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Horsepower vs Boost Pressure comparison for Greddy based turbos

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Old 07-24-2010, 09:52 AM
  #26  
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I can't see how that would help... those ports would just have hot gases running on them all the time even if the WG is closed unless you block the ports from inside the motor.
Old 07-24-2010, 02:12 PM
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so you saying you can have more performance if you remove this?
Old 07-24-2010, 11:17 PM
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Originally Posted by Mawnee
Ok I'm in a random ideas kinda mood...so please bear with me. This is kind of a cross discussion of this thread and the one about your melted housing.

Do the exhaust ports on the center and outer housings share the same shape where the rotor passes them? Or are they smaller for the center housing and the shared ports?

What would happen if I were to make a manifold where the center port was deidicated to the wastege? It would eliminate flow through those ports alltogether until the wastegate cracks. Would it then be subjected to less pressure/resistance under higher boost? Or would forcing all the bleeding of pressure through the center actually create more heat and/or boost creep?
The actual ports on the centre iron are identical to those on the outer irons - its the port runners that are very restrictive on the centre .
Not sure what your idea would do but at high flow rates I doubt it would help .
Old 07-24-2010, 11:51 PM
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My line of thought was to force the flow through the less restrictive runners. And when the wastegate cracks the restrictive runners would be under less backpressure and thus less of a restriction. Kinda making the renesis work like an Rx7 engine most of the time. Just random theorycrafting
Old 07-25-2010, 12:20 AM
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Well that might be ok at low power but as you start pushing things they will still become a restriction IMO
Old 07-25-2010, 12:55 AM
  #31  
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if u closed off the middle wouldnt fuel collect in it then go poof little secondary explosion with force against the waste gate and back into the chambers
Old 07-25-2010, 01:18 AM
  #32  
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Originally Posted by FazdaRX_8
so you saying you can have more performance if you remove this?
possibly - but only when really pushing it to the limit . IE 400whp +
Old 08-02-2010, 05:44 PM
  #33  
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This is a comparison of a stock greddy(wrung out to it's max) vs a 57trim

I thought it interesting because the result is pretty much identical bar that last 1500rpm .

Name:  whpvsboost3.jpg
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Old 03-18-2012, 08:36 AM
  #34  
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hey a two year old bump!

I want to see the Mass airflow readings from this dyno.
Do you still have them Brettus
Old 03-18-2012, 02:39 PM
  #35  
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Originally Posted by wcs
hey a two year old bump!

I want to see the Mass airflow readings from this dyno.
Do you still have them Brettus
I do have them from my last dyno - not shown here . CAn post that up later when i have some time
Old 09-07-2012, 02:55 PM
  #36  
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Attached Thumbnails Horsepower vs Boost Pressure comparison for Greddy based turbos-melted-runner-whp-comparison.jpg  
Old 09-10-2012, 09:57 AM
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Why should a flow restriction in the exhaust make things better? I have three thing I do not understand:

1. I do not understand why you have more torque/power between 4500 - 7900rpm. It does not follow difference in boost
2. I do not understand why do you get higher boost in midrange with flow retriction
3. I do not understand why you make more power at the same pressure between 6- 7000rpm

Why?!?

Education please.
Old 09-10-2012, 02:46 PM
  #38  
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Originally Posted by AAaF
Why should a flow restriction in the exhaust make things better? I have three thing I do not understand:

1. I do not understand why you have more torque/power between 4500 - 7900rpm. It does not follow difference in boost
2. I do not understand why do you get higher boost in midrange with flow retriction
3. I do not understand why you make more power at the same pressure between 6- 7000rpm

Why?!?

Education please.
Good work spotting all that (I thought it was going to pass un-noticed).

It wasn't a restriction , it was actually the removal of a restriction which is why i believe the extra power was there . Also notice there was LESS power in the lower rpms - at NA flow ranges .

The answer to the higher boost question is just that the boost controller was set higher .

Will be testing this more fully in the coming months .
Old 09-11-2012, 02:25 AM
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Originally Posted by Brettus
It wasn't a restriction , it was actually the removal of a restriction which is why i believe the extra power was there . Also notice there was LESS power in the lower rpms - at NA flow ranges .
Damn - Now we have to make a variable exhaust system as well
Old 09-11-2012, 02:46 AM
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Originally Posted by Brettus
Thought this might be interesting to Greddy / Greddy upgrade owners to see what sort of power they can expect to make at various boost levels .
These dynos were all of the same car on the same dyno with more or less the same turbo setup .
Note that boost is not constant for any of the runs so this needs to be looked at in conjunction with the whp result .


not possible running at 0.9 bar with Greddy T618 and making 370-380 hp at the crank (this is about 330 wheel horse power). It is possible to make 330 AT THE CRANK and not WHP !
Old 09-11-2012, 04:36 AM
  #41  
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Originally Posted by rotaryPilot
not possible running at 0.9 bar with Greddy T618 and making 370-380 hp at the crank (this is about 330 wheel horse power). It is possible to make 330 AT THE CRANK and not WHP !
Probably not with a stock Greddy ..no . With an upgraded Greddy ... yes .
Old 09-11-2012, 06:44 AM
  #42  
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^ Even with a modified Greddy ie 620 you will need more than 0.9 bar. Probably if you run at 1.3 bar using meth for detonation you will get close
Old 09-13-2012, 03:54 PM
  #43  
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/\ I have already done it at around 0.7bar ! Read the thread ....

Last edited by Brettus; 09-13-2012 at 04:06 PM.
Old 09-13-2012, 05:08 PM
  #44  
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Originally Posted by Brettus
Read the thread ....
pot, meet kettle ...
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