Can a wastegate be too big?

Post by **Edub1** » Sat Dec 30, 2006 12:13 pm

I have an internal wastegate and I've decided to add an external one and run both. My question is, can a wastegate be too big or should I get the biggest one I can find?

Post by **WDRacing** » Sat Dec 30, 2006 12:15 pm

All depends on what numbers you're looking to run. If its over 400 then as big as you can get, under and you may run into issues with the WG opening and closing alot to keep the turbo spooled up. Also, what turbo are you going with now?

WD

Post by **Edub1** » Sat Dec 30, 2006 1:52 pm

The T04E 50 trim. I just did the math and 38mm is 1" so that plus my internal should be fine. Also, I don't know about the Tial type but my internal W/ the boost controller opens gradually.

Post by **WDRacing** » Sat Dec 30, 2006 3:07 pm

Are you using a boost controller?

Post by **crzycav86** » Sat Dec 30, 2006 4:02 pm

your math is wrong by the way...

Post by **NateDogg** » Sat Dec 30, 2006 4:03 pm

I dunno who taught you math but 38mm = 1.5".

25.4mm/inch. Way to perpetuate the term 'ignorant american' ..lol

Post by **WDRacing** » Sat Dec 30, 2006 4:15 pm

NateDogg wrote:I dunno who taught you math but 38mm = 1.5".

25.4mm/inch. Way to perpetuate the term 'ignorant american' ..lol

I think you need some of these Edub...

Post by **Edub1** » Sat Dec 30, 2006 5:37 pm

WDRacing wrote:Are you using a boost controller?

Yes_____________________________________________________

And yes it is 1.49. Jesus! A guy can't make a simple math error without someone calling him names?

Post by **Edub1** » Sat Dec 30, 2006 5:39 pm

Hay, I know everybody hates knock off stuff and I would never trust one for my primary but for $49 Vs. $200 I'm thinking one will do fine for a secondary.

There are some guys using these without problems aren't there?

Post by **Chezedik** » Sat Dec 30, 2006 6:15 pm

At least one person I have talked to has told me that the real problem with the SSAC WG is that it comes loose, and you just need to use locktite. Research, the way I see it, you have no need for a 38mm+3/4" is TOO MUCH. How much power do you want to make? I would say one or the other, and bore out your stocker if your goal is low. If higher, then go with the external, and you will be safer.

Post by **WDRacing** » Sat Dec 30, 2006 6:39 pm

Well I say prep the SSAC WG as well as possible, if it works you can pave the road for others.

WD

Post by **Chezedik** » Sat Dec 30, 2006 7:27 pm

Oh no, I have the TiAL, just saying what I heard.

Post by **KATwo40** » Sun Dec 31, 2006 4:08 am

Using two wastegates is not a good idea. The only thing you're going to accomplish is choking the exhaust flow behind the turbine, because the add-a-gate flapper assembly that goes on the back of a 5-bolt style turbine housing has a smaller exit than just the turbine exit itself. So, in using this device, you're going to be forcing both the turbine gases and the waste gases through a hole about 2". Yay.

Additionally, this will cause exhaust manifold pressure to rise, and spool will be slower, since the delta P across the turbine wheel is going to be lower.

Use the external 38mm gate, get a $10 5-bolt flange that covers the wastegate hole in the turbine housing and make a nice downpipe.

Using two wastegates will also result in both gates shuddering, rather than having smooth operation.

Post by **Edub1** » Sun Dec 31, 2006 5:26 am

If that's the case I'd rather just stick with the internal. I had a tough time getting my down pipe to fit right and the flapper portion is wlded into it. I'm not about to modify my downpipe.

I have however been kicking around the idea of running a cable from the flapper to a lever so I could use it as a turbo bypass valve for economy driving. One nice thing about this is that with the internal WG wide open I will still get 5lbs at high RPMs and WOT.

Anyway, I know the WG actuator I have now works real gradually with my boost controller. I observed this with an air compressor. One solution, which might even make things easier, is to use a small nipple say 3/4" to mount the external WG flange. This might restrict flow just a little.

Another otion would be to disable the internal and leave it closed.

Post by **KATwo40** » Sun Dec 31, 2006 5:57 am

Disabling would be the best, but man you gotta remember...that T3/T04E you buy has no internal gate. It has a hole on the back of the housing for an add-a-gate feature, but it's not fabbed onto the housing permanently.

FWIW, I had a 3" downpipe and it cleared everything pretty good.

Post by **Edub1** » Sun Dec 31, 2006 10:30 am

I'm upgrading my current turbo. My WG flapper piece is welded to a 3" 90* weld bend that is welded to the down pipe and so on. It can't be removed without cutting it out.

But the thing is, I'd rather not spend $200+ on a WG. Perhaps I'll just see if I can reem the hole a little. Too bad those flapper disks are not changable. I wonder if I could weld a washer on there.

Post by **KATwo40** » Sun Dec 31, 2006 10:36 am

How about if you email me your shipping address and I send you a new flapper adapter assembly for just the cost of shipping?

Post by **Edub1** » Sun Dec 31, 2006 12:04 pm

I would appreciate that but like I said, it's welded into the downpipe. Are you talking about just the disk portion? I can't see how it comes apart.

Post by **KATwo40** » Sun Dec 31, 2006 12:18 pm

No, I'm talkin' about the whole assembly. It has a 5 bolt on one side, and a 3 bolt outlet. On the 5 bolt side there's a flapper that's to be attached to the actuator rod.

Post by **Chezedik** » Sun Dec 31, 2006 9:48 pm

He's saying that you cut your DP a little and put the three bolt flange on it, then you run the newer flapper. Also, you should be able to find a machinist capable of creating a larger flapper for you at the same time he bores out your turbine housing, or were you planning on doing it?

Post by **Edub1** » Mon Jan 01, 2007 10:35 am

I can't change my flapper piece because it is fabricated into the DP and I'm not making another DP.

I was doing some calculating. The area of my internal plus a 35mm WG is about the same as using a 40mm.

I think I might just try the internal plus a $50 Tial knock off and if I have problems I'll eliminate the internal and but a Tial for $200.

But first I'm going to measure my flapper and turbine hole. Does anybody know the size of a T3 hole? I don't have mine here.

Post by **KATwo40** » Mon Jan 01, 2007 10:41 am

Edub1 wrote:I can't change my flapper piece because it is fabricated into the DP and I'm not making another DP.

I was doing some calculating. The area of my internal plus a 35mm WG is about the same as using a 40mm.

I think I might just try the internal plus a $50 Tial knock off and if I have problems I'll eliminate the internal and but a Tial for $200.

But first I'm going to measure my flapper and turbine hole. Does anybody know the size of a T3 hole? I don't have mine here.

The size of the turbine outlet depends on the size of the wheel. Mine is 2.5".

Post by **Edub1** » Mon Jan 01, 2007 11:02 am

I need the flapper hole size.

Just measured my flapper disk it's 1.125" so I might be able to boar it out quite a bit.
Modified by Edub1 at 9:34 PM 1/1/2007

Post by **Chezedik** » Mon Jan 01, 2007 4:56 pm

Yeah, that's why people do it. I think the hole on a T3 is about .5-.75". Plus, you can have a larger flapper made.

Post by **Edub1** » Sat Jan 06, 2007 3:44 pm

I can't do a bigger flapper but I wonder how much I'd gain in reeming the hole to 1.125"

Post by **nissanfanatic** » Sat Jan 06, 2007 4:41 pm

I'm running just a 35mm external on my setup.. Works fine.. My biggest problem is getting the boost to go higher.lol

Can a wastegate be too big?

Can a wastegate be too big?

Re: (WDRacing)

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Re: (Chezedik)

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Re: (Chezedik)

Re: (Edub1)

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