Hj61 on the dyno (1 Viewer)

[Silveredition]

Gday guys
I have had an issue with my hj61 where it would occasionally stall when the clutch was depressed. The revs would free fall to about 500rpm, and would sometimes recover, but other times it wouldn't. The local Fuel Injection and Turbocharger mechanic said he could replace a spring and place some shims inside the back of the injector pump without having to remove it from the car, so I thought while he had it in there I would get him to put it on the dyno and give it a bit of a tune up...
I last got a dyno done when the turbo was running at 7.5psi, and it had the original exhaust and muffler. Since then I had increased boost to 10psi and made a 3 inch straight through exhaust and big dump pipe, which was a huge improvement. On the dyno yesterday boost was increased to 11.5 psi, and the difference was again noticeable...
Anyway, here are the charts from yesterday and 2 years ago for anyone interested. I am surprised I have travelled 70000km in it in the past 2 years!!!

 

[roscoFJ73]

Has the engine done 461kklm without a rebuild? They are a remarkable engine, wish I had of kept mine with 300kklm

 

[Silveredition]

Has the engine done 461kklm without a rebuild? They are a remarkable engine, wish I had of kept mine with 300kklm

541000km now... the 461 was almost exactly 2 years ago...
As far as I know everything is still original, but the previous owner wasn't too knowledgeable about what had been done to it...

 

[Tapage]

from 135 advertised as new ... ( at the flywheel I guess ) to 91 ..

 

[Silveredition]

from 135 advertised as new ... ( at the flywheel I guess ) to 91 ..

Yeah - it looks like half a million k's has eaten away at a few horsepower!!

 

[AussieHJCruza]

That's pretty good, remember average drivetrain loss is probably 30% which is 94.5hp at the wheels approx stock

BTW, auto or manual?

 

[Silveredition]

G'day mate, 5 speed manual

 

[roma042987]

interesting thanks for posting this up

 

[GTSSportCoupe]

Yeah - it looks like half a million k's has eaten away at a few horsepower!!

You can't compare flywheel power (Toyota Spec) to wheel hp (your dyno). As AussieHJCruza said, you were pretty much bang on factory spec with your first dyno. Cruisers seem to loose about 40-45hp between the flywheel and tires from what I've seen. I think the transfer case adds more loss over and above normal RWD differential/transmission losses.

 

[Douglas S]

You can't compare flywheel power (Toyota Spec) to wheel hp (your dyno). As AussieHJCruza said, you were pretty much bang on factory spec with your first dyno. Cruisers seem to loose about 40-45hp between the flywheel and tires from what I've seen. I think the transfer case adds more loss over and above normal RWD differential/transmission losses.

Drivetrain loss is always going to be a percentage. 40-45hp @ 135hp crank is 80-90hp @ 200hp crank assuming loss of 40-45%.

I imagine for a cruiser it's around 30%.

 

[GTSSportCoupe]

Drivetrain loss is always going to be a percentage. 40-45hp @ 135hp crank is 80-90hp @ 200hp crank assuming loss of 40-45%.

I imagine for a cruiser it's around 30%.

Sort of off topic, but....

In the past I've always assumed a constant percentage also, but it is hard to imagine loosing 80-90hp to heat in a drivetrain with a 200 crank hp engine (a tuned 1HDT for example). I've wondered if the loss is not totally linear as engine power increases.

The reason I mention the 40-45hp loss, is that seems to be what most dyno plots of stock diesel cruisers seems to show compared to factory spec. For example, a 3B will typically dyno in at around 40-50 wheel hp, and it's a 90 crank hp motor. A 2LT dynos around 35-40 wheel hp, and it's an 85 crank hp motor. 1HZ dynos 90 wheel hp, but is 130 crank hp. Etc.

My 2LTE used to make 40 wheel hp (motor is rated at 90 crank hp). With many modifications, I'm now making 90 wheel hp. Power calculations based on the injection system specs (cc/stroke, g/kwh etc.) show that I can only support a maximum of about 135 crank hp. My fuel is maxed out, so I'm going to say I'm pretty close to that 135 crank hp. So I'm still loosing about 45hp to the drive train even though I've increased power by about 50%.

 

[gerg]

That's like saying because your engine power doubles so does the drag from your alternator. The alternator drag is a consistent loss regardless of what power your engine makes. Unless you alter your running gear I wouldn't think the required power to run it would change on its own.

 

[Douglas S]

That's like saying because your engine power doubles so does the drag from your alternator. The alternator drag is a consistent loss regardless of what power your engine makes. Unless you alter your running gear I wouldn't think the required power to run it would change on its own.

As power increases so does friction and heat generation. There are some things that would remain constant (drag from an alternator is a good example) but it's been proven that drive-train loss increases with power when other variables are held constant.

I agree it's more complex than a straight fixed percentage, but I think it's generally considered the best way to estimate. The loss is neither a straight amount or an exact percentage, but it's more of the latter than the former.

 

[gerg]

I guess as power increases your friction does based on the force over the gear surfaces but even if the loss in hp is greater, the percentage loss would be less as your power increases. I too have increased my power output a lot over stock yet my loss haven't increased dramatically similar to Nick. I guess its semantics as this can never be acurately demonstrated. It's more of a how much scinerio but it didn't change much on my truck.

 

[Silveredition]

Thanks for all the feedback / comments, and discussion that has resulted!
As far as seat-of-the-pants performance goes, I have a point on the highway that when the turbo was at 7.5 psi I would pass it at 90/hr, 10psi was about 100km/hr, and 11.5psi is about 105km/hr... this was changing at a max of 2500rpm, and over a number of days / runs - getting the changes right.... as a point of difference, I did the same today in a Hilux 3.0L diesel D4D auto, and passed the same mark at 110 without revving the s*** out of it. My 200 series TTD passes the same point about a minute earlier.....

 

[ozcrusier]

Did he manage to fix the engine stalling when lifting the foot.

 

[Silveredition]

Sort of.... it is a bit better, but not fixed....

 

[ozcrusier]

Mine will drop revs when lifting the foot doesn't stall but drops down to 500 rpm then rises back to 750 rpm.

 

[Silveredition]

@ozcruiser The stalling will come.....

 

[ozcrusier]

I know when it starts to happens pump will be sent in for a rebuild after plenty of homework on who to use downunder