Question for turbo guys about wastegate

[Boost21]

I am almost done with my build and have everything done but the turbo itself and a down pipe made. Ive been talking with this guy about a garrett he has for sale and its specs seem like they will do the job for me. There is one issue though, The exhaust side of the turbo is a 6 bolt design. I thought that was going to be an issue untill I found this flange for it...
http://www.atpturbo.com/Merchant2/graphics/00000001/Catalog%20Images/Flanges/Steel/ATP-FLS-033_400.jpg
http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ATP-FLS-033&Category_Code=ATP-FLS2
That will/should work for it but what am I supposed to do about the wastegate that seems to just open into wherever the turbo is(my case the engine bay.
http://i263.photobucket.com/albums/ii130/boostgt/turboooo/100_0022.jpg
This thing is brand new and a awesome price but Im kind leary about the exhaust side of it..

any help/input is appreciated.

edit the turbo is going to go where the filter is or a little bit closer to the bumper (where battery was)
http://i263.photobucket.com/albums/ii130/boostgt/turboooo/CIMG1992.jpg

[udlose98]

what size turbo is that? seems small

Anyways, since it is internally wasgated the WG will route pressure from the incoming exhaust, past the turbine, and out your downpipe (if/when desired psi is reached).

[rally_scort]

what size turbo is that? seems small

Anyways, since it is internally wasgated the WG will route pressure from the incoming exhaust, past the turbine, and out your downpipe (if/when desired psi is reached).

I think hes asking how/where the dumptube should be placed.My opinon would be to look for a downpipe that mates to the turbo, instead of a flange.You might be able to find one with a dumptube that reroutes back into the downpipe.By looking at that design, im kinda confused on how a dumptube would even seal, unless you welded one right to the turbine housing.Another option would be to see if they offer a turbine housing for that turbo, thats setup for external gates.Unless its an ebay knockoff, im guessing they can be found.I agree that the turbo seems a little small for your application.At least for the probe guys, the smallest they go for a turbo is somewhere around an SC61, and that still boosts very quickly.Id say look for a cheap holset hy35.They can be had with low miles, reletavily cheap, and sometimes will include a stock downpipe with em.

[A.Spod]

It dumps internally. Make a downpipe with the 6-bolt flange, bolt it up, and run it.

[Cjburn]

If you look at the inside of the housing, you can see where the wastegate is discharged into (in the picture, if you look at about 3 o'clock inside the housign you see a cutout in the housing). It doesn't dump outside the housing like it looks like at first glance.

[rally_scort]

It dumps internally. Make a downpipe with the 6-bolt flange, bolt it up, and run it.

wow, i totally missed that.I thought the plug was the flapper :chair:

[Boost21]

ok so that isnt a flapper? thats what im confused about. Most external wastegates Ive seen have somewhere that you can bolt a dump onto that ges welded to the downpipe or you can get the flange that is like football shaped that covers the two that leads to the one exhaust out.

for those who asked, the specs are:
compressor a/r is .48 and exhaust a/r is .69
should be alright for a 3.4l v6 right? Im only planning on 7psi


also if that isnt a flapper what is it?:confused:confused

[rally_scort]

ok so that isnt a flapper? thats what im confused about. Most external wastegates Ive seen have somewhere that you can bolt a dump onto that ges welded to the downpipe or you can get the flange that is like football shaped that covers the two that leads to the one exhaust out.

for those who asked, the specs are:
compressor a/r is .48 and exhaust a/r is .69
should be alright for a 3.4l v6 right? Im only planning on 7psi


also if that isnt a flapper what is it?:confused:confused

its an internal gate.You wouldnt have a wastegate actuator attached the the turbo, if it wasnt internal setup.The wastegate dumps back into the exhaust before it even leaves the housing, so just attach a downpipe and run it.

[udlose98]

external wastegate - found on larger turbos, dump excess exhaust into the open, requiring you to have a tube that from your wastegate and hooks back into your regular exhaust past the turbo.

internal wastegate - found on smaller turbos, dump excess exhaust right into your existing exhaust pipe off the turbo.



Don't know if that clears it up, its much easier to explain by showing someone.

[Russ Jerome]

There are a few important questions that need to be answerd before
planning an internaly gated dump:

Boost pressure goal: low boost with higher comp motor (7-14psi).
or higher boost with lower comp motor (14-35+psi)?

Is the turbo specificaly speced for your motor or is it possibly
bigger/smaller than you need?

Street or strip?

There are some drawbacks to that exhaust housing depending on
your goal, not important depending on your goal (boost creep, the
bottleneck in your system, drivability at boost thresh hold).

[Russ Jerome]

PS: I have a few internaly gated setups you could look at to better
make your decision. And some refernce material to read.

[Boost21]

the turbo specs are listed above.(compressor a/r is .48 and exhaust a/r is .69 ) Im only looking for 7psi right now and maby 8-9 later on. The garrett I showed is brand new for 350 and has the internal wastegate set for 7psi. It should bring my car to about 240-260 whp depending on the boost. I just don't get what that "door" is on there. Turbo specs are right around where I need, the compressor a/r could be a tad higher but not necessary.

[boostaddict14]

what are you doing for fuel management

[Boost21]

larger injectors and tune

[Russ Jerome]

(compressor a/r is .48 and exhaust a/r is .69 ) Im only looking for 7psi right now and maby 8-9 later on. The garrett I showed is brand new for 350 and has the internal wastegate set for 7psi. It should bring my car to about 240-260 whp depending on the boost. I just don't get what that "door" is on there. Turbo specs are right around where I need, the compressor a/r could be a tad higher but not necessary.

The .48 ex is on the small size, good news is it will boost quickly.
7psi will be acheived quickly and that little door will let the
exhaust bypass the turbine so not to climb too high. Your going
to have to run a full exhaust system, a freeflowing exhaust is going
to cause whats called "boost creep". That is at higher RPM the
boost is going to want to climb higher than 7psi. One thing you can do
while its off the car is port the little door (there is always room for
improvment there) to help eliminate creep. Another good thing is
your .48 exhaust is going to start running out of steam at your
HP goal so this may work to your advantage. That specific gate
you have is'nt optimum for high HP (turbulance as the wastegated
exhaust mix's with the turbines output) but again with your goals
you may just hit the nail squarly on the head with your sizing.
*set that wastegate looser than it is now for your first run*
The easier that arm moves the lower the boost will be.
I personely love internal gates, making a 3,4 or even 5 stage
adjustable boot controller can be made at home, external gates
are finicky in what tention springs they use and not real usefull
for dual staged controll with rock solid boost controll in my useless
opinion. Im at work but can link you some pics later (boss watching
me now Im typing franticaly!).

[Boost21]

ok that's good to hear, but why would they design the turbo to let hot exhause gas come out of it into an engine bay? usually on wastegates like that you can attach a dump pipe to connect to the down pipe. I'm confused lol

[Boost21]

Ok im back from work and can type on a pc verses my phone lol Looking at the exhaust opening now I noticed that the wastegate does indeed dump into the exhaust opening(look to the right side you see a channel) Now back to my original question, what is that round port thing on the right? An access port for the wastegate flapper or something?

[Cjburn]

Ok, look at the picture you posted, you can see a cutout inside the discharge of the turbo there, like I said about 3 o'clock. That is the discharge of the wastegated gasses after it has bypassed the turbine wheel. All you need to do is hook up a downpipe to that discharge and you're set. There is NO opportunity to run a separate discharge tube for the wastegate as it's dumped directly after the turbine wheel, technically inside the turbine housing. This is obviously a turbo from the GT family since Garrett never had a .69 on any T series housing. My guess it's a straight GT28 and since you have a V6 you're going to have positive pressure right off idle. Russ was making reference to boost creep, since you might have too much exhaust flow for the smallish wastegate to bleed enough exhaust off of the turbine wheel to keep wheel speeds down enough to manage boost levels up top.

[Boost21]

I was looking the other day and think that its a gt32. What are you guys talking about the exhaust pressures? Stock is a restrictive crush bent 2.25", right now I have a 2.5" cat back, but when I have the downpipe done it will be 2.5" from the turbo back. By positive pressure do you meen little vaccum pressure or what? Would it not be a good candidate then?

[pnad]

Now back to my original question, what is that round port thing on the right? An access port for the wastegate flapper or something?

Just a plug

[Russ Jerome]

What are you guys talking about the exhaust pressures?

In a perfect world there is 1psi backpressure in the exhaust manifold
prior to the turbine for every 1psi of boost. Unfortunately in order
to gain boost modern factory systems will actualy create 2psi of back
pressure in the exhaust manifold for every 1psi of boost, so if your GNX is
pushing 20psi of boost your exhaust manifold has 40psi of backpressure,
just physics for every action bla bla bla. Full race cars with carefully
selected turbos will hit 1/1 pressure in both manifolds "but" there are
downsides like lag that has to be overcome.People do everything
from spray fuel in the turbine (rally cars of europe) or crazy electronics
that sway timing off the map (Indy cars) or if you dont have access
to a million dollar dyno and shop ya just spray the crap outa it to
get her spooled.

Anyway we have the high pressure and incredibly fast expanding gass'
trying to leave that little puck shaped wastegate, at some point there
will be a bottleneck. The ideal internal wastegate will dump to atmosphere
and remember it only opens at WOT when you hit your target boost, your
wife driving would never hear it on a 500 mile trip.
The next best would be a divided outlet or a hand made convergence
cone like this I made:
http://hometown.aol.com/russjerome/images/colt63outlet.jpg
They both dump together but the shear size of the 4" OD tubing
pie cut to a manderal 3" elbow will be insignifigant when you only
run a 17" downpipe that bellows out to 5"ID:
http://hometown.aol.com/russjerome/images/4inchdownpipe%20004.jpg
I dont have a pic handy but the hole in my .63 exhaust housing is ported
to perfectly match the puck. I also plan on using "all of it", a term that
means when Im all set up I dont plan on ever letting the wastegate open
at any time. Picture your tubine outlet as one river, the puck opens and
we have another river and they both want out and they are growing in
size as the unburnt gass' come out of the head.

[Russ Jerome]

So all those gass' have found there way to your exhaust system.

If you have no restriction your motor can continue to climb thru
the RPM range, creating more happy exhaust pressure, has to go
somewhere and if it cant it will stack up behind the turbine making
more boost and we call it creep.

If we have a somewhat restrictive exhaust it actualy
fights boost creep in dirty uncool way (cost HP) because
its our bottleneck for more flow/HP.

If we take a stock turbo SRT,Subi,EVO ect and we whack the exhaust
off below the turbo we will see an imediate jump in boost due to the
now uncorked exhaust. This is short lived in a factory car the computer
says "whoa sparky were under warranty yet" and backs off fuel and/or
timing to control the boost. There are always tradeoffs, get her bolted
together and start slow at very low boost, wide band and an EGT gauge.

[Boost21]

Ok, that makes since, but is having positive pressure a bad thing? In back pressure are you talking about vacuum or is it just the exhaust pressure? I understand how the turbo works in all and sizing but this is the first turbo'd car Ill have owned so I would like to learn as much as possible. So all in all this turbo would be a good fit for my application? From what Ive calculated it should be spooled up around 3k rpms, hit the 7psi fairly quickly, and not be too small?
Thanks for all your guys help =)

[Russ Jerome]

Think it will be fine, I would expect you will see your 7psi by
3k RPM easily.

Dated but a good book available at Barnes/Noble is Corky
Bell's "Maximum Boost". "Street turbocharging" another
available off the shelf localy.

Here is a pic before porting, white is the cup contact:
http://hometown.aol.com/russjerome/images/stockwaste.jpg
After it was 1/32" or less overlap and polished perfect.

Remember turbos will give you all the HP you want:
http://hometown.aol.com/russjerome/images/dcp_0006.jpg
Its up to you to tell it when to stop:
http://hometown.aol.com/russjerome/images/dsc03518.jpg
No detonation, no lean burn, I just pushed till the block got pissed.

[Boost21]

how much psi was that? or was it a fuel management issue? I think Im going to buy this guy, but still wonder to why they have that plugged "port" by the wastegate. If it was cast into the housing theres gotta be some reason for it.

[Russ Jerome]

The block off plate was machined there for assembly, its the only way
they could assemble it after casting.

That was mid 20's, 8.5:1comp bouncing off 7k rpm. Hot lapping at GLD I
wasnt gonna let the LS1 Camaro pass me and my street tires against
his slicks........expensive win....but I won!

[Boost21]

haha fair enough hopefully I can get this all wrapped up and have the car running in the next week or 2 :)

btw another Q lol, I found the 6 bolt flange and its about 25 bux...kinda steep in my opinion. I was told that a 3 bolt flange would work, you think it would hold up to the boost?

[boostaddict14]

btw another Q lol, I found the 6 bolt flange and its about 25 bux...kinda steep in my opinion. I was told that a 3 bolt flange would work, you think it would hold up to the boost?

Man if you think $25 is too much for a flange then you prolly shouldn't be doing this. The three bolt would prolly work how ever do you want the majority of the weight of your exhaust being held up by three bolts? I say do it right the first time and spend more money so you don't regret it down the road. especially with forced induction, i mean if you cut corners on your setup especially with tuning your shit could blow. Also i hope you bought a new fuel pump.

[Cryptic]

http://hometown.aol.com/russjerome/images/dsc03518.jpg
No detonation, no lean burn, I just pushed till the block got pissed.

:stare DAMN

nice posts Russ :thumbsup

[Boost21]

Man if you think $25 is too much for a flange then you prolly shouldn't be doing this. The three bolt would prolly work how ever do you want the majority of the weight of your exhaust being held up by three bolts? I say do it right the first time and spend more money so you don't regret it down the road. especially with forced induction, i mean if you cut corners on your setup especially with tuning your shit could blow. Also i hope you bought a new fuel pump.

I was saying compared to other flanges it seems a bit high, of course I'm going to get the right one, just seeing what people thought of what I was told.

[Berettaspeed]

nice to see another 3400 turbo on the streets. the engine should be able to handle 10 psi with a good tune. its smart to run the 7ish until your used to your program. with other numbers on 3400s that are or have been turboed at 10psi were all pushing over 300WHP. then again those were also manual. very few people have dynoed their setups, but the highest with 12psi was 350 somehting whp. one guy had 400 somehing, but i dont know what he had done to it. it was a 2nd gen cavy. the guy lived in appleton WI.

what size injectors are you using?

Im also using an internal wastegated turbo.

[Boost21]

there the gm inline 6 injectors (28lb/hr) They work nicely for my car because it utilizes the same connection and gives me more fuel. I have a friend here with a similar setup who is put really low 13 seccond runs at 9 psi, but turned it up to 12 and blew the head gasket before getting a run in. Right now the cars torn up and hes putting some copper head gaskets in, so now its more of when the trans and or bottom ends going to blow out lol I would love to do a 5 or 6 speed swap but theres only like 2 documented people who've done it and its costed over 3k to do. Did you ever run the beretta at 7? If so what kind of numbers/times did it put out?

[Berettaspeed]

28 lbs?? seems kinda low i think. but as long as your not getting fuel pressure drop and maintain good A/F ratio then i guess it works.

I have taken the beretta to the track once, but the tune was/is still bad. im running 10 a/f's and now thwe clutch is trashed. i run about 6-8ish. i cant maintain anything lower than that if i tried. nothing is done to my engine at all its 100% stock.and im using L67 injectors(36.6lbs) with the multec I style clips. i have beat on it on the street alot. but hit 13.9 @105 and a 14.0 at 109. had huge wheel spinning problems all through 3rd gear. my best 60ft was like 2.4s and my N/A times were all better up to the 1000ft mark. haha.. not to mention my N/A time 14.3@95. i dont think im going to run it at all this year track wise. i dont even think ill really drive it.:crying