Hey Guys, I know its been beaten to death about STAR VS. HRC and I know they both have their good and bads, but as far as the wastegate whether it be internal or external, whats better? I'm just so close to ordering either one in a stage 2 and I'm just unsure?
I know someone made a sheet with the differences, can you refer me or at least give some input to help me out? Thanks!!

Most full blown race cars use an external waste gate. But the internal wastegate is fine. HRC comes with internal and star comes with an external.

external weastegate + open loop. You will gain alot hidden hp.

The truth is, with the Hahn setup, the wastgate never sees over 7psi (or 5psi if you have the 5psi wastgate) so it's not a huge deal. That is unless you strictly a drag car trying to squeeze every 1/100th of a second. IMO it's not the deciding factor between the two kits.

Head external is better because its *GASP* open pipe, you can weld it but if ya got a race car you don't need to, so strictly race car unless you weld it to the downpipe. Hehe external wastegates look cooler :). The HRCs manifold thanx to it having an internal manifold is a better design than the stars though since the turbo sits in the middle.

Either way you stick it either kit is good.

External wastegates mounted on the exhaust manifold take away air from the turbo. The air that could be used to spool the turbo is being diverted before it can even hit the turbine. It also changes the flow characteristics of the manifold itself. At WOT you want as much air flowing as effeciently as possible through the manifold..and with a hole there letting it out, it creates turbulence and can hurt performance.

This is why people try to go with internally gated turbos as long as possible before switching to external. It is also why 4G63 guys with massive turbos mount the external WG on the o2 housing rather than the exhaust manifold. It takes that problem out of the equation.


The factory manifolds for 4G63 turbo engines are all offset. If people are running as fast as they are on those manifolds, and it comes that way from the factory, I think it is safe to say that offset manifolds aren't all that bad. HRC's exhaust manifold is restrictive as hell. It might be centered, but it is still 4 holes merging into one in a tiny little space with no real runners for the expanding gases.

I think both Star and HRC could benefit from a better manifold design.

>External wastegates mounted on the exhaust manifold take
>away air from the turbo. The air that could be used to
>spool the turbo is being diverted before it can even hit the
>turbine. It also changes the flow characteristics of the
>manifold itself. At WOT you want as much air flowing as
>effeciently as possible through the manifold..and with a
>hole there letting it out, it creates turbulence and can
>hurt performance.


What? Nothing could be further from the truth.
That is not correct. An external wastegate isn't directing a thing away from the turbo until it opens in which case that is its purpose to prevent overboost. An internal wastegate is doing the same thing (which is nothing until opened) but when it does open the wastegate gases disturb and cause turbulence to the combustion gases being exhausted through the same turbine housing/downpipe when open. internal wastegates also cause additional backpressure when opened with the additional exhaust that could be routed seperately as with an external wastegate (and an external rerouted back into the downpipe is still less upsetting to exhaust flow than an internal wastegate which dumps into the turbine). At WOT the wastegate isn't directing anything, its closed, non functional, might as well be part of the manifold wall UNTIL the threshold boost pressure is reached at which point thats what its suppose to do, open, how do you think boost is regulated. I think you got the turbolence thing backwards, its the internal wastegate inside the turbine housing and exhaust released from it that causes turbulence. External wastegate causes zero turbulence (if routed outside the primary exhaust system).

>This is why people try to go with internally gated turbos as
>long as possible before switching to external. It is also
>why 4G63 guys with massive turbos mount the external WG on
>the o2 housing rather than the exhaust manifold. It takes
>that problem out of the equation.

No, they dont switch because they dont have to until the size of the internal wastegate becomes too small to effectively divert exhaust gases away from the turbo=boost creep. Very few people mount external wastegates on the o2 housing, hahns o2 eliminator downpipe does. the problem they are fixing is caused by the internal wastegate. If an internal wastegate is big enough to do its job why go through the complexity of welding an extenal wastegate to the manifold and routing additional exhaust=economics is why 4G63 owners keep internal wastegates. For performance an external is better in EVERYWAY.

Like already said its hardly an issue worth choosing a kit over. Internals are more convenient and emmisions friendly while externals are better for absolute performace. The only real issue is if either are big enough to handle your future needs. Both hahn internal (with its large exhaust housing turbines) and star deltagates are proven to 400hp and beyond so really who cares. I'll probably go with an internal this time for convenience and less shit to fabricate.