Thread: turbo for 4bd1, who,what where ??

Originally Posted by 85 county

well actually, that’s impressive

Anyone from the brains trust want to explain how what can’t happen happen

Turbo specs.jpg

Very fishy results I say.

Power = Torque X Angular Velocity

Therefore;

Angular Velocity = Power / Torque

Disregarding units, divide Std Power / Std Torque @ 40kph

Do the same @ 120 kph

We find that the Angular Velocity is 3.78 times faster @ 120kph than @ 40 kph. But as far as I know 120kph is only 3 times faster than 40kph.....

This is just one way to analysis the results to make you wonder.

Originally Posted by the_grubb

Very fishy results I say.

Power = Torque X Angular Velocity

Therefore;

Angular Velocity = Power / Torque

Disregarding units, divide Std Power / Std Torque @ 40kph

Do the same @ 120 kph

We find that the Angular Velocity is 3.78 times faster @ 120kph than @ 40 kph. But as far as I know 120kph is only 3 times faster than 40kph.....

This is just one way to analysis the results to make you wonder.

For the power and torque to line-up, they have to have the engine rpm speed right. It's pretty rare to find a dyno chart where they've got this right.

The torque readings posted could be wheel torque, the dyno could have the wheel diameter, axle ratios or both wrong which puts the scale out. The overall shape of the torque curve remains correct but you need to know the actual engine speed to scale it back down to the numbers it should be.

There was a clown on a NZ 4wd website a while back who was telling everyone he had over 1000Nm from his 4.2 td landcruiser for this exact reason.

Originally Posted by rar110

both post turbo.

If you are running 450-480 POST turbo at 100 on flat ground with no headwind then I would be worried. I am running those sort of numbers PRE turbo under the same conditions (GT2560R). So you are running about 200oC+/-50 more than me. Post turbo EGTs, the maximum safe value you would ever want to see is ~500oC.

Originally Posted by Dougal

There was a clown on a NZ 4wd website a while back who was telling everyone he had over 1000Nm from his 4.2 td landcruiser for this exact reason.

I have seen countless dyno printouts like that...

Originally Posted by Dougal

For the power and torque to line-up, they have to have the engine rpm speed right. It's pretty rare to find a dyno chart where they've got this right.

The torque readings posted could be wheel torque, the dyno could have the wheel diameter, axle ratios or both wrong which puts the scale out. The overall shape of the torque curve remains correct but you need to know the actual engine speed to scale it back down to the numbers it should be.

There was a clown on a NZ 4wd website a while back who was telling everyone he had over 1000Nm from his 4.2 td landcruiser for this exact reason.

Yes agree with you comments on perfect lining up and scaling. But from the quick calc we are talking 26% out. Could understand 10%. But what's the point even providing data that is up to 26% errorneous? Other than for marketing of course.

'Yeah here you go mate, you had 100kW now you've got 150kW' (when really you only have 120kW).

[While handing over an envolope] 'Oh great job, here's the $1000 for the great work', when really there is only $740.

Close enough right?

Well we've got no idea of the units he used or even if it's "corrected" for flywheel or at the ground.

So it's all guesswork really.

I somewhat detract my comments.

Comparing Std to Turbo'ed there is only 10% error between the too. The 26% is when comparing to speed.

But anyway, back to the topic at hand.

A bog standard 4BD1T puts out 100kw, give or take a few at 3000rpm, give or take a few hundred. They need about 13psi boost to do that and run clean and cool. My calcs put it around 22:1 air/fuel ratio.

15 psi intercooled with a slightly hotter tune (18:1 a/f ratio) can give you 140kw. This requires 100 cc/1000 shots of diesel, I don't know what the non turbo injection pumps can put out.
The air consumption is 22 lb/min or 287cfm at this 3000rpm.

Originally Posted by isuzurover

If you are running 450-480 POST turbo at 100 on flat ground with no headwind then I would be worried. I am running those sort of numbers PRE turbo under the same conditions (GT2560R). So you are running about 200oC+/-50 more than me. Post turbo EGTs, the maximum safe value you would ever want to see is ~500oC.

I've had it up over 600 briefly when going up the Toowoomba range with a trailer. I ended up dropping it back to 2nd and crawling up at about 40 kmh. However boost was all over the place but up to about 16psi because I was trailing a manual boost controller and the over boost valve was still fitted. Once I removed the boost controller the wastegate kept boost at about 12 or 13 psi and egts stayed well under 600.