That is labeled as the 'boost signal in' which enters the top of the WG. It's included.

That line runs from the cross-aver pipe to the venturi tube and then to the CV before going to the top of the WG.

 

sorry, i've mis-described it.

the 'intake' side should be shaped like the bottom of a T with the exhaust from the headers passing straight through on its way to the crossover pipe and the turbocharger, bypassing the wastegate.

 

I can't help but think Porsche designed the wastegate to open on high exhaust pressure irregardless of the control signal. That feature makes the whole design more forgiving. The 924 turbo had a bad reputation for reliabilty and I think the 951 engineers were trying to prove to the market that a turbocharged car could be a reliable daily driver. I also believe Porsche did not want the 951 to outshine the 930 so they left some power "on the table", probably increasing reliability and durability at the same time.

Before you answer the question "How much power do you want?", you should decide how long you want it to last.

Lou

 

That part is a given and has no bearing on the function of the WG. It's just the exhaust gases going to the turbine side of the turbo. The wastegate just determines how much exhaust gas is routed to the turbine.

 

Hello Nize,

I am not sure if you will find this helpful, but here is a link to dyno charts on my car with similar mods (different chip, less boost) but with a tial.

http://home.earthlink.net/~jasoncoker/dynoresults/

Sincerely,
j

 

yes, i meant a boost leak (i said vacuum because the intake system also holds vacuum as well as boost).

with the way the tial reverse-valve is described, i'm 100% sure that if you develop a boost leak it will cause overboost. how do i know this?

there were some stock-wastegate cars in the past that developed a leak in the banjo bolt (this is a BIG leak) and it lead to overboosting because the effect was the same as if the CV line was clamped (wastegate control never getting the 'open' pressure). in the case of the banjo bolt, the amount of boost the turbo creates simply overcomes the amount of the leak.

assuming the tial operates as described, i would be willing to bet money that if you purposely remove the banjo bolt on a car that has otherwise stock components (except for the tial), it will overboost dangerously past +30psi.

edit; also, with a tial, what if the control line itself failed? such as would happen if the cv line was clamped? with the stock wastegate the exhaust pressure would eventually force the wastegate to open. i would think with the tial, you'd get +60psi...

 

and thanks jason.

 

Nize - all these things that you are speculating about and "are willing to bet money on" - I have tested.
I have tested backpressure opening against stock spring.

You cannot make ANY claim about how much INTAKE MANIFOLD pressure is necessary to open the stock wastegate beecause this depends on many things - such as the turbine/intake pressure ratio of the system.

You may have a spike to high boost on a k26 equiped 951 with the stock wastegate, but the gate will immediately open. This is the way it was designed, and it is elementary turbo knowledge.

There are MANY threads about the poor 951 wastegate design - with MUCH proof.
Please do not continue to spread misinformation on this forum.

 

Lutjens;

1) i am not debating wether the stock wastegate will open from exhaust pressure or not.
2) i am debating that the stock wastegate is NOT as weak as you claim.
3) where are your backpressure test numbers/results? how exactly did you perform these tests?
4) i am not speculating, i have DIRECTLY observed what happens on an all-stock car when the cv line fails or is clamped shut. many others on here can also attest to the truth in this from their own observations.

you are the one claiming that the stock wastegate is so weak that it opens with very little exhaust pressure.

i am the one who has actually tested and am stating what i have directly observed. i have also provided a method for others to test and observe for themselves.

and again, i'm not debating wether the stock wastegate is a poor design or wether the tial wastegate is better. i am ONLY stating that the stock wastegate is NOT as weak as you (and others) claim.

 

Its pretty weak, dude. Its a gray area, but its pretty weak.

 

my 'test' proves that it's at least strong enough to build (and yes, maintain) +20psi of consistent boost. anyone can independently perform my 'test' themselves and get similar results.

how weak is 'pretty weak' ? where are your test results and data? how exactly did you perform these 'tests' ? or are you speculating?

 

Dude - you are suspecting the WRONG guy
I have a backpressure GUAGE in my 951!!
Copper then -3 braided - you'd love it.

 

Nize:
I have access to a remote temperature sensor/meter. We could clamp the sensor (a thermocople) to the waste pipe and watch the temperature while driving. It won't prove much but it would give some idea when the wastegate was dumping gas to the tail pipe.

Lou

 

I can't imagine, under any circumstances, that happening. Are you assuming perfect turbo efficiency? There can only be so much exhaust gas moving through the turbine which means that the compressor can only spin so fast. How much exhaust volume and at what speed (RPMs) do you expect to put through the tubo to achieve 60psi? A 2.5 ltr spinning at 6k rpms is only moving so much air.
Because of this, the compressor is only going to move so much air. There will be a brief max boost pressure but there is no physical way the K26 will push 60psi on a 951. It's way out of its effiency range well before then.

 

then answer the simple questions;
how weak is 'pretty weak' ? where are your test results and data? how exactly did you perform these 'tests' ?

if you didn't actually perform any tests, that's fine.
if you don't have the data, that's fine too.

just try not to make any wild claims without proof nor repeatable results, and then try to accuse someone else of doing the same.