Author Topic: rpm question (Read 4805 times)

vegfuel · « **on:** December 04, 2007, 07:07:04 pm »

My grandfather, 93 years of age Lord help him, got wind of my new diesel that I bought. He was a machinist his entire life and is extremely mechanically inclined. So I told him all about it and how it gets really good economy but horsepower to boot. He was very interested but gave me some advice:
He told me to not take a diesel engine over a certain rpm as they are a "long stroke engine" he said. "Do that" he said "and it will last you up to 400,000 miles".
Now of course I already new that diesels last alot longer than the crap alternative, but should I really be taking it that easy on the rpm? It's not a turbo but I might need to pass someone going up a hill :wink:

What is the max rpm for a 4cyl na diesel?[/b]

ilomax · « **Reply #1 on:** December 04, 2007, 07:12:50 pm »

Well, if you drive a stock diesel like a gasser engine, it is not going to last long.
If you drive it like a grandma, shifting early, and take care of it, it could last that long.

Your gramps is pretty correct.

vanagonturbo · « **Reply #2 on:** December 04, 2007, 08:43:02 pm »

Almost. The VW Diesel was a revelation in its time. It is considered a "high revving" Diesel. This goes against the grain of everything that the "other" Diesel manufacturers made. The bore and stroke is almost identical to the gasser units, so a "long stroke" is not really applicable.

Ilomax is right though. Drive it hard and it wont last as long. Good high RPM pulls every once in a while are important as it will clear up carbon deposits. These deposits can harden over time and actually make contact with the pistons and shorten the life of the engine.

jtanguay · « **Reply #3 on:** December 04, 2007, 11:42:12 pm »

is it malone who has the 1.6TD revving to 6k??? can't remember... i would not rev a stock TD to 6k... ever. i try my best to shift before 4k rpm. the powerband up there sucks with stock fueling anyways.

with a modded pump you can rev much higher than stock. the timing advance curve needs to increase much higher as the rpm's increase so that the slow burning diesel fuel can have a chance to burn as the rpm's increase. i think Giles has mastered that :wink:

as with any engine, high revs are damaging. i really like hearing those commercials for the honda's that redline at 8k... what the hell am i going to need to rev to 8k for? break in maybe? street racing? the fact that it makes all its power in that range is stupid. hope the parts can take a beating! :lol:

the main reason diesels last longer is because they make low end power so you can keep the motor in low rpm's. low rpm's mean low wear. if a gasser runs too low rpm's the plugs can get fouled up pretty bad. diesels love it though!

for your situation though, i would listen to gramps. stock, the engine will burn a lot of your oil when you rev high. increase the fueling, and oil burning will increase. synthetic will decrease oil burning and wear, but its more expensive. if you are uncertain about the mileage of the engine, you might want to rebuild the injectors as a precaution...

have fun dieseling

spencebm · « **Reply #4 on:** December 05, 2007, 06:18:13 am »

That's good advice but hard to accept for us young guys with lead feet.

When I get my new pump on my car, I don't think I would rev it past 4 and a half. I think that is the stock redline, isn't it? I need to pony up for a tach soon so I don't blow it up. :wink:

Op-Ivy · « **Reply #5 on:** December 05, 2007, 07:49:37 am »

Quote from: "jtanguay"

is it malone who has the 1.6TD revving to 6k??? can't remember... i would not rev a stock TD to 6k... ever. i try my best to shift before 4k rpm. the powerband up there sucks with stock fueling anyways.

I agree. I don't take it past 4k either. Even with better fuelling I would not go anywhere past there. You can just feel the engine screaming when you do. It just doesn't feel right.

jtanguay · « **Reply #6 on:** December 05, 2007, 08:06:50 am »

Quote from: "spencebm"

That's good advice but hard to accept for us young guys with lead feet. When I get my new pump on my car, I don't think I would rev it past 4 and a half. I think that is the stock redline, isn't it? I need to pony up for a tach soon so I don't blow it up. :wink:

i dont think you would blow it up (unless there is huge clouds of black smoke coming out the back). you do need to realize that these engines run high compression though. gassers are what 175 psi per cylinder? and diesels are around 400-500 psi. combined with the fact that diesel burns slower but offers around 20 times the BTU's per same volume as gas means that there is a hell of a lot more going on in a diesel in the upper rpm's than a gasser. so much stress on the engine, but they're built to take it.

just keep an eye on your oil level, use a good quality oil when topping up, and do not use a cheap oil filter. some oil filters like fram will bypass the filter and release unfiltered oil through the engine. the bypass is a good safety feature, but the opening pressure for it is too low.

the main killer of these engines is overheating due to malfunctioning fans or lack of cooling system efficiency. i suggest you get your system flushed, and make sure your rad fan works good. when i replaced my a/c condensor, there was this big sticky glob of something jammed into the rad... looked like dirt and feathers :lol: i cleaned that out and it seemed to help my cooling efficiency a bit. the problem with these cars is that they need to run hot; so hot that it doesn't take much more heat to blow the head gasket, although some overheat without doing too much damage (like mine :roll:.. long story short, my fan failed on the highway and i had to stop because of a collision).

just keep all that in mind. rev it as much as you want because VW engineers made the engine practically bullet proof, and the stock pump is setup in a way that it will not harm the engine if every other system is working properly (cooling, oiling, electrical, etc) and is also designed for long life in extreme conditions.

spencebm · « **Reply #7 on:** December 05, 2007, 09:21:48 am »

Thanks for the advice however my engine is a little different. I have a good fan and I will be putting new coolant in it. I think I will eventually run a turbo pump on my adg engine with a k14 turbo. I am going to get a front mount cooler and change the timing belt. The weird thing is that the generator motor has a thermostat that opens sooner than a normal 1.9 aaz. My engine runs cooler because it is made to sit in a box and generate electricity, not go down the road at high speed. Would you recommend swapping in a normal thermostat? I think everything will be good after the new pump and cooler. I also run a closed waste gate and max psi is about 18. Tell me what you think.

Vanagoner · « **Reply #8 on:** December 05, 2007, 09:34:34 pm »

I have RPM questions too. Since my vanagon has no tach, I rely on the red dots on the speedometer. Does anyone know if they are shift points, max RPM, or both? They are at 14, 26, and 42 MPH (not kidding). I think max speed is 64, but I don't like to take it past 58 for cruising until I get an 091 transaxle put in there. The stock alpine tranny ratios would be awesome if only there were two more gears to go with them.

What RPM is it turning at the shift marks? Thanks.

Op-Ivy · « **Reply #9 on:** December 05, 2007, 09:58:57 pm »

Quote from: "Vanagoner"

I have RPM questions too. Since my vanagon has no tach, I rely on the red dots on the speedometer. Does anyone know if they are shift points, max RPM, or both? They are at 14, 26, and 42 MPH (not kidding). I think max speed is 64, but I don't like to take it past 58 for cruising until I get an 091 transaxle put in there. The stock alpine tranny ratios would be awesome if only there were two more gears to go with them.
What RPM is it turning at the shift marks? Thanks.

They are redline marks. I have a swapped cluster, so a speedo with the lines and a tach. The redlines don't match up well, but i think my speedo is off.

Otis2 · « **Reply #10 on:** December 06, 2007, 01:53:30 am »

For a Vanagon, you can work out the RPM in any given gear, with any given transmission, by playing with the calculator here:

http://www.syncro.ca/tiresize/

Enjoy.

jtanguay · « **Reply #11 on:** December 06, 2007, 09:32:06 am »

Quote from: "spencebm"

Thanks for the advice however my engine is a little different. I have a good fan and I will be putting new coolant in it. I think I will eventually run a turbo pump on my adg engine with a k14 turbo. I am going to get a front mount cooler and change the timing belt. The weird thing is that the generator motor has a thermostat that opens sooner than a normal 1.9 aaz. My engine runs cooler because it is made to sit in a box and generate electricity, not go down the road at high speed. Would you recommend swapping in a normal thermostat? I think everything will be good after the new pump and cooler. I also run a closed waste gate and max psi is about 18. Tell me what you think.

if it gets below 0 where you live, swap in the 87C thermostat. i think that is 192F or something.

always keep an eye on your temp gauge. i'm considering buying a buzzer for when the coolant reaches around 105-110C. i can't always be checking the temp gauge, and sometimes it can just creep right up when the fan dies... the oil pressure has a buzzer but not coolant temp... and both can be just as bad!

spencebm · « **Reply #12 on:** December 06, 2007, 10:18:53 am »

will do

Vanagoner · « **Reply #13 on:** December 06, 2007, 12:15:48 pm »

Thanks for the calculator, and the help. It doesn't want to take my
retro 195/R14 transporter tires as an actual size, but I'll guess.

shegel · « **Reply #14 on:** December 06, 2007, 09:20:52 pm »

can you rev the engine too high. i was driving it the other day...missed a shift. now i think its using a lot of oil