highest boost with stock turbo?
08-28-2007, 12:15 AM
#2
Chapter President
40 Psi is over the limit for the stocker. Most tests show that the performance drops off significantly over 35 psi as the drive pressure on the exhaust side is higher than the output boost. You might find better performance if you opened the gates at a lower boost pressure. I never ran mine over 36, now with the S300 I keep it around 46..
08-28-2007, 09:18 AM
#6
Registered User
Even though your HX-35 will be out of it's efficiency map at 40psi - it'll still be making power-producing boost. Just make sure the intake charge temps are manageable!
08-28-2007, 10:19 AM
#7
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I ran my old stocker to 51psi before I blew it up...not good for power or the charger, but it sounds cool
I'd keep it below 36-38psi, and it'll serve you well!
Chris
I'd keep it below 36-38psi, and it'll serve you well!
Chris
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08-28-2007, 04:20 PM
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I've run mine to almost 40psi.
After about 35psi, you can feel and actually hear the turbo choking. It takes on a gruff sounding growl. It can't be good for the charger.
Drive pressure at these levels is probably around 70psi, as the hot side just can't flow enough. A 14 housing would probably relieve some of the drive pressure, but you're still doing a lot worse than 1:1. You might need a 16 or 18.5 housing to make that hot side somewhat efficient, but that's laggy and the improvement in efficiency is probably more than offset by the lag.
The HX35 appears to have a pretty big gap between the "efficiency" range and the "safety" range. It can make good COOL boost up to 30psi or so. It can make power up to 40 or so. It can stay alive to almost 50-- but man that's pushing it!
IMO, the compressor on the HX35 can actually go pretty far in power support-- but the tight hot side will limit your power a lot more than the smallish compressor. Once you hit the point of "saturation" where the flow in the hot side goes supersonic, you can crank up the drive pressure to the moon and not get any reasonable increase in flow.
Once upon a time, there was a common saying that "20psi will support 350hp with a clean tailpipe on a CTD". This isn't quite the case unless you have temps near freezing and EGTs on the ragged edge. (you can hit dangerous EGT with a perfectly clean tailpipe).
The actual boost required to support X amount of hp depends very heavily on compressor efficiency, ambient air conditions, intercooler efficiency and so forth.
Let's say you want to run 400hp. One one extreme you can have hot weather, very conservative EGT requirements, poor efficiency in the turbo and intercooler, restrictive air intake, etc. In this case, it would take up to 38psi to support 400hp.
On the other hand, you can want 400hp in freezing cold temps, very high efficiencies in the air intake, turbo, and intercooler, and have pretty liberal EGT limits, and in this case it only takes 20psi to "support" 400hp.
Circumstance will change things by a HUGE amount, and everyone has different definitions of "safe" and "enough" and so on...
jh
After about 35psi, you can feel and actually hear the turbo choking. It takes on a gruff sounding growl. It can't be good for the charger.
Drive pressure at these levels is probably around 70psi, as the hot side just can't flow enough. A 14 housing would probably relieve some of the drive pressure, but you're still doing a lot worse than 1:1. You might need a 16 or 18.5 housing to make that hot side somewhat efficient, but that's laggy and the improvement in efficiency is probably more than offset by the lag.
The HX35 appears to have a pretty big gap between the "efficiency" range and the "safety" range. It can make good COOL boost up to 30psi or so. It can make power up to 40 or so. It can stay alive to almost 50-- but man that's pushing it!
IMO, the compressor on the HX35 can actually go pretty far in power support-- but the tight hot side will limit your power a lot more than the smallish compressor. Once you hit the point of "saturation" where the flow in the hot side goes supersonic, you can crank up the drive pressure to the moon and not get any reasonable increase in flow.
Once upon a time, there was a common saying that "20psi will support 350hp with a clean tailpipe on a CTD". This isn't quite the case unless you have temps near freezing and EGTs on the ragged edge. (you can hit dangerous EGT with a perfectly clean tailpipe).
The actual boost required to support X amount of hp depends very heavily on compressor efficiency, ambient air conditions, intercooler efficiency and so forth.
Let's say you want to run 400hp. One one extreme you can have hot weather, very conservative EGT requirements, poor efficiency in the turbo and intercooler, restrictive air intake, etc. In this case, it would take up to 38psi to support 400hp.
On the other hand, you can want 400hp in freezing cold temps, very high efficiencies in the air intake, turbo, and intercooler, and have pretty liberal EGT limits, and in this case it only takes 20psi to "support" 400hp.
Circumstance will change things by a HUGE amount, and everyone has different definitions of "safe" and "enough" and so on...
jh
