I am going to upgrade to a T78 turbo and eliminate all the problems and unreliability with the twins. My question is what type of external wastegate is the one to use for a rotory engine. I will be running 12-15psi for daily driving and then bump it up to about 18-20psi for drag racing.

 

The Greddy T78 includes the wastegate and everything you.

 

No. I bought a greddy T78 turbo and i am going to be buying a exhaust manifold with external wastegate. Buying a kit is a rip off, you can easily piece your own kit together for alot less money.

 

That's if you buy the kit, then it includes it.
If you buy just the turbo and put the rest of the system together yourself it's a little harder and more hassle, but cheaper in the end and better if you do it right.

For wastegates, the fact that it is a rotary engine has no bearing on which one to use. The wastegate is for re-routing exhaust gas... it doesn't know what type of engine is pushing that gas. Basically get a large unit. The Tial one is pretty popular.

 

I was thinking of the standard HKS wastegate as it is 40mm, the Tial one is very cheap that is why i think everyone is buying.

 

I wouldn't use the HKS standard on a rotary, especially a T-78 setup. I think the HKS standard may be too small when you try and run high boost on the track, you may get boost creep.. I would pay the extra for the HKS racing if I were you. There is nothing wrong with the Tial wastegates either, they are definitely not cheap quality. Cheap price, yes, they are made in the USA so the savings gets passed on to you the consumer since it is not coming from Japan with a markup. But again, it is always better to go too big than too small on a wastegate.

Matt

 

Tial now makes a 60mm gate that is just as good (or even better) than the higher priced units , I personally use two 35mm HP Tial gates 'cause , #1 , I am alowed to run a "truely" separate exhaust system to aid in turbo spool.
#2 , Two small gates are cheaper than one large one ,
#3 , Boost creep will never be an issue for me no matter what turbo I may upgrade to because two35mm units will outflow one 60mm unit and last but not least , two gates just looks cool.

 

That's what I wanted to do also Marcel, but with a 20B, it would be pretty tough fabricating a good twin wastegate setup (since there are 3 runners obviously).
I guess I will have to dish out twice the cash and buy a single large one.

 

I thaught of how I would do a 20B , 'cause if I ever go that way I dont intend to sell my gates , anywas I would simply join the three runners at a point using a collector and exit the sollector with two runners for the gates , "true" separation isn't as important on a three rotor because turbo spool is effortless for those *******.

 

Yeah, that's what I thought too, but I worry that with 2 ports coming off the collector, that there won't be enough room up there to fit the piping and wastegates in.
Do you think that it would possibly weaken the collector and maybe even reduce good straight flow to the turbines?

 

After cutting the runners of my manifold for installation of the 1.5" runners for the gates I had a 45deg elbow welded in first before attaching the rest of it (wastegate and other piese of the runner) , I looked in after the welding and the two pieces were flush with each other, not even flux (argon welding was used) got into the main runners to hamper flow in any way.
The collector I spoke of is not the one that is placed upstream the turbine , that would be another one upstream the gates ,basically I am saying that if i were to build a manifold for a 20b , I would be using two collectors , a three into one for the turbo and a "custom" three into two for the gates .
The three secondary runners will be attached to the main ones by cutting a hole with a plasma cutter and welding on the apppropriate fittings , then continue the piping runs until the collector , after the collector two more pipes would be attached for the gates .
As for space . if two , and three decient sized turbos can fit , two 35mm gates will .

 

Marcel could you post some pics of the twin wastegates.

 

Will do as soon as I can.