I believe the stock redline is 6750.. I had a chip in mine which raised it to 7200 rpm

 

yeah, i heard 6800 for the cutout, but close enough.

now did the other focus just stop having power or did it make a funny noise?

its well known that the cam timing from the factory is not always the same from car to car. maybe the other one just didn't have much top end.

it should be really easy to tell if you are hitting the rpm limiter, mine makes a funny noise when i hit it, you can hear and feel it cutting the fuel.

if the other car was in fact cutting the fuel off at 5800, i don't know what to tell you.

 

The redline where you can damage the engine is up over 8000rpms.

The rev limiter is 6750 stock, a chip will bump that up higher 7200 or higer depending on the chip.

Your power band is 100% dependant on how you've tuned the car.

Stock zetec's don't make much power over 5500rpms. This can vary greatly however as the cam timing from the factory varies greatly. (also the reason cam gears have to be dyno tuned and not just set at a predetermined value). The variance can also be effected by little things like how clean is the airfilter? how old is the fuel filter etc.

 

Thanks for the responses. Well, at 5800 rpm it did make a funny noise and there was a cut of power. I guess that was the fuel. But with the current car it goes all the way 7000rpm and there is a very unnoticeable decline in power.
The replies you guys gave me pretty much answerd my questions. Thankx again.

 

Cameroon, what are you talking about?? "Over 8000RPM"??
The REDLINE, the beginning of the redling that is, is the point where a stock engine, ANY stock engine should not be revved past...repeatedly running an engine INTO redline (with or with out a limiter) will harm your engine...period! Sure, it might not blow up the first time you hit 8K (if you were able to do so without slamming it into 2nd gear doing 100Mph), but eventually, the engine WILL let go...
Stock redline is as high as the manufacturer and engineers want you to rev the engine. Beyond the rev limiter, and your messing with piston accelerations higher than what that engine was designed for...and with your cars having cast (yes...CAST) connecting rods, I certainly would not rev it higher than redline...
My SVT redlines at just 7250 RPM, yet Ford decided to use beefier forged rods in it...so if you think your ZX3 can handle repeated runs up to 7200+ RPM, hey, help yourself!

 

so if you think your ZX3 can handle repeated runs up to 7200+ RPM, hey, help yourself!

I've spent a full session (20 minutes) on a track in the California Desert with ZXMurph hitting 8000+ RPM in his engine...

Sooooooooooooooooooooooooooo seems pretty much like it'll stay there if you want it to.

 

All I have to say is, it's your car, your money. I have no doubt a ZX3 will pull to 8000+ rpm if tuned for it. And it'll do it time and time again I'm sure. But it's basically a time bomb if your gonna keep doing it.
With a relatively long stroke of 3.465", your getting piston speeds of around 3893Ft/min. at stock redline. Pretty tame compared to a high performace motorcycle engine for example...
But even look at an Enzo Ferrari or Carrera GT, and they barely reach 4000fpm. Do you think an Enzo uses cast connecting rods?
But run your ZX3 to 8000RPM, and your looking at over 4600fpm!! While not stratospheric compared to let say, a 18,000RPM F1 engine, certainly much more than Ford ever dreamt the stock internals would ever see! Sure, you might think, well hey, 4600fpm....thats only about 52Mph (fpm X .682 / 60=Mph). But your accelerating your piston from a dead stop, to over 50Mph, and back to a dead stop again, in about 3.5"! And doing this 16,000 times a minute...(2 X each stroke)
Now, depending on how much the reciprocating parts weigh(piston/upper portion of the connecting rod/small-end bearing)your looking at around 4000G's of force going thru that connecting rod...
The piston alone might weight 300grams or so...add another 200 for the other parts of the reciprocating mass...
and your looking at conservatively, 1.2Lbs. At 4000G's, thats around 4,800Lbs the connecting rod/crank/bearings/pin is repeatedly being subjected to!! Which, incidently, is almost the weight of 2 ZX3's on a diet!
I hope this doesn't scare you, but it's should at least give you something to ponder...

(While I had my calculator out, I decide to measure the forces of my 3.5cc R/C nitro car engine. With just a .63" stroke and RPM's easily hitting 48,000, I calculated a whopping 29,000G's of force accelerating the piston up and down!! I'm guessing the piston might weigh 1 once, so that ends up being over 1800Lbs! Simply amazing)

 

nice math skills... but uhh...oh well??

 

BTW, "Redline" means "when the valves float"

The Red area of the tachometer is something completely different. It's there for 2 reasons:

1) In stock form, the torque curve is becoming unuseable
2) To keep kids from hitting the fuel cutoff (which IS very hard on the engine, by the way)

Now, just because you take an engine up to where the valves float doesn't mean that the con rods or main bearings can handle it. However, the old school definition of an engine's redline was simply the RPM at which valve float occurs, and when you float valves, you stand to risk damage to your engine, especially in an interference situation.

That said, a bone stock Zetec can physically rev to around 8,000 no problem. These things are well balanced at the factory, and the internals are strong enough to spend quite a bit of time up there without breaking.

The main problem with revving a stock focus up that high is hitting the fuel cutoff. At that point, you are running extremely lean, at 7,000 RPM or so. That's bad news.

The "speed limiter" drops spark instead of fuel, which is a lot safer and easier on the engine. Why the rev limiter doesn't do the same thing is beyond me, but I'm sure there's a reason for it.

 

Is the 6750 revlimiter accurate though? I never go above 5800 because the engine loses power, better just to shift up, but there's been times when I've been times when I've missed an aggressive downshift and hit 7K. Nothing happened, I just got really pissed at myself, but the car wasn't in gear obviously. Does that make a difference with the revlimiter? Anyway, I'm glad to see that the zetec has some room up top above where I usually shift. If I get a new intake mani, I'll probably be shifting up a lot higher, but I'd never do 7K shifts, much less 8K. My internals are far too stock for that.

 

6750 is the point at which the fuel cuts out during acceleration.

If you downshift from 5th to 1st... your engine will see > 10K RPM. The revlimiter can't help those kind of situations.

 

I never go above 5800 because the engine loses power, better just to shift up,...

Sounds like you need intake, exhaust, and a chip.
Mine pulls all the way up to it's cutout, which is around 6850-6900.
I WISH I could get the tune on the chip program that I have right now, but raise the limiter to about 7200RPM.
In Auto-X, there are times on some faster courses when it's just pointless to shift up right before you're about to have to hit the brakes for a turn, yet you're already at the top of the gear you're in, and it's another 20 yards to the braking zone.
Someday I'll probably get an SCT chip, but for now, I'm generally very pleased with the Diablo and what it's done to both my powerband and rev-limit.

 

Hmmm. My tach reads to 7000 and there is NO redline marked.

Discuss.

 

because it goes to the point.

We have a rev limiter.

the redline (theoretical point at which damage occurs) is off the chart of our tachs. So why mark it, when its not there?