Thread: Supercharging a 4BD1

for my rule of thumb, depending on the application and intended delivery of the power.

<10psi intercooling is a nice luxury unless you are likely to wind the boost and fuel up later I reccomend fitting an EGT gauge.

10-15psi Intercooling is a good idea and should be fitted unless youre intending to run at the lower pressures but have the higher pressure available for short term emergancy power, and are setting up the ability to have higher boost to take advantage of a couple of quirks in turbo and wastegate setup. You'll need an EGT gauge.

15psi+ intercooling is mandatory, the EGT gauge is mandatory.

Originally Posted by isuzurover

Why do you think your setup does not require intercooling?

Have you measured intake temps compared to other setups?

Based on (simple) some calcs I did a while back, and system with greater than 3-5 psi Boost will benefit from an intercooler.

It seems logical to me that if the turbo is remoted from the hot exhaust manifold and has the compressor side in front of the turbine the temperature of the compressor and air intake will be lower than one in the normal position where the turbine and manifold in front is going to add extra heat to the compressor side. Air coming through the radiator and scoop on the mudguard top also will help with cooling with the compressor side in front. Mine also has water cooling which must help with lowering shaft temperature heat transfer. I haven't any temperature readings to back this up but from the EGT's I get I consider I don't need intercooling. Have been running 20psi for over 12 months now and the highest temps I can get are 550 pulling about 3 ton uphill at 100k/hr. My probe is post turbo so I would imagine manifold temps would probably be up to 100 degrees higher, but that is still not near max EGT's. The attached pic shows temp/boost/speed towing a car trailer and another County back from Cairns last year.
I guess I am an idiot as I run 20 psi boost and have no intercooling
My engine is a 95 build so has the turbo pistons etc.

Originally Posted by Bearman

It seems logical to me that if the turbo is remoted from the hot exhaust manifold and has the compressor side in front of the turbine the temperature of the compressor and air intake will be lower than one in the normal position where the turbine and manifold in front is going to add extra heat to the compressor side. Air coming through the radiator and scoop on the mudguard top also will help with cooling with the compressor side in front. Mine also has water cooling which must help with lowering shaft temperature heat transfer. I haven't any temperature readings to back this up but from the EGT's I get I consider I don't need intercooling. Have been running 20psi for over 12 months now and the highest temps I can get are 550 pulling about 3 ton uphill at 100k/hr. My probe is post turbo so I would imagine manifold temps would probably be up to 100 degrees higher, but that is still not near max EGT's. The attached pic shows temp/boost/speed towing a car trailer and another County back from Cairns last year.
I guess I am an idiot as I run 20 psi boost and have no intercooling
My engine is a 95 build so has the turbo pistons etc.

In any turbo installation there is no significant heat-transfer between exhaust and intake.
The two sides are joined by a housing and shaft which is lubricated and cooled by engine oil. Oil which is cooler than the air coming out of the compressor.
Water cooling of the core is only for shutdown protection, it does nothing for charge temperatures.
To keep your charge temps down you need:
1. Cold air intake
2. Efficient compressor matched to your engines demands.

At 20psi if you are running a 65% efficient turbine and drive ratio of 1.5 then 550C downstream equates to 815C upstream. That's a 265C drop.

If your drive ratio is 1:1 (possible if everything else is perfect and revs are low) then you are at 730C upstream.

See why I don't recommend post-turbine temps? Even with oil squirters I wouldn't be running that sustained. Do you have oil squirters?

even with only 100 degrees drop (which is a very very conservative number if the turbo is working hard) at 550 at the tail you're at 650 on the nose which means you're on the limit of 650 which is considered about the maximum reliably safe preturbo temp.

Originally Posted by Dougal

In any turbo installation there is no significant heat-transfer between exhaust and intake.
The two sides are joined by a housing and shaft which is lubricated and cooled by engine oil. Oil which is cooler than the air coming out of the compressor.
Water cooling of the core is only for shutdown protection, it does nothing for charge temperatures.
To keep your charge temps down you need:
1. Cold air intake
2. Efficient compressor matched to your engines demands.

At 20psi if you are running a 65% efficient turbine and drive ratio of 1.5 then 550C downstream equates to 815C upstream. That's a 265C drop.

If your drive ratio is 1:1 (possible if everything else is perfect and revs are low) then you are at 730C upstream.

See why I don't recommend post-turbine temps? Even with oil squirters I wouldn't be running that sustained. Do you have oil squirters?

That's uphill towing a 3T load not sustained driving. As you can see in the pic 100k/hr on the flat towing that load is about 12psi and 375 approx. That is lower temp than standard fitments I have seen with post turbo probe. Max recommended sustained temp is 750 so I see no problems with short periods up to this figure. Don't agree with you that there is no heat transfer in a turbo setup especially with the air flowing over the turbine/dump pipe/manifold onto the compressor side. What temp do you reckon the air coming out of the compressor is.

Originally Posted by Bearman

That's uphill towing a 3T load not sustained driving. As you can see in the pic 100k/hr on the flat towing that load is about 12psi and 375 approx. That is lower temp than standard fitments I have seen with post turbo probe. Max recommended sustained temp is 750 so I see no problems with short periods up to this figure. Don't agree with you that there is no heat transfer in a turbo setup especially with the air flowing over the turbine/dump pipe/manifold onto the compressor side. What temp do you reckon the air coming out of the compressor is.

On a flat road when fully warmed up I'm now running about 380C and 9psi. Probe upstream of the turbo.
It used to be 430C, but improvements in my turbo piping and more advanced timing have dropped EGT's markedly.

I have measured my turbo outlet temps. I drilled thermisters through the intake and turbo piping at several points and ran these on a data logger for a short while.
At 15psi on a roughly 15C day it was reading 115C, which fits perfectly with a 70% efficient compressor and no additional heat source. That's why I am sure there is no significant heat-transfer. Because I've taken the measurements to prove it.

I haven't measured 20psi or higher as this is past the max temp limits of the thermistors I was using.
20psi should be ~140C.
24psi should be ~160C.

These temperatures are much lower than a supercharger delivering the same boost.

Originally Posted by Lost Landy

G,day guys just asking if any one has supercharged there 4BD1 and if so what type of supercharger did you use? Not iterested in turbocharging my engine as dont really what the hasstle of fitting an intercooler and all the dramas with heat and high exhaust temps.

To the 1st part, the answer is no. A supplement to this is; I never ever would and would question your motives.

I think I understand where you are coming from, as most responses to fitting turbos rairly fail to get onto the subject of intercoolers and gauges to measure the egt. There are very basic reasons for this, and they would equally apply to fitting a supercharger.

Turbos (or superchargers) are usually added (or upgraded) to increase torque and power from the engine.

In the case of a diesel (unlike petrol) engine, adding a turbo (or supercharger) alone will not increase performance one iota. What they do is increase the air density so the engine breathes more oxygen, which allows it to burn more fuel to create that increases the pressure of the air that pushes the crank around. This leads to higher torque (and power at the same engine speed.

Now the temperatures of combustion can often be higher than the melting point of the aluminium used for the pistons. Fortunately this high combustion temp is present for a short period.

When we change the fuel rate to increase engine performance the temps can be increased very quickly and we (most of us) are unable to measure either the combustion or piston temperatures. However we can measure the temperature of the exhaust gasses and use this to predict a safe/dangerous operating condition. EGT climbs dangerously high as the air/fuel ratio (edit) reduces (richer) (end edit). Hence the reason for why a guage to measure egt is recomended.

The turbo uses the waste heat energy in the exhaust gasses, which is why the temperature drops from the entry to exit sides of the turbine - in other words, the turbine takes heat out of the exhaust gassses.

The excess (beyond what is needed to burn the fuel) mass flow of air through the engine becomes heated and thereby extracts heat from around the combustion area.

Intercooling (or charge cooling) is a complimentary method to increase air density. Increasing pressure increases density, but increasing temperature reduces density. The laws of thermodynamics (and our own observations) show us that increasing the pressure of gas also increase its temperature. So it becomes increasingly difficult to increase the density without addressing the increased temperature. The benefit (i.e. change to air density) vs cost from adding intercooling increases with increasing boost pressure.

Originally Posted by Bush65

To the 1st part, the answer is no. A supplement to this is; I never ever would and would question your motives.

I think I understand where you are coming from, as most responses to fitting turbos rairly fail to get onto the subject of intercoolers and gauges to measure the egt. There are very basic reasons for this, and they would equally apply to fitting a supercharger.

Turbos (or superchargers) are usually added (or upgraded) to increase torque and power from the engine.

In the case of a diesel (unlike petrol) engine, adding a turbo (or supercharger) alone will not increase performance one iota. What they do is increase the air density so the engine breathes more oxygen, which allows it to burn more fuel to create that increases the pressure of the air that pushes the crank around. This leads to higher torque (and power at the same engine speed.

Now the temperatures of combustion can often be higher than the melting point of the aluminium used for the pistons. Fortunately this high combustion temp is present for a short period.

When we change the fuel rate to increase engine performance the temps can be increased very quickly and we (most of us) are unable to measure either the combustion or piston temperatures. However we can measure the temperature of the exhaust gasses and use this to predict a safe/dangerous operating condition. EGT climbs dangerously high as the air/fuel ration leans out. Hence the reason for why a guage to measure egt is recomended.

The turbo uses the waste heat energy in the exhaust gasses, which is why the temperature drops from the entry to exit sides of the turbine - in other words, the turbine takes heat out of the exhaust gassses.

The excess (beyond what is needed to burn the fuel) mass flow of air through the engine becomes heated and thereby extracts heat from around the combustion area.

Intercooling (or charge cooling) is a complimentary method to increase air density. Increasing pressure increases density, but increasing temperature reduces density. The laws of thermodynamics (and our own observations) show us that increasing the pressure of gas also increase its temperature. So it becomes increasingly difficult to increase the density without addressing the increased temperature. The benefit (i.e. change to air density) vs cost from adding intercooling increases with increasing boost pressure.

Just wondering if when you said air/fuel ratio leans the egt's go high i thought leaner was cleaner and cooler for diesels ? I probably misunderstood your post though not the first time and probably not the last