will this work effeicently with about 18 psi or will I have to worry about boost creep and spike. I have a lovefab sst and t3 /t67, I was considering a 40mm will I be fine or should I upgrade

 

If your pushing 18psi I would go with the 40. My 38 works great but im only pushing 10psi. for Tail

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedTegLS &raquo;</TD></TR><TR><TD CLASS="quote">If your pushing 18psi I would go with the 40. My 38 works great but im only pushing 10psi. for Tail </TD></TR></TABLE>

Going with a larger size wastegate is not the answer for higher boost applications. The purpose of a wastegate is to regulate the amount of exhaust gas that travels into the turbine housing. At lower boost levels more exhaust gas is bypassed through the wastegate to keep the pressure lower. So this works opposite of what you are thinking. As more and more boost pressure is to be added the wastegate should get SMALLER since less exhaust gas is to be bypassed.

Compression and displacement will also play a role in this. The more compression and displacement, the more exhaust energy is created and the larger the wastegate should be. On a 1.6/1.8 Honda the Tial 38mm wastegate is sufficient to around 500-600whp.

 

So your saying that for someone going from 15 to 25 psi they should sell their 40mm and buy a 35mm? I guess it just doesnt make any sence to me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedTegLS &raquo;</TD></TR><TR><TD CLASS="quote">So your saying that for someone going from 15 to 25 psi they should sell their 40mm and buy a 35mm? I guess it just doesnt make any sence to me </TD></TR></TABLE>

What part about the function of a wastegate do you not understand? The more exhaust gases you bypass through the wastegate (you can obviously get more through it with a LARGER 40mm diameter) the less BOOST pressure you will create. It makes plenty of sense. 38mm is all you need.

 

agreed w/ ryan civic...

people w/ a 40 shouldn't sell to get a 38, but people running 4psi need a 40mm over people running 18...you are holding more back, and the wastegate is getting rid of more exhaust so your engine doesnt see more than 4psi.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RyanCivic2000 &raquo;</TD></TR><TR><TD CLASS="quote">

What part about the function of a wastegate do you not understand? The more exhaust gases you bypass through the wastegate (you can obviously get more through it with a LARGER 40mm diameter) the less BOOST pressure you will create. It makes plenty of sense. 38mm is all you need.</TD></TR></TABLE>

I agree 100% with Ryan on this one. Not to mention the 38mm wastegate is about $100 cheaper than the 40mm.

 

Save your money and get a 38mm. Unless you just want the bling of a 40mm [what I did].

 

so my 38 will be fine

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BoostedsiR &raquo;</TD></TR><TR><TD CLASS="quote">so my 38 will be fine </TD></TR></TABLE>

Yes. More than fine, better for high boost than the 40mm.

 

Ive seen what ryan said a lot of places, but I have to disagree. Its even on Tial's website, but when an engine is making 100hp, the exhaust energy isnt that high, you could probably use a pinhole to regulate the exhaust energy bypassed the turbo. When an engine is making 1000hp the exhaust energy is slightly higher, and I dont think a pinhole would be able to do much.

That would kind of explain why you see 1000hp hondas with 2 large wastegates even when they are running 40psi of boost. By Ryan's theory they shouldnt even use a wastegate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by st00pid &raquo;</TD></TR><TR><TD CLASS="quote">Ive seen what ryan said a lot of places, but I have to disagree. Its even on Tial's website, but when an engine is making 100hp, the exhaust energy isnt that high, you could probably use a pinhole to regulate the exhaust energy bypassed the turbo. When an engine is making 1000hp the exhaust energy is slightly higher, and I dont think a pinhole would be able to do much.

That would kind of explain why you see 1000hp hondas with 2 large wastegates even when they are running 40psi of boost. By Ryan's theory they shouldnt even use a wastegate.</TD></TR></TABLE>

It is possible when getting to horsepower levels that high (above 600whp), that the 38mm opening may become too small to bypass the proper amount of exhaust gases to maintain the desired boost level. That is why I stated that 38mm is sufficient to 500-600whp. Most of us obviously aren't making that much power or we'd all have 9 second cars. So for the majority of us it is not necessary to spend extra money on a 40mm wastegate based on hp level, the only reason is if you are having problems with unstable boost. Unstable boost is usually caused by improper placement of the wastegate.

 

since most manifolds do not have decent WG placement you can overcome a lot with a larger gate. I usually use a 38 up to 350whp, 40, 44, 46 for anything over that, basically because most people that will make more than 350whp will have a built engine and will be able to make well over 400whp. There is a little tag that comes with the 38mm that says do not use leaded race fuels with the 38mm. People should keep that in mind when deciding on a WG.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by st00pid &raquo;</TD></TR><TR><TD CLASS="quote">since most manifolds do not have decent WG placement you can overcome a lot with a larger gate. I usually use a 38 up to 350whp, 40, 44, 46 for anything over that, basically because most people that will make more than 350whp will have a built engine and will be able to make well over 400whp. There is a little tag that comes with the 38mm that says do not use leaded race fuels with the 38mm. People should keep that in mind when deciding on a WG.</TD></TR></TABLE>

What would be the difference in using leaded race fuel with a 38 mm wastegate?

 

The 38mm will do the work easily. I'm using it on my 383 ci motor with a T88. I doubt you'll have any problems.

Jose

 

I would like to hear from someone who wasnt able to hold boost or make over 500 whp with the 38mm wastegate.