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Can a wastegate be too big

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KevinB

Well-Known Member
Joined
Dec 2, 2004
Messages
6,438
Have a new wastegate I bought for bigger motor and turbo. Going to use it for a v6 build now. It is a PTE 66mm gate. The engine will be less than 250" with a 67 or 70mm turbo. I haven't really found any good info out there. Anyone have any experience in this?
 
Kevin, good to see you coming back to the V6.....
In theory I dont think that the 66 would be too big, but I dont have any real world experience to back that up. The larger the better to me. It should help out with boost creep. Good luck, hope to see you at an event !!

Bryan
 
it depends on how you are going to control it, how much boost you are going to run, and how much backpressure the turbine has.

Also if its mounted in the downpipe or off the header.

But, generally speaking, there should be no downsides to the larger gate that can be overcome by adjusting the control methods....

Bob
 
It will be an external coming out of the headers, most likely controlled with co2 and by the holley efi
 
That should work fine

Posted from the TurboBuick.Com mobile app
 
Not to hijack, but was wondering the same thing on my car.

Running similar turbo and off the header as Kevin, but looking at a 46mm W/G, but not using CO2.

I was going to use a turbo smart controller. Would what I'm proposing work well or is there something that would work better???
 
I run a 46mm off the DP with my 72mm turbo , no C02 , and do not have issues with boost creep. I may be adding C02 down the road with a different boost controller.

Bryan
 
If you don't mind my asking what controller are you using now??
Just a Turbonetics manual boost controller (DO NOT USE THEIR BILLET BOOST CONTROLLER !!!!!!!! That POS cost me an engine !!!). I need/want an AMS1000 but other things keep getting in the way of that purchase.

Bryan
 
As long as the pressure to the wastegate can be controlled the larger wastegate is fine and may actually be beneficial if running high ex pressure.


Posted from the TurboBuick.Com mobile app
 
I need/want an AMS1000 but other things keep getting in the way of that purchase.

Yeah it's called MONEY and in my case the lack of having enough of it.

I'm thinking of getting the TS-0301-1003 E-boost2electric boost controller.
 
The big 66 gate on the header will make more power that the 46 will even though the 46 will control the boost just fine. I have one on my header and it is perfect. I would recommend you do not plumb it back into the downpipe or do it as far down as possible like at the heater box or lower. Mine vented out is not near as loud as I thought it would be
Mike
 
The big 66 gate on the header will make more power that the 46 will even though the 46 will control the boost just fine. I have one on my header and it is perfect. I would recommend you do not plumb it back into the downpipe or do it as far down as possible like at the heater box or lower. Mine vented out is not near as loud as I thought it would be
Mike

Mike can you post a pic of this gate mounted, I have the same one not installed yet.


Posted from the TurboBuick.Com mobile app
 
The big 66 gate on the header will make more power that the 46 will even though the 46 will control the boost just fine. I have one on my header and it is perfect.
.

What makes the 66mm make more power than a 46mm???

If a 66mm makes more power over 46mm and you say the 46mm will do just fine are you saying the 66mm makes more power due to larger volume of flow due to the 20mm difference in size?

I'm planning on getting a new turbo and external gate in the future and would like to do it once and have it right the first time.

At what power level is the 66mm better over the 46mm?? Would it be with my current combo or when I go with low ten, high nine potential like I plan in the future or would it work on both combos??

I don't know what you're combo is so I have nothing to compare that statement to.

When the student is ready - The teacher will emerge

I'm ready, school me.
 
I will take a picture over the weekend the car is at home not at the shop. I have not tested a low power car yet with the big gate so I cannot confidently state a threshold where it will be better. I suspect it will always be better from what I have seen so far. Even on a very small displacement turbo engine (1050CC) a 46MM makes more power than the 38MM did. The key is not bringing it back into the downpipe, once you do that the gain goes away. I want to plumb one back much lower, close to the bottom, on the downpipe. I think that will work. The gains come from getting the exhaust out once the turbo is spinning. I have done it a couple times now and some friends have done it more than me the result is repeatable.
 
I will take a picture over the weekend the car is at home not at the shop.

Thanks, that will give me an idea of where to go. I plan on plumbing the exh. to atmosphere down near the intermediate pipe.

I have not tested a low power car yet with the big gate so I cannot confidently state a threshold where it will be better.

What is your definition of low power??

The gains come from getting the exhaust out once the turbo is spinning.

Is what you mean by that statement is that there would be no creep/more accurate boost level due to the larger volume of flow potential through the bigger gate??
 
-no gains can be made with any gate
-you can't make more power with a gate but you can control more power with a larger gate if your gate is too small

its only job and its a simple one is to open enough to divert exhaust gas away from the turbine ,
large or small gate it wont matter to the hP , if it can divert enough your boost will stop where you want it
and whta you can control on the street may fail to perform at the track once third gear is stretched out into the higher rpms

too small on gate and boost may climb beyond where you set it as rpm rises..you will make more hp on more boost but you had better have the octane and fuel delivery to keep it happy or the grinning feeling of higher boost will be replaced by a frown when things fall apart

run too small a gate on pump gas and you may not be able to get the boost under pump gas levels (17-18psi) regardless of the spring you run and the rising boost at higher rpm could get costly


as far as back pressure (which is typically 2 times boost) and the larger the gate vs smaller gate ... if boost is under control the small gate is flowing away just as much as a larger gate so there is no way it can improve or even change backpressure
but on backpressure subject ..if run tuner style (top open) ...more spring will be needed with a larger gate because of the surface area (sq inches) of the larger valve it can be cracked open at lower pressure ..this can be overcome with dual port wastegate control or adding CO2 assist for a low spring used for launch control

personally i run a pw46 4.5psi spring dual port electronic controlled (co2assist at track) plumbed off the turbine housing (atr external pipe) and run back into the DP ..during WOT pass i see 6 psi climb to 8psi in first and second but in third gear it will creep up to 13psi by the stripe .
granted rpm at stripe is less at that boost than turned up only around 5400 (125) ,
with more rpm the lowest psi it can control to will go up


only downside i see on the big gates like the PW66 is cost$$ , fitting that huge gate under the hood and the plumbing since it takes a 2.5" inlet tube which is larger than the header main run pipe
 
its only job and its a simple one is to open enough to divert exhaust gas away from the turbine ,
large or small gate it wont matter to the hP , if it can divert enough your boost will stop where you want it

That's what I thought, but don't know enough about them and I'm trying to figure out what size would be best for my setup with a 6466bb or equivalent.

I'm also looking at the turbo smart eb2 controller and getting a 46mm gate that was recommended by a friend.

He said 46mm would be big enough, but he races turbo fours and doesn't know the 3.8 TR motors so I was looking for what works in the TR community so it's a one time expense.
 
-no gains can be made with any gate
-you can't make more power with a gate but you can control more power with a larger gate if your gate is too small
i respectfully disagree. There is definitely power running the wastegate open (and or a larger wastegate) in certain instances where backpressure is high. It takes a lot less energy to drive the turbine once its spooled and if the compressor and cover are working together the ex energy needed will be less. It has more to do with the pumping losses on the ex stroke as the piston approaches tdc. It's possible that the manifold pressure may even drop a little while the engines mass flow will increase more than most would think. The first time I noticed this was on a low hp (by today's standards) engine I had in my car back around 2000. It ran 120-121mph in the quarter with boost in the mid 20's. I had an old t-netics race gate on the crossover which only had pressure against the top of the gate to keep it closed. The line that went to the top of the gate became compromised and leaked. The gate opened and I noticed it seemed somewhat stronger out the back with it open and boost was still in the 24-25psi range. Running the car this way netted 124+Mph. Another thing was it didn't require a lot more fuel to feed the extra power(reduced pumping) it was making. Others have seen much more power opening the wastegate once the turbo is spooled. It doesn't seem possible since most would think that the reduced energy available would cause boost to drop off. If the backpressure was low to begin with this wouldn't do much to help but when backpressure is climbing over 50psi the results are almost guaranteed. It also opens up some potential with the lobe spread and cam timing.



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