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Technical Understanding of the IHI (Why does my Power FALL off?)

flug2012

Ready to race!
Has anyone ever adjusted the wastegate rod on these turbos? I used to have a Saab 900 Turbo and it was easy to increase boost pressure by shortening the length.
Just curious as any adjustment would tamper with the charts in this post.
 

Peteriroc

Ready to race!
Has anyone ever adjusted the wastegate rod on these turbos? I used to have a Saab 900 Turbo and it was easy to increase boost pressure by shortening the length.
Just curious as any adjustment would tamper with the charts in this post.
It could be great but in my case my WG is 98,4 % closed, so there´d have little increased doing that in IHI Turbo.

Here you are my N75 duty cicle:



Anyway Forge sells WG improved for our turbo.......

:thumbsup:
 

flug2012

Ready to race!
ok I see, but in my case I'm not chipped so an adjustment could give me more boost! I'm assuming the ECU flash adjusts the N75 electronically, I'm trying to see if the mechanical adjustment can give me more power... Not sure anyone has tested this... or if it's even safe to do...
 

Peteriroc

Ready to race!
ok I see, but in my case I'm not chipped so an adjustment could give me more boost! I'm assuming the ECU flash adjusts the N75 electronically, I'm trying to see if the mechanical adjustment can give me more power... Not sure anyone has tested this... or if it's even safe to do...
Personally I think that if you want more boost in the whole range....you should go for a STG 1..... imo, the solution you propose it´s like a n75 defeat... When the ECU finds a problem wil not be able to fix it via n75....
 
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flug2012

Ready to race!
Personally I think that if you want more boost in the whole range....you should go for a STG 1..... imo, the solution you propose it´s like a n75 defeat... When the ECU finds a problem wil not be able to fix via n75....
You're right, STG 1 is the way to go. I think the ECU has a preset boost limit anyway and messing with the rod on the WG may actually cause the ECU to cut power to avoid detonation. I suppose this is the "Fall Off" the OP was referring to. Just no fooling the ECU unless it's reprogrammed, i.e. chipped.
 

Peteriroc

Ready to race!
You're right, STG 1 is the way to go. I think the ECU has a preset boost limit anyway and messing with the rod on the WG may actually cause the ECU to cut power to avoid detonation. I suppose this is the "Fall Off" the OP was referring to. Just no fooling the ECU unless it's reprogrammed, i.e. chipped.
+1 :thumbsup:
 

grambles423

Automotive Engineer
"Fall Off" is the lack of physical efficiency that the compressor itself cannot maintain during high mass air flow and higher boost. Your engine LITERALLY cannot provide the necessary flow to keep the boost up. That on top of the ECU tapering the N75 function to prevent overboosting, you're power really didnt stand a chance.

I was talking purely the IHI turbo regardless of Stock, Stage 1, or Stage 2 tuning. Regardless if you're tuned or not, you're gonna experience this on the stock IHI turbo. Actually, you'll experience more on tuned ECUs because the peak falls so steep.
 

Deaks2

Ready to race!
"Fall Off" is the lack of physical efficiency that the compressor itself cannot maintain during high mass air flow and higher boost. Your engine LITERALLY cannot provide the necessary flow to keep the boost up. That on top of the ECU tapering the N75 function to prevent overboosting, you're power really didnt stand a chance.

I was talking purely the IHI turbo regardless of Stock, Stage 1, or Stage 2 tuning. Regardless if you're tuned or not, you're gonna experience this on the stock IHI turbo. Actually, you'll experience more on tuned ECUs because the peak falls so steep.
?

I can assure you that the engine has no issue providing adequate exhaust pressure at redline. The problem is since the turbocharger is optimized for power at lower speeds you are out of the turbocharger (not the engine's) efficientlycy range and you risk overspinning the turbocharger and/or simply pumping in hot barely compressed air into the intake.

If it was an issue of engine efficiency then the same engine with a different turbo (K04, for example) would not make any more power up top than a K03.
 

grambles423

Automotive Engineer
?

I can assure you that the engine has no issue providing adequate exhaust pressure at redline. The problem is since the turbocharger is optimized for power at lower speeds you are out of the turbocharger (not the engine's) efficientlycy range and you risk overspinning the turbocharger and/or simply pumping in hot barely compressed air into the intake.

If it was an issue of engine efficiency then the same engine with a different turbo (K04, for example) would not make any more power up top than a K03.
YOu didnt read my post correctly,

I never said engine efficiency, I was pertaining to turbocharger efficiency regarding its own compressor map. Falling off is the turbocharger's lack of efficiency to provide adequate boost at higher mass air flow rates. You cannot blow through a straw quicker and harder at the same time when the air is being pulled on the other end.

EDIT: I took the midrange/surge portion of the discussion out due to the fact I was confusing this thread with another.
 

Deaks2

Ready to race!
YOu didnt read my post correctly,

I never said engine efficiency, I was pertaining to turbocharger efficiency regarding its own compressor map. Falling off is the turbocharger's lack of efficiency to provide adequate boost at higher mass air flow rates. You cannot blow through a straw quicker and harder at the same time when the air is being pulled on the other end.

EDIT: I took the midrange/surge portion of the discussion out due to the fact I was confusing this thread with another.
I agree with this, however, the following is what threw me off:
Your engine LITERALLY cannot provide the necessary flow to keep the boost up.
 

grambles423

Automotive Engineer
I agree with this, however, the following is what threw me off:
I see why. I totally meant the turbocharger cannot provide enough flow to keep the boost requirements met.

That was retarded on my part.....my apologies.
 

Apexeater

Ready to race!
The link is broken.

Grambles, I seem to be following your threads around.
 

grambles423

Automotive Engineer
The link is broken.

Grambles, I seem to be following your threads around.
Haha...,yeah I think its about time to update the information.

EDIT: Updated with a little here and there
 
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