Diesel Tweaks?

[Raz]

I've recently bought my Beemer after 5 years in a 300bhp Nissan 200SX and although it is quite nippy for a diesel I would like to squeeze a bit more power out of the engine.

I know that the turbo is connected to the actuator and this controls the amount of boost. There is a common dodge among 200SX owners to place a couple of washers under the actuator mountings, effectively shortening the actuator arm and therefore making it apply a little more boost (sometimes about 4psi)

My question is - can I adjust the actuator arm on the Beemer to apply a little more boost or am I asking for trouble?

While we are on the subject, are there any more performance enhancing tweaks for the oil burners? I'm waiting for a Viper2 chip to be delivered which claims about 20bhp increase so I guess I'm off to a good start.

[DueyT]

Hmmm...should be able to do that to the turbo, many of them will allow that shortcut to increase boost. I know some guys who do that with VW TDI's, but in the case of the 1.9 TDI (ALH - 90 hp, Bosch inj engine) you can run into a low-rpm turbo surge condition that can stress the turbo...not sure if the 525tds is the same.

Cheers,
Duey

[Anton CH.]

Diesel motors run completly different from gasoline engines. Even though theoretically you can bump up the pressure levels without worryng about pinging, diesel engines have no throttle bodies, so you are always running at max boost. Over a large amount of miles I think the temprature and pressure increase can be harmfull to the diesel engine.

[DueyT]

Diesel motors run completly different from gasoline engines. Even though theoretically you can bump up the pressure levels without worryng about pinging, diesel engines have no throttle bodies, so you are always running at max boost. Over a large amount of miles I think the temprature and pressure increase can be harmfull to the diesel engine.Anton, yes...diesels are different than gassers, most noticably because there is no requirement to achieve a certain air/fuel ratio. In gasser terms, a diesel runs phenomenally lean! Typically, only 1/10th to 1/3th of the air inside the cylinder is used to combust the injected fuel -- this means air:fuel ratios of ~30:1 to 150:1! It is pretty rare to see any diesel fuelling at a perfect stochiametric AF ratio (I believe it's something like 15.5-16:1 for diesel fuel).

However, diesels don't have a throttle plate since cylinder pressure and engine speed is uniquely controlled by the amount of fuel injected per stroke. Boost levels (if the diesel is turbocharged) vary considerably based on metered injection/fuelling rate, and are derived from the remaining cylinder pressure that forces the exhaust out of the cylinder and through the turbo. More fuel injected, more peak cylinder pressure, more boost. Lack of a throttle plate has no impact on boost levels. There only plate most diesels have in the intake system is a butterfly-type plate, normally open, but that is closed during engine shutdown to speed the wind down and keep the engine from shuddering roughly as it comes to a stop.

Incresing a diesel's performance is primarily based on increasing fuel injection while maintaining acceptable peak cylinder pressures and temperatures. Diesel tuners live and die by peak pressure and EGT.

Cheers,
Duey

[Raz]

So if it is largely down to the quantity of fuel injected, a simple pump modification would do the trick ...... or am I oversimplifying? Is that what the diesel performance chips do then?

On the same subject - There was a TV program run in the UK last week showing how they got a standard Golf 1.9 td auto to (nearly) outpace a Honda NSX over a standing quarter mile! This was achieved with NOS - it doubled the bhp!

[Karl]

Some of the things in the engine are going to work like a gasoline car--
-less exhaust back pressure will help the turbo spool up quicker
-freer intake will let it suck the air in easier
but you normally have an excess of air anyway, as Anton pointed out. So it comes down to increasing fuel. I suppose the chip you're antcipating will do that.

And a diesel lives on compression, so adding boost helps too.

Remember that the diesel makes its power at lower RPM that gas engines--torque is a bigger issue. And torque is what you'll notice when you're trying to step out into traffic. Compression (piston + turbo) is good for torque. So do your thing with the turbo controller, and keep an eye on temp.

[Raz]

So do your thing with the turbo controller, and keep an eye on temp.

I will have a play then :D Does anyone know what the stock boost pressure is ? I have heard that it is VERY low compared to a petrol turbo but what are we looking at ..... 2psi, maybe 4psi?

[Anton CH.]

So if it is largely down to the quantity of fuel injected, a simple pump modification would do the trick ...... or am I oversimplifying? Is that what the diesel performance chips do then?

On the same subject - There was a TV program run in the UK last week showing how they got a standard Golf 1.9 td auto to (nearly) outpace a Honda NSX over a standing quarter mile! This was achieved with NOS - it doubled the bhp!

You can increase fuel pressure and thus increase the amount of power the engine makes but after a certain point you will have an incomplete combustion (think lots of black smoke+soot as on trucks and buses). That is the point where you probably want to increase the amount of air. If you want to get into diesel tuning I would highly recomend installing an exhaust temp meter.

[winfred]

if i had to guess on the boost level probably 10-15 psi stock mabie more if intercooled, diesels can take a whole lot more then any stock gas motor


I will have a play then :D Does anyone know what the stock boost pressure is ? I have heard that it is VERY low compared to a petrol turbo but what are we looking at ..... 2psi, maybe 4psi?

[Raz]

if i had to guess on the boost level probably 10-15 psi stock mabie more if intercooled, diesels can take a whole lot more then any stock gas motor

That high? My Nissan was running at 18psi and that used to pop the intercooler caps off!

More air can only mean an induction kit of some sort - probably a K&N jobbie with a direct cold feed. I don't think I will take it much further than this otherwise reliability will suffer.

So to summarise I will do the following:

1. Fit Performance chip
2. Adjust turbo actuator arm
3. Fit induction kit

I will report back with my findings :)

[winfred]

i've never seen a e34 diesel this is just a guess on psi, boost can run well past 25 psi on modded diesel cars and trucks, i've seen big rigs run 80 psi, certainly their are exceptions, the us tdi vw 1.9 is 5-6psi, moms old 85 740 volvo turbo diesel was around 14, my old gas turbo 760 volvo 7-8 bumped to 10-11

[DueyT]

That high? My Nissan was running at 18psi and that used to pop the intercooler caps off!

More air can only mean an induction kit of some sort - probably a K&N jobbie with a direct cold feed. I don't think I will take it much further than this otherwise reliability will suffer.

So to summarise I will do the following:

1. Fit Performance chip
2. Adjust turbo actuator arm
3. Fit induction kit

I will report back with my findings :)
Raz, chip is a good start...look here for Montfort chips (http://www.monfortsa.be/fr2/pg11.php?l=en)made in Belgium. They'll take your TDS from 143 to 173 hp.

Then onwards with injectors if needs, increased boost and intercooling.

p.s. an EGT guage is a very good idea any time you increase fueling beyond stock levels in a diesel.

p.p.s. propane injection is the diesel equivalent to NOS for gassers.

Cheers,
Duey

[Raz]

Raz, chip is a good start...look here for Montfort chips (http://www.monfortsa.be/fr2/pg11.php?l=en)made in Belgium. They'll take your TDS from 143 to 173 hp.

Then onwards with injectors if needs, increased boost and intercooling.

p.s. an EGT guage is a very good idea any time you increase fueling beyond stock levels in a diesel.

p.p.s. propane injection is the diesel equivalent to NOS for gassers.

Cheers,
Duey

The chip is the most obvious (and easiest) option so I got that sorted pretty quickly. Just waiting for delivery and will probably have it fitted 30 minutes later :D

As my car is a daily driver doing about 1000 miles per week I probably won't take it any further than that for reliability's sake .......... although the Propane injection would be fun for overtaking!

I must admit having driven my oilburner for a few weeks now I am getting quite used to the lazy driving style (compared to my Nissan anyway) and I love the buckets of low down torque that it churns out. I guess I just need to chill out a bit more and enjoy the comfort ;)