heavy boost drop off.
03-31-2005, 04:04 PM
#1
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heavy boost drop off.
Hey everyone, I've had my set up going for a few hundred miles now, and I've been having my boost drop off quite a bit by redline. I make boost early (17 psi by 3000 rpm in third) and it's nice, but as soon as it hits its peak its already downhill, and by 6000 to redline, I'm lucky to see 12 psi.
I'm posting to see if its just the setup I have, or maybe something isn't working right. Some will say the K26/6 is running out of steam, and some will say a k26 can hold 25 psi to redline, I've heard both, thats why I post, I'd like some ideas.
~Eyal
I'm posting to see if its just the setup I have, or maybe something isn't working right. Some will say the K26/6 is running out of steam, and some will say a k26 can hold 25 psi to redline, I've heard both, thats why I post, I'd like some ideas.
~Eyal
03-31-2005, 05:13 PM
#2
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I believe it is more of a wastegate and turbocharger. But i also remember Danno claiming that the only way he made the K26/6 hold boost to redline was with a EBC and a good wastegate (not sure which one he used).
03-31-2005, 06:15 PM
#4
Race Director
An EBC will help alot as it can run in closed loop and increase the duty cycle to maintain the boost. I think an SFR bolt on Tial and an EBC will do wonders... you are missing 50HP up top which the $500-$600 will replace. Not bad return.
03-31-2005, 08:15 PM
#5
Rennlist Member
All the EBC and the Tial is going to give you is high readings on your boost gauge; it doesn't mean you're going to be making much more power.
Therefore, what that means is, that the turbo is running out of steam.
You can keep the boost readings up all you want, by whatever method; but the excess heat and back pressure created (by a turbo that's "running out of steam") will nullify any gains that the extra boost was supposed to give you in the first place.
Yet, people still assume: "If I can only get my boost to hold , I'll be making "x" amount more power."
Totally misinformed.
Therefore, what that means is, that the turbo is running out of steam.
You can keep the boost readings up all you want, by whatever method; but the excess heat and back pressure created (by a turbo that's "running out of steam") will nullify any gains that the extra boost was supposed to give you in the first place.
Yet, people still assume: "If I can only get my boost to hold , I'll be making "x" amount more power."
Totally misinformed.
03-31-2005, 08:49 PM
#7
Race Director
More boost does mean more power in this case. The K26/6 can hold 18psi to redline. I did it with a nippon denso solenoid and Tial WG. Laust has maintained over 20psi to redline on the k26/6. Clearly the turbo has more steam than a lucky 12psi. Yes more heat comes, more boost equals more heat on any turbo.
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03-31-2005, 08:50 PM
#8
Race Director
Originally Posted by TurboX
Getting a new By-pass valve might help. the lindsey one that you can shim is supposed to hold the boost for longer 
03-31-2005, 08:59 PM
#9
That Guy
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im saying if it is installed correctly and shimmed with the supplied washers
It should hold the boost longer
I am also saying a new by-pass valve (stock may it be :-\) should help, only if your by-pass is dead.
So my recommendation to you is check your by-pass valve to see if it is dead or not
It should hold the boost longer
I am also saying a new by-pass valve (stock may it be :-\) should help, only if your by-pass is dead.
So my recommendation to you is check your by-pass valve to see if it is dead or not
04-01-2005, 01:45 AM
#11
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Danno also tested the K26/6 for efficiency, claimed 18psi is max before it starts going crazy. Anyways, holding boost to redline does actually mean more power.
Say you are running 18psi, drops off to 12psi by redline as Eyal is facing. If you can hold 6psi more at redline, power would be more and the torque could probably be "flatter" there (not more, since torque is more mid-range based).
The key is a good wastegate
Say you are running 18psi, drops off to 12psi by redline as Eyal is facing. If you can hold 6psi more at redline, power would be more and the torque could probably be "flatter" there (not more, since torque is more mid-range based).
The key is a good wastegate
04-01-2005, 09:26 AM
#12
Rennlist Member
"The key is a good wastegate"
You think Porsche employed a bad wastegate?!
Contrary to popular belief, there's nothing wrong with the wastegate (other than they are getting old now). The stock boost control system (the wastegate is a big part of this) is a reflection of what the turbo is doing. Changing to aftermarket often "hides" turbocharger ineffeciencies.
Yeah, you might be able to get a tad more power if you held higher boost to redline, but not even close to what it should be if you had a bigger turbo.
The acceleration of your car at the higher RPMs with 17 - 18 psi boost will hardly be any more than the acceleration at 12 - 13 psi boost, with a k26/6!
You think Porsche employed a bad wastegate?!
Contrary to popular belief, there's nothing wrong with the wastegate (other than they are getting old now). The stock boost control system (the wastegate is a big part of this) is a reflection of what the turbo is doing. Changing to aftermarket often "hides" turbocharger ineffeciencies.
Yeah, you might be able to get a tad more power if you held higher boost to redline, but not even close to what it should be if you had a bigger turbo.
The acceleration of your car at the higher RPMs with 17 - 18 psi boost will hardly be any more than the acceleration at 12 - 13 psi boost, with a k26/6!
04-01-2005, 03:14 PM
#14
You dont more more HP (on the dyno) but it does make much more tq at 18psi than it does at 15.
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