Think I hit the Rev Limiter 2.3 DOHC Duratec

[TFB1]

Originally Posted By: mechtech2
Originally Posted By: morris
is it possibly the gauge showed a higher RPM than the engine really hit?


Probably not.
But, the tach can read lower than real RPMs if you accelerate hard in first. There is a dampening/lag that can read 200 RPM or so low under those conditions.


In most newer vehicles they are probably fairly accurate, but in vehicles of 20 years ago they were often off calibration by 300-400 RPM in either direction...

 

[TallPaul]

Originally Posted By: mechtech2
Originally Posted By: morris
is it possibly the gauge showed a higher RPM than the engine really hit?


Probably not.
But, the tach can read lower than real RPMs if you accelerate hard in first. There is a dampening/lag that can read 200 RPM or so low under those conditions.


Then a 6250 rev limiter is quite possibly what I hit!

It sure was fun lurching out in second gear a 3500 rpm. That's right near the torque peak of 3750! A very good place to start the next gear.

 

[01rangerxl]

Originally Posted By: TFB1
Originally Posted By: 01rangerxl

One of my friends did have a pre-OBDII 1993 2.3L manual that apparently did not have a rev limiter. This truck's valves floated at least once...which happens at 7000+ RPM on the Lima. Again, no problems.



AFAIK all the OBD-I Fords hit fuel cutoff at 6250, my '87 2.3 Stang & 2.3 Turbo Birds could all hit it easily... Something like the lo-po 5.0 or even a stock HO 5.0 would barely rev to 6K due to valve float, don't remember ever hitting the fuel cut in one of those...


This truck may have been chipped, I can't remember. It was modified a little and was lowered with Pony wheels from a Mustang, and IIRC was running a glass pack or some other ridiculous muffler. It wasn't too fast, but it was fun to wind up that 2.3.

 

[tbm3fan]

Not a problem since I have done that twice in my 2.3L Focus. The second time was today when getting on the freeway. Long flat entrance with cars in front moving too slowly. Glanced over my shoulder to see how clear behind me and then hit it in order to move three lanes over. Forgot I was in second and right about 60 there was that momentary stall in power. Knew right away and got her into 4th and powered on down the road. The 2.3L does move very quickly between 3000-4500 rpm and it is easy to sometimes forget the gear you are in when accelerating in a hurry.

 

[Norm Olt]

Personally I'd be more concerned with an over-rev situation on a downshift (inadvertant, i.e., as in 5th to 2nd?) than running into the rev limiter...

Just IMHO.

Cheers!

 

[Cujet]

I bounce my Jag X-Type's (manual trans) 2.5L duratec engine off the rev limiter daily. At 120,000 miles, it still functions perfectly.

There is nothing damaging about running a modern engine to redline.

However, my current rental Chevy Captiva (4 cyl) does seem to exhibit very noisy valve float at around 6500RPM+ . (yes, I am quite familiar with the sound and feel of valve float) In that case, it would be best to avoid such operation.

 

[morris]

after reading this post i thought i would try to cut back my top rpm, on my 2001 dakota V-6 auto, stock, with 4.1 rear gear. i backed the throttle off to 4000 rpm, factory max 5000-5200 rpm, shifted by trans. it still moved out more than good enough, after all i wasnt racing. something to think about.

 

[TallPaul]

Wait now. I didn't mean this as a "hey guys, don't rev it so high" thread. You all can rev it right up to redline. It's actually good for the engine and makes the car quicker.

 

[lovcom]

I think people that constantly bounce their car off the rev limiter dont really understand how to drive a car, nor do they understand HP & torque curves. Often times an engine's HP will peak long before the red line, so what is the benefit to bouncing against it? Your engine will live longer if you stay clear of constant bouncing off the rev limiter.

 

[OVERKILL]

Originally Posted By: mechtech2
Originally Posted By: morris
is it possibly the gauge showed a higher RPM than the engine really hit?


Probably not.
But, the tach can read lower than real RPMs if you accelerate hard in first. There is a dampening/lag that can read 200 RPM or so low under those conditions.


Oh, the 80's Ford tach's on the fox Mustang's were notorious for being inaccurate. Mine would sometimes be off by as much as 1,000RPM

 

[OVERKILL]

Originally Posted By: lovcom
I think people that constantly bounce their car off the rev limiter dont really understand how to drive a car, nor do they understand HP & torque curves. Often times an engine's HP will peak long before the red line, so what is the benefit to bouncing against it? Your engine will live longer if you stay clear of constant bouncing off the rev limiter.


My M5 makes peak HP at 6,800RPM. The factory rev limiter is 7,000RPM. It is VERY easy to hit the rev limiter.

And it doesn't have much of a torque curve. More of a torque plateau thanks to the VANOS system.

Every car is different, but there are many that are designed to be flogged and run up to the top of their RPM range where they make the most power. Honda's little VTEC motors, Ford's Coyote engine, anything ///M, AMG....etc.

 

[itguy08]

Originally Posted By: lovcom
I think people that constantly bounce their car off the rev limiter dont really understand how to drive a car, nor do they understand HP & torque curves. Often times an engine's HP will peak long before the red line, so what is the benefit to bouncing against it? Your engine will live longer if you stay clear of constant bouncing off the rev limiter.


It all depends on the specific engine/trans/gear combination and what you want to do. Remember HP is derived from torque (HP =(Torque * RPM) /5252) ). For many cars shifting at redline is the preferred way to get max acceleration.

This article explains it better than I ever could:

http://www.allpar.com/eek/hp-vs-torque.html

 

[SteveSRT8]

Originally Posted By: OVERK1LL
Originally Posted By: lovcom
I think people that constantly bounce their car off the rev limiter dont really understand how to drive a car, nor do they understand HP & torque curves. Often times an engine's HP will peak long before the red line, so what is the benefit to bouncing against it? Your engine will live longer if you stay clear of constant bouncing off the rev limiter.


My M5 makes peak HP at 6,800RPM. The factory rev limiter is 7,000RPM. It is VERY easy to hit the rev limiter.

And it doesn't have much of a torque curve. More of a torque plateau thanks to the VANOS system.

Every car is different, but there are many that are designed to be flogged and run up to the top of their RPM range where they make the most power. Honda's little VTEC motors, Ford's Coyote engine, anything ///M, AMG....etc.



As an example my engine's HP peak occurs at the stock shift point, 6200 rpm.

Thus the aftermarket developed a tuner that allows a RAISED fuel cut off at 6600 rpm (stock=6400) and a shift point of 6400.

I've done some spectacular burnouts all the while just a-bouncin' off that 6600 limit. It's a blast.

Live a little. Have some fun. It's ok. Factory limiters are always set to the LOWEST common denominator, with a huge warranty factor in there, too. If the engine is healthy and well maintained it does not hurt a thing.

 

[Cujet]

Originally Posted By: lovcom
I think people that constantly bounce their car off the rev limiter dont really understand how to drive a car, nor do they understand HP & torque curves. Often times an engine's HP will peak long before the red line, so what is the benefit to bouncing against it? Your engine will live longer if you stay clear of constant bouncing off the rev limiter.


Really? Are you saying that my 2.5L V6 makes less HP at redline? Because I can tell you that the car is quicker when run to redline. It has variable cam timing and "loves" to rev. It's also has tiny internals and 7000RPM is not at all stressful on such components.

 

[TallPaul]

Originally Posted By: itguy08

This article explains it better than I ever could:

http://www.allpar.com/eek/hp-vs-torque.html


That is a very good article. For my Ranger I have only the torque at the torque peak and the horse power peak and it clearly shows that I need to be running at least to 5050 horsepower peak and the numbers show that unless the engine goes dead after that (it doesnt) it is better to say in gear up to nearly 6000 rpm (or more but for the limiter).

 

[TallPaul]

I found a torque curve in a 2002 Ranger brochure. According to the curve, and estimates of torque from that curve, and using the method in the linked article from allpar.com, my best shift point for the 1-2 shift is about 5200 rpm, just above the horsepower peak. For the 2-3 and 3-4 shifts, the best point is just under 5000 rpm. Well, it was an experience hitting the rev limiter, but I won't be going there anymore. Can't think of any good reason to go much past the HP peak, at most 5500 (after all, that torque curve was generalized, so need to have some leeway). I'll have to see how it feels tomorrow.

For you Ranger 2.3L Duratec owners, don't copy my info unless you have a 2001 or 2002 (maybe 2003). After that some mods were done to give that engine another 8 hp and that will affect the torque curve.

 

[Klutch9]

Originally Posted By: TallPaul
Originally Posted By: Miller88
The 2.0 duratec redlines at 6500 according to the tach. Never had it above 5000 ... never had a need to.
Oh man, I'd be itching to run it up to at least 6000 every now and then.


I routinely run my Focus 2.0 up to 6,000+. With the CAI I have installed, my Focus sounds wonderful at WOT

My tachometer does not have a 'redline' though, so I'm not really sure where the redline or rev limiter is. On my old Escort Zx2 with the 2.0 Zetec, the redline was at 6,500 rpm, but the rev limiter wasn't until 7,200 or so.

 

[TallPaul]

Everyone should read the allpar.com article. Optimum power band is based on gearing and torque curve, and varies per gear. Redline is not related to the power band but is simply a function of the mechanical durability and balance of the engine for high speed operation. If well balanced, my Ranger engine might be able to run up to 9000 rpm, but the power band would not be any different unless a different cam and other mods were done.