External Wastegate sizing?

[meet07]

Im curious what everyone is using as far as the size of there external gate? I seen alot of guys running 44-46mm gates on an inline 6 but then again ive seen 50mm gates? I personally have a 50mm gate but didnt know the pro's and con's of smaller vs. bigger?? Ive heard that bigger gates help with bigger turbo's and low boost......

Thanks

[Darius]

Depends on the setup. The way I understand it is (assuming the same displacement motor) the larger the exhaust side of the turbo, the more exhaust gas it takes to spin it and therefore less goes through a wastegate = smaller wastegate. For a smaller turbo on the same motor, a larger wastegate is needed to expel the exhaust gases. There is a calculation by Sydneykid on SAU if you search for it. IMO, most people don't need a 50mm gate on an RB motor, nor do they need twin gates. I run a single 39mm Tial on my T04Z and it doesn't boost creep.

[240z4u]

I have excellent boost control with my 38mm tial on my HX35. A lot has to do with the angle of the route to the W/G and exit as well. If it's not well setup flow wise, you may have to compensate with a larger gate. I like running a 38mm just for packaging purposes.. it's not very big.

[meet07]

I always thought that the 38mmcrank was for the 4 banger guys?

[Zacho2]

^It depends. If you wanted to run a low boost you need a much bigger gate.

But wastegate sizing is very dependent on how well the runner is located on the manifold. I had a 38mm with a poor runner location and then modified my manifold and went to a tial mv-r and it is a night and day difference.

[240z4u]

I can run 7psi of boost with my hx35 if I want. No creep. Zacho is correct though, my old setup had a poor "feed" to the W/G and it didn't control boost well at all.

[meet07]

Well I have the stec manifold that has dual runners going to a single 50mm gate flange. I mean thats how they come so when I added my own gate I figured that the 50mm gate flange was up there for a reason.....I mean alot of the skyline boys run the 50mm hks gate over in rice country.... So what about a hp goal of 600-700.....would a 38mm still be sufficeint??

and does the size of the gate change spool up characteristics??

[DRFERO]

wastegate should be fully shut during spool up so it shouldnt effect spool at all..

anyone got any pics of how theyre 38mms are welded on? running a 38mm with hybrid td06 on my RB30DET

[bmxarmy]

here is how mine is done, again, HX35 no boost creep, I made my manifold.



nolan

[Darius]

My eventual hp goal is 700hp and I'm only running a 38mm gate. Like I said before, it is going to take most of the exhaust gas to keep the turbo spooled, so a 50mm gate probably won't be needed.

Here's my 6boost manifold:

[Shocker]

My wastegate setup was run exactly like Matt's shown above, it didn't creep with my old 2.65 ltr setup but once 3 liters was involved the added displacement simply was too much and my v44 was not seeing enough flow to eliminate creep. I got this fixed by having a new routing weldd aiming upstream of #3 and #4 then y'ed them together. creep is now gone. I'd say from experience as displacement is added and HP a better flowing port is most important then secondly a larger gate would be the safe route.

If running a 35r or larger frame turbo I'd have at least a 44mm on it, when upwards of 800 plus HP id be considering a second or a larger single gate.

[meet07]

My wastegate setup was run exactly like Matt's shown above, it didn't creep with my old 2.65 ltr setup but once 3 liters was involved the added displacement simply was too much and my v44 was not seeing enough flow to eliminate creep. I got this fixed by having a new routing weldd aiming upstream of #3 and #4 then y'ed them together. creep is now gone. I'd say from experience as displacement is added and HP a better flowing port is most important then secondly a larger gate would be the safe route.

If running a 35r or larger frame turbo I'd have at least a 44mm on it, when upwards of 800 plus HP id be considering a second or a larger single gate.

I currently have a 57-59mm turbo but my car probably wont be up till next year. Im gonna ditching the ebay turbo I have for a s366. Its suppose to b good up to 800hp. I currently have the hks look alike gate but Darius is talking me into getting something smaller.

[meet07]

Depends on the setup. The way I understand it is (assuming the same displacement motor) the larger the exhaust side of the turbo, the more exhaust gas it takes to spin it and therefore less goes through a wastegate = smaller wastegate. For a smaller turbo on the same motor, a larger wastegate is needed to expel the exhaust gases. There is a calculation by Sydneykid on SAU if you search for it. IMO, most people don't need a 50mm gate on an RB motor, nor do they need twin gates. I run a single 39mm Tial on my T04Z and it doesn't boost creep.

And how much power and boost are you currently running? And how much boost and hp are you going to run in the future? If that was ur car on youtube, breaking traction like u had a 28rs then that's what Im looking for with the s366 extended tip.... turbosmart makes a 40mm gate that I've been looking at....

[Darius]

I was running 21 lbs of boost but my tuner dialed it back to 17 psi due to the DW injectors "maxing out". I'm still not convinced of this and will continue to tune myself.

Anyway, my youtube videos are ancient. I was breaking traction on all-season tires because that's all I had at the time. You should see how the car handles with the same tires on my current setup! It wants to step out sideways at the slightest hint that boost is coming. I'm going to fetch that SAU thread and link it to this one. It is a good resource to have handy.

[Darius]

Here's the link to SAU. Sydneykid's response is on the first page of the thread:

http://www.skylinesaustralia.com/forums ... hp?t=43638

[Shocker]

And how much power and boost are you currently running? And how much boost and hp are you going to run in the future? If that was ur car on youtube, breaking traction like u had a 28rs then that's what Im looking for with the s366 extended tip.... turbosmart makes a 40mm gate that I've been looking at....

I'll add a number to this question since your turbo your considering should make similar numbers. I just dynoed 527rwhp so lets say~580bhp according to SK at 19 psi that would be a 50 mm gate since I'm running 20 psi... I currently have a 44mm gate with zero creep which I attribute more to the wastegate port seeing direct flow from the exhaust than I do its size. Now If I had a 38mm gate or even something smaller I do feel my gate would hinder my engines ability to regulate boost due to it now becoming a flow restriction and the turbo being its "path of least resistance" causing creep. (This is exactly what happened when I had less than adequate wastegate flow porting before)