Where's your redline?

[RabbitJockey]

i read in a bently that you adjust a TD motor to 5850 rpms for the max setting. so if thats a stock absolute redline.. then why cant we balance our bottom ends and turn 6500 or more? i really dont know how many revs im turning, but i shift my gears when the motor starts getting quiet if im really trying to get somewhere fast. i dont really have a top speed limiter screw setting on my pump either. its just backed way way out. this probably isnt the best way to get revs out of your diesel motor, but whatever, i did it when i was still way new to diesels. and it still works too good. so im not gonna fix it.

5850 is a dry rev i doubt anyone could go that high on the road with out the governor mod

[Rabbit on Roids]

since these motors are so similar to the 8v gasser motors, why is everybody so afraid of revs? i want to turn as many revs as i can possibly squeeze out of that little motor. i understand not wanting high rpms for freeway cruising, but c'mon. it would be nice to have 6500 on tap whenever you needed it. maybe im just dreaming tho..

[Vincent Waldon]

I don't think it is a matter of fear, more a matter of "what's the point". ;-)

Mechanically the gassers and diesels are based on some similar factory castings, but the engines are very very different in many many ways.  

Specifically for this thread, maximum torque and power and delivered at a significantly lower RPM on these diesels as opposed to their gasser cousins. As a relative example of two similar MK3 VW engines in the 2l range:

AAZ diesel:     max 75 hp @ 4000 RPM, max 111 ft-lbs @ 2000 RPM
ABA gasser:  max 114 hp @ 5400 RPM, max 112 ft-lbs @ 5400 RPM

Torque's peaked at 2000 RPM, hp at 4000... no point in reving these babies into the stratosphere.

[Rabbit on Roids]

so basically they arent even building anymore power reving them any higher than about 4000?

[DVST8R]

Well as has been seen in the past, add a bigger turbo and some head work, and you can see that TQ peak move to the right a quite a bit. There have been motor's here that have made power right up to 6000rpm. Probably would have gone past that, but ran out of fuel.

[allsierra123]

well my gearing will be low I will probably be seeing 3500 at 60 mph. I wish it were lower. But the auto box just isnt going to do much better I fear. So I just wonder if it will do it any damage or if its just going to be a matter of wasting fuel.

[subsonic]

I don't think it is a matter of fear, more a matter of "what's the point". ;-)

Mechanically the gassers and diesels are based on some similar factory castings, but the engines are very very different in many many ways.  

Specifically for this thread, maximum torque and power and delivered at a significantly lower RPM on these diesels as opposed to their gasser cousins. As a relative example of two similar MK3 VW engines in the 2l range:

AAZ diesel:     max 75 hp @ 4000 RPM, max 111 ft-lbs @ 2000 RPM
ABA gasser:  max 114 hp @ 5400 RPM, max 112 ft-lbs @ 5400 RPM

Torque's peaked at 2000 RPM, hp at 4000... no point in reving these babies into the stratosphere.

Vince,
Those numbers are stock I assume.   I see the difference you are pointing out and agree to a point.  To interject a little chaos theory into the debate, (this is always the fun part ) we need to be able to break our apples and oranges into different sub species.  
1.  Stock 1.6 N/A
2.  Stock 1.6TD
3.  Stock 1.9TD
4.  Modded 1.6 N/A (various fuel pump mods, exhaust mods, cold air  
     intake etc.)  
5.  Modded 1.6TD  ( Huge range of mods.  Need to group similar.
     Example 1.6/1.9 mod,  Super pump, etc)
6.  Modded 1.9TD  (same as above.)

I think that each group or sub-group will have greatly different RPM / TQ / HP ratio’s
Of course it would be cool if we could all dyno before and after mods for hard numbers, but that could get pretty darned expensive. So who wants to be the applied physics guru and help us approximate with different inputs.
 :lol:

[Vincent Waldon]

Vince,
Those numbers are stock I assume.

Yuppers.

Good point in that they will vary as we add modifications... but (since you brought up chaos ) that will also be a challenge putting things into hard defined buckets... I'd suspect *every* engine out there will run a bit different on the dyno, particularly as we add our own interesting mods, in our own way, in our own particular order.

My (albeit small) point... my guess is that (except in cases of extreme modification!) all of the power is long gone by 6000 RPM, so to me there's no point stressing the engine up there. ;-)

[Aki-76]

My old engine (eaton/holset) take 6000rmp very easy (max power is 5500-5700,200kw,in wheel) and new twin turbo,i hope it take 7000 rpm.More rpm=more power  :twisted:

[gldgti]

i ahd the fuel screw on my old 1.5 n/a wound a long way in, and it would rev and rev and rev.... i used to cruise pretty fast too, and it didnt mind.

my aaz with all its mods seems happy enough to shift around 43-4500 rpm... and i've taken it to about 5200 on the odd occasion... but given the aaz crank is 4.5kg heavier than the 1.6 one, i dont think it'd like a lot more. my general shift point for normal driving is about 3000rpm.

[arb]

I dont have the gov mod (yet  :oops:  ), so I dont get past 3800-4000 without bogging down. My usuial shift point is 2250 - 2500

And 6000!!!#!  WOW!  Anything over about 3500 scares me a bit... I have visions of parts coming out of the hood at that rpm!

Not to hyjack, but do these motors make power up that high? (5-6k?)

Yeah, I'm old school. Anything past 4000 scares me too.

[subsonic]

On my the 2.0 16v cr, max torque is between 1500 and 2500rpm.  When I drive it hard, I shift around 4300-4500.  After that it is still pulling, but the amount is small.  It has tapered off and starting to flatline.

[molgrips]

so basically they arent even building anymore power reving them any higher than about 4000?

They do generate more power as you rev higher BUT the issue is that in terms of acceleration you might be better off shifting up and taking advantage of the extra torque at lower revs in a higher gear.  As I had to explain to my Dad as he was driving our rented house-moving van and attempting to pass another car...  He (a non-diesel driver) was quite surprised how much extra acceleration there was upon UP shifting.