mahoney944

im not going to argue with you two all day. on a stock setup or single port setup using a mbc, clamping the line causes over boost. period. running a line stright to the wg will cause you to boost at spring pressure. test it for yourself. in only takes a second to run a line form the j pipe to the wg feed port. and an additional second to clamp the line. ive personally done this test. with several wgs, it holds true.

Paulyy

At least i can admit i'm wrong. Unlike someone.

and running a line directly to the wastegate doesn't give you spring pressure!!!

mahoney944

yes it does, not only have i tested this, but pauer tuning, and his vender "turbos direct" confirmed this, as well as dave lindsey over the phone. i did countless hours of studies on wastegates for the 951 and proven through testing that the lindsey dual port/ clubgate is the best option. i too once thought tial was the go to solution until i discovered their fatal flaw

test it for yourself, your using a tial so run a line from the j pipe to the side port of the wastegate and youll see boost pressure that matches spring pressure give or take 1-2 psi, clamp this line an carefully watch you boost climb way too high, like i said maxing out your boost gauge. when i say carefully, i meant it. though i dont agree with what your saying. i dont want you to damage your car.

this is exactly why you can turn down the boost to 8psi on the lindsey duel port because when you do, you use max boost pressure supplied againt the spring pressure alone. when you turn it up the pressure is increased raising spring pressure raising boost.

on a single port you dont have the luxuary of raising and lower spring side pressure so you simplly restrict flow to the diaphram on the feed side to raise boost. or use a shim to raise the spring side.

another way to test my ideas would be to just disconnect all boost lines to the wastgate and watch it over boost. the valve does bleed slightly from exhaust pressure, but this slight bleed isnt enough to prevent over boost if the boost feed line isnt sending pressure to the diaphram you will boost at a dangerious level

F1nd3r05

First off, I'd like to thank you all for your contributions to this post. I've learned a great deal about wastegates and their respective functions. Second. Regardless of the education provided, which I appreciated greatly, I am getting the idea that the wastegate is the problem with my issue. Third. I dont know if this makes a difference, but before I put the wastegate in this build, It was used with a k26 turbo that on cold nights i could unwind the boost controller and have it hit about 19-20 psi. Im assuming over time considering it was in the car like that over a year ago, that it has worn itself out causing the 15psi maximum with the shims? Lastly, if the wastegate itself or the spring being worn or it being partially open or what have you is my problem I take it majority votes for a tial 38mm with adapter plates? there is one on ebay used that I think im going to purchase so I just thought I'd ask before. Reason being is that it has a 1bar spring which is 14.5 psi and Id like to run at least 18psi if not more in the future once i change fuels. Thank you!

lart951

The tial is dual port and the back pressure is in the opposite direction that the valve opens, so regardless of spring you can definitely can run over. 20 psi to red line. The other guy is very confused about the design and operation of 951 stock wastegate. Smaller turbines like k26-6 plus high boost tend to created higher back pressures, this back pressure pushes the wastegate open , overcoming the spring resistance. On the stock system with the cycling valve which is more like a selenoid there is vacuum that assist the valve to stay shot. Overboost protection exist only with the stock cv and stock Klr chip.

reno808

you can run a tial in single port as well. if you run the wastegate backwards. you can never control the boost and it will keep climbing.

lart951

once the line is clamped the wastegate would open to whatever is the spring capacity, if this is a shimmed stock 15psi is probably right with a tired wastegate the valve is probably opening and bleeding boost, with all the mods you have why would you use a shimmed wastegate, been there done that.

here

https://rennlist.com/forums/944-turb...yno-chart.html

The above was posted at the beginning of the thread last week

UPDATE TODAY, sold a tial 38mm with adaptor plates to the OP and you know what KAZAMMMM problem fixed, lol.

Opppsss, I guess lart was right

https://rennlist.com/forums/11215019-post114.html

all that clarks quoting for nothing, hey tommy boy so who was right after all, lol

lart951

lol

mahoney944

You didn't prove anything. Both of us agreed that the OP's wastegate had failed. We simply disagreed on the reason the wastegate was failing. Get an education.

lart951

My diagnose my right on target I specifically stated that the wastegate was bleeding boost and opening at 15psi, you argued that that was impossible because if you pinched the line blah blah Clark's garage blah blah overboost blah blah, lol , in the words of Danny Glover " boy you lose I win"

mahoney944

Lol you argue that because you disect lots of 951's that you understand them. So in your theory go take apart a turbine for a airplane and become an expert. Lol just because you take it apart doesnt mean you understand what your doing! anyone can turn a few bolts and screws noob.

lart951

This was a car that I had sold a replacement engine to the fellow lister, the shop a reputable one, had the car for 3 months and said that the engine had a problem no compression in # 2, I made arrangements for the car to be brought to me, it was fixed right away, actually i made a diagnosis in 10 minutes.


https://rennlist.com/forums/944-turb...ve-beware.html

the rest of the videos are cars that I have tuned for fellow listers. I dont work on cars except if it's a friend or someone who buys a engine from me or a tranny. I dont have a shop to do repairs plus is a pita and less $$$ than the parts business.











Now show me your stuff, I can show you many pages with my dynos , videos etc here on rennlist, what do you have to show???


Just clark’s garage blah blah blah copy and paste insults blah blah.

Tom M'Guinn

On a bone stock car, if you clamp the line to the wastegate, the car should over-boost. If it doesn't, then something's wrong with the boost-making parts of the car (boost leak, bad wastegate, bad turbo, bypass valve, etc.). This is actually the factory test procedure for low boost -- see FSM (turbo supplement) page 28-33.

mahoney944

Exactly, as the OP was using a stock wastegate setup, this test also works with aftermarket wastegates too.

lart951

Sure that was 30 years ago with new units.

Let's say that in my modded 951 with aftermarket chips and a mbc set a 21 psi and a stock wastegate i proceed to pinch the line to the top of the wastegate should I see overboost?

????


That's what we were talking about here, this was a specific case when a tired weary wastegate couldn't hold boost any longer. That's what op had asked, sure there out to be some stock wastegates that could spike to 21 but substain boost, most that I have seen can barely hold 17-18psi only

That's throwing the book on a 30 year old unit, which is far from being fully functional.

My diagnosis was that the wastegate spring was weak and bleeding so much pressure that it could only substain 15psi even with the lines pinched. The other dude said that something else was wrong with the car, that IT WAS IMPOSSIBLE for the wastegate to bleed so much after the line was pinched that it could only hold 15psi.
So I proved him wrong. In one of my cars I turned the mbc all the way open and all I could see was 17psi, after I installed a dual port and then shazam the problem was gone.