what psi should i tune for stock turbo
- Thread starter h0rsies
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IMHO, it's really pointless to tune for more than 18 psi on the K04. Yes, you can safely tune so that it will spike above 18, but then settle and hold boost value maxes out at 18. But,there's just too much data out there regarding the flow rate of that turbo to suggest that any higher boost would get you anywhere good.
More than 18 psi or more than 6,000 rpm and it simply cannot push the air through without producing extreme heat. When those temps climb like that, you are then working at cross purposes with yourself because the hotter compressed air ends up being hotter boost air temp coming out of the intercooler and you lose power.
On top of that, the K04 has a very small diameter center shaft (only 5mm, if I recall correctly) that overheats easily at higher boost levels and higher rpms. Sustained boost above factory levels, especially when operated under load and above 5,500-5,800 rpm will soften that center shaft and greatly shorten the life of the turbo.
I say this from the prospective of someone who has decided to stay with the stock ECU tune, but who is running a catless dp/rp and a CAI intake. This setup does give me about two psi more boost under most conditions, while still allowing the ECU to step in and either boost cut or fuel cut me if it thinks conditions are unsafe. I spike to 18-19 and settle down to a steady 17 psi up to about 5,500 rpm or a bit above, after which it tapers back pretty quickly as the ECU closes the throttle plate. I think this is safe. Sometimes aggravating, but safe.
I defer to the opinions of those who are running AP tunes with higher boost. I may be wrong, but I doubt anyone would recommend boost levels to hold above 18 on the K04, at least anyone who wants their turbo to last very long!
More than 18 psi or more than 6,000 rpm and it simply cannot push the air through without producing extreme heat. When those temps climb like that, you are then working at cross purposes with yourself because the hotter compressed air ends up being hotter boost air temp coming out of the intercooler and you lose power.
On top of that, the K04 has a very small diameter center shaft (only 5mm, if I recall correctly) that overheats easily at higher boost levels and higher rpms. Sustained boost above factory levels, especially when operated under load and above 5,500-5,800 rpm will soften that center shaft and greatly shorten the life of the turbo.
I say this from the prospective of someone who has decided to stay with the stock ECU tune, but who is running a catless dp/rp and a CAI intake. This setup does give me about two psi more boost under most conditions, while still allowing the ECU to step in and either boost cut or fuel cut me if it thinks conditions are unsafe. I spike to 18-19 and settle down to a steady 17 psi up to about 5,500 rpm or a bit above, after which it tapers back pretty quickly as the ECU closes the throttle plate. I think this is safe. Sometimes aggravating, but safe.
I defer to the opinions of those who are running AP tunes with higher boost. I may be wrong, but I doubt anyone would recommend boost levels to hold above 18 on the K04, at least anyone who wants their turbo to last very long!
mr_mazda329
Member
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- 97 Mazda Miata; 09 CWP Mazdaspeed 3
18psi
You are not wrong. In fact you are spot on correct MSMS3. I said the same thing to the OP when he pm'd me. the small factory turbo is extremly effecient,But its limits are in the higher psi range. Yes you could go over 18 psi..but it wouldnt gain you anything but little more power and severe heat prablems. My 15 psi map makes 285 whp and my 17 psi map makes 296whp.....When my car was getting tuned..Tim was trying to see if 18 psi would work..but said it wasnt looking too healthy and was overheating the turbo somewhat..A front mount intercooler would have solved this for the most part. While I dont have any graphs on hand..when I was looking at the dyno screen when the 18 psi was beign ran..the car was only geting about 299-301 whp..pretty much, very little gain from my perfect running and safe 17 psi map. Now there are ms3's with 18 psi protunes running fmic that are geting 300-310 whp..And that is pretty much the peak of this small turbo on this platform...If you desire more boost for power..then you gotta go bigger turbo..and thats a whole nother story all together. 
