Thread: Various R380 gearboxes

Not expensive when you know how to source. The downside is when it wears it wears the whole flywheel rather than the insert which is replaceable.

I was meaning expensive machining wise. Compared to machining up a flat plate.
The wear doesn't worry me, I'm not hard on clutches and plan to leave plenty of material for future skimming.

Originally Posted by Dougal

Hi Pete

It's not possible to get 420Nm from a TD5 with stock boost without risking meltdown and blowing huge amounts of smoke. My calcs put 25psi as a safe figure for 420Nm from a TD5.

Diesel performance is simple.
Your max A/F ratio is limited by thermal limits of the engine (EGT) and smoke avoidance.
The power you get from the fuel is set by your engines efficiency.
The airflow you get is the displacement, boost and intercooling.

Now the TD5 and 4BD1T are both direct injection diesels with comparable efficiency.
The A/F ratios you can run on each are the same.
Hence the power and torque you will get is dictated by the displacement, boost and intercooling.

Hi Dougal,

Is this actually still a direct comparison with the fact that the td5 has an extra cylinder over the 4bd?

AFAIK there is no way that you can run 25psi (or even really over 18-20psi depending on def/disc) without one of the boost boxes.

I believe neither of the JE setups in those charts run those, so would expect that they may be adjusted to the maximum before the ecu spots overboost, so lets say 20psi.

cheers
Pete

Yes it's still a direct comparison. Cylinder counts don't matter for torque, only displacement and boost/intercooling. If you have 3 big cylinders or 6 smaller ones the result is the same.
If you are chasing top rpm power than more cylinders and more valves makes getting the air in and exhaust out easier. Which is why more cylinders usually get more power for the same displacement. But that's off topic.

JE are remapping the ECU to remove the overboost signal problem at the source. You only need the box if you can't remap the ECU.

I have 3.9 litres running 24psi peak boost with EGT's of 750C and no intercooler. I have around 22psi at 2000rpm. How much torque do you think I've got?
I don't run a landrover gearbox as I don't believe any of them are strong enough, I have the Isuzu truck 5 speed fitted.
The VNT graph you have seen is a previously non turbo engine running less boost than the stock turbo engines. 10psi I believe.

Originally Posted by Psimpson7

Hi Dougal,

Is this actually still a direct comparison with the fact that the td5 has an extra cylinder over the 4bd?

AFAIK there is no way that you can run 25psi (or even really over 18-20psi depending on def/disc) without one of the boost boxes.

I believe neither of the JE setups in those charts run those, so would expect that they may be adjusted to the maximum before the ecu spots overboost, so lets say 20psi.

cheers
Pete

The Td5 may be slightly more efficient at getting air in and out. Plus the higher pressure injection may also give efficiency gains (and or extract slighjtly more power from each ml of diesel). However we are probably only talking 10% or so, which doesn't compensate for engine size differences.

Stock for stock, the TD5 wopuld certainly have a turbo that is more efficient at low rpm.

As an aside, when getting quotes for engine dynos recently, the dyno suppliers all asked what engines I would be running it with. When I said 4cyl, they all said they were the hardest engines on dynos. From what they said, to dyno a 2L 4cyl you need a stronger dyno than for a 6 or 8 cyl!!!

(Although they didn't use the term "torque pulse", I am sure that is the reason).

Originally Posted by isuzurover

The Td5 may be slightly more efficient at getting air in and out. Plus the higher pressure injection may also give efficiency gains (and or extract slighjtly more power from each ml of diesel). However we are probably only talking 10% or so, which doesn't compensate for engine size differences.

I don't think there's 10% in it.

The 4BD1T at max torque (best efficiency) has a BSFC well below 220 g/kwh, the IDI 4BD2T hits 220. The number of car diesel engines with BSFC better than 200 can be counted on one hand, they are all small and they are all German. BMW's 3 litre 6cyl diesel has a BSFC of 206 g/kwh.

I would expect the TD5 to have a BSFC of around 210g/kwh, which is about 2.5% better than the 4BD1T.
The 210 g/kwh is inline with Nissans YD25 engines which are VP44 rotary injection pump but 4 valve per cylinder.

sorry to side track, but Im still not sure about percent???

If say, in my defender, I have a 100kw engine...I have 3 diffs and 2 gearboxes. Lets say they chew up 40kw. which is 40% now if I rebuild that engine to 400kw, why would the same running gear chew up 160kw

Im guessing with power increase there is more power lost in those moving parts....but surely not to that extent and throwing driveline percentages out there would be pretty inacurate?

Originally Posted by uninformed

sorry to side track, but Im still not sure about percent???

If say, in my defender, I have a 100kw engine...I have 3 diffs and 2 gearboxes. Lets say they chew up 40kw. which is 40% now if I rebuild that engine to 400kw, why would the same running gear chew up 160kw

Im guessing with power increase there is more power lost in those moving parts....but surely not to that extent and throwing driveline percentages out there would be pretty inacurate?

I would expect the % loss to diminish with increasing power.
You will have some losses which are pretty static and don't increase with more power.
You will have some linear losses which do increase with power.
There will also be speed related losses, if your new power is found at higher rpm there could be more power lost stirring oil at higher speeds.