2013

Once apon a time I downshifted form forth to second in my track car at about 140 MPH going into turn one at Willow Springs.
I immediately started uncontrolled donuts and took every bit of pad off the clutch.
However did NOT hurt the engine.

Dave

nummypuppies

· #11 · Dec 21, 2013

My wife went into 1st instead of 3rd once while accelerating. Barely hit the limiter and no harm done. These cars are pretty forgiving it seems. In my old 5 speed eclipse, if you hit the wrong gear in the wrong speed and rev range, you were having a bad time.

audiphile

· #12 · Dec 22, 2013

Folks, there is a name for it, it's called MONEY SHIFT. There is nothing modern fuel shut off can do about it. If you downshift and let off the clutch, you're forcing the wheels and engine to interlock. If that happens to be at engine speeds higher than redline, then you might cause damage that no modern tech can prevent..

Reactions: 1

Sekred

· #13 · Dec 22, 2013

Relax, whats the worst that could happen??

audiphile

· #14 · Dec 22, 2013

wash

· #15 · Dec 22, 2013

Have you ever wondered why a Formula 1 engine can run at 20,000 rpm for several races but a NASCAR engine will grenade at 11,000 rpm?

Its because 5.8l v8s use big heavy pistons with a fairly long stroke and 2.4l v-10s use tiny pistons with really short stroke.

Compared with another Ford product, the Coyote 5.0 which is good for 8,000 rpm with reasonable durability, the EcoBoost 1.6 has smaller pistons and a shorter stroke. It has other advantages also like only one rod per crank throw and lighter rods too.

I don't know how high the 1.6 can rev before it pops but I'm certain its far above its artificially low "redline" fuel shutoff rpm.

audiphile

· #16 · Dec 22, 2013

I totally agree with you. I bet our engine can turn much faster without any damage than the fuel cut off.. I'm just making a point about what money shift is and how it works.. On the other hand, if you're WOT at redline in 3rd and shift to 2nd by accident, then fully release the clutch, you'll bend things...

D1JL

· #17 · Dec 22, 2013

As I stated above I was lucky to only take out the clutch.
As the attached 5.8 L would have been expensive.

Dave

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Reactions: 2

Sekred

· #18 · Dec 23, 2013 (Edited)

Want someone to build you a engine for your fiesta, these are the guys to see.

[email protected]

· #19 · Dec 23, 2013

rweidman said:
That is what rev limiters are for. Bounced off of it once and message came up about fuel shut off, Never noticed any further effects.

Others have mentioned it but no one quoted you so just for the record. A rev limiter can't prevent an over rev caused by a missed shift, downshift from 6th to 2nd at high speed and you will very likely damage engine, clutch, trans or axle parts.

Reactions: 2

[email protected]

· #20 · Dec 23, 2013

wash said:
Have you ever wondered why a Formula 1 engine can run at 20,000 rpm for several races but a NASCAR engine will grenade at 11,000 rpm?

Its because 5.8l v8s use big heavy pistons with a fairly long stroke and 2.4l v-10s use tiny pistons with really short stroke.

Compared with another Ford product, the Coyote 5.0 which is good for 8,000 rpm with reasonable durability, the EcoBoost 1.6 has smaller pistons and a shorter stroke. It has other advantages also like only one rod per crank throw and lighter rods too.

I don't know how high the 1.6 can rev before it pops but I'm certain its far above its artificially low "redline" fuel shutoff rpm.

Don't forget the pneumatic valve actuation in the F1 engine and the use of MUCH stronger materials used in the entire assembly.

-Steve

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