K04 turbo capable of 250awhp and fairly cheap....
 

I have done the research and have said turbo in my possession. I am in the process of adapting it to the car (though I strongly feel I would benefit from a better turbo manifold). The turbo I have is from the Mazdaspeed MS3 and has been proven to make 320fwhp in their setups with bolts ons. I already know 320fwhp will not equate to 320awhp but it should easily make 250awhp and given that the MS3 shuts the throttle plate above 5500 where it makes peak hp and our A4 does not it should make even more hp in the 6k+ range. Problem is I am looking for a K03 that is scrapped so I can get everything in its rightful place.

For a comparison the frankenturbo makes 240awhp but uses 42mm inducer and 60mm exducer which is the same as the CX7 turbo. The MS3 uses a 46mm inducer and 60mm exducer. Compare that too 38mm inducer and 50mm exducer of the K04 015 and you will quickly understand the major difference between these turbos. Also the turbine is larger then the regular K04 015 and has a better AR to help handle the additional flow. You can also buy K04 882 (MS3 turbo) for $650 new or used for alot less. I am going to CNC adapter plate and make a test pipe for the setup.

Here is some pictures of the CX7 turbo. The MS3 has a larger compressor but is physically identical. The CX7 should also make 250awhp as well. I am going to use a V band downpipe to attach it to the exhaust.

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definitely interested in seeing if you can get this to work

Sub'd

Pm me I have a blown ko3 I can sell you. Sounds like a great project. flow map for the cx7 turbo?

I'm extremely interested in seeing what the gains are here. Stock programming should still run this turbo with decent gains.

The flow map is on the frankenturbo site. It is literally the EXACT same compressor however the benefit other then cost of this unit over the frankenturbo is the exhaust housing and its AR. The biggest problem with the K04 is that the turbine housing is specifically designed for spool but at higher flow rates the nozzle in the housing becomes a limiting factor as it is not designed to sustain higher flow rates. What happens when the turbine housing can not handle the additional flow beyond its design is that it literally backs exhaust flow back into the combustion chamber and causes pumping loss which robs hp directly from the crank. I feel that I honestly need a better turbo manifold as well to get everything from it but too give you an idea the CX7 turbo makes 240chp in stock form with gobs of torque but it used in 2.3 liter. The MS3 turbo uses an even larger compressor and better exhaust housing. They are both the same size physically and I also have the MS3 turbo as well which I ultimately plan on using.

This the downpipe I am going to modify.

Mazdaspeed 6 MPS 2 3 MZR Turbo Charger Stainess Exhaust Downpipe Gasket Bolts | eBay

I will shorten it up and reuse the flex pipe so that it does not have to be 100% perfect and it also has 3 O2 sensor locations. My car currently has the AWE kit with PC16 upgrade and I am adding a larger front mount. It also has the Carbonio intake and GHL 2.5" exhaust. I would love too see if its possible to make 2 adapters and make it a bolt on affair but if nothing else it would require the manifold adapter and a converted downpipe.

If the exhaust housing isn't the same, how could the flow map be the same?

I think it's because usually flow maps are based solely on the compressor side of the turbo.

The compressor flow map is based completely off the compressor side. Very few manufacturers post turbine flow maps which SUCK. If we had an availible flow map for the hot side we would be able to discern when the turbo would spool and how long it would maintain a set psi. Having had said this the Mazda turbo does have a slightly different AR for the comp side which is a bit larger then the stock unit so it should also help sustain higher flow rates.

The flow on exhaust side does not adversly effect the compressor side except when the turbo will come on but the compressor map stays the same. The compressor flow does effect the exhaust side because what you produce through the compressor has got to flow out the turbine side. If you are flowing an excess amount say 30 lb min through a turbine housing designed for 20 lb min you will back exhaust up into combustion chamber and rob crank hp. It basically works off the simple fact that in nature all pressure flows from higher psi to lower psi. This is how the NA motor works and how a turbo setup works as well. Its the atmosphere pushing air into the combusion chamber to fill a low pressure void instead of being sucked in as most assume. Whenever the psi between the exhaust valves and turbine nozzle exceed the psi at the intake valves you have pumping loss as the exhaust is literally pushing back on the piston and the mechanical work the crank is producing is being robbed to force the exhaust out the exhaust valves and through the wastegate port. This is why porting the wastegate port helps dramatically when adding more flow (or hp) to the setup and in stock setups the turbine nozzle and wastegate port are proportional to each other.

I have literally seen a loss of hp on old T3 turbo setups when increasing boost due to this exact reason. You can still make power with the stock turbine housings but a proportional housing will make better overall hp and hold better to redline. This is specifically why I am looking for an aftermarket unit that has better size to it for the stated reason.

I am looking for specs on the K04 015 but I believe you can take the Mazdaspeed unit turbine housing off and swap the rest of the turbo directly over to the K04 015. Maybe with a lot of porting the turbine housing will work OK.

EDIT: I just found the specs and they are a lot different. The K04 015 uses a 46mm inducer and a 42mm exdcuer. The Mazdaspeed 3 and CX7 uses 50mm inducer and 44mm exducer (I have also seen 45mm exducer). I do know someone that can machine the VW housings to accept the larger K04 turbine and make it a true bolt in affair. If I can buy a stock turbine housing from someone I can tell if it will be a worthwhile investment to attempt to make it a bolt in affair.

You can buy these larger K04's for around $750 new that should have stock like spool but still make 250awhp +.

Ahhh makes sense. Thanks!