What spring rate for Tial 38 with stock ECU chips and no boost control?

[lemikson]

Like title is saying is anyone running or familiar with what should be the spring rate for Tial F38 wastegate with stock DME chips and without any boost control upgrade (manual or electronic)?
I want to upgrade exhaust to 3” from downpipe flange to the end. With HF CAT and Magnaflow Muffler at the back. At the same time want to upgrade 30+ years stock wastegate into Tial F38. I was planning to put 14 psi spring rate but looks like it would be way too much of boost with the stock chips.
Any advice would be much appreciated.

[kdjones2000]

FYI, stock boost on these cars is 10 psig.

Can't tell you more about your Tial WG and settings, sorry.

[DannoXYZ]

You must emulate the stock wastegate with Tial. Not just 10psi max-boost in midrange, but also dropping boost down to 6-7psi at redline. Otherwise you'll blow engine because chips is only programmed to give enough fuel for 6-7psi @ redline. Any more boost than that with stock chips will blow headgasket.

Get Rogue A-tune kit first. Then install upgrades and reprogram for each step.

[lemikson]

Originally Posted by DannoXYZ

You must emulate the stock wastegate with Tial. Not just 10psi max-boost in midrange, but also dropping boost down to 6-7psi at redline. Otherwise you'll blow engine because chips is only programmed to give enough fuel for 6-7psi @ redline. Any more boost than that with stock chips will blow headgasket.

Get Rogue A-tune kit first. Then install upgrades and reprogram for each step.

Back to this same subject again. Thanks Danno for your advise. I figured by now that I must bring more fuel so chip is in the cards. So far A-Tune from Joshua looks like the best upgrade for what I plan to do with my car.
So, can I go with 14psi spring rate on Tial38 with A-Tune and no boost controller?

[DannoXYZ]

No, you still need boost controller because pressure on wastegate valve has multiple contributors. One is diaphragm which pushes against spring and valve. The spring counters boost pressure in diaphragm and excess pressure causes diaphragm to push wastegste valve open.

However, exhaust pressure also pushes on wastegate valve. Higher RPMs causes higher exhaust pressure and opens exhaust valve easier. The result is a dropping boost curve. To maintain a flat boost curve, you need a more comp!icated boost control system that can account for RPM and exhaust pressure.

So yes, you need a boost controller connected between intercoooler outlet pipe and wastegate diaphragm.

[azbanks]

The VEMS PNP from Raceboy will give you what you want plus a LOT more.

https://forums.pelicanparts.com/porsche-944-turbo-turbo-s/844820-almost-finished-vems-plug-play-ecu-951-a-6.html