thanks dylan.
Edit:
Is it possible to run both the internal wastegate and external wastegate? Or do I need to weld up internal?? I'm running the blitz dual solenoid boost controller spec R
Thanks!
show me your external wastegate screamer pipe routes :)
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show me your external wastegate screamer pipe routes :)
as in title want some ideas before i tackle this!
thanks dylan.
Edit:
Is it possible to run both the internal wastegate and external wastegate? Or do I need to weld up internal?? I'm running the blitz dual solenoid boost controller spec R
Thanks!
thanks dylan.
Edit:
Is it possible to run both the internal wastegate and external wastegate? Or do I need to weld up internal?? I'm running the blitz dual solenoid boost controller spec R
Thanks!
Last edited by dylan5084 on Wed May 18, 2016 9:28 pm, edited 1 time in total.
Re: show me your external wastegate screamer pipe routes :)
Mine broke off and it was proving difficult to source another one so I just bought some flexi of ebay, cut the end to fit and welded it to the flange. The logic behind that was for ease of fitting, which worked as I could just bend it around anything that got in it's way.
The logic behind that was for ease of fitting, which worked as I could just bend it around anything that got in it's way.
Re: show me your external wastegate screamer pipe routes :)
also, its a tial vband ewg, and i want to run 1 bar, so should i have a 1 bar spring in there or less? struggling to find springs for them... mine only came with the one fitted in it.
.. mine only came with the one fitted in it.Re: show me your external wastegate screamer pipe routes :)
Martin F wrote:Mine broke off and it was proving difficult to source another one so I just bought some flexi of ebay, cut the end to fit and welded it to the flange.
no pics of it fitted?
Re: show me your external wastegate screamer pipe routes :)
No, sorry, I didn't read you description properly so shouldn't have replied in the first place, however there were two different routes I had to choose from and they both had a lot more space than I predicted beforehand.
One on the inside of the downpipe, the other going over and coming out on the other side of the downpipe.
One on the inside of the downpipe, the other going over and coming out on the other side of the downpipe.
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simpson_eh
- Posts: 633
- Joined: Mon Sep 28, 2009 1:27 pm
- Location: south wales
Re: show me your external wastegate screamer pipe routes :)
il get a pic of mine up tomorrow, it routes down the right hand side of the down pipe and out under the sump and bolts to the crossmember
gt3076r with
tomorrow, it routes down the right hand side of the down pipe and out under the sump and bolts to the crossmembergt3076r with
If you see an MR2 with a raised engine cover, the bottom line is it's probably faster than your car.
Re: show me your external wastegate screamer pipe routes :)
Nice!
Is your heat shield home made? Any pics of it in situ?
Re: show me your external wastegate screamer pipe routes :)
Is it possible to run both the internal wastegate and external wastegate? Or do I need to weld up internal?? I'm running the blitz dual solenoid boost controller spec R
Re: show me your external wastegate screamer pipe routes :)
dylan5084 wrote:Is it possible to run both the internal wastegate and external wastegate?
I'm not exactly sure what your intent is here.
..I'm currently running both simultaneously because it's the only way I'm stopping boost creep given the design of my GT28's external wastegate take-off is less than ideal.
To do this you want the spring pressures to be well matched between them. You would also need to plumb the external wastegate as a single port gate rather than a twin port.With that said, I would recommend against running both gates simultaneously unless you really have a need to.
I guess if either gates does the job well enough by itself then you could wire in a second solenoid such that on one setting only the external gate opens (oh the noise!) and on the other setting the internal gate is used for quieter running. However I guess you're fitting an external gate because the internal one isn't up to the job, right?dylan5084 wrote:Or do I need to weld up internal??
I would suggest no you don't and I regret doing so when I was experimenting with external gate on my CT20B.
If you leave the actuator on the internal gate, but with the vac hose disconnected, that will keep the gate closed plenty well enough for all practical purposes.
Anyone who has had their actuator hose fall off (or have a mechanic incorrectly plumb it in - ahem - JD Modified) will know the boost exceeds safe levels very quickly, meaning the spring keeps the gate firmly shut by itself.And yes, I have tested this.
.. knowing my external gate alone (before fitting an internally gated turbine housing) would creep but boost is held stable with both gates active, I disconnected the vac hose from the internal gate and, hey presto, exactly the same creep as before.Re: show me your external wastegate screamer pipe routes :)
Yea, the internal gate isn't big enough to get rid of enough excess boost, so just disconnect it and plumb in the external one, great!
Cheers mate!
Cheers mate!
Re: show me your external wastegate screamer pipe routes :)
dylan5084 wrote:Yea, the internal gate isn't big enough to get rid of enough excess boost, so just disconnect it and plumb in the external one, great!
Cheers mate!
Having been round this cycle in different ways, that is what I would suggest.
There's no need to weld up the internal gate and doing so only limits your options late.-
masterbateson
- Posts: 547
- Joined: Sat Jan 24, 2015 7:09 pm
Re: show me your external wastegate screamer pipe routes :)
For a dunce like me and or anyone else who isnt clued up on these things, what is a screamer pipe and what is it for/does?
Also whats the advantage of an external doofrey?
The original wastegate actuator is well(external) and from these pics I can see aftermarket actuators but how or where can you fit an external wastegate? 
Also why do this? is the stock wastegate not up to the job? or is it fine up too a certain BHP say if you have modded a lot and only then would this sort of setup be advantageous?
Standard wastegate is good for up to 300bhp/ whatever PSI/boost your running?
is a screamer pipe and what is it for/does?Also whats the advantage of an external doofrey?
The original wastegate actuator is well
(external) and from these pics I can see aftermarket actuators but how or where can you fit an external wastegate? Also why do this? is the stock wastegate not up to the job? or is it fine up too a certain BHP say if you have modded a lot and only then would this sort of setup be advantageous?
Standard wastegate is good for up to 300bhp/ whatever PSI/boost your running?
Re: show me your external wastegate screamer pipe routes :)
my internal gate is too small as my ct26 turbo is a hybrid and producing too much boost for the internal gate to cope with, so i need to add an external one so i can control my boost!
Re: show me your external wastegate screamer pipe routes :)
OK, wastegates 101 coming up...
Lets deal with a common misconception first:
Wastegate size has little to do with power figures. Unlike almost everything else on an engine, you don't neccessarily need bigger to run more power... in fact, you need a bigger wastegate to run less power, all other things being equal (which they generally are not).
It's all about flowing gas, not about horsepower, as we're about to discuss...
What is a wastegate?
A wastegate is a device that diverts exhaust gasses around the turbine wheel. You do this to control the amount of boost your are presenting to the engine. The more gas that is diverted from the turbine wheel, the less boost the compressor wheel produces for the engine. If your wastegate doesn't open, the majority of turbos are capable of pushing far too much boost into an engine. This is certainly true of the CT26 and CT20b that are standard on our engines.
Internal or external?
An internal wastegate(such as is stock on our cars) is a flap in the turbine housing that creates a shortcut around the turbine wheel to control boost. It's actuator is on the outside of the turbo, but the actual flap is inside. The diverted exhaust gasses are put back into the exhaust immediately after the turbine.
An external wastegate is a valve that bolts on to an exhaust system(either designed or modified for this) before the turbo. When the valve opens, it diverts some of the exhaust gasses, thus controlling boost.
What's a screamer pipe?
With an external wastegate, there are two options of what to do with the diverted gases. You could run another pipe from the wastegate to create a "plumb back" into the exhaust, so that all the gases still go through your mufflers etc.
Alternatively, you can fit a"screamer pipe". This just dumps the diverted gas directly into the atmosphere, generally out of a pipe that's aimed at the ground. Because there is generally no muffler on the pipe, these make a very loud noise. Inside the car it tends to sound like an epic roar, while outside the car it can sound like an obnoxious jet engine sound.
So what's boost creep?
Boost creep is where you cannot limit the boost generated to your target level. Mostly the boost will hold at your desired level until a certain RPM, but above this the boost will increase as your revs increase.
This basically means that, although your wastegate is fully open, it's not providing an easy enough path to divert enough gas around the turbine and thus too much of your exhaust is still choosing to go through the turbine wheel. This creates more boost, hence even more more exhaust gas and thus even more gas going through the turbine. Essentially, your wastegate is not up to the job.
Why would a wastegate not be good enough?
To be effective, a wastegate need to be able to provide an easier route away from the engine than the turbine wheel.
There are three main, interconnected reasons why this might be so:
1) The wastegate or it's associated pipework is too small and cannot open wide enough. Hence to hold boost and thus power at your desired level, you need a bigger wastegate (see the very top point)
2) The wastegate connects to the exhaust manifold in such a way that it asks the gas to make a sharp turn. The faster the gas flows (ie. the higher the engine RPM) the less it wants to turn to go down the wastegate.
3) The turbine is too easy to spin! The turbine provides a certain amount of resistance because it needs to be turned; exhaust back pressure(although bad for spool time and volumetric efficiency) essentially multiplies the effort required to spin the turbine wheel. So applying the same backpressure to the exit of both the turbine and the wastegate will affect the turbine path more than the wastegate path, making the gas favour the wastegate more and thus making boost control easier.
Generally, boost creep happens for a combination of all three reasons. And this applies equally to internal and external gates.
OK, how does this affect MR2s? Surely Toyota put a good enough wastegate in!
Toyota designed an overall system that is sufficent for the stock setup. The internal wastegate is big enough given the massive restrictions on the stock exhaust system. The cat presents backpressure to both the turbine and the wastegate, but that's not the real culprit; the stock turbo elbow presents a massive restriction to the exhaust (there's a big constriction right in the path of the exhaust gas) which means the turbine has to work much harder to spin and the small internal wastegate is fine.
The problem comes when you replace the stock cat with a decat downpipe; particularly a 3" straight through system. You've massively reduced the backpressure so that the turbine is much easier to spin up, reducing lag and freeing up some power. BUT, you've disproportionately made the turbine an easier path to take compared to the wastegate. Suddenly a wastegate that was fine is now too small and at an angle that's difficult for the gas to turn into.
Hence creep!
What can I do?
When faced with creep, you can either:
1) Restrict your exhaust again, which is kind-of counter productive.
2) Improve your wastegate, which is often difficult and expensive
(I can discuss all the MR2 specific options if you really wish - I've tried pretty much all of them!)
Internal or external? ... part two!
So why choose one other the other?
OEMs like internal gates because they're easy to build and package. Given they require no extra pipework they also work out cheaper and easier to fit. However they tend to be smaller than even the smallest external gate, so on a free flowing system you may well run into problems.
External gates are very often favoured for turbo swaps and engine builds because they just work better... provided the exhaust system is designed well. there's more pipework to think about, more space needed in the engine bay and maybe even coolant lines required. External gates are also easier to work on / replace / change spring pressures on etc. and you have the option of a screamer if you wish.
If money/ labour / time were no object, I would always say go external. But in the real world comes down to your skills and your project's goals.
..Lets deal with a common misconception first:Wastegate size has little to do with power figures.
Unlike almost everything else on an engine, you don't neccessarily need bigger to run more power... in fact, you need a bigger wastegate to run less power, all other things being equal (which they generally are not).It's all about flowing gas, not about horsepower, as we're about to discuss.
..What is a wastegate?A wastegate is a device that diverts exhaust gasses around the turbine wheel.
You do this to control the amount of boost your are presenting to the engine. The more gas that is diverted from the turbine wheel, the less boost the compressor wheel produces for the engine. If your wastegate doesn't open, the majority of turbos are capable of pushing far too much boost into an engine. This is certainly true of the CT26 and CT20b that are standard on our engines.Internal or external?An internal wastegate
(such as is stock on our cars) is a flap in the turbine housing that creates a shortcut around the turbine wheel to control boost. It's actuator is on the outside of the turbo, but the actual flap is inside. The diverted exhaust gasses are put back into the exhaust immediately after the turbine.An external wastegate is a valve that bolts on to an exhaust system
(either designed or modified for this) before the turbo. When the valve opens, it diverts some of the exhaust gasses, thus controlling boost.What's a screamer pipe?With an external wastegate, there are two options of what to do with the diverted gases.
You could run another pipe from the wastegate to create a "plumb back" into the exhaust, so that all the gases still go through your mufflers etc.Alternatively, you can fit a
"screamer pipe". This just dumps the diverted gas directly into the atmosphere, generally out of a pipe that's aimed at the ground. Because there is generally no muffler on the pipe, these make a very loud noise. Inside the car it tends to sound like an epic roar, while outside the car it can sound like an obnoxious jet engine sound.So what's boost creep?Boost creep is where you cannot limit the boost generated to your target level.
Mostly the boost will hold at your desired level until a certain RPM, but above this the boost will increase as your revs increase.This basically means that, although your wastegate is fully open, it's not providing an easy enough path to divert enough gas around the turbine and thus too much of your exhaust is still choosing to go through the turbine wheel.
This creates more boost, hence even more more exhaust gas and thus even more gas going through the turbine. Essentially, your wastegate is not up to the job.Why would a wastegate not be good enough?To be effective, a wastegate need to be able to provide an easier route away from the engine than the turbine wheel.
There are three main, interconnected reasons why this might be so:
1) The wastegate or it's associated pipework is too small and cannot open wide enough.
Hence to hold boost and thus power at your desired level, you need a bigger wastegate (see the very top point)2) The wastegate connects to the exhaust manifold in such a way that it asks the gas to make a sharp turn.
The faster the gas flows (ie. the higher the engine RPM) the less it wants to turn to go down the wastegate.3) The turbine is too easy to spin! The turbine provides a certain amount of resistance because it needs to be turned; exhaust back pressure
(although bad for spool time and volumetric efficiency) essentially multiplies the effort required to spin the turbine wheel. So applying the same backpressure to the exit of both the turbine and the wastegate will affect the turbine path more than the wastegate path, making the gas favour the wastegate more and thus making boost control easier.Generally, boost creep happens for a combination of all three reasons.
And this applies equally to internal and external gates.OK, how does this affect MR2s? Surely Toyota put a good enough wastegate in!Toyota designed an overall system that is sufficent for the stock setup.
The internal wastegate is big enough given the massive restrictions on the stock exhaust system. The cat presents backpressure to both the turbine and the wastegate, but that's not the real culprit; the stock turbo elbow presents a massive restriction to the exhaust (there's a big constriction right in the path of the exhaust gas) which means the turbine has to work much harder to spin and the small internal wastegate is fine.The problem comes when you replace the stock cat with a decat downpipe; particularly a 3" straight through system.
You've massively reduced the backpressure so that the turbine is much easier to spin up, reducing lag and freeing up some power. BUT, you've disproportionately made the turbine an easier path to take compared to the wastegate. Suddenly a wastegate that was fine is now too small and at an angle that's difficult for the gas to turn into.Hence creep!
What can I do?When faced with creep, you can either:
1) Restrict your exhaust again, which is kind-of counter productive.
2) Improve your wastegate, which is often difficult and expensive
(I can discuss all the MR2 specific options if you really wish - I've tried pretty much all of them!)Internal or external? ... part two!So why choose one other the other?
OEMs like internal gates because they're easy to build and package.
Given they require no extra pipework they also work out cheaper and easier to fit. However they tend to be smaller than even the smallest external gate, so on a free flowing system you may well run into problems.External gates are very often favoured for turbo swaps and engine builds because they just work better.
.. provided the exhaust system is designed well. there's more pipework to think about, more space needed in the engine bay and maybe even coolant lines required. External gates are also easier to work on / replace / change spring pressures on etc. and you have the option of a screamer if you wish.If money
/ labour / time were no object, I would always say go external. But in the real world comes down to your skills and your project's goals.
Last edited by shinny on Sun May 22, 2016 12:45 pm, edited 2 times in total.
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masterbateson
- Posts: 547
- Joined: Sat Jan 24, 2015 7:09 pm
Re: show me your external wastegate screamer pipe routes :)
Well give yourself a big pat on the back Mr Shinny 
That was both interesting and informative 
Was that all your own work?
I had a feeling it might be you who came to the rescue.
Did I imagine this or did i once find a article and some pics were some bod had drilled a small hole into there stock wastegate? pressumably to minimize creep?
On a stock car tho this would be a bad idea NO? and prevent/reduce boost?
Also seen the opposite where someone has welded up the internal wastegate, presumably because they have an external one?
That was both interesting and informative Was that all your own work?
I had a feeling it might be you who came to the rescue.
Did I imagine this or did i once find a article and some pics were some bod had drilled a small hole into there stock wastegate? pressumably to minimize creep?
On a stock car tho this would be a bad idea NO? and prevent/reduce boost?
Also seen the opposite where someone has welded up the internal wastegate, presumably because they have an external one?
Re: show me your external wastegate screamer pipe routes :)
masterbateson wrote:Well give yourself a big pat on the back Mr Shinny
Glad it was helpful
masterbateson wrote:Was that all your own work?
Yup.
.. I just hacked it out before leaving the office.masterbateson wrote:Did I imagine this or did i once find a article and some pics were some bod had drilled a small hole into there stock wastegate? pressumably to minimize creep?
On a stock car tho this would be a bad idea NO? and prevent/reduce boost?
Drilling a hole in a wastegate sounds useless to me.
Perhaps you are thinking of a ported wastegate? This is where you grind away the wastegate passage within the turbine housing to allow it to flow more gas. You'll pretty much need to remove the turbo to do this, which isn't exactly a 10min job on the stock turbo. There's a ablance to be struck here... grind off too little and your work is all for nothing; grind off too much and you risk cracking the turbine housing.masterbateson wrote:Also seen the opposite where someone has welded up the internal wastegate, presumably because they have an external one?
Yup, I've had an internal wastegate welded up too
(hence why I advised against it, above). My CT20B was creeping badly, so I got an external wastegate modified around the stock turbo and plumbed back into the downpipe. That was an awesome setup for about a year and then a weld cracked. (I was then convinced by JD Modified to let them custom weld me a manifold which turned out to be truly awful)Re: show me your external wastegate screamer pipe routes :)
I know absolutely nothing about engines, but found that surprisingly interesting, well done.
Re: show me your external wastegate screamer pipe routes :)
still could be doing with pictures in situation... ive just took the old manifold off and the new one is a mile out from fitting, so i need a rev 2 manifold, preferably with wastegate port, or a standard rev 2 manifold that i can modify...
could be doing with pictures in situation... ive just took the old manifold off and the new one is a mile out from fitting, so i need a rev 2 manifold, preferably with wastegate port, or a standard rev 2 manifold that i can modify...Re: show me your external wastegate screamer pipe routes :)
so, ive just tried to fit my stainless 4 branch with EWG port, and its miles out!, is yours a standard cast manifold with wastegate port welded to it? my plan is to do this but i need advice on how to do it.
... im a welder to trade but cant see how id weld stainless to cast iron.... any advice?