Shimming a TiAL Wastegate

[andymoraitis]

Like the title says, I have a 38mm external on my 50 trim and while I love the rock solid boost, my current spring setup is good for 21-22 psi. Unfortunately, another spring change will only net me 23 psi so it's not worth it. I'd rather run without a boost controller since the gate is so stable, but what I'm wondering is if it's possible to use shims inside the top cap (like very large washers) to put more pressure on the springs and get it to hold more boost.

It sounds like it would work and it wouldn't be too hard to try, but I was looking for feedback for anyone who's tried it. I talked to Cragger at SBR who thought that it would work, but hasn't tried it for himself. Any takers?

Thanks in advance,

Andy

 

[project_tsi]

Andy I'm totally sure it would work, no real reason for it not to, unless the washers can eventually move out of the way.

However, I was under the impression that you could run multiple spring sizes in the Tials, not all that are completely interchangable, but like a bigger outer, and smaller inner.

Right, but the max combined spring pressure is 23.2 psi by using a Large Blue and Small Blue spring.

Andy It will work, Its the same concept as shimming your internal gate, putting more pressure on the spring, or the same as me putting springs inside my BOV to hold more boost w/out leaking.

 

[andymoraitis]

Curtis and Dan,

Thanks for the feedback guys. I think the best way to try this would be to buy washers that have the same diameter as the top of the wastegate (on the inside). That way they'll fit properly without sliding around. I'm going to try a couple tomorrow or the next day and see how they work.

Thanks again for the help,

Andy

 

[99gst_racer]

Andy, I'm going to experiment with shims as well. I want to get my 44mm Tial to run 1.8 bar w/o a boost controller. It only has a .9 bar spring though, so I'm not sure if I can shim that much or not (unless I can steal some of Dan's springs ).

Do let us know how it goes for you.

 

[project_tsi]

Paul, per my research, combining a large blue and small blue on a Tial 44 W/G will only yeild you 20.3psi (1.4bar). Something in the design is making the pressures be less when using a 44 or 46mm. http://www.tialsport.com/documents/w3_tial_44_sp.pdf

Oh and you can BUY some of my extra springs or trade me some parts for them......

 

[andymoraitis]

Will do on keeping you guys posted. It'll really suck if I have to keep tweaking and pulling the gate apart to test new combinations though. Jeez after running this thing for a couple of weeks, I can't stand internal gates.

 

[andymoraitis]

The reason you get less pressure on bigger WG's is because there is more exhaust hitting it Dan.

This is why you want to run Small WGs for HIGH boost, and Large WGs for LOW boost.

However I do wish my 38 was v-band :-(

Good stuff Curtis.

 

[project_tsi]

Will do on keeping you guys posted. It'll really suck if I have to keep tweaking and pulling the gate apart to test new combinations though. Jeez after running this thing for a couple of weeks, I can't stand internal gates.

you said it!! And I quote "I can't stand internal gates." Its about time you saw the light.

 

[andymoraitis]

As a brief follow up, I stopped by ACE Hardware this morning and bought a couple of 2" diameter flat washers. These appear to be about 1/32" thick or so and match the diamater of a large spring perfectly. It's not a bad idea to bring the spring with you for reference. I tried as hard as I could to get both washers in and seat the wastegate cap, but there was no way she was going to go on with a large blue and small green. In the end, I used one large washer and it filled in the top of the cap almost perfectly and didn't slop around.

After tightening everything down, I took the car for a quick road test. Despite the fact that I was initially using 21.75 psi worth of springs, my boost gauge would typically show me 20 in all gears. This could be due to the water grains in the air (it's been very humid out here) and also the heat of the incoming air charge (not as dense as cooler, drier air).

In any event, with the single washer in place, she gave me a rock steady 23 psi and with a cold intercooler, I saw 24 in third gear with more load on the motor. As the intercooler warmed up, I saw a consistent 23 in all gears. Overall, I'd infer a 3 psi gain from shimming with one washer and closer to 6 using two with a spring setup that's close to mine. As it turns out, this is perfect boost for my setup (remember I still have a sidemount) and I saw zero knock in any gear running an 11:1 A/F and 12 degrees of peak timing with 42 psi base fuel pressure on an aggregate of 96 octane. This 50 trim impresses me more and more as I get to feel it out. I'd venture that 26-28 psi is a real sweet spot for this turbo and I may get there one day with some methanol.

So, in the final analysis, you could hypothetically run 23.20 psi worth of springs, add a single washer and end up around 26 without having to touch a boost controller. I paid .40 each for the washers and I'd consider this something that's definitely worth 10 minutes of time, a ton of grunting and a bit of sweat.

For those of you running lower pressure large springs, you could probably stack 3-4 of these in there and gain a significant amount of boost over your largest 1 bar spring, but I can't be sure since I haven't tested it. For a one bar spring, I'd start with two washers and work up from there.

Peace out!

Andy

P.S. Dan: I still have a washer laying around if you want to try one. Also, in comparing the spool between our two setups (yours at 3800 and mine at 4200), it just hit me that I run much more timing in the midrange than you do. I may have Jeff back this down while still peaking at 12 degrees to get it closer to where you are and bring the power on sooner.

 

[DevilSperm]

I'm going to try this in a couple of weeks. I haven't got my Tial on yet, but I am regretting getting the 1bar spring. Thanks for the follow up, hopefully this will save me a little bit of cash.

 

[andymoraitis]

Glad it gave you some food for thought. PLEASE be sure to follow up in this thread so we know how it worked for you. I'd guess that you may need 3-4 flat washers to get to where you want, but it's much cheaper than buying springs and you don't need to wait for shipping.

In looking at the washers, they may be closer to 1/16" than 1/32" thick. Here's a quick shot of what they look like for reference.

 

[DevilSperm]

Thanks. We have all kinds of different thicknesses at work that I can "borrow", so maybe I will try some different ones. And I will definatly post back to share the results.

 

[andymoraitis]

I felt like taking an early morning spin and testing the theory that even with an external, the car would make more boost in cooler weather regardless of the springs and shim pack in the gate. As it turns out, I see 23 psi rock steady in the heat of the day. With ambient temps around 65 and a high water grain content (it's still pretty humid) she made 24 rock solid in every gear and didn't drop even as the intercooler heatsoaked. I'd estimate that even more boost will be on tap as we get into late fall and early winter. The best part was zero knock on pump gas with more room to tune as far as fuel pressure (I only run 42 psi).

So as it stands, shimming the gate won't make it fluctuate, but changing air density will (most of you knew that anyway). Then again, maybe it has something to do with the adiabatic lapse rate of Jupiter. Who knows?

 

[project_tsi]

Then again, maybe it has something to do with the adiabatic lapse rate of Jupiter. Who knows?

Maybe someone had a little too much coffee this morning, eh?

 

[andymoraitis]

Maybe someone had a little too much coffee this morning, eh?

Really, I just had one (really tall though)...

 

[topstreet]

Not to put a damper on things here. I think if you are going for 2 or 3 extra psi this is going to work ok for you. But please keep in mind you are lowering the gates ability to control boost. This spring needs a very exact measured amount of throw. I am not saying it will not work. I am just saying take caution.

unwanted overboost is not always fun. I am glad to see you hitting your extra boost cheap and easy though.

 

[andymoraitis]

Jake,

Thank you for the caveat, however I haven't experienced any issues thus far. As a brief update, I added a second shim to the wastegate and while the first one gave me 3 psi over the spring setup, the second one gave me only another 2. Boost was controllable and I saw an even 25 psi on all of my third gear pulls with no repeatability issues.

In that light, I would follow Jake's advice and only use one shim to see what it nets. Besides, wrestling the wastegate cap on was incredibly hard. As a matter of fact, I'm never taking that thing apart again!

Boost readings were as follows with ambient temps in the low 80's and humidity around 40%:

1st gear: 22 psi (expected since load on the motor is so low and duration in the gear is short)
2nd gear: 24 psi (pretty much the same as 1st gear)
3rd gear: 25 psi
4th gear: 25 psi
5th gear: 25 psi

For anyone who wanted to try this, I hope it helps out.

 

[Enraged78]

...

As a matter of fact, I'm never taking that thing apart again!

...

Andy,

I was wrestling with this same issue when I was working on a turbocharged 331 C.I. Mustang we had at the shop. It was equpped with a Tial 48mm wastegate with 1 .5 bar spring. I swapped in two springs (one small, one large) to get the boost I wanted. The customer wanted more boost, and the wastegate was in a precarious spot in the engine where no amount of me pushing on it could get it to line up right, let alone getting all of the hex head bolts in it. On the larger tial wastegates you guys are working with, they are on a V-band clamp, which makes them very easy to get off. Try pulling the wastegate off, and grab youself some soft cloth. Take the cloth and pad two ends of a bench vise with it. Now, you can install whatever combination of springs and shims you want, and you can use use the vice to keep the pressure on while you line it up and get the hex bolts on. With the cloth padding, you can even swivel the top to get it to line up perfectly. The Tial housings are aluminum, and I was always afraid of stripping them, so this trick always worked pretty well for me. It also keeps the wastegate from getting scratched when your working with heavy springs. Customers always hate it when you scratch their stuff. This works equally well for getting all the bolts out without the top popping on you and possibly warping the bolt holes.

Standard disclaimer for newbs trying this at home: Be careful when working with the Tials like this. If they get cockeyed on you, the spring can wind up in your eye. Common sense applies here.

Good luck,
Matt.

 

[andymoraitis]

Matt,

This is exactly the same advice I gave Dan (project_tsi) last night if he planned on doing this. Unfortunately for me, I have no bench vise so my technique was to hold it wrestle with it while on the manifold until my wife could completely thread in three of the allen heads.

You're right, this method is rather dangerous and I'll issue a warning similar to yours:

Please exercise due care and perform this mod at your own risk. Eye protection is mandatory and it's best to shim the wastegate in a vise with either wood blocks or a soft cloth on either side to prevent scratching.

Thanks for bringing this up,

Andy

P.S. I'm an old Mustang guy and I'll bet that 331 was very stout!

 

[1stGenRocks]

the only problem to watch for is kinda like crushing a bov. the more shims you stack in you reduce how far it can open.

 

[SBR Chris]

the only problem to watch for is kinda like crushing a bov. the more shims you stack in you reduce how far it can open.

I hardly think 2 washers is going to limit valve travel that much.

Andy, thanks for the writeup. Next time I'm in a pinch for a spring, this just might work!

 

[andymoraitis]

Chrs,

I was talkiing to Cragger and he was wondering if it would work so please let him know that it does. What I'm not sure of is if the effect will always be one washer = 3 psi and a second washer = 5 total psi. It may have just worked that way with my combo, but I suppose you guys can experiment and see what happens.

Anyway, I'm glad you found something useful in my attempts

 

[SBR Chris]

Already told him about it!

I'm positive that it has a lot to do with the spring thats in there now. Changeing the install height of a spring changes it's spring rate, so I'd imagine that with a stiffer spring, the change in boost would be greater, and with a softer spring, you'd have less of a change.
Regardless, its nice to know that playing with it can net results. I have a lot of guys who get in a pinch for different springs, and this definately could help. Plus, who here has gone to the track, with a broken MBC, and wanted to run more boost in a hurry? I think I might have to put a few washers in my toolbox from now on.

 

[andymoraitis]

Yeah man, just make sure they're 2" diameter since they won't slop around.

Have fun!

 

[donmagicjuan]

I'm positive that it has a lot to do with the spring thats in there now. Changeing the install height of a spring changes it's spring rate, so I'd imagine that with a stiffer spring, the change in boost would be greater, and with a softer spring, you'd have less of a change.

In theory, this is 100% accurate. The change in controlled boost level should be relative to the change in the preload of the spring. For a given change in length (washer thickness), a stiffer spring will yield a greater change in preload.

Thanks for the great thread, Andy! Very helpful information.