12HT drivers, heres some questions for you

[Vossie]

so have had the 12HT in the 45 for about 7 months now and clocked about 3000kms. loving it. but i do have some questions that maybe more experienced 12HT owners might be able to answer.

how high do you rev your 12ht?
so i barely rev over 2500rpm. and im sitting at 80kph at 2000rpm in 4th (4 speed box). and shes very loud at 2k. it almost feels like going to 3k rpm would be way to high. is it? what do you rev to and what can you maintain for cruising speed?

 

[roscoFJ73]

The Toyota diesels all have a procedure in the manual where they should have a max rpm speed in neutral. Its about 4200 for all of them but you would have to check the manual for the 12HT. From memory its in the Fuel Injection part.

 

[mudgudgeon]

The Toyota diesels all have a procedure in the manual where they should have a max rpm speed in neutral. Its about 4200 for all of them but you would have to check the manual for the 12HT. From memory its in the Fuel Injection part.

The governor should limit max rpm before red line, but for most people, your ears and the pucker factor will cut rpm well before the governor does

 

[Vossie]

The governor should limit max rpm before red line, but for most people, your ears and the pucker factor will cut rpm well before the governor does

thats the thing. my brain is telling me to back off at 2,7k and its screaming at me at 3k. am i just being a big baby?

 

[roscoFJ73]

Revving it to 4200 just tells you the fuel pump and injectors are working ok. You are a baby.

 

[Vossie]

Revving it to 4200 just tells you the fuel pump and injectors are working ok. You are a baby.

i knew it!!!

so grow a pair and boot it?

would you routinely rev yours to 4k?

 

[roma042987]

why do you want to rev it that high? 12ht's make peak torque in the 2-2500k rpm range so I find myself shifting at those points. Just because it has a higher "redline" doesn't mean it needs to be revved to that during normal driving. I can think of very few scenarios where I'd need to rev it to higher rpms. Maybe pulling a heavy load up pass where shifting a gear would cause you to loose momentum.

 

[Vossie]

why do you want to rev it that high? 12ht's make peak torque in the 2-2500k rpm range so I find myself shifting at those points. Just because it has a higher "redline" doesn't mean it needs to be revved to that during normal driving. I can think of very few scenarios where I'd need to rev it to higher rpms. Maybe pulling a heavy load up pass where shifting a gear would cause you to loose momentum.

yes, thats where i find myself shifting too whilst driving in town.

reason i need to know about how high i can rev is bc i need to be able to go a little faster than 90kph. i want to sit at 120kph, which should be around 3600rpm, and to me, with the way she sounds right now, i just wanted reassurance that the 12HT can do that and maintain it for hours at a time cruising down the highway

 

[roma042987]

I definitely would not recommend that. I would either maintain the 90kph or save up for a 5spd or 33'' tires or 3.7 gears.

 

[cruiserdan]

1987 HJ61 tach:

 

[dmjay]

I don't rev mine over 2.5 grand ever.
Not over 2 grand until it's at operating temp.

 

[roscoFJ73]

I think most of you missed the point of my post about revving it to 4200. It is a test outlined in the manual to see if the engine is getting enough fuel. You don't need to hold it there for 10 mins, just a few seconds.
Yes I have done it. For the doubters, look in the good book for yourself.

 

[roscoFJ73]

Its a quick easy way to check it. The other way is to put it on a dyno @$200 an hour. This test is applicable to all Toyota diesels but check the RPM specs

 

[roscoFJ73]

would you routinely rev yours to 4k?

Why would I want to routinely do it? Its something you do as a test when there is a problem.

 

[roscoFJ73]

1987 HJ61 tach:

Whats that got to do with it?

 

[roscoFJ73]

why do you want to rev it that high? 12ht's make peak torque in the 2-2500k rpm range so I find myself shifting at those points. Just because it has a higher "redline" doesn't mean it needs to be revved to that during normal driving. I can think of very few scenarios where I'd need to rev it to higher rpms. Maybe pulling a heavy load up pass where shifting a gear would cause you to loose momentum.

Its done in neutral, did you read the post? The test is telling you that if it reaches 4170 or 4100 rpm in neutral, then you will have enough fuel under load in gear at normal rpm range.
Its a simple concept.

 

[cruiserdan]

Whats that got to do with it?

I simply posted it as a reference. The "yellow" zone is 3,500 to 3,900 RPM and it turns red at 4,000. The original poster may not have seen an OEM 12HT tach before.

 

[mongoose2231]

lol, this was going to go downhill quick

 

[mudgudgeon]

lol, this was going to go downhill quick

Yeah, but how many rpm do you down the hill?

 

[roma042987]

Its done in neutral, did you read the post? The test is telling you that if it reaches 4170 or 4100 rpm in neutral, then you will have enough fuel under load in gear at normal rpm range.
Its a simple concept.

Yes I read the post. I also wasn't replying about your service manual reference.