Hey all...

Ive been doing research and there are too many conflicting answers on this topic.

I am trying to find out what the efficiency level of a stock 9 Evolution turbo can go up to.

How many PSI can the turbo run before it starts blowing hot air and stops making more power? Also, is there a high PSI for the turbo that can endanger it and possibly blow it?

It seems the magical number of loss of efficiency is at 30 PSI and up. I am talking about running this pressure on methanol injection or at least race gas (not standard 93). Is 28 pounds alright or should it be 26?

What do you guys think?

I found a compressor map. It is in post 6. Did I read it correctly?

Thanks!

- Dominic

 

see if you can find a compressor map. That'll basically tell you everything you want to know.

 

The problem with that statement is its in psi when a turbo's effective range has more to do how much you can flow safely and efficiently. There are plenty of things you can do to bump up the effective volumetric efficiency of our cars so even if your running the same PSI its flowing more air because the engine itself is better than stock.

Like.. removing backpressure with big exhaust, cam profile to increase top end effeciency, intake modication..

Turbos pretty much high the wall when the compressor wheel starts to near super sonic speeds even at 25psi on a stockish evo the compressor wheel is going to spinning around a cool 130k rpms and its dropping out of the effective bubble of the turbo getting at most like 71% efficiency for only a small period of time.

On the VE tables I'm using its looking like anything above 26psi on a 2.0L stocker is getting to that point where the turbo really struggles to make any boost at that level. Someone else can chime in on their experience since I'm just reading the chart. On a side note it looks like the turbo will reach near 30psi if you really wanted to but it probably wouldn't last for more than 200-300rpm worth before dropping boost like a stone. Also you probably wont see more than 23psi by redline.

 

the compressor maps I have found for the tdo5hr-16g goes to 32 psi on its rated pressure ratio...this is also a small peak that is mapped out. I have personally driven and dyno'd an evo (the same evo) at 23 psi on 93, 27psi 93 & 50/50 meth and 32 on 93 & 50/50 meth...the later two felt nearly the same and the extra 5psi didn't make massive gains on the dyno...so we turned it back to 28 for daily use...

I didn't fell that the 32 psi was very efficient or safe...I wish I had tapped the charge pipe for our air temp sensor and wish I had run our air flow meter so I could see where we really were on the compressor map.
Either the 264's were starting to reach choke flow (via low valve lift) or the increased pressure didn't overcome (by much) the hotter air fromt the compressor...so the 32 psi didn't pay off off in this case...I would like to see it now that we have bigger cams on the car.

There are also several variables in this situation that could change the outcome of the results so I wouldn't consider the posted results conclusive.

 

Thanks guys!

So 28 psi is not out of its efficiency range?

Any links to the compressor map?

 

I found a map:



Is its limit approximately 32.5 psi?

 

im pretty sure that is reading in bars... correct me if im wrong...

 

uhmm if t were bar wouldn't it be more like 46 ~47 psi.. I am sure is not bars..

 

I thought you are only supposed to read the smallest bubble for the max efficency...

 

it is a pressure ratio... (atmosphere + boost pressure)/atmosphere....
example (14.7+32)/14.7 = 3.18

evolved...that is why there are efficiency islands (read like a topographical map)...but instead of height above sea level, they are differenct efficiencies.
yes, the center is the highest efficiency for the given compressor though

 

So then was 32.5 correct then wrx?

 

33.81 if it is a ratio of 3.3...but it seems to be a bit less than that...

 

its all relative, you may be pushing the turbo out of its efficiency but still making power...its really up to you and your tuner on how much you want to push it...i have pushed the stocker over 34psi before and its a blast (with nitrous of course)...

 

Not that extreme for me Dan heh

 

34 psi with nitrous...well tht nitrous certainly does do some cooling and add the extra oxygen...