86' 951 with a 3 inch exhaust and cup car chips. was only getting 12-13psi and then after 4000rpms the boost falls off to 9-10psi. I installed a boost enhancer and now under 4000rpms it hits the magic 15psi but after 4000 it will start trailing off to 10psi or so again. Is my wastegate spring just not strong enough because of age(120,000 miles)? It is shimmed, but maybe the spring is too weak? Or maybe a vacuum leak somewhere could cause this? the rubber line going down to the wastegate is new. what about the cycling valve?

 

That's the limit of the stock turbo you're seeing.

 

naw, the stock Turbo will put out a LOT more boost that that. Trust me!

 

my car has the same problem. am installing a 46mm tial wastegate. will let you know trhe outcome this week.

 

[quote]Originally posted by rage2:
<strong>That's the limit of the stock turbo you're seeing.</strong><hr></blockquote>

My buddies 87 951 with a stock turbo holds boost way closer to 15psi at 6000rpms, his boost starts trailing off at 5300rpms or so. mine starts falling at 4000rpms...

 

I put in a boost gauge and noticed that my boost would start falling slowly from 15 to 9, something the factory gauge did not show. It was noticable in 3rd gear when I had my foot in it for a long hard run. I shimmed the waste gate then that solved the problem. The car now holds boost with out any problem. The shim can be purchased at kolkeln and I dont know the cost because I got mine from a friend who had an extra one. Despite the above I will still be upgrading to a better waste gate soon.

 

Yup, time to shim the wastegate. Just get some washers from Home Depot and stack them up to 5mm total:



Also check out this thread: <a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=002698" target="_blank">Europroducts chip set with LBE. Are shims required? </a>

 

[quote]Originally posted by Danno:
<strong>Yup, time to shim the wastegate. Just get some washers from Home Depot and stack them up to 5mm total:

Also check out this thread: <a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=002698" target="_blank">Europroducts chip set with LBE. Are shims required? </a></strong><hr></blockquote>

Ok, so i do have shims already with the LBE, so i should shim some more?

 

yeah try stacking up the shims to 5mm. I think the ones you have are around 3mm. Could also be due to your wastegate valve not sealing correctly. When you take the wasteagate off, inspect the valve seat to make sure it's not corroded or has carbon built-up.

 

Just installed a new Deltagate II that I've had for a while. Used TurboTim adapters, went well.
With the black spring and full preload it boosts to 13 psi without controller when hooked direct to banjo. Very noticeable improvement but still drops to 10 psi on autometer somewhere past 5 grand. My turbo has around 60K miles on it. You're not alone! I do have a new K27/6 to install, just no chips or time to fab inlet adapter.

 

I had the LBE on my car but swapped in a different controller. The LBE does not have a bleed hole. This means that any pressure that is stuck between the wastegate and the LBE when the piston in the LBE closes has no place to go but out the wastegate. Other controllers have a small bleed hole that allows this pressure to escape and not hold the wstegate open.

 

Does shimming the wastegate cause any alignment problems when it's re-installed? It looks the torque tube mounting bracket will line up differently. Thanks,