Rev Limit 103 TDI CR

[drbass]

Hi,

After a run-in phase of just over 3,000 km (plenty of loading, slowly increasing the rev range) I decided today to go to the redline.

To my surprise the Eos engine happily revved up to the redline (4,500 rpm) AND KEPT GOING. I went to 4,700 without any ill-effect, and I had the feeling that it would happily have gone further up. Also, there still seemed to be plenty of power.

The 125 PD in my Passat is limited to 4,500 rpm (redline) - the DSG simply shifts up a gear. Obviously not the case with the manual gearbox in the Eos.

So, any idea what the limit is? I'm not a rev-head by the way, much prefer the midrange torque (hence the Diesel) - simply "academic" interest .

Seeya,
Michael

[Preen59]

Most likely 4500rpm i'd say.

[drbass]

Yyyyyyyyyyyyyyyyep, that's where the numbers and lines turn red.

I was simply surprised to find no electronic cutoff, and how willingly it kept going.

Also read yesterday that the 125 CR TDI used in the latest version of the Audi TT revs up to 5,400.

Physical limit is what I'm after - any info would be appreciated.

Seeya,
Michael

[Greg Roles]

Common rail, becuase of the far more precise injection, and far better charge mixture, will rev a lot higher than the cruder PD. The "physical limit" for typical diesel cars has been about 5000 rpm, due to the slower compression ignition over a spark plug, but I'd assume CR can inject earlier, and thus allow a bit more time for ignition to happen.

It's all down to the common rail, which is the way to go with a diesel.

[gldgti]

when you begin talking physical limits... well, its a tricky one in itself. the bottom end of the larger 4 cyl vw diesels probably isnt really happy much over 5,500 rpm, because of the long (92.5)mm stroke, and big heavy pistons, crank, etc.

older vw diesels have been known to rev past 6,500 with carefully tuned injection systems.... but this is because of the shorter stroke (80 and 88mm) in the 1.5 and 1.6's) and the fact that they have pre-combustion chambers (not direct injection) allowing earlier injection.

i would say combining common-rail management with an indirect injection head would allow the best high rpm capabilities... hmm, i want to build one

[oracle1]

1.5 is the revver

1.5 engine likes to rev, rather like 302 and 351 cleveland. Shorter stroke/ smaller pistons = more rpm and more power up high. As yet I have no experience hotting up the 1.5 but I'd be speculating that I will soon have something to post on this subject.

[benough]

Physical limit is what I'm after - any info would be appreciated.

Just rev it till it won't go any further. That's how I found out. It's about 5,300 from memory.

It's not like a fuel cutoff in a petrol it just kinda gets a bit rough/won't go further. Feels more like a physical limit.

Maybe wait till you got a few more km's first but don't be concerned about breaking it

[CatonaPC©]

I was simply surprised to find no electronic cutoff, and how willingly it kept going.

There is an engine cutoff; keep driving like that and you will eventually get the engine to cut-off.

Permanently.

That redline is not there just for good looks. Respect it.

[Silver Caravelle]

By way of comparision, the T5 128KW gets to about 5200 RPM Max. No rev limiter that I can detect, just bit of slight 'valve bounce' rough running

Only done this once to blow a bit of crap out of it, so no harm.

Regards,

Scott

[gregozedobe]

By way of comparision, the T5 128KW gets to about 5200 RPM Max. No rev limiter that I can detect, just bit of slight 'valve bounce' rough running

Only done this once to blow a bit of crap out of it, so no harm.

Regards,

Scott

Remind me to not buy a vehicle off this man

My T5 128Kw R5 is distinctly uninterested in revving above 4,600 in any of the higher gears, and it accelerates MUCH harder by changing up to the next higher gear and getting back into the fat part of the power curve.

[drbass]

Hi all,

Thanks for the replies.

It appears that the "physical limit" is seen to be somewhere around 5,300 - 5,500, from experience and extrapolation.

My intention is not to find that limit myself, I was simply intrigued that there was no rev limiter. Totally agree with gregozedobe that acceleration is best in the high torque region of the rev range rather than up at the "limit".

Will definitely stick to the recommended 4,500!!

Seeya,
Michael

[Greg Roles]

Remind me to not buy a vehicle off this man

My T5 128Kw R5 is distinctly uninterested in revving above 4,600 in any of the higher gears, and it accelerates MUCH harder by changing up to the next higher gear and getting back into the fat part of the power curve.

I'd have to agree that revving my stock TDI above 4000 rpm is a waste of time, and 4500 sure sounds "unhappy". It obviously goes further, but WHY? V-tec yo?
There's no grunt there in stock form.

[Silver Caravelle]

Remind me to not buy a vehicle off this man

My T5 128Kw R5 is distinctly uninterested in revving above 4,600 in any of the higher gears, and it accelerates MUCH harder by changing up to the next higher gear and getting back into the fat part of the power curve.

To clarify, I was referring to revving in neutral to establish max rpm. As an aside, just once or twice to check harmonic vibration through the rev range.

Perfect vehicle to buy .

Agree with your other comments - not much action above 4600rpm.

Regards,

Scott

[CatonaPC©]

To clarify, I was referring to revving in neutral to establish max rpm.

Oh, yeah, that's much better. Wouldn't want to throw a rod while moving.

[recalibrate_ecu]

Hi, your car has an electronic rev limiter embedded in the ECU

Best wishes