Wastegate questions

A little expert advise on a couple wg questions i have.

I recently bought a gt38 turbo and am now in the process of sourcing out a wg to fit an approx 350 hp application

My natural tendancy was to look toward tial, i have seen them used very often in hond/acura turbo builds and they have a good rep.

Are they all universally adaptable to all turbos, could the same wg fit a t3/t04e, a mitsu 19t and a gt38??

What size wg would i need for this application 35mm, 38mm, 44??

I noticed these babies are spring operated, would that mean that i dont need a wg actuator????? If i dont then i can throw my saab apc away, or sell it??

Last but not least i know they have many different springs for different pressure settings, would i need to get a 14 psi if i want to run 14 psi, and an 18 psi if i decided to do that??

As you can see im unfamiliar with wg's and their workings, would appreciate help.

16 views and not a single Answer. Theres is not one person than can give an opinion on one half of one of my questions?

Not even a comment or bad advice??? Whats going on???

You could go with a tial 35mm, or a turbonetics deltagate (both fit the same). Some say they like the Tial better, especially with the high heat durability.

Deltagate is advertized to handle 300-400 hp range.

If you think you need a larger opening to get rid of boost creep, go larger MM--

edit:

to obtain higher boost pressures than the rated spring in the wastegate, you'll need a boost controller--either electronic or manual. All it does is put more pressure on the other side of the diaphram in the wastegate to hold it shut until your predetermined pop off pressure.

External wastegates don't bolt directly onto the turbo, rather the manifold or header you make.

my 2 C

J

phillazenby740t said:

A little expert advise on a couple wg questions i have.

I recently bought a gt38 turbo and am now in the process of sourcing out a wg to fit an approx 350 hp application

My natural tendancy was to look toward tial, i have seen them used very often in hond/acura turbo builds and they have a good rep.

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I?ve heard that too, yes.

phillazenby740t said:

Are they all universally adaptable to all turbos, could the same wg fit a t3/t04e, a mitsu 19t and a gt38??

Click to expand...

Yes, if you welded an extra bung(?) on your manifold/header and downpipe.

phillazenby740t said:

What size wg would i need for this application 35mm, 38mm, 44??

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I don?t know what the best size for your application would be, but I know this: The higher HP you want, the smaller WG you should run.

phillazenby740t said:

I noticed these babies are spring operated, would that mean that i dont need a wg actuator????? If i dont then i can throw my saab apc away, or sell it??

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Think of the external wastegates as a complete unit. The external wastegates already have the "actuator" built in, and they are actuated in the same way as your usual built-in wastegate on the stock Mitsubishi turbo (by air pressure fed from the turbo to the WG).

phillazenby740t said:

Last but not least i know they have many different springs for different pressure settings, would i need to get a 14 psi if i want to run 14 psi, and an 18 psi if i decided to do that??

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If you are using the APC or a MBC, then go with the smallest spring (smallest boost pressure) you figure you will run.

some feedback

phillazenby740t said:

A little expert advise on a couple wg questions i have.

I recently bought a gt38 turbo and am now in the process of sourcing out a wg to fit an approx 350 hp application

My natural tendancy was to look toward tial, i have seen them used very often in hond/acura turbo builds and they have a good rep.

Are they all universally adaptable to all turbos, could the same wg fit a t3/t04e, a mitsu 19t and a gt38??

What size wg would i need for this application 35mm, 38mm, 44??

I noticed these babies are spring operated, would that mean that i dont need a wg actuator????? If i dont then i can throw my saab apc away, or sell it??

Last but not least i know they have many different springs for different pressure settings, would i need to get a 14 psi if i want to run 14 psi, and an 18 psi if i decided to do that??

As you can see im unfamiliar with wg's and their workings, would appreciate help.

Click to expand...

The waste gate will work on any application. It mounts to the header not the turbo, well in most cases, I've seen them mounted to custom mounts on the turbo but that's sorta a wacky way to go. Larger equals less boost creep from my understanding but others ought to chime in on that. If its a real Tial then there should be no issues with it but there are knock off ones that I've heard of folks having problems with. All wastegates are spring operated btw, the spring and rod length are the preload the boost pressure works against to open the waste gate. So if you want to keep your apc you still can as all it does is modify the signal to the wastegate. If you're going to keep the apc you'd want use a spring set at a very low boost say 5 psi so that the apc can open the waste. What are you running for a header??

Thanks
Renny

Edit: Fred said the same things but more eloquently..

get the right housing

Renny_D said:

The waste gate will work on any application. It mounts to the header not the turbo, well in most cases, I've seen them mounted to custom mounts on the turbo but that's sorta a wacky way to go. Larger equals less boost creep from my understanding but others ought to chime in on that. If its a real Tial then there should be no issues with it but there are knock off ones that I've heard of folks having problems with. All wastegates are spring operated btw, the spring and rod length are the preload the boost pressure works against to open the waste gate. So if you want to keep your apc you still can as all it does is modify the signal to the wastegate. If you're going to keep the apc you'd want use a spring set at a very low boost say 5 psi so that the apc can open the waste. What are you running for a header??

Thanks
Renny

Edit: Fred said the same things but more eloquently..

Click to expand...

Thanks guys, really appreciate all the good feedback, didnt expect all my questions answered, im currently running a 90+, which i will either port and polish, or sell and buy a nice equal lenght header right here on tbricks, i think they are around 600 bucks,

Im guessing by header you meant exh mani, in case you meant downpipe, im gonna require the services of senor thelostartof.

Interesting how a smaller wg size will enbale more power, its true, simple, but i hadnt thought about it. But then again if i am using an apc, regardless of wg size, the apc will regulate exhaust flow thru the wg. So boost would climb as well on a smaller or bigger wg, only the bigger one would help prevent boost creep in high revs. I am a little worried about boost creep as ive chosen a rather large turbo. Gt38 1.03 ar ( i like the oomph effect of turbo lag, when you squish back into your seat)

When I said header I ment header. The wastegate has to take exhaust from before the turbo and move it either to the down pipe or to it's own seperate down pipe. I'm not sure how you would do that on a 90+. Is the GT38 normally internally waste gated? If so I've seen external waste gates made to use the internal wastegate port but otherwise you are talking header and external wastegate or possibly (gulp) welding onto the 90+ to add the wastegate. Please clarify how you plan to do this.

Renny

Renny_D said:

When I said header I ment header. The wastegate has to take exhaust from before the turbo and move it either to the down pipe or to it's own seperate down pipe. I'm not sure how you would do that on a 90+. Is the GT38 normally internally waste gated? If so I've seen external waste gates made to use the internal wastegate port but otherwise you are talking header and external wastegate or possibly (gulp) welding onto the 90+ to add the wastegate. Please clarify how you plan to do this.

Renny

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I see now, sorry, i did not mean to offend you. Ive yet to figure this out as the turbo is still in the postmans hands, but I will get back to you on that one

frpe82 said:

I´ve heard that too, yes.
I don´t know what the best size for your application would be, but I know this: The higher HP you want, the smaller WG you should run.

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Not exactly true.

The size of the wastegate does not directly correlate with engine power. It has more to do with matching the wastegate to the exhaust housing of the turbocharger and the engine used.

Think of the 4-stroke internal combustion engine as an air pump. You pump air through it. The more you get air in, the more fuel you can burn, the more power you get, and the more exhaust gas you have to pump out.

As the amount of horsepowers go up, it means that the amount of air pumped through the engine must have gone up too.

Therefore you have more exhaust gas to pump out too. Some of this is used to spin the turbocharger, but usually (99% of the time in real world, in cars) the exhaust housing is sized so that the desired boost levels are reached way before the redline of the engine, so the excess gasses must be vented off.

The wastegate is present in the turbo system to adjust the boost pressure and it does this by redirecting exhaust gas away from the turbine wheel of the turbocharger, once that the desired boost level has been reached that is.

If the wastegate is too small, it will not be able to vent enough exhaust gas away from the turbine wheel, and then you'll have a situation where the boost pressure might rise above what was intented. This happens because the exhaust gasses must exit the system somewhere, and if it's easier for it to exit through the turbine wheel, then it does that (because the wastegate opening already was "full"). Simultaneosly the back pressure is increased, which causes the heatload of the engine to rise. Increase in backpressure also leads to more reversion through the exhaust valve, which hurts cylinder filling, which in its turn hurts engine power.

A small engine with a really big turbo will need a lot smaller wastegate than a big engine with a small turbocharger if we want use the turbocharger at it's efficient area.

Wagner said:

A small engine with a really big turbo will need a lot smaller wastegate than a big engine with a small turbocharger if we want use the turbocharger at it's efficient area.

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Did you mean bigger???

phillazenby740t said:

I see now, sorry, i did not mean to offend you. Ive yet to figure this out as the turbo is still in the postmans hands, but I will get back to you on that one

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Hey no worries, you didn't offend me. I just wanted to be certain you knew what you were getting into with the external wastegate. External waste gates are great as they can be engineered to keep boost much more stable than the internal wastegates. Often they are neccessary becuase the turbo itself does not have an internal waste gate. On the big hp small wastegate idea. The reason you can run a smaller wastegate on a higher hp application is becuase generally you are getting that higher hp by running at higher boost levels. Higher boost levels mean that you are going to send more of the exhaust through the turbine. As an example: with my 16t I get boost creep if I set the wastegate to 14psi. At full throttle it'll creep up to 18 psi. I've bypassed my mbc and and just let the wastegate do its thing and I get the same results. Now if I set my boost to 18 psi I get a boost spike but no boost creep; the reason is I'm directing more flow through the turbine to get that 18 psi so the waste gate is sized appropriately enough to handle the rest of the excess flow. So with wastegate sizing you need to look at what kind of boost you are going to want to run. The lower the boost the larger the wastegate. If you plan on keeping the apc you'll need to run a low boost so that the apc has some where to go when pulling boost on a knock signal so you'll need to choose one of the larger wastegates. If on the other hand you're just gonna run huge boost then you don't need the big wastegate. Hope that helps.

Thanks
Renny

Good stuff, but my idiot self, has just realized two things. Th gt38 i just bought, is NOT a t3 flange, dammit, and its internally gated. So im sorry for wasting your time on this thread but i have learned alot and it will stick with me so thanks.

Now i just gotta figure out what kind of flange it is and get an adaptor plate.

phillazenby740t said:

16 views and not a single Answer. Theres is not one person than can give an opinion on one half of one of my questions?

Not even a comment or bad advice??? Whats going on???

Click to expand...

2 hours isn't much time when most thinking men are at work, sparky.