Carpokes Porsche Forum

Take a look here for the spring pressure reference.
https://www.extremepsi.com/tial-wastega ... -blue.html

Wow you can just get a 1 bar or higher spring for the WG and not even need a boost controller

You can look up some of my responses about boost control. But if you’re going to go with a dual port wg might as well make full use of it right off the bat. It’s a slippery slope for sure, but you will also need a manual boost controller or better yet an electronic boost controller. The control and visibility you get is night and day with the EBC. Pair that with a high flow cat and you will definitely notice a big improvement in spool up. And also the ability to hold boost pressure where you want it sooner and for longer (with the EBC). It’s not rocket science but there is science to understanding boost.

I just read through this whole thread, and I suspect you are on the right path looking at the wastegate. Lazy boost that needs high-gear load to build usually points me in that direction, especially if the boost enhancer seems to help.

You may also be making an already old/tired wastegate setup even less predictable if it is leaking around the broken stud. I’d be tempted to fix the broken stud first and see what changes. That may help both the boost issue and the noise.

That said, you can’t go wrong with a TiAL. Great wastegate. If you go that route, though, you may want to use a boost controller. Otherwise, you could end up with more or less boost than intended, since the KLR and cycling valve are set up around the factory wastegate’s characteristics. You may be able to get close with the right spring rate, but I suspect it would take some trial and error. If you combined the TiAL and boost controller with a performance chip, you’d have a much more lively car. Without a performance chip, you’ll just need to keep the boost around stock levels so you don’t hit overboost protection.

On the bypass valve, you probably mostly ruled that out by confirming boost builds with the LBE in place. If the bypass valve were stuck open, the LBE might still help some, but the car still shouldn’t boost correctly. Since you are new to these cars, you may not yet have a feel for what “normal” is, but odds are your bypass valve is okay.

That said, after trying several “upgraded” bypass valves over the years, I’ve gone back to stock. I’ve never seen a measurable performance improvement from aftermarket valves on typical 951s, but I have seen, and owned, plenty that get sticky and cause problems. Seems like a solution in search of a problem to me....

Very hard to say where the rattle is coming from, but I’d start with the broken stud. Beyond that, check heat shields and anything that could be making physical contact. Also, old catalytic converters can break up internally, and chunks of the honeycomb can cause all sorts of strange noises. You can often spot that by tapping the cat with a rubber mallet.

edit: while typing this others jumped in and made most of my points already.

danmartinic wrote: Thu Jun 04, 2026 9:24 am Wow you can just get a 1 bar or higher spring for the WG and not even need a boost controller

It’s possible but you lose all control, is the way I look at it. The point of the dual port is to assist the spring to keep the wg shut when you want it shut, especially during spool up. And it also assists the spring to open the wg when you want it open. Thus dual port.

944m3 wrote: Thu Jun 04, 2026 9:38 am

danmartinic wrote: Thu Jun 04, 2026 9:24 am Wow you can just get a 1 bar or higher spring for the WG and not even need a boost controller

It’s possible but you lose all control, is the way I look at it. The point of the dual port is to assist the spring to keep the wg shut when you want it shut, especially during spool up. And it also assists the spring to open the wg when you want it open. Thus dual port.

Agreed. Also, the KLR/cycling valve is programmed around the factory wastegate’s behavior. In other words, the system is trying to produce the desired boost curve based on how much exhaust the stock wastegate releases at a given cycling-valve duty cycle.

If you change the wastegate valve size, spring pressure, porting, etc., you change that relationship. The KLR may be commanding what it thinks should produce 11 psi, but the new wastegate setup could produce much less or much more. You might be able to get close to the factory curve by experimenting with spring rates, but matching it exactly would probably be a challenge.

Ofc I was just kidding--clearly there's a need for controllers otherwise why would they bother with the CV and hoses--but nonetheless interesting to imagine a simpler system where the WG IS the control and the KLR with its built-in MAP sensor just protects for overboost by cutting timing, ignition, whatnot

After all.. how many of us ditched the factory sophisticated electronic boost control system for a cheap little psi control kn*b

Which I assume is exactly what is sold along with the TIAL

EDIT: Just realized I only know how Single-Port operates (which is an option with the TIAL I think) so any Dual Port benefit is beyond my experience

danmartinic wrote: Thu Jun 04, 2026 10:33 am Ofc I was just kidding--clearly there's a need for controllers otherwise why would they bother with the CV and hoses--but nonetheless interesting to imagine a simpler system where the WG IS the control and the KLR with its built-in MAP sensor just protects for overboost by cutting timing, ignition, whatnot

After all.. how many of us ditched the factory sophisticated electronic boost control system for a cheap little psi control kn*b

Which I assume is exactly what is sold along with the TIAL

EDIT: Just realized I only know how Single-Port operates (which is an option with the TIAL I think) so any Dual Port benefit is beyond my experience

Plenty of old school racers ditch all controllers and just use the spring to control boost. So you're idea isn't all that crazy.

Tom wrote: Thu Jun 04, 2026 9:32 am You may also be making an already old/tired wastegate setup even less predictable if it is leaking around the broken stud. I’d be tempted to fix the broken stud first and see what changes. That may help both the boost issue and the noise.

I may give this a shot first. What is the best method to test the wastegate? I was thinking about changing all of the sealing rings and hardware around there but that seems like it’s not worth it if the wastegate is tired.. maybe just the studs for now.. I’ve seen some folks using vacuum pumps? Not looking forward to extracting that rusty stud.

Tom wrote: Thu Jun 04, 2026 9:32 am That said, you can’t go wrong with a TiAL. Great wastegate. If you go that route, though, you may want to use a boost controller. Otherwise, you could end up with more or less boost than intended, since the KLR and cycling valve are set up around the factory wastegate’s characteristics. You may be able to get close with the right spring rate, but I suspect it would take some trial and error. If you combined the TiAL and boost controller with a performance chip, you’d have a much more lively car. Without a performance chip, you’ll just need to keep the boost around stock levels so you don’t hit overboost protection.

If I wanted to upgrade to the Tial and for now keep it at stock boost levels, would you just match the spring to the stock boost levels and add a boost controller and call it a day? Keep it in single port mode I assume? https://www.extremepsi.com/tial-wastega ... -blue.html

Also would it be easy to do an upgrade later if I decided to add a performance chip regarding the Tial? What else would it require? Any chip recommendations that wouldn’t be too too ‘lively’ but worth the upgrade? Trying to weigh options. Assuming this option would be best using the tial in dual port mode?

You already have boost control (CV) so
if wish to keep it stock, there's nothing to do except fix that broken stud

Which I suspect will turn into a major job

When I had my exhaust apart, I also broke WG studs... and trying to remove what's left--on a bench with plenty sticking out--turned out to be something wild. A machinist friend brought his acetylene torch and I could not believe how many cycles of red-hot/cool-down/repeat it took to finally remove these seized parts

This is no easy task

Reassembly is also nuts as nothing seems to line up perfect after. Now you have to loosen the crossover--requiring intake removal--and maybe the manifold (more potential broken and/or seized bolts etc) to get lined up and suddenly what seemed simple is a massive job

I find it funny how manuals and people say "remove intake" but don't explain all the stuck gaskets.. need to clean the mating surfaces.. and many of us who aren't mechanics get there and wonder how to even begin those tasks.. and that's easy compared to exhaust work

Anyway... IF you remove the WG, you can test it by putting pressurized air to its top nipple conncetion and see what it takes to open

Not sure how you'd accurately measure how much psi it takes but you could at least watch it open & seal properly

The Enhancer then compensates for opening too early

I am running my original WG. I have an enhancer (unbranded ball & spring boost control) and the A-Tune chip which requires a 3,0 bar fuel pressure regulator (readily available and inexpensive when I got it) and a newer diverter valve

I think the car drives great. I purposely keep total boost low (under 15psi or closer to stock) as daily reliability is number one for me. I am over fifty so my needs there are let's say more calm

Frankly.. I find it enough work just maintaining all the rest in good order, and the closer to stock, the easier to diagnose issues. In fact, it drives better today than ever I remember and that has more to do with years spent ensuring all stock components are finally working good than any "upgrade" I have done.

I currently have a broken exhaust manifold stud but the slight leak there doesn't appear to affect much except the smells inside at startup before the hot engine somehow mostly seals the leak lol

But.. if this is a toy and you want ever increasing thrills, perhaps going through all the effort just to R & R the original WG is enough to warrant going all the way with the TIAL in DP setup which is easy to plumb using the standard MBC from Lindsay (you would disconnect the CV)

If all the rest of the systems from ECU to every wire connection to injectors to sensors like AFM & TPS to cap/rotor/wires to who knows what are in top working order, I would imagine you'll feel an improvement