Need validation on whether my reasoning is logical.

My problem is...Few small leaks in intercooler, but not lost any boost from after market KSB-1 turbo. I do have EGT's way higher than they should be.
My reasoning = Oversized turbo is big enough to maintain boost (45 lbs) in spit of leaks but is working overtime (over-reved) to do it. Leaks are not big enough to lose boost but i get higher egt's because turbo is working harder than it should and is putting out over heated air.
Done lots of searches but can find nothing about this same senario. All I find are stories of low or no boost pressure. Read 2 books on turbo theory & practice but - no help. I would think I would lose a little boost from small leaks...on the other hand, maybe the leaks were there before I installed the TST PM3, which is the cause of the excessive EGT's?

Questions:
Anyone run into this same situation?
Does my logic, of over reved turbo to maintain boost, hold up?


Rowland

 

Your theory is fine. Think of it this way. With no leaks, your turbo takes 50 EGHP (to pick a number for illustration) to deliver 50 HP of air compression at a theoretical 100% efficiency, for our discussion. All of this compressed air, less flow losses, is available for combustion.

Now, with intercooler leaks, let's say it takes 60 EGHP to produce the same boost and airflow (actually, airflow won't be the same at the same boost as case 1, but this is close enough for discussion). To produce this extra 10 EGHP, the wastegate is operating in a more closed position. 10 compressor HP is being consumed for the air lost to intercooler leaks. The other 50 compressor HP is being used to compress the air consumed by the engine, as in case 1.

Since case 2 requires 60 EGHP compared to case 1's 50 EGHP, turbine drive pressure and EGTs must be higher in case 2 to produce the extra 10 EGHP.

Rusty

 

Having an engineers explanation makes me feel much more confident in my choosen (and expensive) solution to my problem.

Just couldn't believe I was the only one to run into this situation.
Especially after my research found that the stock intercooler is only rated for 30 psi. Rod at wildcat agreed with my logic also, but even he had never run into it (leaks without loss of boost). Maybe there is a lot of it, but its undetected?

Thanks again! Anyone else?

Rowland

 

Actually Rowland, I think we may have missed one another when we were discussing it on the phone. I've run into this a fair bit where boost is very close to what we'd expect, but EGTs are up and power is down by a fair bit. We've almost always traced it back to a leak of some sort on the charge air side.

What I did mean is that your power, with your combination of mods, is a little low and your EGTs are a little on the high side. Sorry for the confusion.

Rod

 

I'm sure the confusion was mine, not yours. Your far enough ahead of me on this stuff that many of your one liners are whole new concepts to me. I'm sure I took something you said and translated it (incorrectly) into my own words.

Thanks for chiming in!

Rowland