Boost bleed off issue
05-20-2010, 02:38 PM
#16
Look for vac/boost leaks everywhere.
My stock DV failed (diaphragm ruptured) so I put in a fresh one (Hyperboost.) Shortly after, the output hose coming off the turbo developed a tiny hole. It was small enough that I really couldn't see it, but under pressure it opened up and leaked. I found it by looking at ALL the rubber hoses very carefully.
I'd pull all the boost hoses off and check them out. For good measure I'd also replace all the plastic vacuum lines under the hood. Even though it only has 42k on it, it's 22 years old. 22 years worth of heat cycles will eventually dry out the rubber under the hood. Pumping 17psi through the rubber hoses probably caused one to tear.
My stock DV failed (diaphragm ruptured) so I put in a fresh one (Hyperboost.) Shortly after, the output hose coming off the turbo developed a tiny hole. It was small enough that I really couldn't see it, but under pressure it opened up and leaked. I found it by looking at ALL the rubber hoses very carefully.
I'd pull all the boost hoses off and check them out. For good measure I'd also replace all the plastic vacuum lines under the hood. Even though it only has 42k on it, it's 22 years old. 22 years worth of heat cycles will eventually dry out the rubber under the hood. Pumping 17psi through the rubber hoses probably caused one to tear.
05-20-2010, 06:45 PM
#17
Race Car
look at the couplers at the intercooler. They split on the underside. That said, a k26 doesn't hold great boost to redline anyway. I only saw around 12 psi with the WG clamped (fully)
05-21-2010, 05:41 PM
#18
Instructor
Thread Starter
Thanks for the replies. I guess this weekend will be spent going over vacuum lines. To the wastegate and MBC are all fresh silicone hoses from Lindsey, so they should be good. For replacing lines is it best to just run all new silicone hoses or new factory rubber? I figured the K26/8 is probably on the threshold of it's efficiency range at 17 psi. But like I said, it was holding 17 strong to redline after the install. Was able to spin tires in 1st and now I can't 
05-21-2010, 05:53 PM
#19
Thanks for the replies. I guess this weekend will be spent going over vacuum lines. To the wastegate and MBC are all fresh silicone hoses from Lindsey, so they should be good. For replacing lines is it best to just run all new silicone hoses or new factory rubber? I figured the K26/8 is probably on the threshold of it's efficiency range at 17 psi. But like I said, it was holding 17 strong to redline after the install. Was able to spin tires in 1st and now I can't
Don't forget to look at your other boost hoses closely too (the 2.5" hoses going to/from the intercooler.)
06-07-2010, 01:02 PM
#20
Instructor
Thread Starter
What's the best place for silicone vacuum hose? Kit from Lindsey is about 40 bucks?
Where would I get 2.5 inch intercooler couplers? OEM from the dealer or other parts place?
Where would I get 2.5 inch intercooler couplers? OEM from the dealer or other parts place?
06-07-2010, 01:15 PM
#21
Nordschleife Master
http://www.lindseyracing.com/LR/Part...OOLERHOSE.html
OR you can search at:
http://www.pelicanparts.com/catalog/..._pg1.htm#item2
http://www.paragon-products.com/Sear...ch=intercooler
http://www.944online.com/cgi-bin/ASI...ystem-944turbo
If you contact SpeedForceRacing, they also sell silicone couplers.. in several different sizes... they just don't have them listed on their web site!
http://www.speedforceracing.com/inde...categoryID=588
I am sure I am missing someone...
06-07-2010, 02:13 PM
#22
Rennlist Member
I could never get my K26-8 to hold 15 psi to redline, let alone 17psi.
It does sound like you have a leak somewhere, but the boost tailing off at red line is normal with that turbo.
It does sound like you have a leak somewhere, but the boost tailing off at red line is normal with that turbo.
06-07-2010, 03:56 PM
#23
Instructor
Thread Starter
Yeah, I agree that the 22 year old vacuum line needs to be replaced anyways, so I'll be starting there.
"I could never get my K26-8 to hold 15 psi to redline, let alone 17psi."
Yeah, I would imagine that turbo is pretty maxed out at that point, just strange that it was holding 17 psi fine for 1k miles before it started acting up.
New hose and couplers have been ordered, keeping my fingers crossed.
"I could never get my K26-8 to hold 15 psi to redline, let alone 17psi."
Yeah, I would imagine that turbo is pretty maxed out at that point, just strange that it was holding 17 psi fine for 1k miles before it started acting up.
New hose and couplers have been ordered, keeping my fingers crossed.
