Water Intercooler

[isuzumate]

Hi Guys,

I have been considering installing a water intercooler on my Rodeo 2.8 turbo diesel motor. I do not want to cut holes in the bonnet or install a third core in front of the radiator and aircon so an air to air would not be my first choice.

The only option is therefore a charge cooler. I am just not sure how effective they are and if this is the way to go. Has anyone ever measured the temperature difference between the inlet and outlet of an intecooler? Also, what change should one be aiming to achieve to make a meaningful difference to the performance of the motor?

Any advice from someone who has information on this subject would be much appreciated.

Boet.

[geeves]

It doesnt matter what type of intercooler you use Sooner or later you have to transmit the heat into the air. The big advantage of the water intercooler is your plumbing is mainly carrying water so needs much smaller pipes. You still need an extra radiator although you have a lot more flexibility on where it goes. By charge cooler do you mean some type of refrigerated unit? If so they are used extensivly on trucks and will near freeze the air but this technoligy aint cheap (expect to pay what your car is worth) It still needs the final radiator although this can be smaller as it runs hotter.
I did some testing a few years ago and with a standard top mount intercooler was getting temps of 30 - 35C at the outlet of the intercooler at 100kph on hills and a 25C day. I never tested at lower speeds or the inlet temp

[isuzumate]

Hi Alan,

Thanks for the info and its a good starting point. I can install a probe in the existing manifold to get an idea of what the inlet temperature will be. I have an EGT gauge with 4 inputs so it's quite easy to measure the temperature on either side of the intercooler.

I do understand that I need a heat exchanger core but I just do not want to have to put it in front of the other two cores. With the charge cooler they can be positioned behind the bumper or even have two smaller cores, one on either side.

Any further information would be appreciated.

Boet.

[isuzumate]

Hi again Alan,

Regarding your suggestion to look for a Subaru watercooler - do you know how big the unit is? Also, where is it installed on the car? I am concerned that it will not fit under the bonnet of the Isuzu.

Have you ever looked inside one of these units? How does it cool the passing air? I am surprised that it can change the temperature of the passing air enough to be effective and then pass the heat to the water jacket.

Another query I have is surely that huge cast ali inlet manifold on the Isuzu is really inefficient or does this not matter on a turbo diesel? On petrol motors the higher the velocity of the inlet gasses, the better the torque. Audi 6's even have twin inlet tracts, one thin to improve torque and one fat one for max flow at high speed. Again, does this not matter on TD's because there is no manifold vacuum?

If I am going to make up a watercooler unit I could quite easily change this if it would improve the performance. I was thinking to make up 4 header pipes and terminate them directly in the outlet end pipe of the watercooler unit.

Don't get me wrong, I am not some nut bored out of my mind just looking for a lot of work - if it is not going to make a difference I certainly don't want to do it all just to prove I can!

Your input would be appreciated.

Boet.

[geeves]

ive only had a quick look at the outside of the subaru unit. The section in the inlet is quite small ie no more than 1.5 times the size of the current pipe. The radiator for it though is almost half the size of the subarus proper radiator. It also has a pressure cap and warning about getting hot. Dont know what its like on the inside.
Main reason for high velocity air on a petrol engine is to create turbulance to mix the petrol throughout the mixture. With direct injection diesel and the different way it burns this is far less important. Also turbos negate the effect of tuned intakes as well to a fair amount. There might be an improvement available but it wont be much.

[mudgrip4]

Intercooler is always helpful, but if you are looking to increase the performance of your 2.8, it is not the best option. The 2.8 is easy to tune and simply advancing pump timing, increasing diesel flow, putting on a 2.5" bigbore ex turbo and adding a K&N or similar free breathing air filter will give you far greater performance increase. The pump timing adjustment and increasing of diesel flow take less than an hour and can give say 25hp increase. With all of the above done mine ran at 155hp ( from standard110hp), performing superbly on and off road - and remained at this level of high tune for over 100,000ks. Still going very well.

Mike

[geeves]

All those mods do work for performance but did you ever check your exhaust temp. Even in mid Canterbury temps above 40 are rare. Boet is going places where 40 is considered a cool day. Also theres not very many things in Canturbury that want to eat you and help isnt far away if something does break.
In NZ we can have performance and take a gamble on reliability I imagine everything Boet will be doing will be first on a basis of what will make my truck more reliable. An intercooler will do this and is suposed to be worth 5kw and also knock 50 or more degrees off the egt.

[isuzumate]

Hi Mike,

Thanks for your input. Have you ever checked your exhaust gas temps? I know mine are low at this time (around 600 degrees max flat out uphill) so there would be scope to increase the pump delivery by quite a lot. Remember though, temps of 40 degrees are quite common as we travel into Africa. Ploughing through soft sand (some are called "roads") for long stretches in 4x4 mode in the heat of the day is very stressful for any motor. By the way, I can feel a huge difference in power output when driving on a cool day or during wet weather.

A friend of mine did what you suggested on a 250 normally aspirated Isuzu engine and it went like a rocket. Everyone said it would break but it did more than 100 000km and he later sold it on, still going fine.

I am not really a speed freak or have not yet run out of HP off road really - I would just like to maximize the available power and be able to run with the newer 3L vans fully loaded on long hauls without undue stress on the motor.

Boet.

[mudgrip4]

Hi Boet - did not notice this was your thread and for African conditions with high temperatures. Have not measured exhaust temps, and comment I can make from experience is there are a few isuzu 2.8s tuned as mine and none give trouble long term - we find there is no reliability gamble here. Indicative of fact that isuzus were generally under rather than overtuned.

However, tuning for a pan African safari in high temps would be a different matter- intercooler certainly a good idea. I'd have a chat with specialist diesel tuners or isuzu agents re risk of increased temps with advancing pump timing etc, if you wanted extra power. It is standard procedure in my club and have never heard worries re temperature increases... but that is cooler NZ.

And do tuck that 7x61 under the back seat...

cheers
Mike.

[isuzumate]

Hi Mike,

Yes, I think you guys have an advantage that your temperatures allow you a big safety factor. Africa though, is on the limits of any manufacturer's design criteria from the outset.

"Specialist tuners" here range from the conservative to downright reckless and many an owner has paid the price for engine rebuilds because of this. You don't need to be a genius to turn up the diesel delivery screw on pump and get more power and a little knowledge is a dangerous thing. Of course they all offer great sounding warranties but there is always a reason why the damage is the owner's fault or the guy just goes out of business when a big claim is made. I really don't know who to trust anymore.

It's your call if the motor was designed to deliver 60KW and you increase this by 30%, you better be sure your operating conditions allow this. Africa though is a harsh place and having a motor blow hundreds of kms from nowhere is not worth the risk.

I would like to have the extra power but want to build in a safety margin by cooling the air into the motor which Will compensate for the added heat load in the cylinders. An efficient intercooler is the best way to do this but also not by adding a third core in front of the radiator and the aircon. That is why I would like to do the watercooler but need some data regarding input/output temperatures on cores and what I should be aiming for to make a meaningful difference.

The 7x61 would be great but definitely not be an option!

Boet.

[geeves]

These people have a good reputation for there kits but are not cheap
www.airpowersystems.com/safari/intcool.html

[isuzumate]

Hi Alan,

Thanks for your comments and advice. I do know about Safari and have even driven a vehicle with a Safari air-air cooler. The top end power delivery is very impressive and their quality is excellent but as you say, not cheap - and when converted to our weak SA Rands it is just way over the top. If money was no problem I would have gone for their kit.

Interesting to note that they say they can reduce by half the inlet air temp through their air-air core. This may be at a specific set of conditions but I think it would be difficult to achieve throughout the rev range and particularly at high revs and low forward speed where I need it most. Then there is also the added heat blown into the radiator and aircon cores that will definitely affect their efficient operation.

I am just a bit worried how one can change the air temp in the relatively small watercooler core between the turbo and the inlet manifold. I would think it would not have enough effect on the hot air to drop it's temp before it had traveled through the cooling chamber. For this to be really effective it would have to have a refrigeration plant of it's own as you mentioned in one of your previous comments.

For starters it would be best to make up an experimental core and see if this will work at all. I can start by using almost frozen water which will be as good as it would ever be and do some temperature measurements.

Measuring the space available on the top of the tappet cover, I have 300mm long x 200mm wide x 80mm deep for the core allowing for the inlet/outlet tapered sections. The challenge will be to get max heat transfer in this available space.

Any ideas?

Boet.

[geeves]

unfortuanatly there are no design engineers here to my knowledge. To go further might need a trip to google or maybe have a look at what other people in your area have done.
Air to air is the simplest and most reliable way esspecialy top mount and can be made to work at low speeds by the use of a slimline fan. Some of the stuff on the net seems to sugest that turbos will generate over 100C before intercooling so just getting it down to 50 would be a huge help.

[isuzumate]

Hi Alan,

Wow, 100 degree air temps are very high!

Been thinking about this a bit over the last while. I would think the only way to cool the air down through the intercooler, would be to introduce as much surface area as possible (like the fins of a core).

Now I can't make a core so the next best will be to solder a whole lot of pipes up with a flange on either end through which the air will flow. I can then bend a water jacket around this and cool the pipes which will then cool the air?

What do you think?

Boet.

[geeves]

In theory it will work. In practice how good are you engineering skills. If a air/air cooler breaks you loose boost if air/water breaks you risk water in the cylinders where a tablespoon will make a drowned engine with a possibilty of no way to resusitate. ie broken rod piston or crank.
As a point of interest the standard intake on a 2.8 bighorn is directly above the turbo From there it runs in front of the radiator just in case it wasnt already hot enough and into the air cleaner. Its no wonder fitting a snorkle gives a performance boost. I havnt measured this myself but someone did measure 50 c at the aircleaner

[isuzumate]

Hi Alan,

Well thanks for telling me that! Knowing this, what idiot in his right mind would install a watercooler??

I was going to use copper to make the test core and silver solder the pipes into the core and it would be pretty bullet proof but who knows what can happen on a trip - you could have a minor front shunt on the road and jolt it and it could rupture and that's it with pressurized water supply directly into the inlet - off to the happy hunting ground of diesel engines.... just not worth it.
This is exactly the opposite of what I want to achieve with my simple diesel engine with no cam belts and no electronics - now I introduce a time bomb into the system? No way.

So it's air to air and the aircon core and rad core just have to suffer the higher heat load. I am not convinced that the small core of the top mounted cooler can really work at slow speeds and high ambient temps even with a fan so it really comes down to a front mounted core in the end.

I had always considered squirting a fine water spray onto the core (again from my 80L of shower water) when the temps were really bad in the heat of the day or when the EGT's start climbing. Anything wrong with this then?

I can fit a snorkel inlet pipe - this is a good idea to cut down on desert sand getting into the system.
If water is such a problem how would one stop rain getting down the snorkel pipe and into the cylinders in a heavy downpour? If there is a drain at the lowest point of the pipe, surely water may get back up the pipe during a river crossing? If there is a drain, what if it blocks up - is it goodbye motor?
Also, surely the snorkel must still use the same inlet system through the filter/pipes across the motor and in front of the radiator so the heating effect would be the same except that the inlet air would be slightly cooler to start off with?

Thanks again for the advice - I would prefer to hear this now than when

[geeves]

The comercial snorkles are designed so rain drops hit the back of the inlet then drain though small holes in the back. The tiny amounts of water that get past are not an issue. Home made snorkles though are not always as good Ive heard stories of air cleaners half full after a rain storm. If you use the top off a commercial snorkle you should be fine. The standard airbox/filter housing does have a drain with a funny looking flap valve to stop water going the wrong way although a lot of these valves are well past there use by date. We quite often permanantly seal them.
A comercialy made water cooler should be ok reliability wise I was just pointing out that you need to be very sure that its well enough made if you make your own.

[isuzumate]

Hi Alan,

Thanks for the explanation.

Maybe I will still try the watercooler and mount the outlet side lower than the inlet manifold lip so no water can run into the cylinders. Also, thinking a bit more about it, the inlet is pressurized by the turbo and will blow any water into the water jacket if a leak develops. I could also quite easily put a water detector probe 1mm off the bottom of the outlet flange of the unit with an alarm in the cab. This could trigger for any water and might be a good safety feature but one would have to be quick. I think it would only really work for standing water like an overnight leak.

I'm just thinking of the water cooler again because an air-air is just not a viable option unless you go for a Safari which is half the value of my Rodeo. It must also have a bad effect on the aircon which is not the most effective at the best of times.

Another possibility is mist spraying a top air-air unit when you need to?

Boet.

[geeves]

That has been done useing a windscreen washer pump and aparantly works but could use a lot of water