38mm tial users

[84TXGN]

What is the lowest boost level you can tune to. I am looking to run as low as 10 psi on my car at times and am wondering if the 38mm tial wastegate will be large enough. I have a 4.1 with a PT61 if that helps.

[RUQWKNF]

Honestly, I don't think you will be able to control the boost down that low with only one Tial 38mm and here's why...

The general rule of thumb is, if you want to run low boost levels, you need to run the largest wastegate that you can in order to bleed off the excess exhaust flow. Now, with your motor being a 4.1L, even though you only have a small 61mm turbo, the exhaust flow of the 4.1 will require a larger wastegate. You could try the smallest spring that they offer, but I'm afraid that it would only lead to slow spool up (caused by the wastegate opening up prematurely due to a soft spring) and boost creep issues. A Tial 44mm wastegate should be enough to allow you to run the boost down to 10psi. The other choice you have would be to install a second 38mm wastegate onto the crossover pipe with a matching low pressure spring in it. It's a tough call tho. One question, why are you trying to run the boost so low? You should be able to run at least 12-14psi of boost on pump gas, unless your motors CR is higher than 9.5:1. The rule of thumb for running high boost is you run as small a wastegate as you can get away with.

HTH

Patrick

[84TXGN]

Originally Posted by RUQWKNF

Honestly, I don't think you will be able to control the boost down that low with only one Tial 38mm and here's why...

The general rule of thumb is, if you want to run low boost levels, you need to run the largest wastegate that you can in order to bleed off the excess exhaust flow. Now, with your motor being a 4.1L, even though you only have a small 61mm turbo, the exhaust flow of the 4.1 will require a larger wastegate. You could try the smallest spring that they offer, but I'm afraid that it would only lead to slow spool up (caused by the wastegate opening up prematurely due to a soft spring) and boost creep issues. A Tial 44mm wastegate should be enough to allow you to run the boost down to 10psi. The other choice you have would be to install a second 38mm wastegate onto the crossover pipe with a matching low pressure spring in it. It's a tough call tho. One question, why are you trying to run the boost so low? You should be able to run at least 12-14psi of boost on pump gas, unless your motors CR is higher than 9.5:1. The rule of thumb for running high boost is you run as small a wastegate as you can get away with.

HTH

Patrick

I can only run 10-12 psi on pump gas as my CR is 9.5-10:1. I will be getting alky soon and will run more boost but if I ever need to run without the alky it would be nice to be able to turn the boost down. I was hoping a 38mm would be enough but I didn't think it would be either. I would like to avoid anything on the crossover too.

[d90dan]

I think Patrick is right on this one, you'll probably need a bigger gate to flow enough exhaust to run 10psi.
Here is my experience with the Tial 38mm. I am able to run my setup at 12PSI min with a 8psi spring. I now run a ~14 psi spring and my min is ~15psi. Tial suggests running a spring no less then 1/2 your max boost.

[84TXGN]

Originally Posted by d90dan

I think Patrick is right on this one, you'll probably need a bigger gate to flow enough exhaust to run 10psi.
Here is my experience with the Tial 38mm. I am able to run my setup at 12PSI min with a 8psi spring. I now run a ~14 psi spring and my min is ~15psi. Tial suggests running a spring no less then 1/2 your max boost.

What turbo are you running?

[TiAL Sport]

patrick is correct,
a 44mm is what you would need for consistant boost