Rav T180 Rpm

[kmrobertson3]

My T180 has rpm up to 7000, 0-5000 normal range and 6-7000 in the red.

I can't get the cat to rev past 5000 rpm is this normal? Seems to hit the limiter at 5000.

Cheers

[harleymlb]

Hi, This perfectly normal. Most diesels have a restrictor as its not good for the diesel engine to be over reved!

I cannot imagine why you would want to rev your Rav up to more than 5k rpm. Most of the power is well below 3k rpm.

Hope his helps. Mark

[kmrobertson3]

Diesels need a good reving now and then it clears them out.

Just thought it was pointless the rpm gauge going to 7K if the limiter is set at 5K

[OldSkoO1]

I'm sure someone can explain the longer stroke of diesels. And also heavier pistons with compression ignition and slower diesel burn to translate into lower revs.

Modern diesels do indeed need a clean out and whilst high revving might be a start, you do need good ongoing treatment.

Modern diesels absolutely need good compression to run healthy. Without boost pressure you will get a big soot build up, low oil flow under the pistons, low fuel pressures and most importantly low compression pressures. You simply won't generate enough heat when running at low rpm's all the time.

The catalytic converter despite being extremely efficient cannot clean up the excess carbon produced by combustion. Much more soot is produced with unclean burns, from low compression and colder temps.

Therefore you need to maintain pressure to generate heat. The EGR valve also recycles exhaust gases back into the combustion process/ inlet and even uses gases to maintain back pressure in the exhaust manifold by using the inlet on the VNT. If none of these elements can gain heat and you need a lot of heat to cook the excess carbon in the cat / EGR / DPF etc you can run into problems with poor combustion / injection / limp mode from EGR valve sticking and even turbo failure in extreme cases. Other offsets would be lack of power, sluggishness, noisy combustion, poor idling, excess smoking and poor starting.

The general rule is avoid low rpm's. So avoid changing at around 2k or below every time. And don';t chug along at less than 1.6k min. Don't expect too much from the engine at low RPm's e.g. no high loads at low rpm#s like going up hill.

You should be using the engine when its reaching max cylinder pressure, this is between 1.9k and 2.5k in a t180. You should be revving into this range everytime for gear changes. You should maintain running speeds around 1.8 - 2.2k RPM and go for higher RPM's when under high loads like towing and going uphill. Getting up to speed should be done with a smooth but fairly hard application of throttle. You should vary the throttle openings too to give the car different loads. Max cyclinder pressure is also when your engine is running a clean burn and running most efficiently. Therefore producing the same amount of power for the least amount of fuel, creating the right amount of boost to produce the ideal engine operating temperatures which the engine was designed for, therefore producing less soot and generating the right amount of heat to cook off the soot, maintain good oil flow under the pistons and the seat the rings.

Heat cycling is also another good way to keep operating temps up yet maintain good fuel economy. As i said above. Max cylinder pressure produces the best efficiency anyway. But you be revving up to 2.5k to change and you can go higher. Max power is reached at 3.6k a good smooth but hard throttle up to 3.6k can heat cycle yet you can use it to your advantage by accelerating hard and then coasting in gear back down to traffic speed given plenty of space. You can almost cancel out the fuel used to get to that speed by coasting and works best on downhill slopes.

It's what helps me get those better economy figures and even the hypermiling geek boys do this yet i dont sacrifice the health of the engine components in the meantime. I would just be weary of red lining it every once in a while. Its not like the old diesels where soot just sits in the exhaust. There is a lot more places where soot collects these days.

[igormus]

I'm sure someone can explain the longer stroke of diesels. And also heavier pistons with compression ignition and slower diesel burn to translate into lower revs.

Modern diesels do indeed need a clean out and whilst high revving might be a start, you do need good ongoing treatment.

======

the power factor of the diesel and petrol engines are difer at the same rpm and it is in direct proportion to compression ratio -- for axample -- the compression ration of petrol engine is 8:1 but diesel's is 15:1 ---17:1 ---- it means the combustion chamber is only one part of (15-17) in view of piston stroke. for sure the compression pressure for both type of engnes is difer (12 kgf/cm2 -- for petrol subject to good condition of liner+piston+rings) and (25-30 kgf/cm2 for diesels + subject to good condition of the same). having understood initial compression pressure --- + explosion in the cylinder --- the extreme combustion pressure in the each engiine cylinder is difer, as well ---- it might be 20-25 kgf/cm2 in the petrol engines and 40-50 kgf/cm2 in diesels. as vissible the max P are difer and it means the power of each engine at the same rpm is in fact difer. Taking into account that the petrol is ignited by a spark plug -- not necessary to have a long piston stroke as in diesel engines -- it is because the diesel is injected into combustion chamber at 8-10 degrees before TBC and the max compression temp is reached by 8-10 degrees before TBC for ignit diesel. in order to criate such temp the stroke of the diesel engiine must be longer than in the petrol engines. we are all expperience that diesel engines do not respond fastly to your gas pedal and it is because of long piston stroke + time required for sparking of diesel.

The thermal design of the engine is normally calculated having compared both car weight and volume of the engine + thermal heat to convert all carbon and keep all exhaust gas system clean without contra pressure (EGR; Turbo; Cat) -- it means that the engine must to run with more rpm to produce more heat/power respectively.

Cheers/igor

[OldSkoO1]

I forgot to mention. When driving at higher RPM's especially on the m-way your turbo needs to be cooled. It's not ideal to shut off the car when the turbo is very hot.

Your turbo can reach 600 degrees C. But this temp can drop to about 180 degrees C in a very shot time. If you coast in gear or keep the rev's low around 1.5k RPM it will only take a mile or less to get the temp's down before switching off.

Regardless of thermal efficiency in oil these days which cools the turbo you still need enough time for the heat to dissipate away. Coasting uses the air in compression to further cool.

[anchorman]

I tend to use low revs and decent diesel. In return I get good mpg and as far as I am aware, a relatively carbon free engine. A recent inspection of the EGR revealed some soft soot but no hard carbon deposits.

[rangermastiffs]

I tend to use low revs and decent diesel. In return I get good mpg and as far as I am aware, a relatively carbon free engine. A recent inspection of the EGR revealed some soft soot but no hard carbon deposits.

So what's a definition of "Decent Diesel " and "Not Decent" Diesel ?????

[anchorman]

Sorry! I have voiced my opinion before so took it for granted.

I use "super" diesel - Total Excellium mainly because I can get it locally but if not BP Ultimate or Shell V Power. I know shcm checked his EGR which was similar to mine and he uses high quality diesel.

I don't ever use supermarket diesel and only uses branded if I can't locate super.

[vivianM]

Diesels need a good reving now and then it clears them out.

Just thought it was pointless the rpm gauge going to 7K if the limiter is set at 5K

I think the most effective way to clean out an engine is to use revs near the 'Cross Over' point of highest torque and hightest horse power ie on the T180 engine at about 3000 to 3750 revs - hp & torque both drop off rapidly at higher than these revs.

I think the best way to 'clean out' an engine is not full revs but find a long hill and put full load on the engine at the above revs in the highest gear it will take - it is then running at its highest output and will get the valves etc really hot - back when I was racing you could put the vehicle on a rolling road dynometer on full load (not free running revs) and just watch the exaust manifold glowing cherry red and that was before turbo days!

Guy

Not sure what your oil consumption will be if going up to 5000 revs is standard!

[local hero]

Sorry! I have voiced my opinion before so took it for granted.

I use "super" diesel - Total Excellium mainly because I can get it locally but if not BP Ultimate or Shell V Power. I know shcm checked his EGR which was similar to mine and he uses high quality diesel.

I don't ever use supermarket diesel and only uses branded if I can't locate super.

As most on here know i drive a "black cab" for a living, we have a very stringent council test every 6mths part of which is emissions, we are told before we arrive at the test centre to literally rev the b****x off them prior to inspection this usually works, but i often wonder what harm this could be do'ing to our engines I run my cab on whatever fuel is available, My cab has now done 170,000 mls and had the EGR cleaned once, my Rav has done 13,500mls and always on super diesel, on the rare occasion I can't get super i add Millers diesel additive, but TBH i cannot notice any difference whatsoever, why the rav Egr needs cleaning after very low mileages I cannot fathom Stew

[bomber06]

I had a problem with a blocked EGR valve at the latter part of last year and thanks to Anchorman's help Mr T cleaned it free of charge. Although the EGR had been cleaned I was concerned about carbon deposits in the the rest of my fuel system that might have been affecting the performance of the RAV, it just didnt feel the same as it did when I first got it.

I decided to use a BG 244 fuel system cleaner from powerenhancer.co.uk after reading a review on the fueltech expert website.

http://www.fueltechexperts.com/2008/08/20/...g44k-and-bg244/

Almost immeadiatley I noticed a difference. Initially I thought the improved performance was down to the higher octane of the fuel due to the treatment in the first tank of fuel, but I have probably filled 5/6 times since using regular diesel and the improved performance is still noticable.

I have also noticed a slight increase in my mpg since the treatment.

I know some people are quite sceptical about these sort of treatements but I believe I have noticed a difference.

[rangermastiffs]

I had a problem with a blocked EGR valve at the latter part of last year and thanks to Anchorman's help Mr T cleaned it free of charge. Although the EGR had been cleaned I was concerned about carbon deposits in the the rest of my fuel system that might have been affecting the performance of the RAV, it just didnt feel the same as it did when I first got it.

I decided to use a BG 244 fuel system cleaner from powerenhancer.co.uk after reading a review on the fueltech expert website.

http://www.fueltechexperts.com/2008/08/20/...g44k-and-bg244/

Almost immeadiatley I noticed a difference. Initially I thought the improved performance was down to the higher octane of the fuel due to the treatment in the first tank of fuel, but I have probably filled 5/6 times since using regular diesel and the improved performance is still noticable.

I have also noticed a slight increase in my mpg since the treatment.

I know some people are quite sceptical about these sort of treatements but I believe I have noticed a difference.

------------------------------------------------------------------------------------------------------------------------------------

Going to give this BG 244 a try !!

It can be had on eBay from the above mentioned company for £27.49 delivered (1st class recorded).

B)

[hman1977]

Can someone please explain what is the best way to cope with very high slope.

2and gear doesn't have power and first gear gets high revs.

Also when losing the strength even first gear can't manage exceptif the clutch and diesel are used to manage to increase the revs.