Turbocharger Spinning Too Fast ? ? ?

[TurboR850]

Hi, just wondering if anybody knows what is the max psi on a TD04 Mitsubishi housing before something breaks or becomes overheated ? Some guys with Volvo's run 22/23, another runs 25, would say 26-28 be the max ?

THANKS

[Sluttypatton]

You could theoretically operate a turbocharger until it's choke point, however I don't know which TD04 your car came equipped with so I can't find the correct compressor map to tell you where that choke point is. I wouldn't recommend this however, since you will be operating your turbocharger extremely far outside it's peak efficiency islands. Don't pump up the boost on a turbocharger never meant for that purpose and then expect it to last for a long time, how long exactly it will last is anyones guess. As I mentioned before, you will be running very far out of your compressors peak efficiency, which means the air going to your engine will be very hot, so you had better have a wicked intercooler if you want to avoid detonation. If you want big boost, buy a turbocharger that can do it reliably and efficiently, so your turbocharger and motor last as long as they should.

If you still need to know, find out what type of TD04 is on your car and tell me so I can try and find a compressor map to find out what the choke point is. For instance; TD04-09B.

[TurboR850]

TD04 - 19T is my turbo,


Thanks

[Sluttypatton]

From the compressor map I found, it would seem that the compressor will reach it's flow limits at 19-20 psi. Past that you will not flow any more air than you did at 19-20 psi. Therefor you shouldn't make any extra power after 20 psi. The maximum pressure of your compressor is about 29 psi, but there will be no increase in power past 20 psi so there is no point.



Like I said before, your compressor efficiency will be horrible.

[TurboR850]

Interesting, now if you figure I have a big front mount aluminum intercooler along with water injection do you think that I could make more power after 20 psi ?

Just wondering,

THANKS

[SaabJohan]

The TD04 will take damage if you use too high pressures, the blades tend to bend. The pressure balance between boost and exhaust can't be too large either since this will wear the axial bearing fast. I don't remember the exact numbers but much over 22 psi is unsuitable in the long run, as well as high power levels.

The larger the compressor is the lower boost pressure should be used since the TD04 use the same outer diameter of the compressor but the inlet diameter gets larger with the larger compressor and that causes a larger "trim" which is insuitable for higher pressure ratios.

Use a large air cooled intercooler, don't use any water injection (because of several reasons).

[TurboR850]

Originally Posted by SaabJohan

Use a large air cooled intercooler, don't use any water injection (because of several reasons).

And why is this .. . . ?

[SaabJohan]

Originally Posted by TurboR850

And why is this .. . . ?

Water decrease the efficiency of the engine, water is distributed uneven in the combustion chamber = risk of knock or loss of power to not risk knock, it only works when the car has water (and risk of failure during boost), extra parts need to be installed, it makes soot to loose partly (can damage the turbine).

[TurboR850]

Originally Posted by SaabJohan

Water decrease the efficiency of the engine, water is distributed uneven in the combustion chamber = risk of knock or loss of power to not risk knock, it only works when the car has water (and risk of failure during boost), extra parts need to be installed, it makes soot to loose partly (can damage the turbine).

Well I have three different size water injectors, so i can't run too much water. It will help decrease knock, I bought from http://www.aquamist.co.uk/. It also gets rid of deposits in the engine, decreases turbo temp by 100 degrees. I don't agree with you at all. It also doesn't decrease efficiency of engine, water, H20 more oxygen means faster car . . . .

[TurboR850]

Originally Posted by SaabJohan

water is distributed uneven in the combustion chamber .

How so when I am spraying it well before the throttle body, does air get unevenly distribued in the combustion chamber ?

[SaabJohan]

Adding water does decrease engine efficiency since it decreases the combustion temperature, this is very well known. In water the hydrogen is oxidized, therefore it will not add any oxygen to the combustion, nor will it increase the volumetric efficiency since it cools the air mainly during the compression phase.

When injecting water into the engine the water will not be even mixed in the chamber therfore there is still a chance that a place where there is little water causes a detonation. This was noticed by Ferrari when they used it in their turbocharged F1 engines during the eighties, so instead they mixed water and fuel, when the amount of fuel then was limited they stopped used it altogether.

Another way to be sure that there is enough water in the chamber to supress knock is to add more water than needed, this do however decrease power output and this wasn't concidered to be beneficial.

Water removes some deposits, which then can damage the turbine.

Water also give corrosion problems, this is also very well known.

[TurboR850]

Okay, whatever you say, water injection is bad. okay.

Back to the question, SluttyPatton, would I be able to make more power (past 20 psi) with a big aluminum intercooler and water injection ?

THANKS

[Sluttypatton]

I have no idea about the water injection as I have no experience with it aside from what I have read. I would trust SaabJohan's judgement on that one, he is one of the more knowledgeable people on this board. The intercooler will definately increase your power, simply as a result of cooling the charge air and making it denser. This will also be needed if you wish to have any hope of avoiding detonation. As for the question about higher boost; I can't say for sure, but I estimate that at 20 psi your engine will consume somewhere around the maximum flow of your compressor. It is worth noting that it isn't boost pressure directly that creates power, it is what the boost pressure represents, air density. Increasing boost pressure means that the air being flowed by the compressor will take up less space, so more of it will fit inside your cylinders. However, if your compressor cannot flow any more air, and the maximum flow of the compressor will fit inside the combustion chamber at the current pressure, then increasing the pressure will do little good, as you are already packing the cylinders with as much air as the compressor can provide. At best you might hope that the increased pressure will help increase low RPM power by packing denser air into the cylinders, but at high RPM you will not make any extra power since the compressor will choke and boost pressure will fall to it's highest sustainable point, in your case 20 psi. I could be wrong here and if I am, I'm sure SaabJohan will correct me. After all, I am not an engineer yet, just an enthusiast.

Edit: Also, remember what SaabJohan said about damage occuring beyond 22 psi. It would be wise to note that, since that is another excellent reason why you shouldn't exceed it. Good luck controlling detonation at 20 psi, I hope you give intercooling, fuel correction, and ignition timing due consideration. I'm not saying it is impossible, it is just that the margin for error is much smaller at uber high boost, and absolutely no detonation can be allowed (not that it ever should be). Let's face it, 20 psi is high, and if you aren't happy at 20 psi, you may want to consider upgrading your turbocharger.

[SaabJohan]

When really high pressures are used the air gets hotter and especially so since the compressors efficiency drops in this case. Increasing he pressure does therefore very little for power.

Waterinjection can be used to boost the power if the downsides are accepted. But personally I don't think it should be used instead of a good intercooler.

With a MHI TD04HL-19T turbocharger it's possible to get over 300 hp with a safety margin, or closer to 400 hp but the turbocharger will get a very short life in that case.

It should also be noted that the original sintered con-rods in Volvos "white" engine can't handle much more than 300 hp.

[TurboR850]

yeah, I bent three rods on my car, so getting forged stuff, I am sure it can handle a lot of boost, ill upgrade my turbo soon to a TD05 or a T3/T4